HR: 0800h
AN: PP11A-0222    [Abstracts]
TI: Glacial age precipitation and temperature estimates for the tropical Guatemalan highlands
AU: * Roy, A J
EM: roya3@unlv.nevada.edu
AF: University of Nevada - Las Vegas, Dept. of Geosciences, 4505 Maryland Pkwy, Box 4010, Las Vegas, NV 89154, United States
AU: Lachniet, M S
EM: matthew.lachniet@unlv.edu
AF: University of Nevada - Las Vegas, Dept. of Geosciences, 4505 Maryland Pkwy, Box 4010, Las Vegas, NV 89154, United States
AB: The Sierra Cuchumatanes of Western Guatemala supported a large ice cap of approximately 44 square km area, and a group of 5-6 small valley glaciers during the local last glacial maximum (LLGM). We propose that a temperature reduction during the Guatemalan LLGM was between -4.5 degrees C and -6.0 degrees C from present accompanied by precipitation totals that fall between 80-100% of present day levels. Our new field work on moraine limits expands upon previous reconnaissance-level studies. Here we present a comprehensive reconstruction of the Guatemalan glacial geomorphology on a high limestone plateau; including delineations between morphologically different moraine sequences, boundaries of sub-glacial till deposits and locations of dry moraine dammed lakes. The glacial geologic map was produced via field mapping and GPS surveying, coupled with aerial photographic analysis. A 50m digital elevation model (DEM) created for the mapping portion was employed as input for a physically based GIS mass-balance model, developed by Plummer and Phillips (2003). The mass-balance model data was calculated for varying precipitation, temperature, environmental lapse rates, cloudiness, wind speed and humidity. A sensitivity analysis using variations in temperature and precipitation provided constraints on Guatemalan highland paleoclimate. Although the ages of the glaciations are unconstrained, a qualitative assessment of moraine morphology suggests correlation with the LLGM (20 – 17.5 ka) moraines of Mexico.
DE: 0720 Glaciers
DE: 0762 Mass balance (1218, 1223)
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 1637 Regional climate change
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting