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A User`s Manual - Berkeley Geochronology Center

1. ri 91 RODREE m cite 91 SINBICSTASEPDT MEE 91 SingleStage PDR Rn 9 SQ WADA sa oss csc cn tbc 9 ATARI 91 UL I 92 TUZSIOA B CAN IMU e a dai 92 y PSIUDPANy DE 92 LIRUJFOMPDS lt lt 92 UZI fare ana ii ia dias 92 UPAD UTITUR 92 LBS LUZ NEUE 92 Output The present day SUP U activity ratio eere tte ttet testen nenne 92 MOVIL E M 92 VOICE M E M 93 Or KMS WD t ond t a onn ad ite inti 93 Moda menm 93 YOTKSlODe t ee E ter equ e D Gu EOD qe a gu e 95 ForkSlopeEYTr0 ete ette a RP FO EE pe er et eU A m RT ees 95 APPENDIX VI USEFUL ISOPLOT TOOLS FOR SQUID ee eeeeeeee eee eene eese en setatis staat tn senses senes tas senec 94 APPENDIX VII DEFINITIONS OF TERMS e eeeeeeee eese eese ento sesso sense tastes sts sess tss ta setas sense enses stas senes taeea 95 204 COFTeCled lt A a eet en e e ref e et ess 95 207 GOKFTecled lt A a e ete en eee ee 95 LOS COME 3 eod tet e e e ye nee teer e eet d e ec 95 Array function or formula iii oett ene e ten p e 95 Common Pb 25 tse a t disc ette acts 95 Concordance i et etes tee eit ete E te iiti A 95 CONCOT AIG S DNO TR OE e O E A 95 Concordid age eoo aide at
2. esee 33 normalizing equation esses 28 EE Switch 24 numeric MASS occccccnnnnnnnnncccccnnnnnnnnnnnoss 17 18 OVerCOUDtS ccooooocccccccnnnnnnnnaninonoconononananinoso 9 64 PASE SIZES ces tue da 2 Parallels Windows emulator for Macintosh Macte DC GEI Ee er eid 2 Parallels program aiii 2 EY PLUG Siz wares Fes A ve Re 18 PD Tile octets ntes etate 23 PD files dere 2 7 14 pIOCGIBSEIS Gum oU Mela ENCEINTE EDS 8 Preferences 5 6 8 34 52 59 60 61 64 95 Printer Setupiice e eed and ane RI MN RUE 2 RAM id 2 Raw data files ei rero nien 7 REFSTENEO peak atra ono 13 Reference peak trim mass 13 FESTESSION oa 30 31 78 rejection manual eorr ette 35 RUE E CS 14 Run Table 4 14 16 18 59 60 70 71 72 Sample ea 6 9 97 SampleData sheet 9 20 22 26 29 34 97 SM uude die DEN 6 60 SBM secondary beam monitor 6 34 59 97 SG Mitosis 22 23 24 26 27 76 Scan Order iocis tte cass averse ieee 18 TA eS 17 Secular drift correction for 10 smoothing window for secular drift COMO COT oi dete eo Ree 11 SON seen ette eei esses 33 sorting by sample age s 63 Spot NAMES roD deo etta deas 9 spot scan graphics esssse 34 35 SQUID toolbar ooccccccnnnnnononancnonccinanannnnnnnos 4 SOUM d i ss eat aida 8 9 ST BWIUCI E uiis aS ae atm 24 76 Stacey Kramefs aic oet tama ees 64 Standar
3. If the Make trim mass graphics box is checked when starting data reduction SQUID will con truct scan by scan charts of the trim masses for each of the centered mass stations for Standard spots only Click OK Data reduction will typically take a few tens of seconds and yield an Excel workbook containing not only the usual StandardData and SampleData sheets but also the original PD data con densed and reformatted for ease of examination Fig 8 p 7 An optional Within Spot Ratios sheet Fig 7 containing the calculated scan by scan isotope ratios for each spot burn can also be requested from Preferences p 52 178m0 1 1 Time 204 206 err Time 207 206 err Time 208 206 err Time 206 238 err Time 208 248 err 5 10 16 16 33 112 5 1 8E 06 1 8E 06 139 75 0 29983 0 00159 147 5 0 26374 0 00243 154 25 1 45176 0 00959 176 0 06533 0 00059 Spot 4 242 1 5bE 05 166 05 5 0 0016 276 75 0 26424 0 00245 83 0 00931 305 25 0 06609 0 0006 371 5 23E 05 1 5E 05 0 00161 406 25 026904 0 00249 413 1 37414 0 00903 43475 006565 0 0006 501 2E 05 1 9E 05 0 00161 536 0 26401 0 00246 54275 1 36088 0 00891 5645 0 06456 0 00059 630 5 23E 05 1 5E 05 5 0 00161 665 5 0 26276 0 00245 67225 1 35988 0 00888 694 0 06425 0 00059 gt gt i Within Spot Ratios SampleData StandardData GA_GA5003_06101615 11 w ds IERI Figure 7 Fragment of an optional within spot isotope ratios sheet Condensed raw data sheets produced by
4. Then define _ 6 pp OW pp E 206 pp E 207 pp gm S 23577 206 Pb 207 Pb 207 pp 207 pp 2381 y E Te p Pero 2 pp 207 pp r 1 f r pr a 7 S 1 4 Jour fh ur Bsq m Ax 1 1 r m Ass 1 F s As 1417 Azs ll 9 p f Jur Ans gn Ass 1 s A where T indicates total 0 indicates common and f age and find the partial differentials ar alala ae e la ap PIE from which follows ia E mt 0 4 f us O m O m rm m m and 2 3 p Ar 0 uir m o t 0 moo ignoring any uncertainty in po and any COV 47 Equations for Isotope Geochronology Simple Daughter Parent ages r e TU ERE EE S p o r Oo o re pg At 1 r pog 207 Dh Ph age error as a function of 27 Pb pp ratio and of errors in decay constants e 1o ute jo ritjo 2 E dial Asst Y ui Sw Af ml where r pp Pp u U y ds 2 Y error in conventional concordia curve at a specified X Oy o2 i 01 re ad 235 2 2 M Dass 235 X error in conventional concordia curve at a specified Y o Ois 2 po te 38 X and Y error in conventional concordia curve at a specified t Oy t to dong Es 238l Oy te O ios Y error in Tera Wasserburg concordia curve at a specified X 2 o uxt o uj 2 2 Ass 48 Equations for errors of common Pb isotope ratios in zircon sphene a common 206pp b common 207 pp w
5. ee 85 APPENDIX V SOME USEFUL EXCEL AND ISOPLOT FUNCTIONS eeeeeeee eese essen testes tests etas tn status 86 NATIVE EXCEL FUNCTIONS M X s 86 AVERAGE tido 86 nip por oia 86 SEDEN rara EE 86 LINES Toe ER 86 INTERCEPT REN 86 SLOR P wesc E RE R E E R E E E E E A E Suucaaeets 86 MAX MIN m n T E A E E R A E A R EE 87 ISOPLOT AND SQUID FUNCTIONS esses enar n eia a Eae sentes eO aS AE aO EESO AEE T ER EEEa EE Taa nenne 88 SgBi Weis hit A A E E E R E EE E 68 BAT E aii inca 68 CON COVA o E MB LEE MU M 68 CON COVAIOT Weste sto Eton Red MEI M MU M 88 DISEJOSA Leica ados 89 DISEG SABC iis EET 89 Dis Eg TIRANO lt a 89 DisEg 6Rdtlo Ni 89 DISEQPDPDA BE iaa 89 DM T E ES E E hacia Gna eee ae eee 89 ExternalStBmas 55 steht E E etie A A eter A eie 89 Halle ais 90 INtUZILUZIS a eos 90 Ea230 La232 La234 Lda233 T0238 sitientes atate is 90 Pop E X M 90 LOL O me M 90 Mad ai ee e bn edite stint e ied perse ME Dae e Le E E Ee trece 90 MS WD HE 90 nU mno mE iaa 90 nU T A P 90 POD EC
6. Next 230Th U aged Return Metal and oxides Task name Enter a name for the Task that distinguishes it from other Tasks Task description Enter a brief description of the Task Primary mineral The mineral that to which the Task will most commonly be assigned Task Editor Task Editor Edit Constants Refresh Task Catalog Isotope Ratio Existing Tasks from Task Catalog EE sid AC xenotime PDUO2 MH a AC xenotime AC9 Monazite floating slope ThO test Titanite floating slope Z5 9pk GA 207 206 normalised via Ot Zircon canonical anu UO2 Zircon canonical anu with floating slope Zircon canonical anu Description Mineral Creator 68 z Save all changes Discard all changes EET Save changes to selec ted Task don t Exit Help for this panel Edit view a Task panel y Run Table y y Special U Pb Eqns y General Eqns y Auto Charts version 2 21 08 03 16 K R Ludwig BGC 16 Mar 2008 U Pb Geochronology Edit view the U Pb geochronology Tasks Isotope Ratio Edit view the General isotope ratio Tasks 69 Existing Tasks NEW Define a completely new Task RENAME OR COPY Rename or copy the selected Task DELETE Remove the selected Task cannot be undone SINGLE CLICK A TASK NAME Selects the Task for editing by any of the colored buttons to the right DOUBLE CLICK A TASK NAME Selects the Task and opens
7. Note that the rejection algorithm is not at all rigorous Its intent is merely to offer the user an example of possible true outliers and that the user should only accept the results of the above re jection algorithm if he or she would select the same rejections independently preferably on the basis of objective criteria such as 204pp206pp U or Th concentration et cetera 86 Appendix V Some Useful Excel and soplot Functions Native Excel Functions AVERAGE Argument Values range Output The simple average of the numbers MEDIAN Argument Values range Output The median of the numbers STDEV Argument Values range Output The standard deviation of the population Divide by Jn for the standard error of the mean LINEST Arguments Y range X range include stats The x and y ranges are usually 2 columns of numbers add the optional IncludeStats if slope and intercept errors are desired in the output Output Parameters for a simple y on x linear regression Typically from a 1x 1 up to 3x2 row column output range containing Slope Intercept slope tinter Rho where the errors are 1 standard error and rho is the x y correlation coefficient INTERCEPT Arguments Y range X range Output The intercept of a simple y on x linear regression SLOPE Arguments Y range X range Output The slope of a simple y on x linear regression MAX MIN Arguments Values range Output
8. Help for this panel Edit view a Task panel Existing Tasks from Task Catalog Mew Copy Common Pb no 204 Common Pb with 204 Common Pb with 204 amp bkrd temp Common Pb no 204 Xenotime matrix corr factors no 207 Xenotime matrix corr factors no 207 3000000000000000 Delete Run Table General Eqns Auto Charts Description Metal and oxides Td krl version 2 30 08 11 28 Mineral Creator K R Ludwig BGC 28 Nov 2008 Figure 15 First panel of the Task Editor 16 The Task Name Panel Each Task is assigned a unique name Figure 16 preferably a reasonably pithy one that fits within the Task list box of the Task Editor The Task Description should contain additional in formation about the purpose of the Task and type of data required The Primary Mineral and Creator name of initials fields are self explanatory Edit Task name description Task name Next Retain panel changes 5 go to Run Table CanonicalZirconPlus270 Retain panel changes Task description return to Task Editor UC2 peak included to test for odd spatial ef fects as well as alternate U Pb calculation Primary mineral zircon and baddelyite x Discard panel changes return to Task Editor Creator name or initials Alistair Schnuckf III Figure 16 The Task name description mineral and creator panel The Run Table Panel Defining the Run Table From the
9. The true Pb Pb is calculated by assuming that the true radiogenic Pb isotope ratios yield concordant 7 Pb 8U Pp4Th ages determining the 7 Pb Pb that produces this result then subtracting common Pb using 204 as the index isotope and the isotope ratios assigned in Preferences Array function or formula See p 25 Common Pb For the purposes of SQUID the Pb present at the time the mineral to be dated formed Also comprises environmental Pb has contaminated the grain Concordance The state of having equivalent Pb U 7 Pb U 9 pp 6pb apparent ages Concordia The locus of concordant ages on the Db ad U 207pp aa U or SU S Ph 2 7pp206pp dia gram Concordia age The most probable age of a system having a arguably concordant U Pb ages Constants Constants defined and named by the SQUID user and available for use in Task equations Discordance The absence of equivalent Pou 9 Pb U pp 6pb apparent ages for a U Pb system 96 Dropdown An Excel or SQUID menu of items from which the user can choose Error correlation A statistical measure of how much two parameters covary An error correlation of 1 implies a precisely proportional straight line relationship between two parameters zero implies complete independence of one parameter with the other 1 implies a precisely proportional negative varia tion of one parameter with respect to another gt x xk
10. cccccncnnnncccccncccnnnnnono 23 24 27 Auto Charts oocccccnnnnnninncccnccnnnnnnnn 30 77 78 background box eese 18 Calibration constant U Pb correcting for OTE OLS ai EG EE 10 Celeron eec ete 2 Charge desc a te Rare oer EN 12 charge nuclide specifying 18 chart insets ooocccccnnnnnnnnninoccncnnnnnnnnnnnoso 14 53 coherent age group eseeeeees 9 63 column swapping in U Pb Tasks 28 common Pb sse 63 Common Pb see 95 concordance cooococcccnnnnnnnnnicococcnnnonono 59 63 64 Concordance ed n nie 95 Concordia unicidad 8 88 counts second columns specifiying 18 CPS column iren 18 CPS columns hide eeee 71 CPS column eene 18 CCTOSSOVOE sno RUDI DIES 2 decay constants ci ii ii 21 Drift of U Pb calibration constant correcting O vase T 10 Equation patiels oe cte 21 25 Equation switches 23 75 TT Equation switches oooooccccnocccnoocccnonnnononoss 23 Equations Tasas 20 Excel 2 6 14 22 24 25 29 30 34 36 37 86 96 97 99 external error eerte 8 11 FO switch oii Am te 22 24 25 26 Fusion Windows emulator for Macintosh 2 FUSION program isi eere trier en 2 General Isotope data 13 20 A he tbc I de eR Gnas 9 63 AO ai 9 grouping spots by sample name 62 63 100 Hi
11. y NG 3Y Y The formula for the error correlation is When referring to errors the error correlation reflects the likelihood that the error in one parame ter s measurement is in the same direction too high or too low as that of the other parameter External error A component of measurement error that is constant from sample to sample but not comprised by the assigned analytical error Grouping to be added Internal error The analytical error assigned to a measurement Ionic species A particular molecular combination of elements and isotopes with a particular charge Isoplot to be added m e Mass charge of an ionic species often loosely substituted by mass MSWD Mean Square of Weighted Deviates see p 37 97 Normalizing equation An equation that yields a constant value when a parameter of interest Pb U U is constant so that the ratio of normalizing equations for an unknown sample to a standard equals the ratio of the unknown s parameter value to the standard parameter value Panel A Excel dialog box that allows the user to make one or more choices PD file Probability of fit The probability that the observed weighted mean or weighted regression MSWD will be ex ceeded if the assigned data point errors are entirely responsible for the observed scatter See p 37 Radiogenic Pb Pb produced in situ by the decay of U and Th in a mineral or rock Range A suite of
12. 3 d f 43 A 2x X u A T End If sa Y A 4 SB 1 w 0 5 sc Yu 1 47 o nx SA SB X TxSC SB Loop until oj 0 and Xj X j Within spot numerically evaluated Task equations Same as for isotope ratios but instead the equation itself is calculated N times N scans 1 at the mean time of all of the mass stations involved in the equation Errors of each scan s equation are calculated numerically by perturbing all of the peaks involved in the equation Overcounts on Pb Apparent overcounts on 2 pb are calculated in two ways 1 assuming that the true pp 1 and Pb U ages are concordant and 2 assuming that the true pH P355 and Pb 4Th ages are concordant The 22pp 2 Ppb ratio required to achieve concordance is calculated and thus the number of non Pb counts that must be present to explain the apparent discordance Outlier Resistant Linear Regression This outlier resistant linear regression algorithm is used by SQUID 2 for Task Autocharts and when invoked by the user in a Task equation The regression line slope intercept is the median of all pairwise slopes intercepts with errors based on code in Rock amp Duffy 1986 derived from Vugrinovich 1981 Concordia Ages See Ludwig 1998 for a detailed explanation of the definition and algorithm for the Concordia Age 44 Converting Tera Wasserburg to Conventional Concordia Slope Intercept With x SUZ Pba and yos CPP PD rai m
13. o level of errors Output The Concordia Age Ludwig 1998 for the specified U Pb ratios and errors ConcordiaTW Arguments Uf Ph UPYPD err Pb Pb 07ppj 06pr error 23 206pp 207pp 06pp Output err corr The Concordia Age Ludwig 1998 for the specified U Pb ratios and errors 89 DisEq68Age Arguments 7 Pb 3U initial U U activity ratio initial THU activity ratio Output The corresponding i 16 a age DisEq68Ratio Arguments Age ma initial UU activity ratio initial Thu activity ratio Output The corresponding Pb U ratio DisEq75Age Arguments 7 Pb U initial Pa U activity ratio Output The corresponding 2 pp 25U age DisEq75Ratio Arguments Age ma 207pp 235 initial Pa U activity ratio Output The corresponding pp ratio DisEq76Ratio Arguments Age ma initial U U activity ratio initial Th U activity ratio initial pay activity ratio Output The corresponding 22pp 2 pb ratio DisEqPbPbAge Arguments PbPPb ratio initial U U activity ratio initial 9 Th U activity ratio initial Pa U activity ratio Output The corresponding 2 pp 25U age Drnd Arguments Number The number to be rounded SigFigs The number of significant figures to return Output The number rounded to the specified number of significant figures ExternalSigma Arguments ValuesAndErrors 2 column range PercentErrs False SigmaLevel 1 Outpu
14. Cleveland 1979 which fits an outlier resistant smoothing spline for a moving spot window The degree of smoothing is con trolled by the size of the spot window the larger the window the greater the smoothing Large windows are best for say a pseudolinear drift smaller windows for drifts with abrupt changes or cyclic appearance SQUID 2 offers two choices for determining the width of the smoothing window fixed you specify the window and automatic SQUID 2 determines the best window If you select Fixed the initial smoothing window will be the one you specify here You can al ways change the smoothing window however after the data have been reduced 57 If you select Automatic SQUID 2 will find the largest smoothing window whose resulting ex ternal error is not less than the specified Minimum acceptable external error This Secular Drift Correction algorithm is experimental should be used with care and trusted only after considerable comparison with conventional SQUID 2 data reduction Preferences U Pb Standards panel You can specify up to 50 common U Pb age and or concentration standards from this panel When the U Pb data reduction panel is being filled out SQUID will look for spot names whose first few characters match those of an age standard If a match is found that standard s name Pb U age if defined Pb Pb age if defined and U or Th concentration if defined will entered into the appropriate boxes prefer
15. Coef2 Coef3 Coef3 Coef4 If the cell whose value is to be minimized is part of an Array equation you can use the row col umn values to specify which parts of the Array function output to use Thus if a Task equation named biwtthpbage is defined as sqBiWeight WeightedResids with the FO AR switches set and with ARrc 3 2 i e 3 rows 2 columns the output cells created by SQUID 2 might look like xeno1 mean 8 2 age 994 25 Biweight Mean 21 77 Biweight Sigma 14 19 95 conf error If the cell BiWeight Sigma contains the parameter to be minimized the Task equation would look like biwtthpbage 2 1 Coef1 Coef2 Coef3 Coef3 Coef4 indicating the value in the second row first column of the Array equation s output Solver will be invoked after all of the data columns in the output worksheet have been calculated and filled with values 34 Isotope Ratio Chart Insets After PD file data reduction is complete and if the Construct within scan box in the Prefer ences panel p 52 is checked SQUID will construct a Within scan isotope ratios eqns sheet figures 7 29 as part of the data reduction process so that chart insets of any of the isotope ra tios or Equation results can be constructed on demand To invoke one or more within scan isotope ratio or within scan equation chart select the cell s whose row s and column s correspond to the spot s and isotope ratio equation s of interest then click the 4 button in th
16. EN B mm gm mm E AAN AECE CCCECE E N EE al 3 0 Nuclides E p HS c ala cl D Am 2 a Insert Clear one Clear all TUT Figure 17 The Run Table panel 1 Set the active lonic Species or numeric mass box the one in the right half of the panel to Scan Order 1 using either the mouse or the a control The active lonic Species box is tan rather than pink as for the lonic species box for scan order 10 in the example panel figure 17 We now wish to enter Zr 0 for the first mass position in the run table 2 Click on the zirconium Zr box in the periodic table The resulting isotope selection dropdown figure 18 will show all of the stable and long lived isotopes of the element with the most abundant selected by default relative abun dances are shown to the left of the isotopes In this case the default of 07r is fine to select any other Zr isotope click on one of the black isotope boxes 3 Select the number of atoms of this isotope in the ion ISOTOPES ic species using the How Many spin box then click sbundancs 222 Complete Hops gn gcse OK Zr will appear in the active lonic Species re Bl Then select another box in the right half of the panel 23 20 MEN ver doe MM nu coon 4 We know that the final nuclide will have a charge of 17 4 om 1 so we can leave the Charge box as
