A collaborative biogeochemical study of the Jurassic Lower Oxford Clay, England

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The project is detailed isotopic biogeochemical study of the Jurassic marine Lower Oxford Clay. Its goal is to understand sedimentary microbial processes and how they affect preservation of carbon, nitrogen and sulfur in organic and inorganic phases and the relationship between those microbial processes and depositional environments. Effects of specific microbial processes and the environments in which they are prevalent will be identified. Results of analyses of organic-sulfur compounds in these rocks should provide new information on the role of these compounds in the carbon-sulfur-iron system. Samples for this study were collected from active quarries in central England. The quarry exposures allowed acquisition of large, fresh samples of this immature, organic-carbon-rich mudrock. The samples, representing all stratigraphic horizons and biofacies, were obtained in collaboration with experts on the vertebrate and invertebrate paleoecology of the Lower Oxford Clay. Measurements (i) will include carbon, oxygen and sulfur isotopic compositions of the extensive and well preserved biominerals in this unit; (ii) carbon and nitrogen isotopic compositions of the organic materials preserved in the bones and shells; (iii) abundances and carbon- isotopic compositions of individual molecular fossils (i.e., biomarkers); and (iv) abundances and sulfurisotopic compositions of organic sulfur compounds and pyrite. The results should provide unique taphonomic information.