HR: 0800h
AN: H51E-0809    [Abstracts]
TI: Near surface geophysics and sediment analysis to precise the outbreak of glacial Lake Devlin, Front Range Colorado, USA
AU: * Leopold, M
EM: matthiasleopold@web.de
AF: Technical University Munich, Geomorphology & Soil Science Department of ecology and ecosystem management Science Center Weihenstephan, Freising-Weihensteph, D-85350, Germany
AU: Dethier, D P
EM: ddethier@williams.edu
AF: Williams College, 303 Clark Hall Massachusetts, Williamstown, MA 01267, United States
AB: Beside the geomorphological setting and the associated lithologic sphere the distribution and genesis of glacial, periglacial and paraglacial sediments is affected also significantly by climatic parameters. The time of deglaciation of the last glacial period is especially valuable to investigate the correlation between climatic shifts and possible geomorphological response. Ice-dammed lakes and their outbreaks are ideal archives to study this climate-geomorphological link. Glacial Lake Devlin is a key area of Pinedale deglaciation in the Front Range of Colorado, USA, because it catastrophically drained after the retreat of North-Boulder-Creek-Glacier. The breaching of the moraine is determined by Radiocarbon data from disperse organic matter within the uppermost lake sediments to about 13 ka 14C BP, an important date of the Front Range deglaciation (Madole 1986). A reinvestigation of the site allows a 3-dimensional mapping of the distribution and the depth of different glacial, periglacial, fluvial and lacustrine sediments by using various near surface geophysical methods such as seismic refraction, ground penetrating radar and electric tomography. Results of shallow geophysics help to determine positions to dig for sediment exposures. Detailed images of the different sediment units enable reconstructing a stratigraphic and genetic model of lake sediments, deltaic deposits, glacial till and fluvial sediments from the outbreak of the lake. Together with that 3-dimensional sedimentary model, new AMS-radiocarbon data combined with data derived from optical stimulates luminescence (OSL) will precise the date of the outbreak. MADOLE R.F. (1986): Lake Devlin and Pinedale glacial history, Front Range, Colorado. - Quaternary Research 25: 43–54.
DE: 1105 Quaternary geochronology
DE: 9350 North America
DE: 9604 Cenozoic
DE: 9820 Techniques applicable in three or more fields
SC: Hydrology [H]
MN: 2007 Fall Meeting