Organic Matter Preservation and Thermal History of the Nonesuch Formation
Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
The Late Mesoproterozoic Nonesuch Formation is an organic-rich sedimentary unit exposed along the Lake Superior coast of Michigan and Wisconsin. It is unique among rocks of its age because it was originally deposited in a lacustrine environment and never deeply buried. The nature and amount of organic matter preserved in the Nonesuch Formation is highly variable. The mechanism behind this uneven distribution is poorly understood.
The objective of this study is to evaluate whether the variability in organic matter across the Nonesuch Formation is a function of paleo-redox conditions at the time of deposition or later burial diagenesis. The thermal history of the basin will be characterized using carbonate clumped isotope thermometry and preservation conditions at the time of deposition will be reconstructed using trace element geochemistry.
I hypothesize that evidence of elevated thermal alteration will be limited primarily to sites in close proximity to major regional faults. The remaining variability in organic material will be explained by preservation bias due to variable paleo-redox conditions. These results would imply a complicated history of organic matter preservation and illustrate the utility of our multi-proxy approach to reconstructing environmental and diagenetic controls on carbon preservation.
AAPG Search and Discovery Article #90199 © 2014 AAPG Foundation 2014 Grants-in-Aid Projects