HR: 1340h
AN: U13B-1155    [Abstracts]
TI: Evidence for Mid-latitude Lake-level Response to Millennial and Milankovitch Forcing: The Past 65 kyr at Mono Lake, CA
AU: * Zimmerman, S H
EM: zimmerman17@llnl.gov
AF: CAMS - Lawrence Livermore National Laboratory, P.O. Box 808 L-397, Livermore, CA 94551-9900, United States
AU: * Zimmerman, S H
EM: zimmerman17@llnl.gov
AF: Dept of Earth & Environmental Sciences, Columbia University, 61 Route 9W P.O. Box 1000, Palisades, NY 10964, United States
AU: Hemming, S R
EM: sidney@ldeo.columbia.edu
AF: Dept of Earth & Environmental Sciences, Columbia University, 61 Route 9W P.O. Box 1000, Palisades, NY 10964, United States
AU: Hemming, S R
EM: sidney@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W P.O. Box 1000, Palisades, NY 10964, United States
AU: Hemming, N G
EM: hemming@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W P.O. Box 1000, Palisades, NY 10964, United States
AU: Hemming, N G
EM: hemming@ldeo.columbia.edu
AF: School of Earth & Environmental Science, Queens College, CUNY, 65-30 Kissena Blvd, Flushing, NY 11367, United States
AU: Pearl, C
AF: School of Earth & Environmental Science, Queens College, CUNY, 65-30 Kissena Blvd, Flushing, NY 11367, United States
AU: Hartin, C
EM: c.hartin@umiami.edu
AF: School of Earth & Environmental Science, Queens College, CUNY, 65-30 Kissena Blvd, Flushing, NY 11367, United States
AU: Hartin, C
EM: c.hartin@umiami.edu
AF: RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149-1098, United States
AB: Mono Lake, California (38°N, 119°W) lies in the western Great Basin in the rain shadow of the Sierra Nevada, and preserves high-elevation strandlines indicating that lake level was much higher in the past. Comparison of stratigraphy-based relative lake level with geochemical records from three sites around the lake (overlapping between 40-32 ka), reveals high carbonate fluxes at times of high lake level on precessional (20-kyr) time-scales. Although absolute values are different in different locations representing slightly different paleoenvironmental settings, the timing and relative amplitude of changes are similar on orbital as well as millennial time-scales. Within the established regional 100-kyr pattern of wet glacials-dry interglacials, we find that during the last glaciation (Marine Isotope Stages (MIS) 4-3-2) times of high spring insolation were generally wetter, represented by lacustrine silts rather than sand facies and greater carbonate flux to the deep-lake sediments. This interval is also characterized by high-amplitude variability. Age model errors of ~1 kyr or less during MIS 3 allow correlation of sharp increases in carbonate deposition with Dansgaard-Oeschger warmings in Greenland. If the high carbonate-high lake relationship holds at millennial time-scales, this would indicate increases in lake level coeval with warming, opposite to the 100-kyr regional pattern. Alternatively, carbonate precipitation may be triggered by lake level peaking and beginning to drop, suggesting that lake level began to fall about the time of Greenland warming. Regardless, the correspondence in phasing between Mono Lake and Greenland, also demonstrated in the nearby Santa Barbara Basin, suggests that Mono Lake responded rapidly to the atmosphere-ocean changes invoked to explain the global nature of the D-O events. The suppression of this variability during times of low spring insolation may be due to a reduced sensitivity of the recorder, and we are looking for additional proxies to explore these intervals more carefully.
DE: 1051 Sedimentary geochemistry
DE: 1065 Major and trace element geochemistry
DE: 1105 Quaternary geochronology
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1630 Impacts of global change (1225)
SC: Union [U]
MN: 2007 Fall Meeting