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``Dynamics of the Neoproterozoic carbon cycle''
Proceedings of the National Academy of Sciences USA, 100, 8124-8129, July 8, 2003.
Abstract:
The existence of unusually large fluctuations in the Neoproterozoic (1000--543 Ma) carbon-isotopic record implies strong perturbations to the Earth's carbon cycle. To analyze these fluctuations, we examine records of both the isotopic content of carbonate carbon and the fractionation between carbonate and marine organic carbon. Together, these are inconsistent with conventional, steady-state models of the carbon cycle. The records can, however, be well understood as deriving from the non-steady dynamics of two reactive pools of carbon. The lack of a steady state is traced to an unusually large oceanic reservoir of organic carbon. We suggest that the most significant of the Neoproterozoic negative carbon-isotopic excursions resulted from increased remineralization of this reservoir. The terminal event, at the Proterozoic-Cambrian boundary, signals the reservoir's final diminution, a process which was likely initiated by evolutionary innovations that increased export of organic matter to the deep sea.
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