Acquiring the ET535 and ET2535 mixed U-Pb tracers

How to qualify for an aliquot of EARTHTIME 205Pb-233U-235U tracer solution (EARTHTIME tracer #1)

  • Demonstrate that you can calibrate your existing spike accurately with the ET and JMM gravimetric standards available from EARTHTIME.
  • Develop a data set for synthetic zircon solutions (available from Dan Condon) ideally with sub per mil reproducibility on single analyses.
  • Develop a data set of single crystal analyses using chemical abrasion (Mattinson 2005) for one or preferably more internationally recognized zircon standard material (e.g. TEMORA, R33, FC1, 91500, or similar), which demonstrates per mil accuracy and precision on single analyses, and less on weighted mean dates.
  • Demonstrate low total common Pb for zircon analyses. If a lab’s only has a 205Pb/235U or a 208Pb/235U tracer we would like to see a discussion of tracer calibration and limitations on determining total common Pb with the assumption that for natural zircons all common Pb comes from the laboratory. Small aliquots of calibrated enriched 208Pb tracer can be made available for labs that need to trace sources of blanks. Once low blanks and reasonable reproducibility mixed tracer available for final testing, in some cases we will provide small quantities of non EARTHTIME 205Pb-233U-235U tracer.

Send all of this data fully documented, either via Redux (Bowring et al., 2011) or the “yourlab” spreadsheet (Schmitz and Schoene, 2007) to Jahan Ramezani for committee review.

These are demonstrations of performance that ensure the benefit of using the EARTHTIME U-Pb tracers will be realized. If you have any questions please contact us (email Jahan Ramezani) and we will work with you.

How to qualify for an aliquot of EARTHTIME 202Pb-205Pb-233U-235U tracer solution (EARTHTIME tracer #2)

In addition to the criteria above, you must have published or had accepted for publication three papers using the EARTHTIME tracer #1 solution.  There is much less of EARTHTIME tracer #2 than the #1 and thus you must agree to use it only for studies where the fractionation is the dominant source of your total analytical uncertainty.


Decisions on provision of ET535 and ET2535 are made by a committee that comprises the following people:

Jahan Ramezani
Albrecht von Quadt
Mark Schmitz
Blair Schoene