LIFE DURING SNOWBALL EARTH: MICROFOSSILS FROM THE NEOPROTEROZOIC KINGSTON PEAK FORMATION, DEATH VALLEY, USA

The Neoproterozoic Kingston Peak Formation, Death Valley region, California, contains two distinct packages of glacially-derived diamictite, each overlain by a cap carbonate, an association thought to represent "Snowball Earth" conditions. In addition, the Kingston Peak glacial units were most likely deposited at low latitudes (5°-10°, through correlation to the broadly coeval Chuar Group, Grand Canyon region). A thin, unusual carbonate unit interbedded with, or capping, the lower iron-rich diamictites in the Kingston Range area contains evidence of a thriving microbial community preserved in chert as well as oncoids and rare stromatolites. The microbial fossils are similar to those found in the underlying pre-glacial Kingston Peak Formation, the Beck Spring Dolomite, and the uppermost Crystal Spring Formation, and include prokaryotic and eukaryotic autotrophs and eukaryotic heterotrophs. They indicate that microbial life adapted to shallow-water carbonate environments did not suffer significant extinction during this phase of glaciation and that trophic complexity survived through the Snowball Earth times.