HR: 1340h
AN: T23B-0539    [Abstracts]
TI: Is Heat flow in Sierra Nevada really as low as suggested?
AU: Wang, C
EM: chiyuen@berkeley.edu
AF: Department of Earth & Planetary Science, University of California, Berkeley, Berkeley, CA 94720-4767 United States
AU: * Brumm, M
EM: mbrumm@berkeley.edu
AF: Department of Earth & Planetary Science, University of California, Berkeley, Berkeley, CA 94720-4767 United States
AU: Manga, M
EM: manga@seismio.berkeley.edu
AF: Department of Earth & Planetary Science, University of California, Berkeley, Berkeley, CA 94720-4767 United States
AB: Heat flows measured in Sierra Nevada, California, are among the lowest known on continents - similar to those in some Precambrian shields. Since heat flow of a geologic province is often a proxy for its tectonic activity, this low heat flow seems to be at odds with the suggestions that the uplift of Sierra Nevada is geologically recent. Hypotheses explaining this low heat flow include shallow subduction of a cold plate beneath the base of the Sierra crust, delamination of the lithosphere and a low concentration of radioactive heat-producing elements in the Sierra granodiorite. Here we use the temperatures of spring water in Sierras Nevada to estimate the amount of heat removed advectively by groundwater. Most precipitation on the Sierras accumulates as snow during the winter. A significant portion of the snowmelt infiltrates the subsurface and recharges the groundwater during the spring. The high elevation of Sierra Nevada promotes deep circulation of groundwater which eventually re-emerges as baseflow and springs down slope. Since the temperature of springs represents the integrated average of groundwater temperature over an area, the temperature of springs may be used to estimate the amount of heat removed advectively by groundwater. Here we report measurements and analysis in the Sagehen Creek Basin in northern Sierra Nevada. The result shows that in this part of Sierra Nevada groundwater circulation may have removed a substantial portion of the heat conducted from below.
DE: 1832 Groundwater transport
DE: 1847 Modeling
DE: 1876 Water budgets
DE: 1879 Watershed
DE: 8130 Heat generation and transport
SC: Tectonophysics [T]
MN: Fall Meeting 2005