HR: 11:10h
AN: V52C-04    [Abstracts]
TI: High Permeability of Yellowstone Quaternary-age Volcanics: Evidence From Streamflow Hydrograph Analysis and Ground-water Ages
AU: * Susong, D D
EM: ddsusong@usgs.gov
AF: U.S. Geological Survey, 2329 W. Orton Circle, Salt Lake City, UT 84119, United States
AU: Gardner, W P
EM: wgardner@usgs.gov
AF: U.S. Geological Survey, 2329 W. Orton Circle, Salt Lake City, UT 84119, United States
AU: Solomon, D K
EM: ksolomon@mines.utah.edu
AF: University of Utah Dept. of Geology and Geophysics, 135 S 1460 E RM 719, Salt Lake City, UT 84112, United States
AU: Heasler, H
EM: henry_heasler@nps.gov
AF: Yellowstone Center for Resouces Geology Program, National Park Service, Yellowstone, WY 82190, United States
AB: Hydrograph analysis and ground-water age of water from low-temperature springs in the greater Yellowstone area provide evidence of high permeability at the basin scale and rapid ground-water circulation in Quaternary- age volcanic rocks. Ratios of annual maximum to minimum mean daily discharge, recession index, base-flow index, and mean annual basin recharge were calculated from streamflow data for the period of record at 32 U.S. Geological Survey gaging stations in the area. Ground-water age was determined from tritium and CFC analyses of water from 30 low-temperature springs discharging from Quaternary volcanics in the Norris area of Yellowstone National Park. The ratio of annual maximum to minimum mean daily discharge varied from 1.9 to 226. Streams with basins underlain by Quaternary-age rhyolites and tuffs had ratios ranging from 2 to 7, indicating that these streams were dominated by ground-water inflows. Streams in basins with high ratios (30- 226) generally were underlain by Precambrian crystalline, Paleozoic sedimentary, and Eocene volcanic rocks and streamflow was dominated by runoff. Recession and base-flow indices have similar characteristics and correlation with geologic units. Water from all springs sampled had measurable CFC and tritium concentrations and a substantial fraction of modern water, indicating rapid flow rates through Quaternary volcanics. Ground- water recharge calculated from base-flow hydrographs with RECESS indicates that 50 percent of precipitation becomes recharge, providing further evidence that Quaternary volcanics are highly permeable. Becasue of the high permeability of volcanic rocks, the ground-water flow system is dynamic and likely an important component in the surficial expression of the Yellowstone geothermal system.
DE: 1040 Radiogenic isotope geochemistry
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1860 Streamflow
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting