U-Pb Analyses of Zircons from the Popigai Impact Structure, Russia: First Results

Abstract

Zircons were extracted from impact melt rock samples from the 35.7 MaPopigai impact structure in Russia. U-Pb SHRIMP age dating of fourzircons resulted in ages of 1982 Ma for two of the zircons and youngerages for the other two grains. Minimum age estimates of the youngergrains can be derived from their 912 and 306 Ma Pb-207/Pb-206 ages. Noshock features are obvious in these grains; thus, the Pb loss could berecent. The older ages represent ages of zircon derived from the targetlithology. No evidence for resetting of the isotopic system at 35 Ma inthe zircons was found in this pilot study.