Tales of Deep Ocean Circulation Told by Tiny Fish Teeth Dr. Ellen Martin, University of Florida Marine sediment deposition during the Cretaceous “greenhouse” period was punctuated by intervals of extensive organic carbon burial known as Oceanic Anoxic Events (OAEs). The sediments laid down during OAEs represent important sources of hydrocarbons, record dramatic changes in the ocean environment, and reflect variations in the global carbon cycle. Competing theories attribute the cause of OAEs to either excess organic matter generated by high rates of surface productivity, or to stagnant, warm, deep ocean conditions that prevented regeneration of surface-derived organic matter. Until now there have been few good proxies capable of differentiating between these two hypotheses. Evidence of deep ocean circulation patterns is preserved in the neodymium isotopic records of tiny fossil fish teeth found in Ocean Drilling Program (ODP) sediment cores, however, and analyses of Nd isotopic signatures from teeth deposited across an OAE episode in the tropical North Atlantic suggest that circulation became more vigorous during that episode. These results indicate that deep ocean circulation was an important component of OAE formation and that this circulation, coupled with enhanced upwelling, led to high rates of surface productivity. Dr. Martin’s research relies on deep sea sediments recovered by ODP. She has been active in the advisory structure of the ODP, having served on the Scientific Measurements Panel and the U.S. Advisory Committee for Scientific Ocean Drilling (USAC). Lecture Schedule October 19, 2007: University of North Carolina at Charlotte (Charlotte, NC) | |