17. Non alphanumeric characters are ignored Leave the Age field blank if the standard will be used only for uranium or thorium concentration and vice versa Click an Index to insert a Standard Shift Click to delete Figure 4 The U Pb Standards page of the Preferences panel Specifying the common Pb index isotope U Pb geochron panel Select pb 207 pp or 2WPb from the Index isotope dropdown common Pb isotope ratios are specified in the Preferences panel p 52 The use of common Pb index isotopes is discussed in pages 46 63 44 and 95 Index isotope for 204Pb y common Pb Pb U Figure 5 Selecting the index isotope for od 204Pb eni correction of common Pb 207Pb 208Pb Parameters SBM Normalization Indicate whether or not the secondary ion beam pp 34 59 61 96 97 is to be normalized to the SBM secondary beam monitor Trim Mass Charts gt a ies 195 9782 era non Jr 238 2610 o o Y 238 2410 o o 172 c c oO 195 9582 4 06 0886 2382210 4 238 2010 4 195 9382 206 0486 t 238 1810 0 20 40 0 20 40 0 20 40 196 Time hrs 206 Time hrs 238 Time hrs 248 2791 y 254 2798 Laa rta yita ote Figure 6 Trim mass charts 248 2591 254 2598 4 Q 2482391 Q 2542398 4 o o co is 248 2191 254 2198 248 1991 254 1998 248 1791 y y 254 1798 4 0 20 40 0 20 40 248 Time hrs 254 Time hrs
18. Return Save any changes to the Run Table panel then return to the main Task Editor panel Cancel Discard any changes to the Run Table panel then return to the main Task Editor panel Insert Insert a row of blank boxes nuclide true mass nominal mass before the Active Nuclide Delete Delete the Active Nuclide and associated true and nominal mass boxes Clear one Clear the Active Nuclide and associated true and nominal mass boxes Clear all Clear all of the nuclide true mass and nominal mass boxes 12 The Isotope Selection Sub Panel ISOTOPES Then select another How many Enter element to add to the active nuclide How many atoms of the selected isotope blue are in Add then proceed 3 abundance Complete next nuclide the Active Nuclide Note that 1 all stable and long EE lived isotopes of the selected element are shown 2 the 25 15 206rb default isotope will be the most abundant isotope and 3 the relative isotopic abundances summed to 100 of s NEN Tr E En z the natural element are shown at the left of the inset Cancel How many Charge 206Pb Charge Specify the charge of the active nuclide Enter Enter this isotope in the active nuclide box then add another element or isotope Complete Add this isotope to the active nuclide then move down to the next mass station 73 Isotope Ratios Step 2 specify isotope ratios x Click on a blue ratio box to ac
19. based in the initial characters of the spot names Change Time window Define a time window within which spot analyses are selected for data reduction Other spots are ignored Reduce General Isotope Data Reduce General Isotope data Normalize to Std New PD Load another PD file then return to this panel 61 Task Select the Task for data reduction from the dropdown list of all defined Tasks Normalize to SBM signal Ion beams normalized to the SBM secondary beam monitor may be unaffected by any instabil ity in the secondary ion beam If there are doubts as to the functioning of the SBM i e the SBM is not constant over the mass range of the Run Table leave unchecked Make trim mass charts Construct trim mass charts for each peak centered mass station Spot subsets for user parameters Shows spots having Task equations that are specifically applied Process spots within Time Window The time window within which spot analyses are selected for data reduction Other spots are ig nored Change Subsets Specify Task equation that are to be applied only to a selected group of spots based in the initial characters of the spot names Task Editor Invokes the Task Editor panels returning to this Setup panel when done Preferences Invokes the Preferences panel returning to this Setup panel when done Change Time window Define a time window for spot data reduction 62 Sample Grou
20. u b and b 2 m b where m b u are as before and m b are the Tera Wasserburg slope and intercept the transformed errors are given by z Q2 2 Q2 2v S S 8 282 S 25 SD ry m Sw Pm p So b where On cov m b Sn m Pmb Toa 207PpF pPb age error including errors in decay constants The simple first derivative expansion expression for 27 pp 6pp age errors is oo Ifo utor rto uA eo ES J 238 O t where r 207 pb Pb and u 235 U 2380 45 208 Corrected Ages and Ratios Constrain the Pb SU age to equal the 28pp Th age so that l taf pt cr l taf geass r Aass Ar zas By Then define iem qe f i F D Pb 23817 239 7 206 Pb 2 Pb ph 207 pp 2387 E 206 pp Pel rere 2 l s 1 f pur ji m Azs 1 1 f r m A 1 1 F s As 1 4 4f ur f ur dde f de As 1 r 244 6 7 Asl s DTP Ey 23517 E EA ES E E OM o F urQ aan xu abo where T indicates total 0 indicates common and f age Find the partial differentials dr r dj A dt _ Pdr r af 2 r f ar p dr r df 1 So that 2 P3 i je T en a o mo m and 2 po tro 2pr cow r f t 2 m p 2rj j po ro m ignoring any covariance among the measured or common Pb isotope ratios 46 207 Corrected Ages and Ratios Constrain the Pb y age to equal the 207php E age so that l taf pen mr l zt ase r Aass Ar Aas By
21. 0 ute jo iesto 2 Ot t ogg ui e r Af E where PO Pb judi acl 2 E 2 Arse 2 gY Y error in conventional concordia curve at a specified X 0 Oona A O5 s t d 235 2 2 X error in conventional concordia curve at a specified Y Ox oit Ga OF sas te di 38 X and Y error in conventional concordia curve at a specified t Oy t to aua f 238l o te C oo Y error in Tera Wasserburg concordia curve at a specified X 2 o uxt o s 2 Asa X error in Tera Wasserburg concordia curve at a specified Y A ae jos XV joi pardo 51 7 Equations for Isotope Geochronology Simple Daughter Parent ages r e 1 o BUT dp o r o o re p Ara r pom 27Pb pp age error as a function of Pb Pb ratio and of errors in decay constants cafe utes ot e 07 2 s A gast A ty 235 238 usse TA 3ge 2 2 where dl Pb 206pp c U y cf 2 Y error in conventional concordia curve at a specified X aed eee M3 2 ragt Y Oy Me 238 azs 235 2 X error in conventional concordia curve at a specified Y PE MS Joss 5 t Aout y ex rens ji As NC 238 a4 Ast X and Y error in conventional concordia curve at a specified t Oy te m6 235 ta238t Gy te so a Y error in Tera Wasserburg concordia curve at a specified X ariance among the measured or common Pb isotope ratios 52 Appendix Ill The SQUID 2 Panels and Cont
22. 03 246 06 248 251 254 lx PD file click to change __JNA_A225_050502095 45 pd Cd dd FD file Task Task Editor peaks 196 290 HEU ages gt Preferences 203 97 Help 204 02 v Normalize to SBM signal 206 Make trim mass charts 207 208 _ Normalize to Std 238 248 l Spot subsets for Task Equations 254 Change SecEquiStd SecEquiStd o Process spots within Time Window No time window process all Change Time Window version 2 22 08 04 06 K R Ludwig BGC 6 Apr 2008 Figure 14 Setup panel for General Isotope Ratio data reduction The Reduce General Isotope data panel for General Isotope data Fig 14 is similar to though much simpler than that of U Pb geochronology 14 Tasks Introduction Tasks are the templates used by SQUID 2 to process the raw PD files Each Task contains the algorithms by which the data is processed into final isotope ratios ages element concentrations and any other parameter of interest to the user The gateway into defining viewing and editing Tasks is the Task Editor panel Fig 13 press F onthe SQUID 2 toolbar There are two classes of Tasks U Pb Geochronology and Iso tope Ratio The former is specifically constructed for processing analyses on minerals such as zircon into a complete set of relevant total and radiogenic isotope ratios together with their asso ciated ages The latter is for any other type of analysis Each SQUID 2 Task is
23. 204p b blank t total i initial a common Pb Pb f common Pb Pb Qt W QW Aw lw w a ii us Mp tp jw ses ra A W W W W w a QW w a aw da da dw dw 1 da dw dw w w w w W W t 2 2 2 2 j o JL a e QG o 12 o t t 2 2 7 2 2 a 0 W W W 422 o7 4 o gt 4 e 1 o W w W d W w t Qu cov a B 3 cov a B 49 Equations for Isotope Geochronology Simple Daughter Parent ages r e 1 EE o r C o ret i A l r r Z2 207 Ph Ph age error as a function of 27 Pb pp ratio and of errors in decay constants hank 2 2 hast Y 2 Asst K lt 2 poz eno t 2 Angst hast usse Th 39 207 2 2 2 where r 97 pp 06pp ipe U 2 Y error in conventional concordia curve at a specified X Gies y Joss 6 teo j Y A238 X Jas 235 2 X error in conventional concordia curve at a specified Y a PS N s 62 te 2ss y Xx Js x A238 238 i ais Angst X and Y error in conventional concordia curve at a specified t Oy te 5 O p X 1935 toA23et Oy te Oo Ens Y error in Tera Wasserburg concordia curve at a specified X 2 c Asst P 02 Mas 2 o uXte 25 Oi Gs 9 238 50 Miscellaneous Equations for Isotope Geochronology 27Pb pp age error as a function of Pb Pb ratio and of errors in decay constants e 1
24. 238U sss 63 Age Standard 5 8 9 31 AR SWC oi catu teo c dus 25 27 76 m 3 110 EMEN IRR UN RT NEIN 25 ARrc switch enian 23 24 27 Auto Charts occcccnnnnnnnncccnncncnnnonono 30 77 78 background box eese 18 Calibration constant U Pb correcting for GEHE OL a entre ne o PR eni an 10 COM A eiue te 2 Chat RE 72 charge nuclide specifying 18 chart insets eere ettet 14 53 coherent age group sans use eee eren 9 63 column swapping in U Pb Tasks 28 COMMON PD idad 63 Common Pb uio tota ts 95 concordance coooccccccnnnnnnnnnnnococcnnnonono 59 63 64 Concordance iio ei Re Deest ena 95 Coneotdl es ret eese e Ete tee nsi 8 88 counts second columns specifiying 18 CES CONAN cI pac ode E OT 18 CPS columns hide eeee 71 CPS Coli 18 CTOSSOVEE aries oL PUER ISP rane 2 decay CONS CANES cssc dd 21 Drift of U Pb calibration constant correcting TOI oor VIS acu at ND S d ire 10 Equation panels 2 25 Equation switches 23 75 TT Equation switches esses 23 Equations Task dais 20 Excel 2 6 14 22 24 25 29 30 34 36 37 86 96 97 99 external erTOT ooccccnnnnnnnincccncncnnnononininoso 8 11 FO SWIC iio cit 22 24 25 26 Fusion Windows emulator for Macintosh 2 Fusion program ecards d
25. Red t dei tse Iv que sb bes de idas 98 Standard sheet is i e Re ddnde datus Asad et natn 98 Trim m ss reference iui aie d a o tei getestet bei e HER e Re tet vede tede 98 REFERENCES ese pop 99 Ilis C ECL 100 Introduction Purpose of SQUID 2 SQUID 2 5 processes PD and XML files produced by a SHRIMP Sensitive High Resolution Ion Microprobe into a variety of parameters including raw isotope ratios radiogenic Pb isotope ra tios ages for the U Th Pb system The processed data can be applied to a broad range of run ta bles and applications ranging from U Th Pb geochronology THU geochronology light sta ble isotope geochemistry and cosmochemistry Processed data is placed in an Excel workbook that for most output parameters makes the formulae used in each data processing step explicitly available to the user Requirements Software SQUID 2 was developed using Excel 2003 service pack 3 and Windows XP service pack 2 Earlier versions of Excel and other versions of Windows are probably compatible but have not been tested SQUID 2 requires the soplot add in ver 3 7 or later Only English versions of Windows and Excel are compatible with SQUID 2 and Isoplot ISOPLOT is BGC s Visual Basic Add in for Microsoft s Excel for data analysis and graphi cal presentation of geochronology earth science and other radiogenic isotope data only BGC s ISOPLOT is not the Isoplot for analysis of any measuring system as described at h
26. SQUID When accessing a SHRIMP raw data file SQUID first parses the PD or XML file then converts it into a formatted space efficient and user friendly format XML files Can take as much as a minute to load and parse Can only yield a Short condensed raw data sheet see below If the XML file contains more than about 65 000 lines Contain extra information such as primary beam current stage position and Qt1y Qt1z settings all of which can be plotted versus time as Autocharts p 30 Can easily accommodate future additions to existing data parameters PD files e Load and parse rapidly e Can always produce Long see below condensed raw data sheets if desired From the Preferences panel p 52 you can specify whether or not the condensed sheet should retain the unformatted raw data in the first column of the condensed sheet hidden by default thus automatically archiving the original PD or XML file Such auto archiving slows down data processing slightly so if these files are normally archived elsewhere is not recommended Auto archived condensed sheets are identified as PD file Long rather than PD file Short for a PD file in the top row of the condensed sheet Fig 8 O A A AAA AAA AAA AAA p SEITE AA AE 1 STERN GA5005 07062511 58 pd 25 06 2007 11 58 AM PD file short _3_Janalyst STERN mount GA5005 4 117 Spots 7 1 1 2007 06 25 12 16 10 peaks 6 sc
27. The maximum or minimum value of the range 87 88 Isoplot and SQUID Functions sqBiWeight Arguments Rangeln Tuning Mean only False All comers False Rangeln contains the input values in a single column Tuning optional must be 6 or 9 controls the degree of outlier resistance 6 being more outlier resistant than 9 Mean only optional If False default returns the mean and standard error in two 1 x 2 row column cells If True returns the mean only in one cell All comers optional If False default accepts only non blank cells with numeric contents without the strikethrough font attribute if True accepts all non blank numeric cells in the input range Output The Tukey s biweight Hoaglin et al 1973 outlier resistant mean More efficient than the median for distributions that are fundamentally Gaussian For SHRIMP data BiWt is almost always preferable to the simple average ChiSquare Arguments MSWD Degrees of freedom MSWD is the mean square of weighted deviates of a weighted mean or regression see p 37 Degrees of freedom the degrees of freedom for the calculation 2 N 1 for a weighted average N 2 for a linear regression Output The probability of fit probability that the specified MSWD or greater will occur for the specified degrees of freedom Concordia Arguments ppp PoPPU err Pou 206pp 2380 err 1 Po U SPb U err corr with decay const errs False errors False
28. To the extent that this is the case it is quite possible that attempting to correct for such drift will degrade rather than improve the accuracy and precision of the resulting U Pb ages Of particular concern is the possibility that though the apparent external scatter of the Standard spots mad be reduced drift corrected Sample spots of the same true age will have increased scat ter thus making it impossible to find a coherent statistical group without excessive rejection as well as displaying an more or less inverse secular drift from the Standard Note also that the algorithm used to infer external scatter from the secular drift curve may yield under or over estimated values as it has not seen extensive testing with real data 13 Reducing General Isotope Data For SQUID 2 all analyses that will not be used for U Pb geochronology are considered General Isotope analyses For General Isotope analyses no separate StandardData worksheet is pro duced though normalization to a standard is straightforward and the only data columns that are automatically produced are those for burn time cps of the Trim Mass Reference peak and the isotope ratios specified for the Task Basic processing such as correction for mass fractionation correction for isobaric interferences secular changes in ratios and normalization to a standard are readily handled by Task equations Reduce General Isotope data 230Th U ages peaks 224 234 238 246
29. U PB WITH DIRECT PB TH other panels as Canonical Zircon U Pb Equations specifically for U Th Pb geochronology Equation for 2321 Isotope Ratios and Special U Pb Equations 81 ZIRCON WITH FLOATING SLOPE other panels as Canonical Zircon U Pb Equation for 208Pb 2321h const Step 4 Define user parameters 82 Th ages insignificant Th 83 Simple Monazite cps ref Ionic species True Nominal U Th Pb equations col pk bkrd e g 90Zr2 160 mass mass F m SU ST m e m e Equation for 206Pb 238U normalization ifV 140Ce 31P 1602 202 869 203 206 238 J 254 238 expopbu adagi 204Pb 203 973 204 3m Pl 204 1 4 2041 Equation for 208Pb 232Th normalization 208 232 248 232 expopbth Sa 206Pb 205 974 206 aa 207Pb uineam 207 Equation for 2327h 238U ora jam E i ie 232Th 232 038 232 ETT 238U Equation for uranium concentration EM 258 209 J254 238 0 66 248 033 WEM ile lisa Ez cannot refer to equations defined in next panel wy Tf 238U 160 254 046 254 A 2092006 e _20720 cams 03857 E 2062358 F 254238 mero ETE 1 248232 3 208232 Switches Equations Ln 254 238 Equation names Ln 248 232 fixed robreg LnUO T LnPb U 2 fixed robreg LnThO Th LnPb Th 2 ETA 1 Je PbTh 84 85 Appendix IV Weighted Average
30. U Pb calibration CONSTI oos os eot ARTT A RETE A E SER See EMS 56 CORRECT FOR SECULAR DRIFT oracle EO PRECOR HP Ui 56 U Pb Siandards uu e IA E IE A RETE eA RUA AD TORRE ES 57 y M r EE 58 New PD file cesses taie RE T GERE FE AT GEI n SU HP GER pu C UH 58 Number of characters to show in Standard names esee nne eene nennen 58 PD U OF Pb Th AGE i i i e m T NE A e ERE ee debt eg 59 Index Isotope for common Pb s tc dier e tite E ELT te eee eed Eee eae 59 Normalize ion beams to SBM signal essent enne RE EE KRE RE ETE 59 Spot subsets for user parameters eese eene nne teens e eene eterne renes ener treten TEI ER 59 Time WINdOW NI EE 59 Trim mass Charis oun eee E esce peter BERLE RE RE ERE 60 Task Editor toto tent auttm e te ones 60 Preje reh eS MH 60 TAE ounan i i qe t E ED E du ei eres 60 Cha nge Iime WIhdOWs eti ire qe ae HE E teen RE RR C aea 60 REDUCE GENERAL ISOTOPE DATA 1 5 t http uttter oni potins oni i E Har argen teta e on E TERRE E EUR eT 60 PATE 60 jp M 61 Normalize to SBM sign l e n re e C I a e PP HEP Ce RUMORES 61 Make trimmass CHATS ei e gu Pu e HR OE AT pe i er e e RI Cle dore ieu 61 Spot subsets for user parameters eese eese eene enne enne nne RR RR ORO RARO RR RR teret rennen enne nnn
31. and slightly increase the possibility of out of memory problems under some conditions do this only if you do not intent to archive the original PD or XML files Even if the box checked however SQUID 2 will be unable to retain the original lines of some large XML files simply because the number of lines of these files exceeds the 65 336 row limit of Excel 2003 53 Place data reduction parameters in a separate worksheet Put data reduction parameters specified in the PD file and Preferences on a separate worksheet attached to the reduced data workbook Place auto charts in a separate worksheet Put auto charts in a separate worksheet rather than in the reduced data worksheet Attach Task sheet to reduced data workbook Attach a copy of the Task sheet to the reduced data workbook Freeze header rows and spot name column Forces the first column spot names and the column header row to always be visible when the output worksheets are scrolled 207 corrected 208Pb 232Th ages Check this box if you require an output sheet column containing 208pp 23 Tph ages corrected for common Pb with the assumption that the 29 207pp235 ages are concordant 208 corrected Concordia plot ratios and 207Pb 206Pb ages Check this box if you require output sheet columns containing the pu Pb U ages errors and error correlation where the common Pb correction assumes concordance of the 206pp 235pj Pp UTh ages Checking this box also enables the calcul
32. defined by an Excel workbook xls file contained by the SquidUser folder located in the same folder as the SQUID 2 add in file Names of Task files always begin with SquidTask_ followed by the name of the Task and name or initials of the Task s creator Existing Tasks defined in the default SquidTasks file are shown in the scrollbox at the lower left of the panel After you create any additional Tasks of your own all of your interactions with the Task editor will be to modify existing Tasks via one or more of the Edit view buttons Task definition is a four or five step process General Isotope and U Pb geochron data respec tively in which you will 1 Define mass stations for the PD file s Run Table 2 Specify isotope ratios to be calculated from the Run Table 3 Define equations for calculation of U Pb or Th Pb and 2324 27 ratios and for U or Th concentration U Pb geochron only 4 Define equations for any additional data processing and 5 Specify chart insets for x y plots means or secular trends of any of the final data col umns The best way of to get an idea of what a Task consists of is to go through the process of creating one from scratch using for example the canonical ANU RSES run table and equations 15 Task Editor Save all changes Purpose then exit Discard all changes then exit Refresh Isotope Ratios Task Catalog Save changes to selec ted Task don t Exit
