Reconstruction of regional atmospheric circulation features during the late Pleistocene in subtropical Brazil from oxygen isotope composition of speleothems

摘要: Two high-resolution oxygen isotope records of speleothems from caves located in subtropical Brazil provide a broad view regional climate variations and related forcing during the late Pleistocene Holocene. Here, we present new record precisely dated by U-series extending back to 131 kyr BP speleothem collected Santana Cave. Comparison with 116 Botuvera Cave confirms that seasonal change rainfall distribution is primarily controlled summer insolation on Milankovitch timescales. However, significant negative anomalies δ 18 O 60 10 suggest Northern Hemisphere glacial boundary conditions, particular Heinrich events, impacted mean location and/or convective activity South American monsoon (SASM), resulting enhanced transport depleted moisture Amazon Basin into region. In addition, comparison two indicates steep north–south gradient throughout, which interpreted as reflecting different relative contribution extratropical monsoonal precipitation locations. For some time periods, more pronounced occur northern part positive southern region, appear be associated abundant rainfall, respectively. The last interglacial period characterized highest values entire St8 record, indicating dominance winter thus, most northward position SASM for BP. © 2006 Elsevier B.V. All rights reserved.