Reconstructing the Biogeochemical Carbon and Sulfur Cycling for the Ediacaran Dengying Formation, China
Geology, University of Maryland, College Park, MD, USA
Currently oil and natural gas production worldwide is primarily derived from Phanerozoic strata. Hence the exploration for hydrocarbon in older Proterozoic successions is a speculative and expensive endeavor. Nonetheless, several Ediacaran Period sedimentary successions are known to contain both source and reservoir rocks, including the Dengying Formation in South China. Thick carbonates of the Dengying Formation represent one of the most prolific natural gas reservoirs in China. While many studies have focused on the source, migration, and accumulation of oil and gas in Dengying, little is known about paleoenvironmental condition during its deposition.
Insofar as carbon and sulfur isotopes in marine proxies are linked to oceanic primary productivity and redox state, I propose to conduct a coupled carbon and sulfur isotope study of the carbonate-dominant Dengying Formation. Stratigraphic samples have been systematically collected from outcrops and shipped to the US. Thin sections have been carefully examined to evaluate the degree of diagenetic alteration. I propose to extract pyrobitumen and kerogen from these samples for organic carbon isotope analysis, micro-drill specific carbonate textures for carbonate carbon and oxygen isotope analysis, and to extract pyrite and trace sulfate for sulfur isotope analyses. The coupled measurements will allow me to estimate carbon and sulfur isotope fractionation that may be related to environment changes in the basin through time. The study will provide insight to extant microbial communities and should allow me to reconstruct the biogeochemical cycling of elements in the basin related to the accumulation and preservations of organic-rich source rocks.
AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects