UNDERSTANDING GLACIAL FLUCTUATIONS USING CLASTIC SEDIMENT FLUX IN CORDILLERA CENTRAL, PERUVIAN ANDES

Variations in the timing and magnitude of clastic sediment flux to proglacial lakes can yield insight into glacier fluctuations and dynamics. This project focuses on a glacial lake within the Cordillera Central of the Peruvian Andes, Huaylillas, at ~4000 m elevation. In 2017 a 5.2 m overlapping sediment record was collected and analyzed for glacial-interglacial transitions. Radiocarbon and ²¹⁰Pb dates are used to create an age model for the core. Additional measurements on the sediment cores include magnetic susceptibility, bulk density, and organic/carbonate content. Stratigraphy and sedimentology indicate multiple transitions between organic material and iron-stained varved clay indicative of shifts between glacial and interglacial environments. These units vary in size, with glacial pulses ranging from a few centimeters to over 1 m. This may suggest that the glacial pulses and interglacial intervals occurred for varying durations of time or alternatively may be related to the weatherability and erodibility of the catchment.

By obtaining radiocarbon dates on the termination of each of these units, we aim to better understand climate dynamics in the late Pleistocene/Holocene of the Cordillera Central. With further refinement of the age model, clastic sediment flux will be calculated for the glacial pulses in the record. Dates for glacial pulses will then be linked to nearby proglacial lake sediment records from the northwest-southeast trending Lagunas Queshquecocha, Jahuacocha, and Lutacocha from Cordilleras Blanca, Huayhuash, and Raura mountain ranges, respectively.