Data Tables

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ID	Temp	40Ar/39Ar	37Ar/39Ar	36Ar/39Ar	39ArK	K/Ca	40Ar*	39Ar	Age	±1s
	(°C)			(x 10-3)	(x 10-15 mol)		(%)	(%)	(Ma)	(Ma)
Sample ABC123, 10.15 mg biotite, J=0.004321, Lab#=4567-89
A	700	28.44	0.0666	79.51	0.581	7.7	17.3	0.6	29	12
B	800	14.38	0.0127	13.61	4.52	40.2	71.8	5.5	59.45	0.85
C	920	11.64	0.0052	2.001	13.7	98.9	94.7	20.3	63.37	0.27
D	1000	11.46	0.0045	1.517	10.1	114.5	95.9	31.2	63.14	0.32
E	1075	11.62	0.0102	2.217	8.47	49.8	94.1	40.3	62.87	0.39
F	1110	11.45	0.0137	1.719	5.57	37.1	95.3	46.3	62.73	0.56
G	1180	11.47	0.0413	1.363	13.3	12.3	96.3	60.6	63.45	0.26
H	1210	11.27	0.0547	0.6794	19.3	9.3	98.0	81.4	63.46	0.20
I	1250	11.24	0.0457	0.4782	16.5	11.2	98.5	99.3	63.64	0.21
J	1300	11.57	0.0231	2.289	0.665	22.1	93.9	100.0	62.5	4.3
total gas age			n=10		92.8	41.8			62.92	0.41
plateau		MSWD=0.8	n=8	steps C-J	87.7	42.1		94.5	63.39	0.20*
Notes:
Isotopic ratios corrected for blank, radioactive decay, and mass discrimination, not corrected for interferring reactions.
Individual analyses show analytical error only; plateau and total gas age errors include error in J and irradiation parameters.
Analyses in italics are excluded from final age calculations.
n= number of heating steps
K/Ca = molar ratio calculated from reactor produced 39ArK and 37ArCa.
* 2s error
** MSWD outside of 95% confidence interval

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Properties of a Data Table:

1. The first column in the data table is the analysis identification (ID). The letter is assigned to each progressively hotter temperature step as a sample is heated in the furnace. This post-script is appended to the unique laboratory number assigned to each sample. In this example, the laboratory number (Lab#) is 4567-89, so the first heating step would read 4567-89A (700°C).
2. Column 2 is the set-point temperature (in degrees centrigrade) of the furnace for each heating step. Typically, we start degassing samples at about 500-700 degrees and increase the temperature approximately 100°C per heating step. The "heating schedule" varies depending upon what type of material is being analyzed and how much information we are trying to obtain.
3. Column 3 is the ⁴⁰Ar/³⁹Ar ratio of each single analysis (heating step). This ratio is the primary ratio for determining the age of a sample. This ratio is corrected for extraction line and mass spectrometer blank, any radioactive decay that may have occurred since the neutron irradiation and mass discrimination of the mass spectrometer. It is not corrected for interference isotopes produced during irradiation.
4. Column 4 is the ³⁷Ar/³⁹Ar ratio of each single analysis (heating step). This ratio is useful for correcting against nuclear interference reactions (specifically ³⁹Ar_K produced from calcium) and determining the Ca/K ratio of an analysis. This ratio is corrected for extraction line and mass spectrometer blank, any radioactive decay that may have occurred since irradiation and mass discrimination of the mass spectrometer. It is not corrected for interference isotopes produced during irradiation.
5. Column 5 is the ³⁶Ar/³⁹Ar ratio of each single analysis (heating step). This ratio is necessary for determining the radiogenic yield of each analysis (based on the amount of ³⁹Ar_K and the ⁴⁰Ar/³⁹Ar ratio). This ratio is corrected for extraction line and mass spectrometer blank, any radioactive decay that may have occurred since irradiation and mass discrimination of the mass spectrometer. It is not corrected for interference isotopes produced during irradiation.
6. Column 6 is the amount of ³⁹Ar_K (moles) released for each single analysis (heating step). This value is necessary for determing the number of moles of ⁴⁰Ar (radiogenic and atmospheric), ³⁷Ar (total) and ³⁶Ar (atmospheric) of each analysis. Total ³⁹Ar_K (moles) is also given for the entire sample (total gas age row) and any defined plateau (plateau row). This value is corrected for extraction line and mass spectrometer blank as well as radioactive decay, mass discrimination and interference reactions.
7. Column 7 is the K/Ca ratio for each single analysis (heating step). This value is calculated from the corrected ratio ³⁹Ar_K/37Ar_Ca. This ratio is useful for determining what mineral phases may be degassing at certain temperatures. Cl/K ratios are also occasionally listed on data tables. The Cl/K ratio is calculated from the ³⁸Ar_Cl/³⁹Ar_K ratio and is also useful for determining what mineral phases may be degassing at certain temperatures.
8. Column 8 is the radiogenic ⁴⁰Ar (⁴⁰Ar*) yield for each single analysis (heating step). This is determined by subtracting the atmospheric ⁴⁰Ar component from the total ⁴⁰Ar measured by the mass spectrometer (correcting for blank, mass discrimination and interference reactions).
9. Column 9 is the percent ³⁹Ar_K(³⁹Ar %) released for each single analysis (heating step). This number is calculated dividing the ³⁹Ar value from a given analysis (heating step) by the total ³⁹Ar released for the whole sample and summing the result with all of the previous single analyses (heating steps). This provides a "running total" of the ³⁹Ar released from a given sample. This is the same value that is plotted on the x-axis of an age spectrum. This column is useful for determining the temperature(s) of predominant argon release.
10. Column 10 is the Age of each single analysis (heating step). This number is calculated from the ⁴⁰Ar/³⁹Ar age equation (see Methodology for details).
11. Column 11 is the Error (±1s Ma) of each single analysis (heating step). This is the one-sigma error calculated for each analysis from analytical uncertainties only. This value does not include the uncertainty in J-value or nuclear interference reactions.
    

Additional information:

total gas age - this row provides the mean age of all of the individual analyses (heating steps). Total gas ages and errors calculated by weighting individual steps by the fraction of ³⁹Ar released. This age/error is analogous to a conventional K/Ar age determination. Other information in this row include the number of steps included in the weighted mean (n=10), the total moles of ³⁹Ar_K contained within the sample and the mean K/Ca ratio for the sample.

plateau - this row provides the mean age of those individual analyses specified by the geochronologist. Plateau weighted mean ages are calculated by weighting each age analysis by the inverse of the variance. Weighted mean error calculated using the method of (Taylor, 1982). Plateau must comprise at least two contiguous steps. Beyond this requirement, different ⁴⁰Ar/³⁹Ar laboratories have different criteria for defining plateau segments. Other information in this row include the MSWD (calculated for n-1 degrees of freedom using method of Mahon, 1996), the number of steps included in the plateau age, the steps (ID) included in the plateau age, the moles of ³⁹Ar_K contained within the plateau, the mean K/Ca ratio for the plateau and the cumulative percent ³⁹Ar_K released for the plateau.

Notes: - these rows include any additional information the geochronologist would like to provide about the dated sample (eg. isotopic ratio correction factors, calculation methods for errors, mass spectrometer settings, etc.).