The Mid-Miocene "Monterey Event": A global productivity increase?

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We investigate the Mid-Miocene “Monterey Event” (Vincent and Berger, 1985), a positive carbon isotope excursion of 4.5 my duration, in order to contribute to a better understanding of the processes that control the distribution of carbon in the terrestrial, atmospheric and marine reservoirs. This δ13C excursion during a period of extreme warmth has been attributed to the enhanced sequestration of organic carbon in the margins of the northern Pacific ocean (op.cit.). We aim to clarify whether pelagic sediments also reflect increased productivity that might have contributed to the δ13C shift. If this is the case, we further aim to identify the sources of nutrients responsible for a 4.5 m.y. period of globally increased productivity. Finally, we aim to investigate if productivity variations can be related to pCO2atm variations (as proposed by Pagani et al.(1999)), by means of δ13C analyses of bulk marine organic matter in our samples by D. Groecke (fractionation between δ13Ccarb and δ13Corg).