GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 265-11
Presentation Time: 9:00 AM-6:30 PM

ISOTOPIC ANALYSIS OF DEAD SEA SEDIMENT FROM THE LAST GLACIAL


CRAIG, Bridget C., Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027, KIRO, Yael, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 and GOLDSTEIN, Steven L., Department of Earth and Environmental Sciences, Columbia University, New York, NY 10027; Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964

The Dead Sea is a terminal hypersaline lake located in a rift valley between Israel, Jordan, and Palestine. Its watershed spans between the Mediterranean and Saharan-Arabian climate zones. The International Continental Scientific Drilling Program - Dead Sea Deep Drilling Project yielded 460 meters of sediment reflecting a high-resolution continuous climate record of the past 200,000 years. While there is extensive data from the western catchment of the Dead Sea, there is a lack of information from the eastern catchment that is necessary to better understand the spatial distribution of past lakes and how the sediment core reflects past climate. This project aims to fill that gap. Alternating intervals of aragonite, detritus, gypsum, and halite in Dead Sea sediments reflect precipitation patterns. The aragonite and detritus studied in this project reflect glacial, wet conditions. Ages of sediment samples were calculated with U-series dating. Initial 234U/238U activity ratios were calculated as well. These results can be used to show how lake level and water sources are affected by climate changes. Our samples are between 60 ka and 75 ka, with initial 234U/238U activity ratios of ~1.44 and ~1.47, suggesting that during that time ~90% of the Dead Sea’s water input came from the Jordan River.