Joint 52nd Northeastern Annual Section / 51st North-Central Annual Section Meeting - 2017

Paper No. 69-21
Presentation Time: 1:30 PM-5:30 PM

A HOLOCENE RECORD OF CHANGING MONSOON STRENGTH FROM PERU


HART, Emily1, OHARA, Sandra L.2, LARSEN, Darren3, KINASH, Nikki4, COOK, Ann4 and ABBOTT, Mark B.5, (1)University of Pittsburgh, Pittsburgh, PA 15213, (2)Department of Geology and Environmental Science, University of Pittsburgh, Pittsburgh, PA 15260, (3)Geology Department, Union College, 807 Union Street, Schenectady, NY 12308, (4)The Ohio State University, Columbus, OH 43210, (5)Department of Geology & Environmental Science, University of Pittsburgh, Pittsburgh, PA 15260, ejh44@pitt.edu

Laguna Mehcocha is a small overflowing lake located at 11°S in the Central Andes at an elevation of 4300 meters. Three, 5+ meter-long cores were collected using a Livingston corer from the lower basin of Mehcocha in July of 2015 from a raft in 10 meters of water. These successive drives of lake sediment were first scanned using a CT prior to opening to document sedimentary changes. Once opened, the cores were measured for magnetic susceptibility, organic matter, carbonate content, and dated with radiocarbon and lead-210. Authigenic calcite was isolated and used to measure the oxygen and carbon isotopes in the cores. These measurements can be used to determine changes in the isotopic composition of precipitation over time. These changes can be supported using the magnetic susceptibility data, organic matter and carbonate content measurements, and radiocarbon/lead-210 dating. Laguna Mehcocha is hydrologically open, and therefore the lake water is not isotopically enriched with respect to oxygen and hydrogen.