Geochemical Analysis of the Triassic-Jurassic Boundary at Ferguson Hill, Nevada
Department of Earth Sciences, University of Southern California Los Angeles, California, USA; [email protected]
The Triassic-Jurassic boundary coincides with one of the five largest mass extinction events of the Phanerozoic. Of these five, the Triassic-Jurassic extinction is the most poorly understood. A complete section, located at Ferguson Hill (also referred to as New York Canyon or Muller Canyon), Nevada, is an ideal locality to perform fine-scale geochemical studies, which provide useful constraints and insight into the mechanisms that controlled the extinction. Previous studies of this section have produced excellent ammonite biostratigraphic information, but yield varying chemostratigraphic results.
This study will be the first work to document a carbonate δ13C isotope curve for this section and will extend previous organic δ13C isotope curves, percent carbonate, and percent total organic carbonate profiles through forty meters of section. The lateral continuity of these geochemical signatures will also be investigated in order to determine the cause of the discrepancy in previously reported geochemical results. If the geochemical values are laterally continuous, different methods will be employed in order to establish whether the inconsistency can be attributed to sample processing methods. If, however, this is not the case then other variables will be considered, such as meteoric overprinting and sample depth from the surface.
Since the cause of the Triassic-Jurassic mass extinction is so enigmatic, rigorous geochemical studies such as these can help refine our understanding of the mechanisms operating during this period in Earth history. Furthermore, analysis of various geochemical methods and sampling procedures will lead to greater accuracy and reproducibility in future studies.
AAPG Search and Discovery Article #90083 © 2008 AAPG Foundation Grants in Aid