T225 From Alpine Glaciers to Ice Sheets: Understanding Glacial Dynamics, Landscapes, and Environmental Change

Wednesday, 7 November 2018
8:00 AM - 12:00 PM
Room 136-137

COSMOGENIC 10BE SURFACE EXPOSURE DATING AND NUMERICAL MODELING OF LATE PLEISTOCENE GLACIERS AND LAKES IN NORTHWESTERN NEVADA

Paper number: T225-11
Program: Technical Sessions
Time: 10:35 AM – 10:50 AM

Authors

Abstract

The Great Basin region of the southwestern United States features a rich geologic record of Pleistocene climate change. The timing of the last Pleistocene glaciation in mountains of the northwestern Great Basin is poorly known, however, especially compared to the timing of pluvial lake highstands. This study focuses on the glacial record in the Pine Forest and Santa Rosa Ranges, utilizing cosmogenic beryllium-10 surface exposure dating to develop a chronology of moraines and numerical modeling of glaciers to infer climate during the last glaciation. Preliminary cosmogenic exposure ages in the Santa Rosa Range support the idea that glacier maxima and lake highstands occurred at the same time and indicate that the timing of glacier maxima in the Santa Rosa Range was similar to that in other mountains of the northern Great Basin. Results of numerical model experiments that simulate Last Glacial Maximum (LGM) and Lateglacial ice extents include a range of temperature and precipitation combinations accompanying glacier maxima in the northwestern Great Basin. If precipitation in the Pine Forest Range was similar to modern, then the temperature depressions during the last glaciation were -9 to -8 °C. If precipitation in the Santa Rosa Range was similar to modern, then the temperature ranges were -6 to -5 °C. Temperature-precipitation combinations for the Pine Forest Range compare favorably with results of model applications to other mountains in the northern Great Basin. Model results for the Santa Rosa Range,however, suggest that these mountains experience either a lesser temperature depression or drier conditions compared to other mountains of the northern Great Basin. Overall, the chronology of glacial deposits in the northwestern Great Basin and inferred climate during the last glaciation show consistency acrosst the northern Great Basin and suggest that precipitation in the region was similar to modern.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-320730

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