Upcoming Colloquium Series Speakers
Friday March 16th, 2018 - 3:30-4:30PM - BGS 0153
Dr. Uwe Brand
Professor, Department of Earth Sciences, Brock University
Title: "The Doushantuo cap dolomite: rapid biogenic-methane driven Marinoan Icehouse to Greenhouse transition"
The Marinoan glaciation of the Cryogenian Period (635 Ma) was the last of the global ice ages (Snowball Earth’s) reaching low latitudes and the end of it is marked by a carbonate with distinct depositional and geochemical features. The appearance of the cap carbonates ushered in a new climatic era with its explosive expansion of animal life. A number of models, for example, from massive drawdown of atmospheric CO2, to methane oxidation and postglacial upwelling have been suggested for the origin of the cap carbonate. However, clues to the rapid deglaciation process of the Marinoan Ice age must be sought from the cap dolomite immediately overlying the glacial diamictites. Here, we report on an extensive and integrated suite of petrographic, geochemical and gas-inclusion results of the cap dolomite (member 1) of the Doushantuo Formation, China. The outgassing of subaerial volcanic CO2 triggered the release of the methane clathrate instrumental in the end of the Marinoan glaciation and its major role in the formation of the widespread microbial dolomicrite cap.