33. its General Equations panel Edit view a panel for the selected Task Click a colored button to edit or view the specified panel for the selected Task Refresh Task Catalog Rebuild the Task Catalog by abstracting the name description mineral and creator for each Task in the SquidUser folder OK Save all changes and exit Cancel Discard all changes and exit Constants Edit view the user defined constants Save Save all changes but remain in the Task Editor Run Table x 1 Change the active nuclide E Ne Nominal iN go to Isotope Ratios ET Retain panel changes 70 oa rer bkri Gees Md mass col hide pk d ig OH 5 Discard changes go Ek SS mie m e Bae back to Task Name Er las 90212 160 195 604 195 lt nas turn to Task Editi errr ees EE EE Discard panel changes uj mi mi cl Ese ates 2041 retum to Task Editor gg mi m mi 206Pb 205 974 26 ERN BI Nu D 207Pb 206 976 27 ET NU B 208Pb 207 977 3 E Nm B 238U 238 051 39 EI mim 232Th 160 248 033 29 ET NN m 238U 160 254 046 24 em oC ELT E a E Clear one WE instructions A oe ES Click desired element EI NU E a On the ISOTOPES dropdown specify number of atoms of the element e g 2 ES BEES B i for 232 Th then the isotope Click Complete if this is the last element pa isotope to be added to the active
34. itt o et Ut tige tet eer etre SIA 8 The SampleDGta SNe et i Oe Obras e tie b e her ee 9 SAMPLE GROUPING AND AGE EXTRACTION cccsssscecessssecsssssecesssnseceusauecessaseccssanecessaueeceususessesauessusauseceusnsessssatenens 9 CORRECTING U PB GEOCHRONOLOGY DATA FOR SECULAR DRIFT OF AGE STANDARD SPOTS senes 10 Cavedts nusing secular drift COTE CON i t eere im ip E EUER UR 12 REDUCING GENERAL ISOTOPE DATA 5 2 ree rte ch eoe ce e d o esee b a 13 TASKS E 9 14 INTRODUCTION senio ine Ib Nm RI meteo einen ii o 14 THE TASK NAME PANEL 2 5 eer e te oe eai died va epe eiie iaa 16 THE RUN TABLE PANEL ccoo died idad eee AES Res Fere ne eee d 16 Defining the Run Table ite etti entire est tette reete ee te Abe Tn etin 16 Specifying Isotope Ratios e itr EI E RR E E EUER e e dee irte HIE 19 Specifying Isotope Ratios eere te i ge e i ete rg eee A bee 19 THE EQUATION PANELS 2 ree td o esie dese ares iia E E SESEO Fere Pe edes 20 Eph m i ie 20 Restricting equations to subsets of spots sessi ens enne en ens en rese tense nest nnne nns ennns enne enne 26 Sp cial U Pb EgudtiOhs iai Re a eie a te ie a d 27 Swapping data columns with U Pb Geochronology Tasks eese nennen een eene 28 Referencing data in other workbooks or worksheets eese eee eere nnne 29 Viewing Task Equations in the reduced data
35. nuclide or Enter if you wish to add additional cm m a a isotopes as NN ND oe __ Click the Specify mass station numerically button and enter the mass as eel D a number e g 204 15 EJ ms Ee If the nuclide mass station will be used as a trim mass reference or background m imm SSS mm position check the appropriate box in the Mass station attributes area E BmU BH oo m i mi mi El Ionic species Shows the ionic species or numeric m e of the Active nuclide The Active nuclide is shown in a tan box the other nuclides in pink boxes Clear Clear the Ionic Species box Specify mass station numerically Type in the numeric value of the mass position for the active nuclide bkrd Is the mass station to be used for background subtraction of the secondary ion beam ref pk Is the mass station to be used as a trim mass reference a trim mass reference is relevant only to the construction of optional charts of centered peak trim masses versus time cps col Construct a column in the processed data worksheet for counts second at this mass station 71 Hide Hide the CPS column in the reduced data workshet Periodic table of the elements Commonly used elements for geochronology are shown in bold font short lived elements not selectable in gray background and rare earth elements in green boxes Next Save any changes to the Run Table panel then go to the next isotope ratios Task Editor panel
36. of the relevant isotope ratio errors and error correlations correctly propagated For example consider a U Pb zircon Task that has two User Equations defined in addition to the four special U Pb equations as shown above Equation 1 Ln 254 238 2 Ln 96pp 2550 Equation Name 2 The first part of the output worksheet will look something like the example in Figure 23 with the results of the two equations red arrows placed in columns to the right of the Task s speci fied isotope ratios REFERENCING AN ISOTOPE RATIO IN THE EQUATIONS PANEL To add an isotope ratio reference as an argument in a Task equation you can e Type in the literal ratio enclosed in square brackets plus a quotation mark e g 207 206 or e Type in the ratio s index letter adjacent to the blue isotope ratio boxes as in figure 22 enclosed in square brackets without quotation marks e g b or e Just click on the blue isotope ratio box for the ratio you want L Tot Tot Bkrd 204 206 Spot cts cts cts 204 207 208 206 208 254 248 238 Log Log Name Date Time Hours sec sec sec 1206 err 206 err 206 err 238 err 1248 err 238 err 254 err 196 err UO U err Pb U err r33 1 1 2005 05 02 10 28 0 0 0 05 0 08 395 8 8E 5 69 0 0575 1 6 0 208 2 1 0 162 0 76 0 00868 1 9 6 45 0 41 0 598 0 32 0 103 0 55 0 809 0 22 0 791 0 42 r33 2 1 2005 05 02 10 44 0 3 0 00 0 11 352 3 2E 4 22 0 0567 1 7 0 192 2 3 0 1
37. prise a 4 or 5 column range where the columns contain x x error y y error x y error correlation the last column is optional and assumed to be zero if missing YorkSlopeErr95 Arguments xyValues amp Errors range errors in as o level Output The 95 conf slope error of a 2 error linear regression The xyValues amp Errors range must comprise a 4 or 5 column range where the columns contain x x error y y error x y error correlation the last column is optional and assumed to be zero if missing 94 Appendix VI Useful soplot Tools for SQUID e Concordia plots e X Y plots e Cumulative Gaussian plots e Histograms e Linearized Gaussian plots e Multicomponent deconvolution Sambridge amp Compston s MIX e Weighted averages Tukey s Biweight means Medians sq RISO UPU plots including evolution curves and isochrons e Ages of stacked beds Bayesian constraints e Youngest detrital zircon 95 Appendix VII Definitions of Terms 204 corrected The amount of common Pb to subtract is calculated assuming the isotope ratios assigned in Pref erences using 204 as the index isotope 207 corrected The true Pb Pb is calculated by assuming that the true radiogenic Pb isotope ratios yield concordant 7 Pb 8U pp U ages determining the 5Pb Pb that produces this result then subtracting common Pb using 204 as the index isotope and the isotope ratios assigned in Preferences 208 corrected
38. sheet s radiogenic Pb 4 Pb col umn e g 4corr207 206 with the SA FO and LA switches 2 Name the equation e g RRrhy rad 7 6 rrhy 3 Add an equation for the resistant mean of the RRhy pp bpb e g BIWt rrhyrad7 6 named say Mean RRrhy rad7 6 with the SA SC FO and LA switches Note that nei ther this equation nor the two that follow are marked as Subset equations since they op erate on all of the spot data within each column 4 Add an equation for the mass fractionation factor for Pb e g Mean RRrhy rad7 6 0 10736 with the SA FO and LA switches where the number in the denominator is the known 2Pb 2Pb for the RRrhy standard Name the equation say MassFract 5 Add an equation approximate since the 204 206 is to be left uncorrected for the frac tionation corrected Pb Pb of all of the non RRrhy spots e g 4corr207 206 MassFract named say Fract corr 207 206 You can also restrict Task equations to spot subsets via the data reduction startup panels p 26 to avoid defining separate Tasks if only the names of say a normalizing standard change from one PD file to another 27 REFERENCING ERROR COLUMNS To reference an error column of an isotope ratio or Task equation include just after the left hand square bracket e g 3 LogUO U b or 207 206 The reference will then refer to the column immediately after that of the reference immediat
39. the Run Table for the actual PD or XML file If the two run tables don t match SQUID will refuse to process the file Note that when you select a PD or XML raw datafile SQUID will attempt to find a data processing Task whose Run Table matches that of the PD file This Task may or may not be the one desired If not select the proper Task say Zircon canonical ANU UO2 from the Task dropdown Run table box Reduce data for U Pb Geochronology PD file click to change Task OG1 070625 GASOD05 pd Zircon canonical anu UO2 STANDARDS ircon canonical anu Cancel U02 Number of characters to peaks E show in Standard names Task Editor 196 Pb U or Pb Th Age U or Th concentration 204 Name No U or Th Preferences OG1 standard Pb U or Pb Th Age ma SLi v 3441 ppm Y 238 207Pb 206Pb age same as Pb U if left blank 3465 4 U concentration for 204 overct correction only Th concentration Index isotope Normalize ion beams 204Pb for common Pb v to SBM signal subtraction Spot subsets for User Parameters Change No Subsets subsets Time Window _ __ _ gt __ No Time Window process all spots Time Window E v Standard spots only Make trim mass charts Qe version 2 31 09 02 10 K R Ludwig BGC 10 Feb 2009 Figure 3 Setup panel for U Pb Geochronology data reduction U Pb Th Pb Standards Specifying standards when starting data reduction
40. workbook eese rennen nennen 30 E QUGULON TADS P Rc aE e E ENER EEE AA EA E AE A RE EO OI EAEE EEA E a E AEAT ES 30 THE AXUTOCHARTS BANEL 5 aae whe eel As 30 SETTING A TIME WINDOW FOR SPOTS 1 n inane A a de ero ete 31 SPECIFYING SUBSET RESTRICTED EQUATIONS AT THE TIME OF DATA REDUCTION ccs scccccccessssssceeeceesessssseeeees 32 INVOKING EXCEL S SOLVER AS PART OF A TASK eee eeeee ee een eee en esten esteso stans sten e stans sten e stans sten e etas eta 32 INVOKING EXCEL S SOLVER AS PART OF A TASK 4 cresce eene eene eene tenes etas ten o seen stans seta seen see ena sean 33 ISOTOPE RATIO CHART INSETS eere esee teen ense EEEE EAEE REEERE EEEE EREE EAEE EREE EEEE 34 SPOT SCAN GRAPHIECS wos c H 34 MANUAL REJECTION OF SCAN OUTLIERS VIA SPOT SCAN GRAPHICS eeeeeeeeee tenete eenetntnne 35 APPENDIX I THE SQUID 2 TOOLBAR e eeeeee eene nete s tust tn sess tn senta senses eines etas en sens tn senses essen suus 36 APPENDIX II ALGORITHMS USED BY SQUID 2 eerie cesses eene eene en etna tn sensns esses esent ens en senses esses een snae 37 WEIGHTED AVERAGES MEANS INTERNAL AND EXTERNAL ERRORS cessere nennen nennen nnnnn sienne nenas 37 The MSWD pardteter i oe e mte ttl ete e errat ean ses qiero eee 37 Probability of fit sait s ate te D ERU e to e ARE R
41. worksheet cells usually contiguous in an Excel worksheet Resistant mean regression A mean or regression calculated using an algorithm that is insensitive to outliers in the data Robust mean regression See above Sample sheet The worksheet containing the reduced SHRIMP data for all spots but the U Pb age standard and named SampleData SBM Stands for Secondary Beam Monitor a collector that measures the secondary ion beam at a point in the flight tube and ion optics such that in favorable cases essentially the entire secondary ion beam is meas Scan order The order of a mass station in the peak jump mass jump sequence of a SHRIMP analysis Single cell formula A Task equation that operates on a columnar range of data whose output occupies a single cell rather than a data column 98 Spot A single spot on a mineral grain used for one SHRIMP analysis and assigned a unique name as part of the analysis Stacey Kramers Refers to the single stage Pb isotope growth curve presented by Stacey and Kramers 1975 Predicts the average crustal Pb isotope ratios at a specified age Standard sheet The worksheet containing the reduced SHRIMP data for the U Pb age standard and named StandardData Trim mass reference The mass station to be used as a reference when constructing charts for the trim masses used for each spot 99 References Dodson M H 1978 A linear method for second degree i
42. y intercept False include errors False Output The results of a robust resistant linear regression of a suite of x y points as a 1x2 to 1x4 cell range containing the line s Slope optional Slope error 95 conf optional Y intercept optional Y intercept error Output of the optional parameters depends on the values of with y intercept and include errors SingleStagePbT Arguments PbP pb pp tpp Output The Stacey Kramers single stage Pb growth curve age corresponding to the input values SingleStagePbR Arguments Age Ma Which ratio Output The Stacey Kramers single stage Pb growth curve isotope ratio corresponding to the input values The isotope ratio returned is pp pp 207 ppj20 pp or 208b5 2 pb for Which ratio 0 1 or 2 respectively sqWtdAv Arguments Values range Errors range PercentErrsIn False PercentErrsOut False CanReject False Output Up toa 7X2 cell range where the first column contains the weighted mean lo prob fit 20 05 or 68 3 confidence prob fit lt 0 05 error in the weighted mean external error for the data points if prob fit lt 0 05 probability of fit number of data points rejected index numbers of rejected data points if non zero The second column contains explanatory labels for the values in the first column StudentsT Arguments Degrees of freedom confidence limit 95 Output The Students s f value for the specified or defau
43. 0 time window cceeee 59 60 61 Time Window ccccccnnnnnnnnncccncncnnnnnnaninos 31 65 Toolbar SQUID sesss 4 34 trimim ss iei tet ite celia 60 MEM MASS a ene e renes 60 98 Trim Masai 13 trim mass charts oocccnnnnoonnnnnnnnccononananos 60 tF ednass esatto ris 18 U Pb geochronology 4 9 13 20 23 26 27 28 30 31 38 65 weighted average plots 30 A E 2 within scan isotope ratio 93 within scan ratios equations 34 XML files ds tirenecri tb hoarse 7
44. 00 rows 6734 6739 33 Units are total counts 37 254 27 SBM aa M MN Within Spot Ratios SampleData StandardData JNA A229 05042213 00 R33 14 1 fal Figure 30a A spot scan graphics sheet Manual Rejection of Scan Outliers Via Spot Scan Graphics SQUID s algorithm for within scan isotope ratio and equation means is extremely resistant to outliers so that manual rejection by the user of individual scans peak top measurements should not be needed If however you do wish to reject scans for whatever reason you can do so from any spot scan graphics sheet in the following way 1 Request construction of spot scan graphics for the desired spot 2 Click on the chart for the mass station of interest A bar containing num bered light blue boxes will appear at the top of the chart figure 30D 3 Click on the box corresponding to the scan number to be rejected figure 28c The box will turn light red the rejected data point will disappear from the chart the curved line through the data points will be redrawn and the values in the condensed PD file worksheet will change as shown in figure to un reject a scan click again on the numbered light red box Now when you re process the PD file SQUID will ignore the rejected scan figure 31 tot cts tot cts 30 mass 30 mass Secs 206 946 1sig Secs 206 946 1sig 67 71539 331 67 716 599 331 182 830443 281 12 830449 281 27 REJ 17 297 44414
45. 204 059 t1sig SBM mass Secs 204 099 t1sig SBM mass Secs 206 050 1sig SBM mass Secs 207 048 t1sig SBM mass Sec 18 31838 2 178 372678 195 909 29 3 0000 1 73 3722318 204 054 51 1 0000 1 00 3716532 204 094 74 426699 207 1855114 206 046 96 380434 273 5559677 207 045 11 28 172 33657 6 210 369814 195 912 184 3 0000 1 73 3694847 204 057 206 0 0000 0 00 3690998 204 097 230 42196 2 225 1843363 206 047 252 377565 194 5528330 207 045 27 Figure 8 PD file after condensation and reformatting by SQUID Reduced data sheets produced by SQUID The StandardData Sheet pained 238U The Standard sheet contains processed data for only the fse er uow em Poo en const enda Ho Age Standard spots Among the changes from SQUID 0103 055 0809 022 0 791 0 42 0 087 0 52 0 817 0 23 0 772 0 46 0 00389 0 55 are 0 170 0 41 0 818 0 17 0 767 0 33 0 00393 0 39 0 279 0 35 0 818 0 13 0 765 0 22 0 00395 0 30 0 313 0 35 0 818 0 11 0 766 0 20 0 00394 0 25 e Additional data columns containing the results for 2 52 225 0222 076 0755 02860981 one any Task equations e g the Log UO U and Log 0 151 0 39 0 820 0 16 0 766 0 29 0 00389 0 41 a 0 110 0 43 0 821 0 19 0 752 0 35 0 00401 0 42 Pb U columns in the example at right p 20 0 343 0 38 0 820 0 11 0 759 0 20 0 00398 0 24 0 165 0 38 0 821 0 16 0 762 0 28 0 00392 0 35 0 148 0 39 0 814 0 17 0 760 0 30 j B ass 0 287 0 36 0 812 0 12 0 767 0 21 0 00404 0 26 e Up to eight user specified Task linked
46. 3 197 411 7394447 357 411 794447 357 67 716588 331 Source data for plot after rejection 182 830 449 281 4n 794 447 357 Figure 31 Change in the condensed PD file for the chart in 28b after scan rejection 35 900 206 946 gt 206 946 C 206 946 Figure 30b Manual rejection of scan 3 of mass 207 Remember that deleted scans will only affect subsequent processing of the PD file and will have no effect on existing SampleData or StandardData worksheets 36 Appendix The SQUID 2 Toolbar to make the toolbar visible select View Toolbars Squid2 from the Excel dropdown menus Load and process data from a U Pb geochronology PD file a o Load and process data from a General Isotope PD file 0 xm Group samples from a processed U Pb geochronology workbook Condense and reformat one or more PD files Task Editor Preferences w Kd Construct one or more chart insets of the within spot isotope ratios for the spot and ratio defined by the selected row and column of the SQUID StandardData or SampleData worksheet To obtain more than one plot at a time select more cells each indicating an isotope ratio Construct charts of cps versus time for one or more spots defined by the selected row s of the SQUID StandardData or SampleData worksheet for all of the mass stations Constr
47. 69 0 81 0 00893 2 1 6 55 0 44 0 553 0 35 0 087 0 52 0 817 0 23 0 772 0 46 r33 3 1 2005 05 02 11 48 1 8 0 10 0 08 670 22bE 5 93 0 0551 1 2 0 200 1 6 0 171 0 59 0 00890 1 5 6 58 0 32 0 583 0 25 0 170 0 41 0 818 0 17 0 767 0 33 r33 4 1 2005 05 02 12 53 24 0 00 0 00 1108 100 0 0553 1 0 0 152 1 4 0 172 0 39 0 00883 1 3 6 58 0 26 0 445 0 26 0 279 0 35 0 818 0 13 0 765 0 22 r33 5 1 2005 05 02 13 59 35 0 00 0 05 1256 3 7E 5 85 0 0552 1 0 0 188 1 2 0 172 0 35 0 00864 1 1 6 58 0 22 0 561 0 19 0 313 0 35 0 818 0 11 0 766 0 20 r33 6 1 2005 05 02 15 04 46 0 00 0 09 561 17E 4 22 0 0558 1 4 0 231 1 6 0 175 0 53 0 00908 1 5 6 63 0 32 0 668 0 27 0 138 0 39 0 822 0 17 0 757 0 30 r33 7 1 2005 05 02 16 12 5 7 0 20 0 13 593 12E 4 12 0 0538 1 4 0 239 1 6 0 173 0 51 0 00864 1 5 6 64 0 31 0 716 0 25 0 148 0 38 0 822 0 16 0 762 0 29 r33 8 1 2005 05 02 17 19 6 9 0 06 0 04 614 38E 5 85 0 0564 1 4 0 211 1 6 0 174 0 50 0 00887 1 5 6 58 0 30 0 629 0 26 0 150 0 47 0 818 0 16 0 759 0 29 Figure 23 A reduced zircon SampleData worksheet for a Task having two user defined equations red arrows If you append a ratio by just clicking its ratio box the ratio will be appended to the end of the existing expression if any in the active equation box You can choose which style will be used by toggling between Index appends the letter index of the ratio e g h and Literal appends Append eqns ratios the ratio itself e g 238 196 with the ADDING A REFERENCE T
48. Algorithm for U Pb Age Standards Reject points whose difference R between the internal error and median internal error is greater than 5x Nmad where Nmad 14826 1 x Median R and N is the number of Age Standard spots Calculate the weighted average of the remaining points in the usual way weighted by in ternal errors only e g B Paes mo Y 1 a ec f Ese where o is the internal error of the spot calibration constant If the probability of fit of the above weighted average is less than 0 05 as calculated from the X distribution of the MSWD about N 2 calculate another weighted average but this time assuming that a constant but unknown external error also exists for each data point The Maximum Likelihood Estimator of both the mean calibration constant and the external error o are determined by simultaneously solving 1 Y e 1 12 _ Ls is t T x X O o o to y c to p Apparent outliers are then rejected if The wtd residual of the point is less than Toler where p is the number of the rejection pass and E is the 95 conf error of x as determined via 3 above and p 1 Toler eZ 6 072 El o The number of un rejected points is no fewer than 85 of the original number and o The data point is nonzero Steps 3 4 are repeated until no rejections occur Note that with each pass through steps 3 4 the bar for rejection Toler is raised
