Precambrian-Cambrian transition: Death Valley, United States

Abstract

The Death Valley region contains one of the best exposed and often visited Precambrian-Cambrian successions in the world, but the chronostratigraphic framework necessary for understanding the critical biologic and geologic events recorded in these sections has been inadequate. The recent discovery of Treptichnus (Phycodes) pedum within the uppermost parasequence of the lower member of the Wood Canyon Formation allows correlation of the Precambrian-Cambrian boundary to this region and provides a necessary global tie point for the Death Valley section. New carbon isotope chemostratigraphic profiles bracket this biostratigraphic datum and record the classic negative carbon isotope excursion at the boundary. For the first time, biostratigraphic, chemostratigraphic, and lithostratigraphic information from pretrilobite strata in this region can be directly compared with similar data from other key sections that record the precursors of the Cambrian explosion. Few Precambrian-Cambrian boundary sections contain both the facies-restricted boundary fossil T. pedum and carbon isotope data, as found in Death Valley. Thus, the Death Valley succession provides a critical link toward our understanding of the correlation between siliciclastic-dominated and carbonate-dominated Precambrian-Cambrian transition sections.