Isotopic paleo-climate records of MIS 2 to MIS 4 through Andean speleothem proxy analysis

Through analysis of paleoclimatic proxies, climate scientists are able to reconstruct the complex climatic changes both global and local. I am focused on the Peruvian Andes throughout the Last Glacial Period (115,000 to 11,500 years ago). This interval is marked by Northern Hemispheric millennial-scale climate fluctuations known as Dansgaard/Oeschger (abrupt warming events) and Heinrich events (abrupt cooling events), mainly documented within the Greenland Ice Sheet (NGRIP). These climatic oscillations affect the mean position of the ITCZ, which, in turn, control the strength of the SASM and the isotopic composition of precipitation in the Amazon Basin. Cave deposits are known as speleothems record changes in precipitation and here we present the δ18O and δ13C records of speleothems 19-1 and 19-7 collected from Huagapo Cave in the Peruvian Andes in 2019. Collectively, these two speleothems cover the time frame from about 23,000 to 66,000 years ago, encompassing Marine Isotope Stages 2 to 4. Our results highlight the occurrence of these DO events, noted by an increase in δ18O values in speleothems, as well as Heinrich events, seen by a decrease in δ18O values. The record will also be used to replicate and extend previous records from the region with evidence of Heinrich and Dansgaard/Oeschger events not seen in the other records. Furthermore, the record will reveal the disparities in interpreting δ13C for paleoclimatic records, where local effects tend to control the trends noted.