Variability of Summer Monsoon System over the Central-West Brazil during Holocene, based on paleoclimate records from speleothems.

Abstract

This research proposal aims to investigate the paleoclimate changes occurred in the last 10 thousand years during the Holocene over states of Goiás, Mato Grosso and Mato Grosso do Sul. The study is based on high-resolution records of oxygen and carbon isotope ratios from speleothems, and also includes measurements of layer thickness and frequency within the same samples, which can be precisely dated by U/Th method.The research will focus on the study of high frequency climatic cycles interpreted from isotopic composition and microstratigraphic features of speleothems, with the use of time-series statistical analysis. The records from different cave site locations in Western Brazil will allow comparisons of the intensity and variability of the rainfall associated with South-American Summer monsoon System (SASM) in a regional scale. It might be possible to make link with climatic features originated in Atlantic or Pacific oceans such as El Niño-Southern Oscilation (ENSO), North Atlantic Oscilation (NAO) e Pacific Multidecadal Oscilation (PDO) with the rainfall that propagate from Amazon Basin to surrounding areas. Furthermore, we intend to discuss the effect of some highly discussed events such Medieval Climate Anomaly and Little Ice Age on the precipitation related to SASM in Brazil. This study already has available a significant number of U/Th ages that will make possible to constrain the chronology of the speleothem stable isotope records. The project is part of a scientific cooperation with researchers from United States and France that is supported by FAPESP (Grant Numbers 2006/06761-0 and 2006/0283402).