CALCIUM-CARBONATE DISSOLUTION CYCLES AND STRATIGRAPHY RECONSTRUCTED BY MULTI-PROXY EVIDENCE IN A SEDIMENT CORE FROM THE EASTERN EQUATORIAL PACIFIC

The carbonate chemistry of the deep ocean is continually adjusting itself to maintain a balanced input and output of alkalinity by the addition or removal of carbonate ions. With more carbonate ions present, there is an increase in the preservation of calcium carbonate used for shell formation, while less carbonate ions present is more corrosive. These changes may indicate the degree of isolation of the deep ocean from the atmosphere. We examine the percent carbonate of a deep-sea sediment core from the Eastern Equatorial Pacific, RC 10-79. This core, taken at 9˚19.3’N and 110˚32.9’N at a depth of 3630m is previously unstudied. In addition to percent carbonate analysis, ratios of whole planktonic and benthic foraminifera are compared to fragments by weight. Based on these findings, we reconstruct the dissolution of calcium carbonate in this area through time. Stratigraphy of the core is based on new oxygen isotope records of Uvigerina, which indicate the glacial-interglacial periods. Thus, we reconstruct a multi-proxy index of the ocean’s corrosiveness through time down 200cm of the core. We find dissolution cycles in each proxy associated with glacial –interglacial cycles, and discuss differences among them, as well as the timing relative to major climatic transitions.