Late Quaternary paleoclimate in Sergipe and Bahia States from oxygen and carbon isotope ratios on speleothems

Abstract

This proposal aims to study paleoclimate changes mainly occurred in the last 100,000 years during the Late Pleistocene and Holocene in Sergipe and Bahia states, Northeastern Brazil. The study is based on high-resolution records of oxygen and carbon isotopes ratios on speleothems, precisely dated by U-series method. These are potential records of the past climate changes and of soil processes in the cave area such as rainfall amount, soil and vegetation cover. These speleothem records can allow us to discuss the importance of climate events at orbital time-scales (periodicity of ~23,000 years), millennial events such as Dansgaard-Oeschger e Heinrich (~1500 a 3000 years) to the regional precipitation regime as well as observed in southern and southeastern Brazil. In addition, it is also possible to discuss climate events at centennial (e.g. Little Ice age Medieval Warm Period) to interannual scale (e.g. ENSO) which intrinsically depends on the time resolution of isotopic profiles to be obtained from stalagmites. In this regard it is very important to improve the understanding of climate variations associated with the seasonal movement of Intertropical Convergence Zone and South Atlantic Subtropical High in Nordeste. (AU)