THE ROLE OF THE SIBERIAN TRAPS IN THE PERMIAN-TRIASSIC MASS EXTINCTION: ANALYSIS THROUGH CHEMICAL FINGERPRINTING OF MARINE SEDIMENTS USING RARE EARTH ELEMENTS (REES)

The Permian-Triassic boundary (PTB) mass extinction at ~252 Ma was the largest biotic catastrophe in Earth history, resulting in the disappearance of ~90% of marine invertebrate species. Recent work has shown that the most likely trigger for this event was eruption of the Siberian Traps, the largest sub-aerial flood basalt province of the last 500 million years. However, direct evidence linking the Siberian Traps to the marine mass extinction has been lacking. Volcanic units are commonly characterized by unique rare earth element (REE) signatures, and published studies show that the Siberian Traps had an unusual REE chemistry (Lightfoot et al., 1990, 1993; Arndt et al., 1993, 1995, 1998; Federenko et al., 1997, 2000). In this study, we are examining the REE chemistry of eight marine PTB sections having a wide global distribution with the goal of determining whether the characteristic REE signature of the Siberian Traps can be recognized in ash beds or in background sediments of these successions. If recognized, this signature could provide information regarding the geographic dispersal of volcanic ash, its relationship to regional environmental changes, and its effects on marine and terrestrial ecosystems. Our work is currently in progress, but preliminary results suggest that REE signatures potentially characteristic of Siberian Traps source material are present in some, but not all, marine PTB sections.