Record of the paleoclimatic and paleoceanographic conditions of the past 2500 years in the region of São Sebastião Island, located in the Southeastern Brazilian Continetal Shelf, through the use of geochemical proxies

Abstract

The understanding of sedimentary processes during Late Holocene is very important to support the predictive models about the human impact on future climate. Despite being considered a climatically stable period, studies have shown that the Holocene climate is more dynamic than previously thought, showing significant variability on millennial scales. Evidence for changes in the climate can be obtained through different records, such as sediment or ice cores. Such records allow studies about a relatively short period of time, that can be expanded to the understanding of both local and global climatic mechanisms. Continental shelves are natural reservoirs of sediment containing organic and inorganic compounds derived from the adjacent continent and marine productivity . The Southeastern Brazilian Continental Shelf can be divided into two distinct zones of sedimentation and organic matter composition, due to the different hydrological processes that operate in this region. São Sebastião Island, located in the northern coast of São Paulo, marks the convergence pointe between these zones and, therefore, the adjacent continental shelf in this region has a high sedimentation rate. Marine environments with a high sedimentation rate present sedimentary records with high temporal resolution. The combined use of different geochemical proxies such as stable isotopes of carbon and nitrogen, metals and organic molecular markers, is an important tool in the study of climatic and oceanographic changes in the past. Changes in the abundance and the distribution of these compounds over the sediment cores can provide records of continental and marine paleoenvironments. The present work aims to evaluate the paleoclimatic and the paleoceanographic conditions and of the last 2,500 in the region near São Sebastião Island, in the southeastern Brazilian Continental Shelf, through the use of different geochemical proxies.