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Project Progress

During the past year, I have completed my thesis work at Penn State and submitted two of three main thesis chapters for publication.
The first of the submitted chapters is entitled “Opening Pandora’s Box: Implications of open-system modeling for interpretations of anoxia” and is in press in Paleoceanography. This study reveals that the short-term responses of marine phosphate and oxygen cycles captured by closed-system box models may be reversed on long timescales (>50,0000 years)and that the open-system and vertically stratified nature of the ocean must be captured in order to accurately assess the causes of long-term anoxia using box-models of ocean biogeochemistry.
The second submitted chapter is another study of controls on deep-sea oxygenation entitled “Ocean stagnation and Permian Anoxia” and has been submitted to Geology. We find that high-latitude warming roughly consistent with records of Late Permian climate causes reduced thermohaline overturning and deepwater anoxia in a simulated Permian ocean, a result that supports previous suggestions that anoxia may have played a role in the End-Permian extinction.
In the next few months, I will be preparing the third and final chapter of my thesis for publication. This chapter, entitled “Interpretation of a Neoproterozoic _13C gradient from the Pethei Platform (Great Slave Lake Supergroup, N.W.T.),” presents the results of a carbon isotope study of a 1.9 Ga stromatolitic reef. We find only a small vertical gradient (about -0.5â?°) between _13C of marine cements formed in shallow environments and cements in basinal carbonates inferred to have been deposited at ~1km depth. We attribute the small gradient to high marine DIC rather than weak biological pumping.
In addition to completing this third publication, I am continuing to work with Lee Kump over the summer to improve our biogeochemical general circulation model for work on Astrobiological problems.