49. ERENCES M ao 52 Show splashzscreen Qtsstktup z ua eite ERO RR e e ertet p eterne 52 Retain nonessential rows of PD or XML files file length permitting eee 52 Place data reduction parameters in a separate worksheet esee nennen eene 53 Place auto charts in a separate worksheet esee eene eene nre rennen entente eene neret 53 Attach Task sheet to reduced data workbook eese esee eene nennen enne tentent nnne 53 Freeze header rows and spot name column esee eene nennen nne ren nen enne enne nennen ens 53 207 corrected 208Pb 232Th ges ct t EU REO ipe 53 208 corrected Concordia plot ratios and 207Pb 206Pb ages essen eene 53 Create concordia plots for U Pb Age Standards U Pb only eene 53 Always construct within scan isotope ratio sheet eese eene enne remettre 53 Set Y axis minimum on isotope ratio plots to zero essere nennen eren entren nennen 53 Maximum permitted mass difference between measured and true nuclide masses esses 53 Default folder for PD and XML files ti at aie tie E e ERE AT CEP e SERRE 54 Rebuild Task Catalog files ERE e ATQ Gu a n e D RI Gg eie Ret 54 Isotope Ratios of Common Pb U Pb geochron only eese nennen een enne 54 Calculation of within spot scan by scan means easet en eene nenne ener enne enne nnne 56
50. ETAINS tre CERA TIAS EUR 37 External errors and Weighted Averages assuming the presence of external errors esee 38 OUTLIER REJECTION FOR THE INTEGRATIONS COMPRISING A SINGLE SCAN OF A PEAK ccesseeessneeeeseseeeeneneeeeeseee 39 W ITHINSSPOTISOTOPE RATIOS ahi ette Pad ep rtr e e eb Da ER LIRE ENEAN EE ERE ERE rete babe e eve 39 OUTLIERS OF WITHIN SPOT INTERPOLATED RATIOS c ceccsscsscsseesesscesecseeseesscssesscesessessessessecssesscsssssessesssssessseneeneengs 41 THE TUKEY S BIWEIGHT ALGORITHM 5 cot 3 npe dante talante bs 42 WITHIN SPOT NUMERICALLY EVALUATED TASK EQUATIONS cccccccssssssseeeecceeesssssseeeceecessessseeececeeeessseeeceeeeesetaaes 43 OVERCOUNIS ON PR Scutum dad pde a onte RD M SA a RUN ME 43 OUTLIER RESISTANT LINEAR REGRESSION eene nnne nnne nette sina tn sintesi ns E iin sinas tnis insania 43 CONCORDIA AGBS rere be trie UG IR P axles Bee e EO EG EEE o 43 CONVERTING TERA W ASSERBURG TO CONVENTIONAL CONCORDIA SLOPE INTERCEPT ooococcoccnccnnonnnonanininninncnnonos 44 Ppg Pp AGE ERROR INCLUDING ERRORS IN DECAY CONSTANTS cssssssssesssssessseessseessseesnscesnceeascesneesneensseesneessees 44 208 CORRECTED AGES AND RATIOS 4 pert rune te pe eae eva E A AA 45 207 CORRECTED AGES AND RATIOS tte E RR Pel ede aia VR Pp De PRESE REY Exe aaa ies 46 APPENDIX III THE SQUID 2 PANELS AND CONTROLS eeeeeeeeee eene een enses ees sin sensns tasto senses sese sn suus 52 PREF
51. Existing Tasks list of the Task Editor Fig 15 click the New button thus invoking a blank Run Table panel For illustration figure 17 shows a completed Run Table panel for U Pb zircon but of course when defining a new Task all of the entries in the right hand scrollbox will be empty The steps for definition of the canonical zircon Run Table are Run Table x Change the active nuclide Retain panel changes go to Isotope Ratios Next cps ref Ionic species True Nominal col hide pk bkrd e g 9ozr2 160 mass mass um Di E 4 pm n or numeric mass m e m e Bac Esci del ivf wr 907r2 160 195 804 Retain panel changes Pore a 55 EA return to Task Editor Discard panel changes EU I Jv aud s return to Task Editor avy LL 206Pb 974 ZELLE 207P E an B 208Pb TELE alv rr 232Th 160 alv VT 238U 160 ar PCr AS EU Bu d lei Instructions on lig Click desired element ml I On the ISOTOPES dropdown specify number of atoms of the element e g 2 omy g for 232Th then the isotope Click Complete if this is the last element isotope abs added to the active nuclide or Enter if you wish to add additional E NI I Lele IE iil on NS Click the Specify mass station numerically button and enter the mass as 1 a number e g 204 15 EJ ij I If the nuclide mass station will be used as a trim mass reference or background Jims position check the appropriate box in the Mass station attributes area
52. O A NAMED NUMERIC CONSTANT 238 US consts as LITERAL button You can define view and insert up to 250 constants constants such as the decay constant of U natural 238 PSY ratio age of a secondary standard by clicking IIS at the bot tom the Equation panel Select a constant from the dropdown figure 24 then click Append to append the constant to the end of any existing text in the active Equation box The constant will appear either as its name enclosed in angled brackets e g lt Lambda238 gt 2 Lambda230ke 00919525 3 Lambda232 000049475 4 Lambda232ka 000000049475 Edit 5 Lambda234ka 002834 1 1 1 6 Lambda235 00098485 Constants can also be edited from the main Task Edi E UE m E 8 Lambda238ka 000000155125 tor panel via the 9 MG20638 079 10 MGage 490 Delete 11 MGppmTh 1380 12 MGppmU 900 13 MgREEfix 3 Exit 14A MaMieat 127 00 Figure 24 The Constants dropdown 22 Named numeric constants are stored both in the User Preferences workbook and with the Task itself If a conflict in the values stored for a named Task is detected when the Task is loaded you will be prompted to resolve the conflict and the selected value will be made consistent in both of the stored locations ADDING A REFERENCE TO OTHER TASK EQUATIONS Any equation can use the results of any other equation as an argument To do this you can 1 Type in the name of the equation see below enclosed in squ
53. O EE o eens 2 decay constants ccoooccccoocccnoncncnoncncnonannnncnos 21 Drift of U Pb calibration constant correcting DOT mca RN E 10 Equation panels cen 21 25 Equation switches 23 75 TT Equation switches sees 23 Equations Tatil EE ES 20 Excel 2 6 14 22 24 25 29 30 34 36 37 86 96 97 99 external erTOT oocccccnnnnnninoccnoncnnnonanininoso 8 11 BO SSH RA 22 24 25 26 Fusion Windows emulator for Macintosh 2 Fusion program eeeeeeeennre 2 General Isotope data 13 20 GROUP sd cde s Ive eat 9 63 groupn uei aoi eM tue oe in erede iE 9 grouping spots by sample name 62 63 Hidden CPS columns 71 ionic species Dax iier eret tret 18 ionic dDecles sitas di 17 index isotope for common Pb correction 63 Input Data Piles 3 5 2 uui de 2 ionic species box 17 18 TONIC Species DOK ass aen a eren es 70 Isoplot 2 24 25 30 88 94 96 99 isotope FAUIOS cuide 23 isotope ratios panel seees 19 Isotope ratio equation charts 34 Isotope RAMOS ra redeant 73 75 TT B MN A E O 24 A SSAEC A eiea 23 24 26 76 Literal references to ratios or equations 21 Macintosh an e dette texieier tia eiu 2 mass stations occcccnnnnnnnoccncncnnnnnono 14 18 73 nominal mass nado eee ape eto enki 18 Nonlinear equations
54. Pb as the index isotope for common Pb correction Age Groups Grouping Criteria Min prob of fit The minimum acceptable probability of fit that defines an age group 64 Min fract of spots The minimum fraction of spots in the group that defines an age group Correction for 204 overcounts on Standard How to correct for apparent overcounts at the A Standard spots as a guide Pb mass position using calculations from the No correction use measured 204Pb Assume that there are no 204 overcounts Force concordance of 207Pb 235U 206Pb 238U ages Subtract the mean 204 overcts sec from 207 calculated in the Standard worksheet from each of the Sample spot Pb measurements Force concordance of 208Pb 232Th 206Pb 238U ages Subtract the mean 204 overcts sec from 208 calculated in the Standard worksheet from each of the Sample spot Pb measurements Common Pb Use Stacey Kramers ratios for the age type specified at left Correct each spot s U Pb Pb Pb and Th Pb age assuming common Pb isotope ratios calculated using the single stage evolution Stacey Kramers method Stacey and Kramers 1975 for the age type specified in the Type of age box Enter specific ratios Correct each spot s U Pb Pb Pb and Th Pb age with the common Pb isotope ratios specified in Preferences Construct concordia plot for groups if possible If an age group is requested and found construct a concordia plot inset with the grouped w
55. Pb panel preferenees i x General Common Pb Interpolation U Pb Standards Isotope ratios of default Common Pb Cancel Use Stacey Kramers ratios for the apparent age of the sample using the age type and common Pb index isotope specified at the time of data reduction Help Ey Ez S K Age ma L Use Stacey Kramers ratios zi for the age specified at right Use the ratios entered below 206 2055 207Pb 204pb z0ppb 2049p 272095 2ospb 2oerb Isotope Ratios of Common Pb U Pb geochron only Refers to the Pb subtracted from the total Pb to obtain the isotopic abundances of the spot s ra diogenic Pb These corrections will be applied in the StandardData and SampleData worksheets The common Pb used for Grouped sample worksheets is assigned separately 55 Use Stacey Kramers ratios for apparent age of sample Use the single stage evolution Stacey Kramers ratios Stacey and Kramers 1975 for the sam ple s age using the age type specified for data reduction Use Stacey Kramers ratios for the age specified at right Use the Stacey Kramers ratios corresponding to the specific age entered in the S K Age box Use the ratios entered below Enter an arbitrary set of Pb isotope ratios to use for common Pb correction Preferences Interpolation panel preferences 04 General Common Pb Interpolation U Pb Standards Calculation of with
56. SQUID 2 Rev 2 50 A User s Manual Ken Ludwig Berkeley Geochronology Center April 12 2009 To reference Ludwig K 2009 SQUID 2 A User s Manual rev 12 Apr 2009 Berkeley Geochron Ctr Spec Pub 5 110 p INTRODUCTION pst cer MEIN 2 PURPOSE OF SQUID 2 enu upeu E Baw Hoe nee UNDC 2 REQUIREMENTS a 2 O EE EE A EN E RTE E S AET R AE E ER TARER 2 Jal NEED 2 Printer SOUP c aeseant 3 Input Data Files ania css eae eee ette o idet even wate eee ete ti eee i enit 3 INSTALLATION e candado rodas 3 DATA REDUCTION FOR U PB GEOCHRONOLOGY e eeeeeee esee esee stessa etas etas tensa senos east ea setas teas tes tenue 4 U PB TH PB OSTANDARDS dd tedio 5 U PB TH PB STANDARDS uti itae ate te dedit e a 5 Specifying standards when starting data reduction eese ren eem nennen 5 The CommonU Pb Standards List ai a ect d ded edat dade 5 SPECIFYING THE COMMON PB INDEX ISOTOPE U PB GEOCHRON PANEL ccssseeceseseeeesseeeeseneeeeseneeeeseseeesseeeeens 6 SBM NORMALIZATION ied Ere a tesi ote E E A heed cee 6 TRIM MASS CHARTS n tie eere atte teet eunte tige Hina tete d a eese eibi ttes ibi ve eerte eds 6 CONDENSED RAW DATA SHEETS PRODUCED BY SQUID cccccccccsssseceeeeseeeessnseeessneeecsaeeeesaeeceseeeseseaeeesseseseseaaees 7 REDUCED DATA SHEETS PRODUCED BY SQUID riteni e E E S nene innen enne nnne 8 The Standard Data Sheet ii eet
57. SQUID requires a pp U or 5pp Th standard to be among the analyzed spots in the PD file A standard for U or Th concentration is optional and can be either the same or different from the age standard To specify a standard from the U Pb data reduction panel 1 Select the number of initial characters to characterize the age standard spots e g 4 for Standard spots with names such as SL13 1 1 SL13 2 1 SL13 3 1 then select the name of the age standard from the spot name fragment dropdown 2 Enter the 5pp U or Pb2Th age of the Age Standard Enter the Age Standard s apparent 207 Pp pr age only if different from its Pb U or Th U age 3 Select the U or Th concentration standard if any and enter its U or Th concentration The Common U Pb Standards List You can specify up to 50 common U Pb age and or concentration standards from the Preferences panel p 57 When the U Pb data reduction panel is being filled out SQUID will look for spot names whose first few characters match those of an age standard If a match is found that stan dard s name Pb U age if defined Pb Pb age if defined and U or Th concentration if de fined will entered into the appropriate boxes x General Common Pb Interpolation U Pb sends Index Name Pb U Age Pb PbAge U conc Th conc stchars Ma Ma ppm pm cea Clear All Enter only enough initial characters to distinguish the Standard name from other spot names
58. Task panel The Equation Panels Basics m Isotope ratios a 204206 2077206 e c 20206 23896 o To append an isotope ratio s index letter Click one of the blue boxes above 20 ENS xi mag Retain panel changes ex go to Auto Charts bat ns Retain panel changes return to Task Editor Cancel Discard panel changes return to Task Editor Equations To refer to cell 41 in another workbook TWbkName ShtName lA1 To refer to cell A1 in the Sample worksheet from the Standard worksheet SampleData lAl Task equations are the backbone of the built in flexibility of SQUID 2 The variables in a Task Equation can be any of the worksheet cells in the processed data sheet s including isotope ra tios and the results of other Task equations There are two Equation panels for U Pb geochro nology and one for General Isotope data I will discuss the General Equations panel first as it exists in Tasks for both U Pb geochronology and General Isotope Ratios The simplest type of equation have no switches p 23 set and use only the Tas s isotope ra tios and numeric constants as arguments for the algebraic functions Equation results are placed in the SampleData or StandardData output sheets in data columns to the right of all of the iso tope ratio output columns If no switches are set uncertainties for each of the equation results are calculated numerically by SQUID 2 with all
59. This switch specifies an equation that operates on whole col umns of data using Excel functions such as Average Median STDEV and Isoplot or SQUID functions such as BiWt RobReg AgePb76 Th230age InitU234238 An SC switched equa tion is placed in only one cell rather than each cell in a data column Thus if interested in say the median of the measured 204 206 ratios one would create an equation with the formula Median 204 206 The LA switch U Pb geochron If a cell reference in a numerically evaluated User Equation hasn t been calculated and placed on the output sheet the output cell of the equation will either incorrect or an Excel error Unless the Equation s SC switch is on data for isotope ratios and lower numbered equations will always exist However the radiogenic isotope and age columns created by SQUID 2 are placed on the output sheet after all equations except for those equa tions whose LA switch is on The FO and NU switches SQUID puts the results of its calculations in the output sheets cells as either the numeric value of the calculation e g 1 234 or as an Excel formula e g C13 F13 SQRT SAE13 AF13 ppmu Advantages of a NUmeric result are e Quickest start to finish data processing e east fragile output sheets in that the equation result cells are invulnerable to changes or errors in the source cells arising from later changes to the worksheet e Automatically calculated errors
60. Y intercept of a 2 error linear regression The xyValues amp Errors range must comprise a 4 or 5 column range where the columns contain x x error y y error x y error correlation the last column is optional and assumed to be zero if missing YorkInterErr95 Arguments xyValues amp Errors range errors in as o level Output The 95 conf Y intercept of a 2 error linear regression The xyValues amp Errors range must comprise a 4 or 5 column range where the columns contain x x error y y error x y error correlation the last column is optional and assumed to be zero if missing YorkMSWD Arguments xyValues amp Errors range errors in as o level Output The MSWD of a 2 error linear regression The xyValues amp Errors range must comprise a 4 or 5 column range where the columns contain x x error y y error x y error correlation the last column is optional and assumed to be zero if miss ing YorkProb Arguments xyValues amp Errors range errors in as 96 o level Output The probability of fit of a 2 error linear regression The xyValues amp Errors range must comprise a 4 or 5 column range where the columns contain x x error y y error x y error correlation the last column is optional and assumed to be zero if missing YorkSlope Arguments xyValues amp Errors range errors in as o level Output The slope of a 2 error linear regression The xyValues amp Errors range must com
61. a e pa e c au eure a RE ed 95 Constantius c itt tette ds et tetto titula ste 95 Discordance i etta etui itt ti E ete ea A 95 DYrODpdOWn d ect etie aA hn A MA ea eae e re eme 96 ELTOrCOTTelation seed eio iste vet e ite ete ise ethos 96 EXIeYhab error x s eti tau mida 96 GTOUplhg aita nio aid an a dd 96 Internal erro ist et a E teint anota siititenitee 96 TONIC SPECIES EE 96 ISoplot tice Ales e hive ihe Ala e RAW eal i A tenis eRe nl i dea Bie ees ae Ai a ed 96 UL M 96 MES WD aia 96 Normalizing equation ai RR nu o Red eu eS HRe st ROA 97 hour C 97 PDfile OG 97 Probability of fit i eR RR nu t e me d n p RR a Rd 97 R diogenic PD cscs o RR aR Ec ess Ron Red e a RH A a 97 horreum A 97 Resistant mean regression iii iii teneo eI eet Fe I een ode eae de ena Faden eR eet rene eto ende ee tek eh 97 Robust mean regression ias ca eed d te NE INE E RES USER eue adan b tiep petens 97 Sample shell tee a tea did eg covets eique eai desee iei EA br eders 97 SBM usciti ESI m nag aa emu enimse 97 Scan order is s s ed une Bau ie eae ad BA ead et nated 97 Single cell formula a dec aa i a e He S i Hte Ivi que sb Htc iria 97 SDOt i ci acd eu b b d E He aa aede d etg tes a quite iuter ab d ERE dero 98 Stacey Kramers xia iiie gute iaa edita aie
62. ain take into account the error correlations between time adjacent ratios so that for r mt b where r are the doubly interpolated isotope ratios and f are the corresponding times of interpo lation and m t is the time slope and intercept of the linear regression The best fit slope and in tercept are given by go OWE ER P mP 4WM P 2W where P D Y er 1 1 00 M gt Y 11 0 P dds 1 0 P 7 7 w re and Q is defined in p 40 Error for the slope and intercept are obtained from inversion of NE P W pP o cov m b E cov m b O The error in r at any time t is then obtained from which gives e 2 t0 0 2cov m b Outliers of within spot interpolated ratios For calculation of isotope ratio means by either a simple weighted average or error weighted lin ear regression at mid burn time the following algorithm is used 42 1 the effect on the MSWD of the error weighted average of removing each of the n 1 ratios is calculated n scans and the ratio whose rejection results in the greatest re duction in MSWD is determined 2 Ifthis lowest MSWD is lower than the no rejection MSWD by a selected factor the point is rejected A second rejection pass is permitted if there are more than 8 or 9 weighted average and linear regression respectively ratios 3 If the probability of fit of the weighted average or linear regression is lt 0 05 the internal sigma mean of the weighted average is acc
63. ame Tift ia aaa 65 SUBSET pr qu RR D TU REED DII 66 COPY OR RENAME A TASK eet etcetera ee ieri ri dee etes 67 Task AIC m E tad 67 Task descriptiOT u uoti erm eee te e ee ne ti e ni evt te eem 67 Primary mineral oet d nde t e ee ete en ndi it ee teas 67 TASR EDITOR e P 68 U Pb Geochronology 2o dt fb t eI ee ent dt t ced aei eret 68 IsOlopecR tlo La iiem b eta eee nf be ate etes 68 EXISTULS T ASKS se recte et een cti dee bia net eed ed n idt e itia 69 Edit view a panel for the selected Task in irn iE eene nennen nnne rennen SRA NKA ene 69 Refresh Task Catalog uti cct tide aie tie ea n i d de edet 69 OK 69 Cancel ati tap o tra Hee iD eed uade ote 69 COonstants o tetto ei a eat deutet td 69 SAVE i dieat tea oan aie dera A dd 69 RUN TABLE eene eusetsuinde ete novem ete ed OI e IE ROTATOR 70 TOnl 35D6Cle ctf pev ade E COS ERES R OUR QUEE RE TR EU EE ATE eT EDI CO ERIS RR UR 70 Clear zi attico AAA d teme map ite ure ted ees 70 Specify mass station n m rically de t te ei iet e aep ee Hr eer Hoi endo 70 Dd tact date t ao di eaae us 70 POP N EP RES 70 COSCO S tto A id 70 Hide 45 auta cota toic aie utei te tei eau ema 71 Periodic table of the elements urat oet aede ae tei 71 P EE 71 Cancel ssi ee DIT e eei t pecie pacar ade Lie Pr So buta etse esci tS ek se
