Zircons from Permian-Triassic Boundary at Meishan!!

Using a small grant from the NASA exobiology program, Frank Kite, Doug Erwin, and Sam Bowring collected a complete suite of samples across the Permian-Triassic boundary at Meishan. The samples were prepared for distribution to all parties interested in searching for evidence of an extraterrestrial component. In addition, ash beds from the section were also collected and prepared for U-Pb analysis. Zircon was separated and is available for distribution to those interested in analyzing the grains. Please send requests for zircon to S.A. Bowring.




Sample descriptions for EARTHTIME reference zircon volcanic ash from adjacent to the Permian-Triassic boundary, Meishan, China

Bed 28 (sample MBE-02-05)
Among eight analyzed grains, none are xenocrystic. Six grains have between 10 and 25 pg of radiogenic Pb and two grains have 9 pg. Low (sub-picogram) procedural Pb blanks are necessary to obtain meaningful results.
Bed 7 (sample MBE-7b-96)
Among nine analyzed grains, three are xenocrystic. Eight grains have between 50 and 100 pg of radiogenic Pb and two grains have 35 pg. Meaningful results can be obtained with procedural Pb blanks of a few picograms.
Bed 6 (sample MC03 6-3)
Among nine analyzed grains, one is xenocrystic and one has suffered moderate Pb loss. One grain has 110 pg of radiogenic Pb, seven grains have between 40 and pg, and one grain has 35 pg. Meaningful results can be obtained with procedural Pb blanks of a few picograms.

EARTHTIME is supported by the National Science Foundation.