Ar-Ar Labshare
This page is for the promotion of sharing and cooperation between labs united under the common goals of EARTHTIME. It should be used for the posting of longer technique-oriented papers, data templates, suggestions etc. Dialogue should still be done on the FORUM page. Please submit content for this page to Sam Bowring
Fire Clay tonstein
Sidney Hemming reports on an inter-laboratory experiment on sanidine from the Fire Clay tonstein. A summary of her talk presented at 2012 Goldschmidt is located here.
A recent NSF sponsored 40Ar/39Ar intercalibration experiment revealed discrepancies significantly greater that what would be expected given the reported analytical uncertainties. To try and better understand the discrepancies, a pipette system, that will allow participating labs to measure gas samples with exactly the same isotopic composition and similar gas volumes, will travel from lab to lab. We now have a blog that will serve as a place to talk and discuss the device as it is constructed and circulated.
A new EARTHTIME tool is now available for recalculating Ar-Ar dates in light of new decay constants and fluence monitors. A detailed description of the methodology is located here. The tool itself is here.
Alder Creek sanidine available
This 1.19 Ma 40Ar/39Ar standard is in large scale preparation for distribution to interested labs. Small aliquots (ca. 5 gm) are currently available; larger ones will be available within about 3 months. Contact Paul Renne if you are interested. IMPORTANT: Please use "Alder" in the subject line of any email to facilitate searching and spam-blocker obviation.
Ar-Ar Templates
These templates for Ar-Ar (and U-Pb)? were discussed by Anthony Koppers at the EARTHTIME II workshop (see post on Ar-Ar forum).? Please compare both versions and discuss on Ar-Ar forum.

This version was presented during EARTHTIME II workshop in which the 40Ar/39Ar definition is based on the total 40/39, 38/39, 37/39 and 36/39 ratios only and not the intercept values.? Use this version for testing out the RiG Console Software which allows you to manage all data and metadata.? One example file has been included and one RiG format text file.

RiG.v15.template.xls | RiG.v15.console.xls | RiG.v15.template.definition.xls | Koppers_et_al_2004.xls

This includes baseline, blank- and fractionation-corrected intercept values and optionally procedure blanks in the ARAR measurements table.

EARTHTIME is supported by the National Science Foundation.