Water-table decline in the south-central Great Basin during the Quaternary Period; implications for toxic-waste disposal

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Authors:Winograd, I. J.; Szabo, B. J.
Author Affiliations:Primary:
U. S. Geol. Surv., United States
Source:Open-File Report - U. S. Geological Survey, No.OF85-0697, 18p. Publisher: U. S. Geological Survey, Reston, VA, United States. ISSN: 0196-1497
Publication Date:1986
Note:In English. 26 refs.
Summary:The distribution of vein calcite, tufa, and other features indicative of paleo-groundwater discharge, indicates that during the early to middle Pleistocene, the water table at Ash Meadows, in the Amargosa Desert, Nevada, and at Furnace Creek Wash, in east-central Death Valley, California, was tens to hundreds of meters above the modern water table, and that groundwater discharge occurred up to 18 km up-the-hydraulic gradient from modern discharge areas. Uranium series dating of the calcitic veins permits calculation of rates of apparent water table decline; rates of 0.02 to 0.08 m/1000 yr are indicated for Ash meadows and 0.2 to 0.6 m/1000 yr for Furnace Creek Wash. The rates for Furnace Creek Wash closely match a published estimate of vertical crustal offset for this area, suggesting that tectonism is a major cause for the displacement observed. In general, displacements of the paleo-water table probably reflect a combination of: (a) tectonic uplift of vein calcite and tufa, unaccompanied by a change in water table altitude; (b) decline in water table altitude in response to tectonic depression of areas adjacent to dated veins and associated tufa; (c) decline in water table altitude in response to increasing aridity caused by major uplift of the Sierra Nevada and Transverse Ranges during the Quaternary; and (d) decline in water altitude in response to erosion triggered by increasing aridity and/or tectonism. A synthesis of geohydrologic, neotectonic, and paleoclimatologic information with the vein-calcite data permits the inference that the water table in the south-central Great Basin progressively lowered throughout the Quaternary. This inference is pertinent to an evaluation of the utility of thick (200-600 m) unsaturated zones of the region for isolating solidified radioactive wastes from the hydrosphere for hundreds of millenia. Wastes buried a few tens to perhaps 100 m above the modern water table--that is above possible water level rises due to future pluvial climates--are unlikely to be inundated by a rising water table in the foreseeable geologic future. (Author 's abstract)
Subjects:Carbonate rocks; Cenozoic; Drawdown; Engineering geology; Ground water; Levels; Movement; Quaternary; Radioactive waste; Sedimentary rocks; Surveys; Toxic materials; Unsaturated zone; USGS; Waste disposal; Basin and Range Province; California; Furnace Creek; Great Basin; Inyo County California; Nevada; North America; Nye County Nevada; United States; Ash Meadows
Coordinates:N361500 N365000 W1160000 W1170000
Record ID:1986045355
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from USGS product, Selected Water Resources Abstracts, Reston, VA, United States
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