64. ans tot cts tot cts tot cts tot cts tot cts 8 2 mass totcts trim 20 mass totcts trim 20 mass totcts trim 10 mass totcts trim 30 mass totcts trim 5 9 Secs 195 913 t1sig SBM mass Secs 204 057 tisig SBM mass Secs 204 097 t1sig SBM mass Secs 206 049 tisig SBM mass Secs 207 047 1sig SBM mass Sec 16 313438 177 366625 195912 29 2 0000 141 3663750 204 057 51 0 0000 0 00 3659015 204 097 75 54333 73 7 1828407 206 049 96 967 144 37 2 5486041 207 047 111 171 33188 7 182 384848 195 915 183 20000 141 3649334 204 059 205 0 0000 0 00 3649302 204 099 229 52583 734 1821901 206 049 251 898 001 30 0 5457595 207 047 271 319 34146 1 185 361688 195 914 332 1 0000 1 00 3818083 204 059 354 0 0000 0 00 3613908 204 088 378 50948 714 1809463 206 050 399 900 001 31 8 5515429 207 048 41 469 34799 0 187 364457 195 915 481 1 0000 1 00 3638475 204 060 503 1 0000 1 00 3629826 204 100 527 51865 117 1812860 206 050 549 875 558 31 2 5434350 207 048 561 618 354652 217 361853 195 814 630 1 0000 1 00 3616917 204 059 652 0 0000 0 00 3617268 204 099 676 50127 70 8 1808556 206 050 698 881 001 29 7 5423708 207 049 71 767 35971 1 204 360583 195 913 779 0 0000 0 00 3601385 204 057 801 0 0000 0 00 3603056 204 097 825 51284 71 6 1799586 206 049 847 840 001 30 6 5408522 207 047 86l OG1A 1 1 2007 06 25 12 38 10 peaks 6 scans tot cts tot cts tot cts tot cts tot cts 2 mass totcts trim 20 mass totcts trim 20 mass totcts trim 10 mass totcts trim 30 mass totcts trim 5 Secs 195 915 1sig SBM mass Secs
65. are if the equation references only isotope ratio col umns rigorously accurate and placed in the column to the right of the equation column 25 Advantages of a FOrmulaic result are e The equation s output cells are updated automatically when changes are made to cells referenced by the equation e Other equations on whose results are referenced by an FO equation need not have been calculated before the FO equation e The user can check the contents of the equation cells to make sure that the equa tion actually implements the user s intent The H switch Tf set this switch causes the column containing the Equation s results to be hidden useful if the output worksheet is too cluttered with non essential information To unhide a hidden column select the two columns flanking the hidden column then un hide with Format Column Unhide To unhide all hidden columns in a worksheet select all cells by clicking on the blank rectangle at the interestion of the Row and Column indi ces The AR switch This switch which requires some knowledge of Excel s Array functions adds another level of flexibility in data processing You will have to use the Excel documentation to learn the general ins and outs of Array Functions but an important feature is that the output of these functions can occupy not just one cell but any group of contiguous cells with an arbitrary number of rows and columns For example the complete output of the soplot arra
66. are brackets plus a quota tion mark e g Log UO U Case spaces and slashes are ignored by SQUID so you don t have to type them in when defining an equation 2 Type in the equation s index number in the orange equations box to the left of the equa tion box itself enclosed in square brackets without quotation marks e g 13 or 3 Just click the equation number box to the left of the equation box Unless you use the FO switch see below you should make only forward references to other equations that is to higher numbered equations so that the results of the equation referred to will have been calculated when needed EQUATION NAMES Each Task equation must be assigned a name in the corresponding Equation Name box figure 20 The equation name will be used as the column header for the equation s output column the SampleData or StandardData worksheet and if the equation s SC switch is set as an Excel range name To avoid overly wide columns for the equation results you can use the character to indicate a linefeed Thus an equation name entered as Mean rad ppm Pb uncorr would appear in the equation s column header as For Array Equations see p 25 whose output occupies more than a single column you can spec ify names for each of the output columns using a double vertical line as the column delimiter Thus the output for a name such as SQUID will ignore non alphanumeric characters un
67. ation of 207 corrected 20 pp 06pp ages Create concordia plots for U Pb Age Standards U Pb only If checked a small conventional concordia plot for the Standard spots will be placed within the Standard worksheet Always construct within scan isotope ratio sheet A within scan isotope ratio sheet contains the within spot i e scan by scan isotope ratio and Task equation results for each spot formatted for clarity of viewing This worksheet is required by SQUID for construction of chart insets of isotope ratios Task equationsError Bookmark not defined versus time Set Y axis minimum on isotope ratio plots to zero If unchecked the Y axis the ratio values for isotope ratio chart insets will be auto scaled to the plotted data Maximum permitted mass difference between measured and true nuclide masses If the apparent PD file value and true masses of a mass station are within this difference SQUID 2 will accept the measurement Otherwise SQUID 2 will not recognize the mass station as simply a measurement error on the true mass so that the Setup panel will refuse to reduced that PD file 54 Default folder for PD and XML files The folder SQUID 2 opens when asking for a raw data file to process Rebuild Task Catalog file Reconstruct the TaskCatalog file contains basic information about each valid Task file in the SquidUser folder used to determine compatibiity for data reduction with a raw data file Preferences Common
68. baric interferences and mass fractionation However Task equations can be modified using a column swapping feature which permits modification of any of the isotope ratio columns and thus most of the otherwise unmodifiable SQUID columns The general idea is to create a Task equation that modifies corrects an iso tope ratio in some way say by correcting the ratio for an isobaric interference then to add The four Special U Pb equations are exceptions as they are calculated directly from the within scan peak height measurements 29 lt gt to the equation directing SQUID to exchange the modified value with the original result For example suppose there is an interference on 2 pb that is roughly proportional say about double to the counts on mass 203 The correction can be made as follows 1 Add the Task equation 204 206 2 203 206 lt gt 204 2067 2 Name the equation When done the 204 206 column of output data sheet will contain the raw measured 204 206 minus double the measured 203 206 and retain the original 204 206 column header and the Task equation s column will contain the original measured 204 206 with the header RAW 204 206 Referencing data in other workbooks or worksheets For U Pb Tasks the same column header can exist in both the SampleData and StandardData worksheets SQUID will first look for the referenced column header in the worksheet doing the referencing then i
69. btraction Spot subsets for User Parameters Changs No Subsets subsets Time Window No Time Window process all spots Time Window E H Standard spots only Make trim mass charts Qe version 2 30 08 11 28 K R Ludwig BGC 28 Nov 2008 Task Select any of the existing Tasks to use for data reduction New PD file Load another PD file without leaving this panel Number of characters to show in Standard names The number of initial spot name characters that will be shown in the Name dropdowns and that will be used to categorize a spot as a Standard 59 Pb U or Pb Th Age NAME The initial spot name characters that define a spot as a Standard PB U OR PB TH AGE The apparent age of the Standard Though this is generally the same as the true age it can be different if the Standard is known say to have a consistent amount of Pb loses 207PB 206PB AGE By default i e left blank this is the same as the Pb U or Pb Th age However if say the Stan dard s Pb U or Pb Th age is discordant with its 27 pp 6pp age a different value can be entered here The Standard Pp 5 pp age is used only for 204 overcount calculation U OR TH CONCENTRATION The average concentration of either U or Th in the concentration standard NAME Select the initial characters of the U or Th concentration standard names If no such standard was present in the mount leave blank th
70. ches AR rows cols If the AR switch is set enter the number of rows and columns of the formula output separated by a space Constants Click to invoke the user defined constants dropdown Append column header reference Click to invoke the column headers dropdown Append LITERAL equations ratios Click to append the equation name rather than its index and literal isotope ratio rather than its index letter when an equation number or isotope ratio box is clicked Next Save any changes to the Equations panel then go to the next panel Auto charts 77 Back Save any changes to the Equations panel then go back to the previous U Pb equations or Iso tope Ratios panel Return Save any changes to the Equations panel then return to the main Task Editor panel Cancel Discard any changes to the Equations panel and return to the main Task Editor panel Delete active equation Delete the active equation and shift all higher number equations down Insert active equation Insert a blank equation box before the active equation Clear Active Clear the active equation Clear All Clear all equations Help Display detailed information about Task Equations and Switches Auto Charts Column headers Select the column headers of the x and y parameters to chart The x parameter is not needed if a Y mean calculation is specified Axis scaling Autoscale Let SQUID determine the bounds and tick i
71. ches are set e Automatically calculated columns radiogenic isotope ratios U concentration apparent ages e Task equations whose SC but not LA switch is set e Task equations with the LA switch set The order of calculation within each category follows the equation index number 24 FOrmula The Formula for the Excel equation is to be placed in the output cell s rather than its numeric result NUmeric The Numeric value of the Excel formula for the equation is to be placed in the output cell s rather than its Excel formula Hidden The worksheet column containing the Equation results will be hidden ARray formula The equation is an Excel Array Formula whose output can occupy more than one row and or column ARrc The number of rows and columns occupied by the output of the array for mula two numbers separated by a space The ST and SA switches U Pb geochron When examining and calculating data that is relevant to say just the age standard spots the output of user equations that have been created for this purpose say to examine the Log Pb U vs Log UO U slope would only clutter up the Sample output sheet With the ST switch on the column headers and output for such equations will be calculated and placed only on the Standard sheet Conversely the SA switch restricts the equa tion to the Sample worksheet If neither of these switches is on the equation is placed on both sheets The SC switch U Pb geochron
72. d sheet occccccccnnnnnnncnccnncnnns 8 24 98 Standard spots 5 8 31 53 64 65 standard age U Pb sermo 24 standard U Pb 5 13 21 26 28 59 74 StandardData sheet 20 22 SUBSETS ic heh GR ER Ed 61 SUbSets iiec iiie eibi Pelis 26 66 SWILCheS ie e iive ee ETE 23 Switches for Task equations 75 TT UT quM MORTE 53 68 69 Task constant ooooooonccnncccnnnnnnnananononcccnnnannnos 21 Task EditoOT ooccccccnnnnnnncncnnncnnnonanininos 60 61 Task Equations quce desistere tact 60 Task Equation panels 20 Task equations cosida 13 26 59 Task Equation 20 21 Task Equations eere 22 Task equations ca ense ges I qure UOS 20 time window cceeeeee 59 60 61 Time Window eeeeem 31 65 Toolbar SQUID srr rnontras 4 34 rim massi REN Ree 60 TANE MASS ose ete tior tett tee torneos 60 98 Trim MASS tiit ete ER or He etam 13 trim mass charts oocccnnnnooonannnonoconnnananos 60 TUE TASS do AO 18 U Pb geochronology 4 9 13 20 23 26 27 28 30 31 38 65 weighted average plots 30 WindOWS sepe leds as ed o ia 2 within scan isotope ratio 53 within scan ratios equations 34 204 corr 206Pb 238U sssss 63 207 corr 206P5 23 Unai 63 Pb PB Ase ederet 5 59 63 208 corr 206Pb
73. dden CPS columns 71 ionic species DOK sio ii 18 ionic decies iiie pi 17 index isotope for common Pb correction 63 Input Data Ple eei drei dto tm egt tits 2 ionic species bOX 4 ao ees 17 18 Jonic Species DON atte 70 Isoplot is 2 24 25 30 88 94 96 99 isotope ratios ci 23 isotope ratios panel esess 19 Isotope ratio equation charts 34 Isotope RAUOS ie eter 73 75 TT EA uoo A OS 24 LAS Winona 23 24 26 76 Literal references to ratios or equations 21 Macmtos a orbc epo EORR 2 mass SCALLIONS encre rase d Rehd 14 18 73 nominal Mass id 18 Nonlinear equations eese 38 normalizing equation eere 28 UP SWIC nsa poer Te eed Pe cades 24 numeric mass occcccnnnnnnnnioccccnnnnnnananinoss 17 18 OVerCOUDtS ccooooocccccccnnnnnnnonicoccccnnnnnnnnaninoss 9 64 Pale SIZE cae a ou m M AEN 2 Parallels Windows emulator for Macintosh 2 Parallels program earn 2 BID BIOS o teo STIS 18 O osi Rose ssp pts 53 PD files sicot tr ei 2 7 14 plot sets isis 8 Preferences 5 6 8 34 52 59 60 61 64 95 Printer Sep oo sed tee OOo MARI 2 RAM o ce ddp E aerate anata 2 Raw data files adicit 7 Reference peaks es raataa 13 Reference peak trim mass 13 TESTESSION tdo 30 31 78 rejection MANUAL oo eed rre oven 35 PRUNE UD cease 14 Run Table 4 14 16 18 59 60 70 71 72 Sampl
74. derscore excepted in SC equation names as only alphanu meric characters are permitted in Excel range names Initial number characters are also forbidden 23 Th230 raw age ka err Init 234 238 err assigned to the array equation Th230AgeAndlInitial 3 ze 1 f true with the ARrc switch marked as 14 output occupies 1 row 4 columns would be something like Th230 raw age Init ka err 234 238 err 104 22 1 44 1 1472 0 0001 EQUATION Switches To provide more control over how and when the Task Equations are evaluated SQUID 2 pro vides up to 7 switches that can be turned on or off for each equation The Switches and their abbreviations are shown in blue font if restricted to U Pb geochron Switch Function Standard The equation is placed only in the Standard output sheet default is both SAmple The equation is placed only in the Sample output sheet default is both Single Cell The equation results occupy a Single Cell rather than a column and oper ates on whole columns of data rather than the data in just one row LAst The equation is to be calculated last after all of the other equations with out the LA switch and after all of the columns produced automatically e g radiogenic isotope ratios U concentration apparent ages by SQUID 2 The column order of calculation for U Pb geochronology is e Isotope ratios as specified in the Task e Task equations for which neither the SC nor LA swit
75. e 4 14 16 18 59 60 70 71 72 Sample sheet e eue 6 9 97 SampleData sheet 9 20 22 26 29 34 97 SBM oie toos ied ado 6 60 SBM secondary beam monitor 6 34 59 97 SC switch 22 23 24 26 27 76 A e ens ated 18 Scan Order enenbeltesdswediene ues 17 Secular drift correction for 10 smoothing window for secular drift COITeCLiOD MAENOR AEAEE EEEE 11 SOLVET i sse ees 33 sorting by sample age 63 SpOt HD SS s coto MERE iE 9 spot scan graphics usss 34 35 SQUID toolbar eese 4 SOLID Ta 8 9 o A tiers arent 24 76 Stacey Kramers eene 64 Standard sheet occcccncnnnnninoncccncnnns 8 24 98 Standard spots 5 8 31 53 64 65 standard age U Pb sssss 24 standard U Pb 5 13 21 26 28 59 74 StandardData sheet 20 22 SUDSEtS c ie REPORTE 61 SUD 26 66 AO A A A 23 bb 104 Switches for Task equations 75 7 UIS TFT PRI 53 68 69 Task constant ooooooooonnncccnonnnnonannnnnnncccnnannnns 21 Task EditoOT occcccccnnnnnnnnncnnncnnnonanininos 60 61 Task Equations urls 60 Task Equation panels 20 Task equations 5 erre ote 13 26 59 Task Equations cue ides tute eA 20 21 Task Equations esee 22 Task Gquatiofl sz oe es a Re E ers 2
76. e Age Standard calibration constant relative to its median value red line Estimated external non counting statistics error is shown in the blue boxes Small red circles indicate the Age standard calibration constant black vertical lines their 26 internal errors If however the user has selected Automatic for the smoothing window SQUID 2 will automati cally find the largest smoothing window that yields an external scatter no greater than the assign ed Minimum acceptable external error for the age Standard p 57 The Min spots parameter p 12 sets the lower bound on the automatic smoothing window The secular drift of Age Standard s calibration constant relative to the median value is then used to correct the calibration constants of the Standard spots i e to remove the presumed ef fects of the Standard s drift Note that secular drift correction will only be applied for Tasks with a single parent daughter system Pb U or Pb Th specifically calculated that is where calculation of the non Primary parent daughter ratio is specified as Indirectly in the U Pb Special Equations panel p 27 12 Caveats in using secular drift correction It can be argued that calibration constant secular drift should not occur in a properly constructed mount analyzed with a properly functioning SHRIMP and that when such behavior is observed the best remedy is to solve the instrumental problem rather than trying to cleverly manipulate the data
77. e SQUID toolbar Figure 29 Some isotope ratio and Equation result charts The Y axis of the chart insets will be auto scaled to the data plotted unless the Set Y axis minimum on isotope ratio charts to zero box in Preferences is checked Spot Scan Graphics You can request spot scan graphics by which I mean charts of the total counts at each mass sta tion for each peak jump for any spot by selecting one or more cells whose rows correspond to the desired spots in either the StandardData or SampleData worksheets then clicking the d button in the SQUID toolbar The resulting charts figure 30a one for each mass station plus one for the SBM will all be placed on a single new worksheet having the same name as the spot Clicking the E button produces spot scan graphics for all of the spots in the raw data file This can take several minutes For extremely large files or run tables it is possible for Excel to run out of memory resulting in some obscure and misleading error message such as too many fonts o o o m n o E ES A i p d o v o 20 000 10 10 je E ESSE 3 195 982 165 als ES El 206 146 900 450 AS Cee E si See Ex m m m mI Ir i FESS Sos 207 14 208 133 238 271 25 000 248 27 350 000 macco oaneoo o cpeoo 0 orroge e Saa CRUDO Spot 55 R33 14 32 JNA_A229_05042213
78. e first item in the dropdown list PPM U OR TH Enter the average concentration of U or Th for the concentration standard Leave blank if there is no concentration standard Index Isotope for common Pb The common Pb correction for radiogenic U Pb isotope ratios can be corrected using any of Pb corrects assuming the default common Pb specified in Preferences Pb corrects using the assumption of 206pp 238pj 207pp 206pr age concordance or pb corrects using the assump tion of Pb 8U Pb Th age concordance Normalize ion beams to SBM signal Ion beams normalized to the signal of a perfectly reliable SBM secondary beam monitor should be unaffected by any instability in the secondary ion beam If there are doubts as to the function ing of the SBM i e the SBM is not constant over the mass range of the Run Table leave un checked Spot subsets for user parameters Shows those spots for which one or more Task equations are specifically applied Time window Shows the time window within which spot analyses are selected for data reduction Other spots are ignored 60 Trim mass charts Construct trim mass charts for each peak centered mass station Task Editor Invokes the Task Editor panels returning to this Setup panel when done Preferences Invokes the Preferences panel returning to this Setup panel when done Change subsets Specify Task equation that are to be applied only to a selected group of spots
79. e sheet ue e prre Un 6 9 97 SampleData sheet 9 20 22 26 29 34 97 A idea pea 6 60 SBM secondary beam monitor 6 34 59 97 SC switch usu 22 23 24 26 27 76 Scan Order ini 18 SCAN Order ida Een enn 17 Secular drift correction for 10 smoothing window for secular drift COME iro th te Y e er e 11 OA 33 sorting by sample age 63 Spot Dames sorbet tidad 9 spot scan graphics sess 34 35 SQUID toolbar cit i ii ieis 4 SOLUTI es catt sec r a aeris 8 9 ST Switche in DES 24 76 Stacey Kramlts 5 denken eris enni epa 64 Standard sheet cccccccnnnnnnnnonccnnnnnns 8 24 98 Standard spots 5 8 31 53 64 65 standard age U Pb ss 24 standard U Pb 5 13 21 26 28 59 74 StandardData sheet 20 22 UD RON nS 61 SAA A 26 66 SWITCHES io EGER i 23 Switches for Task equations 75 11 Task ii 53 68 69 204 corr 206Pb 238U eese 63 207 corr 206Pb 238U sesess 63 AT Db DB doe cite te onm oom 5 59 63 208 corr 206Pb 238U suse 63 Age Standard eee ies 5 8 9 31 AR SWH Git ar 25 27 76 A bdo 25 ARrc switch cccccncnnnncccccncccnnnnnnno 23 24 27 Auto Charts occcccnnnnnnncncccncccnnnonono 30 77 78 background box oeste ades 18 Calibration constant U Pb correcting for ri
