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Geology Club Seminar

Thursday, November 15, 2018
4:00pm to 5:00pm
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Arms 151 (Buwalda Room)
Biogeochemical change associated with the end-Triassic extinction
Joyce Yager,

The end-Triassic extinction (ETE) was one of the largest faunal turnovers of the Phanerozoic and the most severe biotic crisis for the "modern fauna" (Sepkoski 1981) during Earth's history. Since some members of the modern fauna (e.g., scleractinian corals) are severely affected by modern day atmospheric CO2 addition and associated climate change, the ETE is an important case study, providing unique opportunities to understand the cascade of effects from atmospheric CO2 addition to environmental change and biotic crisis.           

Here, we utilize the temporal and biostratigraphic framework from the Levanto section in Northern Peru, which spans four million years and provides one of the best records of chronology available for the Triassic-Jurassic transition in the marine environment. We report geochemical proxies that fingerprint CAMP in the sedimentary record (Hg concentrations, Hg isotopes) and that record environmental and biogeochemical change (δ15N, δ13Corg, trace metal concentrations). Using the temporal framework from the Levanto section, we can estimate durations of change associated with the ETE and compare with other sedimentary sections across broad geographic and depositional settings. Correlation demonstrates that the durations derived from Levanto likely reflect globally relevant signals. The temporal information from this section greatly enhances our understanding of the timing of events and provides ground truthing for future modeling studies seeking to understand the ETE, which will aid in our understanding of increased atmospheric CO2 transitions.

We also discuss new developments in the Hg proxy for volcanism in the sedimentary record and preliminary results from silicon isotopes in sponge spicules as a proxy for silicic acid concentration.