Core-top calibration of paleotemperature geochemical proxies: a case study in the Southeast Brazilian continental margin

Abstract

This project aims to produce a calibration of marine proxies derived from marine sediments and in tests of three species of planktonic foraminifera in order to improve the reconstructions of the paleotemperature in the Brazilian South-Southeast continental margin, since it lacks of a calibration and, consequently, the temperature estimates are imprecise. The material that will be analyzed was collected during three oceanographic cruises performed with the Oceanographic Institute of University of São Paulo's ship Alpha Crucis, where 25 core-top samples were retrieved with a multiple-corer and with a box-corer throughout the São Paulo Bight, between the latitudes of 24°S to 27°S. The planktonic foraminifera species Globigerinoides ruber (morphotypes pink and white s.s) within two different size fractions (250 - 300um and 300 - 355um), as well as the species Globorotalia inflata in the size fraction of 315 - 400um will be selected in order to obtain the Mg/Ca ratio and the isotopic composition of ´18O. Also, the marine sediments will be analyzed to obtain the alkenones unsaturation index. The results of the proxies will be used to test the paleotemperature equations to each individual proxy. Furthermore, the paleotemperature coefficients of the Mg/Ca ratio will be tested and compared to the present SSTs data in order to identify the most suitable coefficient to the Brazilian South-Southeast continental margin. This calibration will provide more robust data to the Paleoceanographic and Paleoclimatologic studies conducted in the Southeast Atlantic, assisting the scientific community to understand the paleoceanographic evolution of this margin during the Quaternary. (AU)