80. e tenente 61 Process spots within Time Window eese eene nene eene nennen EE enne nennen neret 61 Change Subsets 4 ot IRURE RE E a 61 Task Editora e n RR nU ee ERE ini tp da 61 PRESENCIA tie eee RT A AA eet esu vec eae AL Ep a Eee Yen ced redeo ees e HERE ee 61 Ch nge Time WindOW e Se 61 SAMPLE GROUPING a PEERS 62 Spot Names soia ee QU HR Ata outs ee RU e e eatis e eae d 62 letters to show in Spot names dropdown esee eene een nennen nre renne nennen nnne eren 62 Disregard Case Spaces Dashes Slashes ecccescccssscssscceesscesseeesseeesaeeesaeeesaeeesaeeesaeeesaecesaeceaeeesaeeesaesesaesesaeeesaeeee 62 Extr ct coherent age group eee t e tries ene des EI ee ee eee eaa tini ASADA ads ESO 63 Sort samples by ALC EG A TOUR I REPRE tee TEN 63 Group all Spots together iai ete T It DR I EO ET Re ERR Ee E hia E ee 63 Type EE VT EE 63 Grouping Criteria rion LC P REA 63 Construct concordia plot for groups if possible eese eene nennen rennen nnne 64 Correction for 204 overcounts on Standard eese nee eene nennen eene ennen rennen 64 Common Pb ete ER CO P ERO ER ae RE UII ap ERIT 64 TIME WINDOW s ire rate tona E ERU RIBUS HR MU om HEU ge 65 Limits to specify with Standard spots esses eene enne rennen eren eret nenne nennen trennen enne 65 Starting Name Itme ein RA RR edt o Ue P tU ERE HER Rp ose 65 Ending N
81. ely following Example complex Sum 1 1 100 1 2 Sum 1 4 1 100 1 2 with switches SC TRUE AR TRUE ARrc 1 1 will yield the error weighted mean of the column values for Task equation 1 Special U Pb Equations Step 3 Special equations for U Th Pb geochronology Next Retain panel changes 208Pb 232Th go to General eqns Discard panel changes Back Calculation of 208Pb 232Th 3 4 9o back to isotope ratios 8 Indirectly from 232Th 238U Directly from the the age standard Ret Retain panel changes UI return to Run Editor U Th Pb equations Ratios available Discard panel changes a Cancel A 204206 B 207206 iue deg Equation for 206Pb 238U const dytr 2 c mm o mem te e 2 92 45 F 259239 Equation for 208Pb 232Th const C Z CHE sEXER 1 5 232Th 238U equation K L M N Equation for ppm U o P h fJ 0 66 Append cannot refer to user defined parameters Append LITERAL y zl am Click ratio box to insert ratio index into active equation Figure 25 The U Pb Special Equations panel Tasks for U Pb geochronology have this extra panel which pertains only to the partic
82. ences x General Common Pb Interpolation U Pb Standards Index Name Pb U Age Pb Pb Age Uconc Th conc istchars Ma Ma ppm ppm Cancel Clear All Enter only enough initial characters to distinguish the Standard name from other spot names Non alphanumeric characters are ignored Leave the Age field blank if the standard will be used only for uranium or thorium concentration and vice versa Click an Index to insert a Standard Shift Click to delete When adding Standards to the U Pb Standards panel keep in mind that SQUID will search the spot names for a Standard in the order that they appear in the panel 58 Reduce Data for U Pb Geochronology Run table box Reduce data for U Pb Geochronology P x PD file cligk to change Task JN A225 050502095 45 pd Zircon canonical anu X STANDARDS Cancel ircon canonical anu fal 3 Number of characters to peaks E show in Standard names Task Editor 196 Pb U or Pb Th Age r U or Th concentration 204 Name a No U or Th Preferences standard 204 1 r33 y 206 Pb U or Pb Th Age sli v r 419 208 ppm U 238 238 207Pb 206Pb age 248 248 same as Pb U if left blank l 419 e U concentration 254 254 for 204 overct correction only C Th concentration Index isotope Ilem 204Pb for common Pb Jv pea ear to SBM signal su
83. epted as the 1 sigma error If not a Y MSWD multiplier is applied The regression is error weighted by counting statistics and removes outliers by sequentially deleting each data point the isotope ratio or equation result If any single deletion drops the MSWD of the regression by a factor of 3 or more the point is rejected and the process repeated The maximum permitted number of rejections is 1 for fewer than 9 ratios or equations 2 if more Or e Calculates the error weighted mean of the interpolated ratios If the probability of fit calculated from the MSWD of the weighted mean is greater than 0 05 this mean and standard error propagated from the counting statistics errors of the individual scans is accepted e Otherwise the mean and standard error of the outlier resistant Tukey s Biweight algo rithm Hoaglin et al 1983 is used The Tukey s Biweight algorithm The initial estimate of mean x is the median and of o is MAD the median absolute deviation from the median Schematically the algorithm is T tuning const X o The tuning constant is either 6 or 9 SQUID 2 uses 6 A x x where x is the ith point of the data set and x is the jth iteration for x Do For each data point i 1 to n If IA lt T then 0 15 0 2 0 2 0 25 for 3 4 5 6 and 7 d f degrees of freedom n 1 for weighted average n 2 for linear regres sion respectively 0 3 for 8 or more d f Outlier rejection is forbidden for
84. etters to show in Spot names dropdown Select how many of the initial spot name characters will appear in the Spot Names dropdowns Disregard Case Spaces Dashes Slashes Select characters that SQUID is to ignore when grouping the spot names 63 Extract coherent age group After grouping extract a statistically coherent age grouping if possible Sort samples by age After grouping sort the data alphabetically by spot name Group all spots together Treat all spots in the Sample worksheet as a single group Age Groups Type of U Pb Age The type of age to be used for spot age grouping Total 206Pb 238U The Pb age with no correction for common Pb 204 corr 206Pb 238U Use the Pb 8U age using 2 pb as the index isotope for common Pb correction 207 corr 206Pb 238U Use the Pb U age with Pb as the index isotope for common Pb correction and assuming 206pp238 pj 207pp 206pp age concordance 208 corr 206Pb 238U Use the Pb U age with 208Pb as the index isotope for common Pb correction and assuming 206pp238 208p 23 Th age concordance 204 corr 208Pb 232Th Use the Pb UTh age with 204bb as the index isotope for common Pb correction 204 corr pp 6 pp Use the pp 296pp age with 204bb as the index isotope for common Pb correction 207 corr 208Pb 232Th Use the Pb UTh age with 277Pb as the index isotope for common Pb correction 208 corr 207Pb 206Pb Use the Pb Pb age age with
85. f not found in the other StandardData or SampleData worksheet To reference data in either another workbook or to override the above procedure you must in clude the workbook and worksheet name using Excel s syntax required characters in red e g To refer to cell A1 in another workbook IWorkbookName SheetName IRowColAddress Or IWorkbookName SheetName RangeName for example MonaziteStd Data CorrectionFactors B23 to reference cell B23 in the worksheet CorrectionFactors contained in the workbook MonaziteStdData To refer to cell A1 in another worksheet in the same workbook as the PD file being processed SampleData A1 30 Viewing Task Equations in the reduced data workbook Equations associated with the data reduction Task used for data reduction are always shown in either the StandardSpots or SampleSpots U Pb geochronology or General Isotope Ratio Tasks respectively worksheets via the Equations Box see example at right If the Attach Task sheet to reduced data workbook box in Preferences is checked the equations will also be shown in the attached Task sheet Equation Tips e Use the sqBiWeight p 88 or Median functions instead of Excel s Average to avoid wor rying about outliers If you need to use an error weighted mean use the sqWtdAv function p 91 e Use the RobReg function p 91 instead of Slope Linest Yorkfit or Yorkslope functions again to eliminate sensitivit
86. ft OE ordern entes 10 Celeron ssi RISU Ud 2 A E a E a 12 charge nuclide specifying 18 chart insets eese 14 53 coherent age grOUP ccccoocccononcnonancnonnncnnno 9 63 column swapping in U Pb Tasks 28 common Pb rieten er E EE 63 Common Pb sinsa is 95 concordance cooccccccnnnnnnnnnnocccncnnnnnnns 59 63 64 Task constatons 21 Task Editor occcccccnnnnnnonncnncnnnnnananinos 60 61 Task ESUatlOfis iris pe acus 60 Task Equation panels 20 Task equations aeter tette 13 26 59 Task Equation Rs 20 21 Task Equations ucciso ec ivre tte trs 22 Task equations us 20 time WINdOW occcccccnnnnnnnnccncncnnnonono 59 60 61 Time Window eeeeeerm 31 65 Toolbar SQUID ssesss 4 34 triti nasse e iod eise it 60 Tum mass co eed tede et dn 60 98 Trim Mass ie acepte eite et 13 trim mass charts oocccnnnnoononnnnonccononannnos 60 A iet Si ES 18 U Pb geochronology 4 9 13 20 23 26 27 28 30 31 38 65 weighted average plots 30 WInDndOWSz dec oie ia 2 within scan isotope ratio 53 within scan ratios equations 34 A O ORE 7 CONCORDANCE suite poro M ES petita 95 Concordia eee 8 88 counts second columns specifiying 18 CPS colmi Li ores qiio Queens 18 CPS columns hide 71 CPS COMME at cd rre Race 18 COS
87. ghted mean x squared So N 1 note that degrees of freedom is used as the divisor rather than N Intuitively one can see that if each o is truly the cause of scatter from x on average the residu als for the x should be oj so that the expected mean of the both the weighted residuals and their square should be about 1 An MSWD much greater than one therefore implies that the assigned data point errors are unlikely to be responsible for the observed residuals or amount of scatter and an MSWD much less than one implies that the assigned data point errors are probably too high Probability of fit It turns out that MSWD xv where v N 1 for a simple weighted average follows a chi squared distribution about v so that the probability that one will obtain a given MSWD or greater in other words the probability of fit can be calculated from the Excel function as 38 CHIDIST MSWD 0 0 External errors and Weighted Averages assuming the presence of external errors If the probability of fit is low say less than 0 05 it is likely that some other source of error in addition to the assigned data point errors is present If one assumes that this external error is the same from data point to data point so that for each data point the true variance is Mad od E int ernal o extemal g where Orena 18 the data point s assigned error and that this external error has a Gaussian distri bution both of which seem to be t
88. he case for SHRIMP analyses its likely magnitude can be calculated For U Pb geochronology SHRIMP analyses if the age standard analyses indicate that an external error for the U Pb calibration constant likely exists as indicated by a low prob ability of fit the additional variance should be added to the internal variance of the sample non standard spots before taking a weighted average To solve for the external error we first set up the Maximum Likelihood Error MLE equation x x 1 1 L x 02 constant 5 loglo 02 225 HET 2 where x is the MLE estimate of the true mean x and o is the constant external variance We then set up the first derivative constraints which when solved numerically yield the desired MLE x and o oL 1 1 lu x x dlo E 14g d 22 6 402 x oL LE NES Ox RA s So X us om d ceu gp aoo Lae c 07 eu TO Uncertainties of the two parameters are given by inversion of the negative values of the second derivatives of L which are ou a o D 1 2 _ 3 2 9L fi Ok 3 ucc aL oxo oi 20 39 where W UNDE and r x X and then substituting zero for the r their expected o TOR L value to obtain the expected value of the second derivatives Ge E pL Spr Ext E TL The variance covariance matrix of x and 0 is then obtained by inverting the Fisher Information Matrix lyw 0 Oz cov x o 2 t 2 o ayw eme el Outlier reject
89. he ionic species you are defining m s Ionic species True Nominal is say doubly or triply charged you can col hide pk bkrd Gis sal eo de specify the charge with the spin button to the EI RAT XU 5 Grau right of the box you used to enter the numeric eds E mass The mass charge ratio of the ionic Figure 20 Completed entry for scan order 1 species will automatically adjust If you want to have a column containing the total counts second of a mass station placed on the output worksheets check the corresponding cps col box to the left of the ref pk box figure 20 Cps col boxes are automatically checked for reference and background mass stations and also for the Pb and Pb mass stations When you re done look at the Nominal mass column to the right of the True mass column The Nominal masses are usually but not always an integer but SQUID 2 if necessary will have added just enough additional decimal places to distinguish the masses of each mass station from the other Thus true mass of 204 09 that you entered for the background mass position will be shown as 204 1 to distinguish it from the nominal 204 assigned to the 2 Pb mass station When referring to the isotope ratios or mass positions of the Run Table in the Equations panels always use these nominal masses 19 Specifying Isotope Ratios The next step is to specify which isotope ratios should be calculated The order of the ratios will be preserved in the output work
90. hes EU Retain panel changes m s dll go to Auto Charts Indexs Equations LA Equation names A 393 2027203 e al See NO Jens mem Lam amo REND a A EEHCEE E bcm Cancel i return to Task Editor all Ln 264 232 E Ln ThO2 Th e 20206 2041206 H ES Help B A CHEST Camas sme E Equations RobReg LnUO2 uo Ln Pb UO2 ELE TT EmU aaa L a mires Pnthoarth Mnara e T A T e m ars JA e a ii robes nuove E O EI A je jp ez jr E all RobReg Ln ThO2 Th LnPbkho2 Expo Th 2 o 205577 203520 r cer acre Gol 208Pb 206Pb 264 254 StdRad8Sfact E Thu s 20289 20339 T Gea af average fThU meanfThU W _ To refer to cell A1 in al exp l ageQia 1 651256 4 1 ppmu 0 0925 0 86 eT T TA peroaoe ista w Ex ana WbkName ShtName lA1 as ppm206std l 208Pb 906 Pb 1 0097 BE TINI prm208 std ug lI z Er AB ull 207Pb 206Pb ppm206std 1 0049 ppm207 std SEO M R LA TT ITE acl Eda the Standard worksheet as ppm206std ppm20Tsta ppm208std totPb std isi sl BempleDstalA1 ea E hs To append an Isotope Ratio reference a Index eft of equation Click one of the blue boxes above Next previous equation spinner Click on one of the spinner arrows to move the active equation up or down ST SA SC LA FO NU HI AR Sets clears the Standard Sample SingleCell Last Formula Numeric Hidden or Array formula swit
91. ie deg 76 SRSA IC EA FO VNU HE AR e e DAUERN REDI ee 76 AR EroWSsICOlsi 5 alite aia ae tle rei ed div eh v ea tinte e dd add 76 CONSTAIIS oie a m seabed tds dea vant Coen m e bce veat lec le ds tete ah end 76 Append col mn zheader ref reriCes di e e ea alice ente ape nde c es 76 Append LITERAL egu tion ralos isnin sii i c et e e iei e e tem rtl ede en 76 n2 76 BOCK eet hoc HH 77 T n 77 CaliGel5 iet e m tti m meret m ioni beds 77 Delete active egua on Ner 3 deese c dee ede e te ee eee e ee e e enu e aee et ait vea 77 INSEE ACTIVE equ tiQmn s coe ve ied qa ettet e eee o a i e e t de e e mi E N 77 Clear AGHYve o uo sch et ee cette eem i eee et ede t ce eet ee b i 77 Clear Al ttt do de est dite e eitis 77 Va LA ATEETAN E stes iii 77 Column headers o ah T EE EEES 77 AXIS SCQlihg a oe to toit ea p M OO o 77 Calculations sete o e obe uu 78 DB Ck 3 5 stt Ne adt eta MS 78 RU babet s dS 78 Cancel taken t ut abe tette esso tna he t RS 78 CONSTANTS 35 estote ter Dt EO RR NY ER ER CURE UR RESI A de ii 79 Edith Eo t E not ttu o ttes ek ie bs 79 Add new ise t tetto 79 Dele n tet a iet 79 Append TOBA NH ado 79 A EE 80 LUCO ripio 80 bates NCAA 82 TAE NCAA Ti ia 83 UI AA 84 APPENDIX IV WEIGHTED AVERAGE ALGORITHM FOR U PB AGE STANDARDS
92. in spot scan by scan means By linear OK By regression weighted interpolated average to mid time Cancel for Special U Pb Th Task equations recommended for other Task Equations Dil Help for isotope ratios of the same element for isotope ratios of different elements U Pb calibration constant Minimum acceptable external error os in U Pb and Th Pb ratios 1 sigma p v Inhibit initial auto rejection of Standard spot calibr constants Iv Correct for secular drift not applicable to Tasks that calcula calibration constants for both U Pb and Th Pb Secular drift smoothing window spots spots in fixed window Fixed e 10 An automatic smoothing window finds the Automatic C smallest window giving an external error larger than the minimum external error 56 Calculation of within spot scan by scan means The mean isotope ratios or Task Equation values assigned to each analyzed spot can be done ei ther by 1 Calculating the outlier resistant mean of the N 1 interpolations for the N peak scans or 2 Using an outlier resistant linear regression of the interpolated values to deter mine the value of the interpolations atg mid burn time Because in many most analyses ratios or equations involving different elements seem to in crease or decrease in a pseuo linear manner during the spot burn selecting the Linear Interpola tion option generally results in better i
93. inds the solution to a wide variety of nonlinear equations having more than one unknown In particular Solver will calculate and place in specified worksheet cells the values for one or more parameters that minimize the value in another cell Thus one could determine the values of say a b c and d that minimize the sums of squared weighted residuals or equivalently the sigma mean of a column of data thus providing a least squares solution to an column of scattered data that you wish to fit to say y ax bx cx4d To have a Task invoke Solver add a Task equation into the list of Task Equations and enter first the location of the single cell whose contents are to be minimized followed by semicolon then the location of the parameters whose values you wish to optimize Assign a name which will be ignored to the equation followed by lt lt solve gt gt Enter two worksheet range names or cell ad dresses separated by a semicolon The first of these names specifies the single cell whose con tents are to be minimized the second the range containing the parameters to adjust for example SumWtdResids CubicEquationCoefficients where SumWtdResids is the range name of the parameter to be minimized and CubicEquation Coefficients is the name of the range containing the trial values for a b c and d If the parame ters to adjust are in separate cells separate the range names or cell addressed by a comma For example SumWtdResids Coef1
94. ion for the integrations comprising a single scan of a peak SHRIMP s raw data PD file reports the secondary ion beam counts as ten integrations for each mass station regardless of the time of the integration If the median of these ten integrations is 100 SQUID 2 identifies 95 confidence outliers as being any integration whose value is out side the Poisson distribution for the 10 integration median and uses the mean of remaining inte grations If the median is 2100 counts SQUID 2 uses the Tukey s Biweight algorithm to obtain an outlier resistant mean Within spot isotope ratios If either the numerator or denominator peak of a ratio comprises fewer than 32 counts during a burn that is the sum of the peak top integrations for the n scans isotope ratios are calculated as the ratio of the sum of the peak top counts for the two isotopes rather than by interpolation Otherwise SQUID 2 calculates ratios and NU switched Task equations either regressing the double interpolated ratios 1978 versus time and takes the value of the regression at mid burn time to cancel out any secular trends during the burn The errors of individual interpolations are calculated by l f Lcd 4 f T LL 2 fi 2 ha 2 A fia fain B fab fib 1 aut AP qs 0 B hrat dia M B E Lo fib i 1 b where 40 a and b are the two peaks comprising the ratio r a b T is the time of interpolation fis the fraction of the time interva
