Radiocarbon Dating of Cores Collected from Bear Lake, Utah and Idaho.

摘要

The overall goal of our research on Bear Lake is to obtain records of past climate change for the region, including changes in precipitation (rain and snow) patterns during the last 10,000 years and longer. As part of the project, we are attempting to determine how the size of Bear Lake has varied in the past in order to assess the possibility of future flooding and drought. We also seek to understand human influences on sediment deposition, chemistry, and life in the lake. Evidence of past environmental conditions comes from sediments deposited in the lake, so reconstructions of these conditions require accurate dating of the sediments. The study includes the upper Bear River watershed as well as Bear Lake. The Bear River is the largest river in the Great Basin and the source of the majority of water flowing into the Great Salt Lake. In this region, wet periods may produce flooding along the course of the Bear River and around Great Salt Lake, while dry periods, or droughts, may affect water availability for ecosystems, as well as for agricultural, industrial, and residential use. Here we report the results of radiocarbon analyses of sediments in several cores from Bear Lake and compare the radiocarbon ages with independently estimated ages derived from amino acid analyses in ostracodes. We develop age models for each core to form the chronological framework for other paleoenvironmental studies.