Biomarker climate reconstruction of the past two glacial cycles at Bear Lake (UT/ID)
Abstract
There is considerable concern over water availability and near-future climate change in the western US. As part of a previous study to understand Holocene climate variation, we generated a biomarker reconstruction of the past 7.2ky at Great Salt Lake (UT), a hypersaline, alkaline terminal lake where salinity proxies were approaching the limits of sensitivity in that extreme environment. We expand upon this work by generating a biomarker record back to the last interglacial at Bear Lake (UT/ID), a mesosaline montane lake located at 1,805masl and with a catchment area of 1,300km2. Bear Lake is a promising location to study late Pleistocene hydroclimate changes within a small catchment and a less extreme system compared to Great Salt Lake. Sediment cores GLAD1-BL00-1D and 1E were retrieved from Bear Lake in 2000, composed of lacustrine carbonate muds that span the past 220ky with carbonate-enriched sequences during interglacials. Here, we reconstruct climate and vegetation at Bear Lake by applying a suite of organic biomarker proxies, including leaf wax molecular abundance distribution and their carbon and hydrogen isotopic compositions. Similar approaches have been used recently at Lake Elsinore and Searles Lake in southern California. We seek to detect hydrogen isotopic evidence for precipitation changes across glacials and any evidence for wet-dry vegetation shifts. This study is motivated by the hypothesis of greater atmospheric river incursion during Heinrich Stadials, increasing moisture delivery to California and the Mojave Desert during the last two glacial terminations. At Bear Lake, we will test the extent of atmospheric river moisture delivery further inland. Our Bear Lake record will be compared to regional lake and cave records, to understand the spatial patterns of late Pleistocene climate variations in the region. Chemical work on Bear Lake core samples is underway and preliminary data will be presented at this meeting.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMPP12E0669S