95. it is S _ 962 B El 5 Click the Enter button which will dismiss the Select How many Charge Isotope panel then click on the yellow O xygen box ici in the periodic table Select 160 quantity 1 charge Figure 18 The Select isotope box 18 1 Click the Complete button The nuclide ionic species box should now contain ui 160 ref in the lonic species box with 195 804 as its mass to charge ratio and the active ionic species box should move down one in the list 6 Check the small ref pk box to the left of the lonic species box figure 20 so that this nuclide will be used as the reference mass for any Trim Mass graphics 7 Enter the singly charged Pb ion as the next scan order 2 ionic species mass station by se lecting Pb as the element and Pb as the isotope Click Complete again to move to scan or der 3 In PD files that this Task will process scan number 3 is the background mass of say 204 09 Because the background CERNI o mass doesn t correspond to that of any actual nuclide m c you must click the Specify mass station numerically button just above the periodic table figure 17 type in 204 09 then click OK Now check the Bkrd box to the left of the lonic species box to indicate that this mass station is to be used for background Move on to the next mass station as Clear p Specify mass station numerically Figure 19 The Specify mass numerically before box And so on Note that if t
96. l between successive integrations of peaks a or b iis the scan number index 0 and O are the counting statistic errors of peaks a and b and A and B are the interpolated values of a and b Because each pair of time adjacent interpolated ratios shares two of the four peaks used to calcu late each ratio the errors of such ratio pairs of necessarily correlated which must be taken into account when calculating the error and MSWD of the mean ratios for a spot using fp o Pr f mm to Ua ABB 5 5 tis i i ic Good approximations which assume the absence of major changes in the size of the peaks dur ing the spot burn are 2 Ll S2 S and EIE DN MiS For non negligible error correlations the general formula for the weighted mean and error must be used and 2 1 ici where Q is the variance covariance Lj matrix for the interpolated ratios r and Q indicates the element in the ith row jth column of Q If the r are uncorrelated Q is simply the diagonal matrix for the inverse variances of the r For doubly interpolated ratios however the near diagonal terms are nonzero so the variance covariance matrix is 7 QU a molii ao 0 cov n r a ij cov n r Oe 0 cov 75 73 cov r i ry 0 e cov r NA o 41 If user Preferences specify that isotope ratios be calculated as the estimated value at mid burn time via a linear regression versus time the error weighted linear regression must ag
97. l changes ME return to Task Editor U Th Pb equations 7 Ratios available PRA Discard panel changes a ms return to Task Editor Equation for 208Pb 232Th normalization Ma c 38897 E 206238 Equation for 206Pb 238U normalization 206 238 254 238 ExpoU G 2482 1 248 199 Equation for Z32Th 238U K 208248 L NENNEN E N Equation Equation for thorium concentration Oo P Constant Q R Constant cannot refer to equations defined in next panel Append INDEX s T z ratios Click a blue ratio box to insert its letter index into the active equation AGE OF PRIMARY INTEREST 206Pb 238U Use pp U ages for normalization to the age standard 208Pb 232Th Use pp Th ages for normalization to the age standard CALCULATION OF 208PB 232TH Indirectly from Th U Determine pp Th ratios by multiplying the calculated age standard normalized pp 2y by the measured 208pp9P Pb and the A Th U calculated from the defined Th U equation Directly from the age standard Determine Pb Th ratios in the same way as the 206pp 255U ratios by normalizing the results of the pp Th equation to that of the age standard 75 Equation for 206Pb 238Uconst An expression derived from the measured isotope ratios that is ideally constant for a given 206p 238 Pb U Equation for 208Pb 232Th const An expres
98. less at least 2 spots are thus defined To Group samples Process Samples as a Group Samples Spot Names Clear NEM 5 Disregard 2 a characters to show in Spot names drop down V Case Aa v Spaces a Cancel Di al I Extract groups based on spot names and v Dashes t ul place in separate worksheets OR v Sisshas i ZR JE But all spots together in a single worksheet V Periods v Commas NENNEN mi V Extract coherent age from group s V Colons EN 4 Sort worksheet rows by age v Semicolons Age Groups Common Pb Type of age C 204 corr 206Pb 238U C 204 corr 207Pb 206Pb Use Stacey Kramers ratios for 207 corr 206Pb 238U C 204 corr 208Pb 232Th VN Sun E padarei 208 corr 206Pb 238U 207 corr 208Pb 232Th Total 206Pb 238U 208 corr 207Pb 206Pb OA Grouping criteria oo 2 Min proba Min fract 4 0 50 Dus 4l bility of fit of fact al 0 60 Enter specific ratios Correction for apparent 204 overcounts on Standard No correction use measured 204Pb Force concordance of 207Pb 235U 206Pb 238U ages Force concordance of 208Pb 232Th 206Pb 238U ages v Construct concordia plots for groups if possible v Compare UO U or UO2 U or UO2 UO of Grouped spots with Std Figure 11 The Sample Grouping panel 10 e Click tin the SQUID toolbar or press the Group Me button at the top of the Sam pleData sheet e Select the number of i
99. lt confidence limit 92 Th230Age Arguments THU activity ratio UU activity ratio Output The Th U age Ka for the specified activity ratios Th230A geAndInitial Arguments 23072387 BOTU err UASU 23405 2386 err p 230 pp 2380 2346 2380 err correl errors as o level with decay const errs as atomic ratios Output A 1x5 cell range containing the Th U age Ka age error initial 2340 P38U ac tivity ratio error in Te U o error correlation between age and initial ratio Th230U238AR Arguments Age ka initial 060 activity ratio Output The TU activity ratio for the specified age and initial 775 790 ThUfromPb86 Arguments Age ma meas Pb Pb meas Pb Pb initial 9pp pp initial 208 pp 204 Pb Pb Output The Th U corresponding to the input ratios calculated assuming that the system s 5pp U and pp Th ages are concordant U234age Arguments Present day Pp U activity ratio Initial 2348y activity ratio 234 7 238 U Output The U age in Ka for the input ratios U234ageAndErr Arguments uu activity ratio 2342887 err Initial UU activity ratio error as errors Output The U 4u age Ka and error in a 1 X2 cell range U234U238AR Arguments Age ka initial 7 4 activity ratio Output The present day POS U activity ratio YorkInter Arguments xyValues amp Errors range errors in as o level 93 Output The
100. mputer Make sure that the folder in which the SQUID 2 5 folder resides is one for which you have full read write permiss ion This folder should probably not be on a network drive Add Ins available Squid2 07 07 04 08 X C Analysis ToolPak Analysis ToolPak VBA cmd Browse Automation Conditional Sum Wizard Euro Currency Tools Internet Assistant VBA Y Isoplot Ex Lookup Wizard Shows chart data labels only when mouse hovers over data point _ Solver Add in Virtualzircon43 Figure 2 With the Tools Add ins box open click Browse and navigate to the folder containing SQUID 2 5 and its compatible soplot Select the Isoplot add in click OK then OK again from the Add ins box 7 Repeat Step 6 but this time select the SQUID 2 5 add in SQUID 2 5 s splash screen should appear if installation was successful 8 Before trying out SQUID 2 close then re open Excel The compatible pair of SQUID 2 5 and soplot should now load automatically whenever Excel is opened Data Reduction for U Pb Geochronology Click in the SQUID toolbar p 36 or select Process a Pb U Th Run from the SQUID drop down list then navigate to and select the PD or XML file of interest The data reduction setup panel for U Pb geochronology will appear Fig 3 Two Run Tables will appear in the pink box at the left of the panel the first being the Run Table for the data reduction Task already in memory the second
101. ng a reasonable external error based on an experienced operator s judgment from past data sets is impor tant if the age standard has low enough count rates that the counting statistics errors mask a smaller external vari ance In such a case if the sample spots have a significantly higher count rate so that the external error is compara ble to or greater than their counting statistics errors the errors assigned by SQUID to the sample spots will be un derestimated so that even well behaved age equivalent spots will not yield a statistically coherent Group standard spots can then if desired be used to correct 204Pb measurements for all of the Sample spots when the samples are Grouped p 9 The output columns related to calculation or 204 overcounts are shown in Fig 10 The SampleData Sheet As in SQUID 1 the Sample sheet contains the basic raw and processed data for all spots but those of the Age Standard For U Pb geochronology the Sample Sheet is to be used only as an intermediate step in producing the final Grouped Sample worksheets Sample Grouping and Age Extraction Data reduction for U Pb geochronology is not complete until the sample spot data has been grouped by spot name Group names are selected from one or more of six drop down lists con taining all Spot names trimmed to the number of initial characters shown in of characters spinner box red arrow fig 11 The dropdown lists will not show spot name fragments un
102. nitial spot name characters to define a Group red arrow below e Indicate whether case is significant in the name fragments and whether or not to ignore spaces dashes slashes when identifying name fragment matches e Specify from 1 to 6 spot name groups e Indicate if a statistically coherent age group is to be extracted from each spot name group e If age grouping is requested then e Indicate whether the data rows in each grouped sample worksheet should be sorted by spot age e Specify the type of age to use for age grouping the criteria that define an age group and whether to construct a concordia plot inset for the spot group e Specify the method of correction if any for Pb overcounts No correction is recommended unless you have a good understanding of the concept e Define the common Pb ratios for the groups Correcting U Pb Geochronology data for Secular Drift of Age Standard Spots Normally the calibration constant e g Pb U UO O measured for the differ ent Pb U or Pb Th age standard is expected to remain within some statistical scatter constant during the length of the analytical session so that extracting the true Pb U or Pb Th ratios of samples is a simple matter of normalizing the sample calibration con stant to the average value of the Standard spots If however the analyst can plainly see a trend in the Standard calibration con stants whether monotonic or cyclic it is C
103. nternal within spot precision It can be argued that for consistency other ratios or equations should be treated similarly U Pb calibration constant MINIMUM ACCEPTABLE EXTERNAL ERROR IN U PB AND TH PB RATIOS 1 SIGMA SQUID 2 always calculates the most probable external that is in addition to counting statistics error spot to spot error for the calibration constants of a U Pb Task If the Age Standard yields rather low count rates for Pb statistical resolution of any external error is poor so that an appar ent external error of zero is possible If you believe that some external error is always present in SHRIMP U Pb analyses you may wish to specify a lower bound for the external error regard less of the statistical calculation The external error is included in the error assigned to sample spot U Pb ages so is important to consider carefully INHIBIT INITIAL AUTO REJECTION OF STANDARD SPOT CALIBRATION CONSTANTS If this box is unchecked SQUID 2 will attempt to reject obvious outliers subject to later user revision before calculating the weighted mean calibration constant Check the box to inhibit such rejection CORRECT FOR SECULAR DRIFT If the calibration constant displays an obvious drift or variation with time whether monotonic of cyclic you can correct the sample spots for the observed drift by clicking this box SECULAR DRIFT SMOOTHING WINDOW SPOTS The secular drift curve is calculated via the LOWESS algorithm
104. nterpolation in cyclical data collection J Phys E Sci Instrum 11 296 Cleveland W S 1979 Robust locally weighted regression and smoothing scatterplots J Amer Statist Assn 74 829 836 Hoaglin D C Mosteller F and Tukey J W 1983 Understanding Robust and Exploratory Data Analysis John Wiley and Sons 345 349 Ludwig K R 1998 On the treatment of concordant uranium lead ages Geochim Cosmochim Acta 62 665 676 Ludwig K R 2001 SQUID 1 02 A User s Manual Berkeley Geochr Ctr Spec Pub 2 Ludwig K R 2003 Isoplot 3 A Geochronological Toolkit for Microsoft Excel rev August 27 2003 Berkeley Geochr Ctr Spec Pub 4 McIntyre G A Brooks C Compston W and Turek A 1966 The statistical assessment of Rb Sr isochrons J Geophys Res 71 5459 5468 Stacey J S and Kramers J D 1975 Approximation of terrestrial lead isotope evolution by a two stage model Earth Planet Sci Lett 26 207 221 Titterington D M and Halliday A N 1979 On the fitting of parallel isochrons and the method of maximum likelihood Chem Geol 26 183 195 Vugrinovich R G 1981 J Math Geol 13 443 454 Index 204 corr 206Pb 238U sss 63 207 corr 206Pb 238U esses 63 obi SPB doe o omitti 5 59 63 208 corr 206Pb 238U sues 63 Age Standard 5 8 9 31 AR SW T der n reete bes 25 27 76 Fl With ais 25 ARrc switch
105. ntervals of the specified axis Starts at O Set the lower bounds of the specified axis at zero SQUID determines the upper bound Log Use logarithmic scaling for the specified axis 78 Calculations X Y REGRESSION Determine and plot an outlier resistant best fit line to the data None Don t perform any calculations Y mean Calculate and plot the outlier resistant mean of the y values and make hours the x axis Back Save any changes to the Auto Charts panel then go back to the previous Equations panel Return Save any changes to the Auto Charts panel then return to the main Task Editor panel Cancel Discard any changes to the Auto Charts panel and return to the main Task Editor panel 79 Constants Constants for User Equations x Append 1 Lambda230ka 00919525 to Eqn 1 2 Lambda232 000049475 3 Lambda232ka 000000049475 4 Lambda234ka 002834 Edit 5 Lambda235 00098485 6 Lambda238 000155125 7 Lambda238ka 000000155125 Add new 8 NatUrat 137 88 Delete Define constant EJ Exit Lambda230kal 00919525 Name Value Edit Change the name and or value of the selected constant Add new Add a new constant Delete Delete the selected constant Exit Close the Constants panel Append to Eqn 1 Place the constant at the end of the active equation Zircon CANONICAL ANU 9 PEAKS Run Table togo E E E toreo Al Example Tasks Task Equations Auto Charts 80 ZIRCON
106. nywhere on the Windows desktop not the Parallels or Fusion desktop and select Proper ties then Settings If possible set the resolution to either 1440 x 830 or 1920 x 1200 pixels Remove or rename all existing SQUID and Isoplot add in file on your computer Excel tends to copy add in files to its own folders so you must to a complete search of your hard disks including wmat Tools Data Window Help Full Screen El ER jv Speling F7 Hidden and System files to make sure that Excel will not screw A M aisat everything up by having multiple incompatible copies of Isoplot EE and SQUID loaded at the same time m Track Changes bi Start Excel 2003 If you find that Excel has automatically loaded either Isoplot or SQUID close Excel and go back to step 2 oe Goal Seek Select Tools Add ins from the Excel toolbar at the top of Excel s Scenarios window Figs 1 2 Check any boxes labeled soplot or SQUID E in the Add ins list Excel should display a message each time say AutoCorrect Options ing that the add in can t be found and asking if the soplot or SQUID add in should be deleted from its list Click Yes If such a message does not appear close Excel and go back to step 2 Customize Options Figure 1 Transfer the SQUID 2 5 folder CE hl 3 x containing the matched pair of SQUID 2 5 and Isoplot 3 7 add ins the SquidUser folder and the SQUID 2 5 manual to your co
107. ork sheet Compare UO U or UO2 U or UO2 UO of Grouped spots sith std Construct a chart inset in each Grouped Spots sheet showing the UO UO ratio for the Stan dard and in a different color the Grouped spots Values of n and m can range from 0 to 2 and depend on what was measured for the spots 65 Time Window Limits to specify with Standard spots Lower first only Ignore spot analyses acquired before the Starting spot process all spots after Upper last only Ignore spot analyses acquired after the Ending spot process all spots before Both lower and upper Ignore spot analyses acquired before the Starting spot and after the ending spot No window reduce all spots Cancel the Time Window Starting Name Time The first spot to process For U Pb geochronology restricted to age standards Ending Name Time The last spot to process For U Pb geochronology restricted to age standards Standard spots that bracket the window m Limits to specify with Standard spots Lower first only Upper last only No window reduce all spots Name Time Starting r33 1 1 2005 05 02 10 28 e Ending r33 24 1 2005 05 03 09 04 Figure 29 The Time Window panel Subsets See instructions in the blue box at the top left of the form below Scope of user parameters spots for which equations will be applied 66 67 Copy or Rename a Task Rename and Copy a task
108. orrect for secular drift not applicable to Tasks that calculate calibration constants for both U Pb and Th Pb Secular drift smoothing window spots spots in fixed window Eixed 10 m An automatic smoothing window finds the Automatic 7 smallest window giving an external error larger than the minimum external error Figure 12 Setting parameters for correction of secular drift of the U Pb calibration constant Preferences panel possible that the Sample spots will have been similarly affected SQUID 2 provides a very flex ible tuneable assumption independent method for dealing with such cases enabled by checking the secular drift box right in the Preferences Interpolation panel p 52 If the user has selected Specified the secular drift correction algorithm starts by fitting an outli er resistant smoothed spline curve a LOWESS fit Cleveland 1979 to the Standard calibration constants using a moving window for smoothing comprising the specified number of spots In stead of the usual weighted average chart SQUID 2 will then construct a chart showing the rela 11 tive change of the calibration constant versus spot time and the corresponding smoothed spline curve Calibr const drift Calibr const drift Hours Hours Figure 13 Showing the effect of different smoothing window widths yellow boxes in number of spots on the secular drift curve of th
109. ping x Samples Spot Names Clear El sch a Disregard characters to show in b su gt tna sad Vom ta Lu vY nu Ea a v Dashes EP Extract groups based on spot names and B E place in separate worksheets or Y Slashes i ZRD bb C putall spots together in a single worksheet v Periods 7 d aM i V Extract coherent age from group s Y Colons C l mj Sort worksheet rows by age v Semicolons Age Groups Type of age 204 corr 206Pb 238U 204 corr 207Pb 206Pb Common Pb Use Stacey Kramers ratios for the age type selected at left 8 207 corr 206Pb 238U C 204 corr 208Pb 232Th r 208 corr 206Pb 238U 207 corr 208Pb 232Th Total 206r6 238U 288 corr 207Pb 206Pb OR Grouping criteria Enter specific ratios o0 Min proba Min fract 4 oso E ae i bility of fit of fact 18 Dien 18 3 206 204 Correction for apparent 204 overcounts on Standard 0 8536 207 206 No correction use measured 204Pb Force concordance of 207Pb 235U 206Pb 238U ages 2 093 208 206 Force concordance of 208Pb 232Th 206Pb 238U ages Construct concordia plots for groups if possible Compare UO U or UO2 U or UO2 UO of Grouped spots with Std Spot Names From any of the 6 spot name dropdowns select from 1 to 6 spot name fragments to use as a se lection criterion for each group Only the initial number of characters shown in the dropdown will be used l
110. plot insets 0232 0 43 0825 0 17 0745 025 0 00399 0 39 0 371 0 38 0 825 0 11 0 747 0 19 0 00399 0 34 e g Log UO U versus Log Pb U each linked to 0 259 0 42 0 825 0 13 0 753 0 23 0 00394 0 29 one or two of the data columns p 30 Wtd Mean of Std Pb U calibr 0 00395 1c error of mean 0 21 Redo D 10 external spot to spot error 0 90 e A minimum Pb U external error can be assigned to iut MB FN the Age Standard in the Preferences panel p 52 rejected spot s 1 20 For visualization amp preliminary evaluation only e Automatically generated Concordia plots for Figure 9 Portion of StandardData worksheet showing the Age Standard data can be requested p the U Pb calibration columns 53 e A correction can be applied for obvious secular drift of the Standard calibration constant p 10 CORRECTION FOR OVERCOUNTS ON Pp augen quor 206Pb 206Pb SQUID will attempt to quantitatively assess the presence of non SAFE USER iaae qosB 204 204 e i s 208Pb 206Pb const const Pb counts at the Pb mass position by 1 assuming precise con fr 207 fr 208 delta deltat cordance of the Pb 8U 7 Pb U ages and also 2 assuming PE precise concordance of the 205 pp P35r pp Pr ages The resis overcts overcts jsec sec fr 207 fr 208 tant mean value of the calculated 204 overcounts on the age Figure 10 Column headers for 204 overcounts on the U Pb age standard Assigni
111. r tn cedo ena 71 rl ne 71 Delete te eati ausente a IMMENSE 71 ur uan EE 71 Clearallz etta i I iecit eot er tra IT eti 71 THE ISOTOPE SELECTION SUB PANEL 3 2 teinte tei pez ete aee epe TO e slab t TE Te de RO ia 72 HOW many 5e eta east Sean o e D ta ud ege Aa EU 72 A eate qe m Ou e m ROTG een e o ede m etes 72 ENO ad M 72 Complete EP 72 ISOTOPE RATIOS EE CD M En 73 Ratios from mass stations at left cti eee etti teen I cosatctstvesvansWuadacbacdetces eR Yt Pane een ede ARIS 73 noo a 73 BGK qa X 73 NT AEE E E E 73 U PB SPECIAL EQUATIONS ainan e ce e e VO er EE rere rere per t E 74 Equation for 206Pb 238U CONSE 5 i tede A 75 Equation fJor 208PD 232Th const A A A E e e ede e tere 75 2321h 238 UC GUA ene tp ei DU etenim peg 75 Equation for PPT U o Rie CR Rr DUE ende IS 75 nan C IO 75 Id cT ewe ge ev en ew nen vee tet 75 ROUT es see E Se ages a es EROR Ma EUM 75 O7 Ta em 75 2o 75 Append COnstant 4 os ee D P HO ed ER EE RT RE EE HE epe Le 75 Append LITERAE TAMOS a TUI Hd eres 75 Append INDEX of ratios tn besado 75 GENERAL EQUATIONS 4 2 ene RARE MB NUI E iii 76 Next previous quation spinner iie tm a te idea es
112. rols Preferences General panel Preferences x General Common Pb Interpolation U Pb Standards v Show splash screen at at startup Reduced data workbook j um Cancel Retain nonessential rows of PD or XML files file length permitting Place data reduction parameters in a separate worksheet Help Place Task autocharts in a separate worksheet Attach Task sheet to reduced data workbook Rebuild Task Catalog file EN E v Ereeze header row and spot name column Special output columns U Pb only v 207 corrected 208Pb 232Th ages v 208 corrected Concord ia plot ratios and 207Pb 206Pb ages Chart insets V Create Concordia plots for U Pb Age Standards U Pb geachron only v Always create a worksheet containing the scan by scan isotope ratios v Set Y axis minimum on isotope ratio plots to zero Maximum permitted mass difference ppm between measured 400 and true nuclide masses to recognize 2 peaks as the same 4000 Default folder for PD and XML files C Documents and Settings KRL Desktop Squid Desktop Xla Show splash screen at startup Display the SQUID 2 splash screen when the SQUID 2 add in is installed Retain nonessential rows of PD or XML files file length permitting If this box is checked the entire original PD or XML file will be retained in the hidden col umns A of the condensed raw data worksheet Because this will slow construction of the con densed sheet somewhat
113. s 2 General Isotope data 13 20 A ep R 9 63 XML Mesias 7 BEOUBID ES O 9 grouping spots by sample name 62 63 Hidden CPS columns uti 71 ionic Species BOK Siesta 18 ionic dpecies niei eio ort tenen us 17 index isotope for common Pb correction 63 Input Data Flles s aee erred ed 2 ionic species DOX iii 17 18 Tonic Species DOX criba 70 Isoplot 2 24 25 30 88 94 96 99 TSOCOPS FAO iii 23 isotope ratios panel sssss 19 Isotope ratio equation charts 34 Isotope ROS vicios 73 75 TT EA us tym darte eis 24 LA Witch 23 24 26 76 Literal references to ratios or equations 21 Mac mtosIiz cette bic eres 2 mass stations sesser 14 18 73 nominal 11358 aii eit t etate 18 Nonlinear equations eeeeees 33 normalizing equation s es 28 NUS mitra ita 24 NUMET C MASS 2 2 ecd sd is 17 18 OVerCOUDtS sieisen i iieii ense 9 64 PALO EL 2 Parallels Windows emulator for Macintosh m TEN 2 Parallels program iier eure 2 A Hg Hen 18 PII Aaa 53 PI TSS etr dern B RUNS 2 7 14 A dira ae UR Reto nde 8 Preferences 5 6 8 34 52 59 60 61 64 95 Printer Setup iie eren Re POM RR 2 RAM RM Ea T Ea Maen 2 Raw data Iles Jie eot asceds 7 Reference peak etes 13 Reference peak trim mass 13 TE SESSION esas tases tro edt as 30 31 78 rejection manual o uso etie eris 35 Run EUR 14 Run Tabl
114. sheets but otherwise is unimportant To enter a ratio e Click on a blue ratio box figure 21 to activate it its color will change from blue to orange when activated e Click on one of the nominal masses in the green boxes to the left say 204 to use as the nu merator of the ratio e Click on another of the green boxes to select the denominator isotope say 206 giving 204 206 in the ratio box whose color will have changed back to blue e To clear the ratio box and start over click it a third time e The ratio boxes don t have to be all filled in sequence empty boxes are ignored Step 2 specify isotope ratios Click on a blue ratio box to activate or clear it then click on the green mass boxes numerator then denominator to create the ratio Mass Stations Ratios from mass stations at left mE mem A x7 peg CERE ees Pag Cm BEER ees Gana p SCE 1 rmm eg tE 3L A A EL LS NEED E ME E e a A B EE me E ms oe 0 LL EE EEEEN 000 2 as fee 0 01 s 7 sl Figure 21 The Isotope Ratios panel User defined equations zl Next previous equation Switches Index Equations La eese MET EET 1 MT a NN Y 1 Matte i To append an Equation reference Click its index left of equation Figure 22 The General Equations
115. sion derived from the measured isotope ratios that is ideally constant for a given 208 pp 2327 232Th 238U equation An expression derived from the measured isotope ratios that yields the true 23278 Equation for ppm U An expression derived from the measured isotope ratios that is ideally constant for a given ura nium concentration Next Save any changes to the U Pb equations panel then go to the next panel equations Back Save any changes to the U Pb equations panel then go back to the previous Isotope Ratios panel Return Save any changes to the U Pb equations panel then return to the main Task Editor panel Cancel Discard any changes to the U Pb equations panel and return to the main Task Editor panel Help Display detailed information about Task Equations and Switches Append constant Select and or edit a constant from the dropdown list of defined User Constants and append to the active equation Append LITERAL ratios When an isotope ratio box is clicked append the literal ratio to the active equation rather than its number Append INDEX of ratios When an isotope ratio box is clicked append its index letter to the active equation rather than the literal ratio 76 General Equations User defined equations E E x Next previous equation Switc
116. t The external 1 sigma error required to account for the presence of extra scatter that 1s not accounted for by the assigned errors of the Values 90 HalfLife Arguments IntegralNuclideMass InMyr Output The half life of the nuclide in years default or millions of years InitU234U238 Arguments Age Ka meas eui UE U activity ratio Output The corresponding initial UU activity ratio La230 La232 La234 La235 La238 Arguments None Output The decay constant in years of 230Th 232 Th ZI 233 U or TATE respectively Lambda Argument Integral nuclide mass Output The decay constant in years of the indicated nuclide Log10 Argument Value Output The corresponding base 10 logarithm Mad Argument Numeric range Output The median absolute deviation from the median of the range MSWD Arguments ValuesAndErrors 2 column range PercentErrs False SigmaLevel 1 Output The MSWD mean square of weighted deviates parameter for the weighted average of ValuesAndErrors NukeMass Arguments Nuclide significant figures Output Mass of the nuclide C 12 000 Pb76 Argument Age ma 9 Output The radiogenic 2 Pb 6pp for that age ProbFit Arguments ValuesAndErrors range PercentErrs False SigmaLevel 1 Output The probability that the assigned errors will yield at least the amount of observed scatter of the Values RobReg Arguments x range y range with
117. tion is a user defined Task equation that will operate only on a subset of the spots in the PD file where the subset is defined by the initial characters of the spot names This can be very useful for example if one wishes to know the mean U concentration of just those spots whose names start with MG Subsets can be assigned either by the data reduction Task p 37 or at the time of data reduction by clicking the Subsets button on the data reduction panel Scope of user parameters spots for which equations will be applied To restrict the application of any equation to a subgroup of spots that share the first few letters of their names 1 Specify using the of initial spinner the number of initial spot name characters that are shared by the subgroup for example 2 for all spots whose names start with say SW 2 Select from the Trimmed spot names the first N letters that define the subgroup say SW where N is the number specified in the spinner box above 3 Click on the yellow box corresponding to the name of the equation whose application is to be restricted only those spots whose names start with say SW Click the box again to cancel the action SUBSET EQUATIONS DO NOT APPLY TO AGE STANDARD SPOTS Figure 28 The Subset panel for specifying subset equations at the time of data reduction 33 Invoking Excel s Solver as part of a Task Excel includes a powerful Solver add in that numerically f
118. tivate or clear it then click on the Save changes green mass boxes numerator then denominator to create the ratio mE go to U Pb eans Mass Stations Ratios from mass stations at left Back Discerd panel changes d go back to Run Table Retain panel changes return to Task Editor Discard panel changes return to Task Editor Help e m o gt A AS x x Ratios from mass stations at left To specify the calculation of an isotope ratio 1 click on one of the blue isotope ratio boxes to activate it turns tan 2 click on one of the green boxes to left to specify the numerator isotope of the ratio 3 click on the denominator isotope To clear ratio box click it a second time Next Save any changes to the Isotope Ratios panel then go to the next panel equations Back Save any changes to the Isotope Ratios panel then return to the main Task Editor panel Cancel Discard any changes to the Isotope Ratios panel and return to the main Task Editor panel 74 U Pb Special Equations Equations specifically for U Th Pb geochronology x Age of primary interest _ _ _ _ __ __ _ __ _ _ _ ___ _ Rea parle 206Pb 238U 208Pb 232Th Ses go to General eqns Back Discard panel changes Calculation of 208Pb 232Th _ cg xS ga back to isotope ratios Return Indirectly from 232Th 238U Directly from the the age standard eturr Retain pane
119. ttp www shainin com BGC is not affiliated with Red X Holdings LC Isoplot is a registered trademark of Red X Holdings and is licensed to Shainin LLC At present SQUID is not compatible with Excel 2007 Hardware WINDOWS A mid or high range CPU gt 1 Ghz non Celeron dual core preferred and 2 Gb or more RAM is recommended The screen resolution should be at least 1280x800 EMULATED WINDOWS UNDER MACINTOSH OS X At least two of the several programs enabling running of Windows on an Intel Mac at least two Parallels and Fusion seem to work very well with virtually no speed penalty compared to Windows Crossover cannot run soplot or SQUID Before installing SQUID on your Mac please ensure that your screen resolution is adequate For wide screen desktops set your screen resolution from Windows right click anywhere on the desktop select Properties Settings to about 1920x1200 For laptops or smaller desktop screens use 1440x830 if possible Printer Setup Upon first installation of Excel a printer must be selected via Page Setup before running SQUID 2 or Isoplot and the page size must be set to Letter or A4 Input Data Files SQUID 2 5 only processes PD or XML files for a single ion counting collector Installation l If you re running Windows from an Intel Mac under Fusion Parallels is incompatible you must set Windows screen resolution to somewhat higher than the default setting Right click a
120. uct charts of cps versus time for all spots in both the StandardData and SampleData worksheets for all of the mass stations m y Freeze the active worksheet by replacing all cell formulae with their numeric results Vi Freeze all of the worksheets in the workbook Make a publication type table from the processed U Pb geochronology data Widen all columns of the worksheet by 1 point Narrow all columns of the worksheet by 1 point Update all SQUID and Isoplot references to the currently installed versions Quit SQUID 2 uninstall the SQUID add in You can re install SQUID 2 at any time Unhide Rehide toggle for hidden columns in SQUID 2 s SampleData and StandardData sheets cmo Show this description of the toolbar buttons 37 Appendix Il Algorithms Used by SQUID 2 Weighted averages means Internal and External errors The term weighted average is generally used to imply a mean weighted by the inverse variance variance 07 of the assigned errors to each data point so for N data points N 2 N 2 X es 1 o i with the internal error on x that is the error propagated from just the N calculated as The MSWD parameter Two extremely useful parameters associated with the error weighted average are the MSWD and probability of fit MSWD mean square of weighted deviates is defined as the mean of the N inverse variance weighted residuals residual 2 measured x minus wei
121. ular needs of this type of analysis In this panel you will specify e Which parent daughter pair is the one of primary interest 96pp 238 j or 208pp 23 Th 28 e Whether you want the Th U calculated directly by an equation that you specify or indirectly from calculated 22659387 and Pb Th ratios As well as e The normalizing equation to use for Pb U or Pb Th e Either the normalizing equation to use for Pb Th direct calculation of Pb Th or an equa tion to calculate Th U from the isotope ratios defined in the isotope ratio panel and e The normalizing equation for U or Th from a concentration standard By normalizing equation I mean an expression whose numeric value remains constant for the parameter of interest Thus in the present example Pb U UO UY is expected to be constant during the analytical session for any given value of Pb U and U Zr UO IU yos should be constant for any given U Zr the proxy for U Swapping data columns with U Pb Geochronology Tasks For U Pb geochronology data SQUID produces several data columns having to do with calibra tion constants radiogenic isotope ratios and U Pb ages that are produced in addition to and inde pendent of any Task equations Most of these data columns reference one or more of the isotope ratio columns which cannot normally be directly modified by Task equations thus limiting the ability of the user to compensate for factors such as iso
122. urn to Task Editor Clear e None 52 gt Autoscale C Startsato Log X Y regression Y Autoscale C Startsat0 C Log Ce Clear Els al Autoscale C StartsatO C Log None X Y regression e Autoscale C StartsatO Log ranean Autscale C StartsatO Log None C X Y regression Autoscale C Starts atO C Log Clrmen Figure 26 The Auto Charts panel In figure 26 above for example the results of the two user defined equations corresponding to Ln Pb 2 U versus Ln 254 238 are plotted as well as the line and numeric results of the x y regression Normally Autocharts will be placed on the reduced data worksheet of the spots themselves will be placed on the Standards reduced data sheet Setting a Time Window for spots Standard spots that bracket the window m Limits to specify with Standard spots Data reduction can be restricted to any sequentially meas C Lower first only ured series of spots For U Pb geochronology the series Upper last only of spots is defined by the bracketing Age Standards For General Isotope data the time window is defined by any pair of bracketing spots No window reduce all spots Name Time Starting r33 1 1 2005 05 02 10 28 Ending 133 24 1 2005 05 03 09 04 Figure 27 The Time Window panel 32 Specifying Subset restricted equations at the time of Data Reduction A subset restricted equa
123. written Restricting equations to subsets of spots The operation of a Task equation can be restricted to a specific suite of spots that like the Age Standard spots can be grouped by the first few characters of their spot names Subset restricted equations can be defined either at the time of data reduction p 29 or as part of the Task equa tions When a Task equation is restricted to a subset of spots cells in the equation s output col umn will be empty for all spots but those in the subset Subset restricted equations are normally defined along with the data reduction Task p 26 You can however also restrict any equation to a spot subset at the time of data reduction which is convenient if the names of the subset spots tends to vary from one PD file to another Instruc tions are within the panel itself Spot subsets are defined for a Task equation by appending the appropriate spot name fragment to the Equation Name enclosed in curly braces e g Mean 207Pb 206Pb rad qgng Spot subsets are useful when you want to use certain spots as a normalizing standard for some parameter For example suppose that for U Pb geochronology data you wish to correct Pb iso tope ratios for mass fractionation and that you have included in the grain mount a secondary standard say RRhy with a known 27 pp pp the Age Standard 2 pp 6pp being insufficien tly precise To do this one could 1 Add an equation consisting simply of the SampleData
124. y function 230ThAgeAndError occupies up to 5 contiguous cells in the same row comprising Age age initial ZU oad OF initial age initial error correlation Other array functions may occupy say a 2 column by 5 row range You must therefore specify the number of rows and columns in the output sheets that SQUID 2 will need to reserve To do this enter first the number of rows 1 to 9 then the number of columns 1 to 9 in one of the Equation panel s AR rows cols boxes without spaces or commas for example as 24 to indi cate a 2 row by 4 column output range If the array function s output range occupies both multiple rows and multiple columns the out put cells can be referred to by other equations by their assigned name plus the characters for the rows and columns For example the second row first column of a 3 row by 2 column array function output named ThAge would be named ThAge21 See p 22 regarding other nam ing conventions for Array equations If for an Array equation you specify fewer rows or columns than the maximum possible for the equation e g 2 rows 1 column instead of the 3 rows by 2 columns that the Array function in the equation s can populate only the that number of rows columns will be occupied in SQUID 2 s reduced data worksheet 26 The above description of how to use Array Functions is admittedly inadequate but should be enough to allow you to experiment until better documentation is
125. y to outliers e Use the Min and Max functions to restrict the range of an output e g Min 3 Max 1 Median CalibrSlope to force CalibrSlope within the range of 1 and 3 e To deal with initial disequilibrium in the U or U decay chains use one of the rele vant Isoplot functions p 89 DisEq68Age DisEq68Ratio DisEq75Age DisEq75Ratio DisEqPbPbAge DisEq76Ratio The Autocharts Panel The final panel in the definition of a Task is for Auto Charts figure 26 Auto Charts are simple x y or weighted average plots of any of SQUID 2 s output sheets that are placed as insets in the these sheets Up to 8 Autocharts p 30 can be requested You can choose the x and if not a weighted average plot y axes from any of the output sheet s column headers using the x y drop down You may also request that an outlier resistant linear regression be calculated and plotted for x y data or an outlier resistant mean for just the y data If Y mean is selected the x axis is always Hours For U Pb geochronology Tasks Autocharts will be created only for the age standard spots Auto Chart insets x PERE Retain panel changes Chart Column headers Axis scaling Calculations sis return to Task Editor E Discard panel changes Back 5 F o Back ta Gen PGMs m Ln UoJU Autoscale C Statsat Log C None so Baek ty General se v up El 8 Y regression PE Discard panel changes Ln Pb U 8 Autoscale C Statsat C Log LES ees ret

A User`s Manual - Berkeley Geochronology Center

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