Climate variability during the mid-Holocene at northwestern of Minas Gerais and isotope calibration

Abstract

This projects aims to assess the impact and the extent of Bond event 4 (~ 5.1 a ~ 6 kyr B.P.) on the South America monsoon based on d18O speleothem records of stalagmites from central-eastern. Previous works of Stríkis et al. (2011) shows that during the Holocene abrupt multi centennial cold event known as Bond events play an important role on monsoon rainfall variability over central eastern-Brazil. The expression of those events it is characterized by the significant increase of monsoon precipitation in response to changes in the interhemispheric sea surface temperature gradient and consequent southward displacement of the Intertropical Convergence Zone. However, due to the lack of high-resolution paleoclimate reconstruction little is known about the impact of Bond events over the South America monsoon precipitation. In this context, high-resolution speleothem stable isotope records are of great relevancy in order to understand the structure and duration of these events over South America monsoon as well as a scientific test of reproducibility of the paleomonsoon reconstruction.In order to make the paleoclimate interpretation of the proxy used in this study more robust, isotopic analyzes will be carried out on a well-dated stalagmite record covering the last 100 years. The results will be compared with instrumental records of meteorological station allowing us to better understand the hole of reservoir effect as well and the sensibility of the stable isotope signal of this particular cave system to the rainfall variation.