| Abstract: | 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) |
| Genre: | USGS Numbered Series |
| ProdID: | 16594 |
| Citation Author: | Winograd, I. J.; Szabo, B. J. |
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| Citation Language: | ENGLISH |
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| Citation Phsyical Description: | iii, 18 p. :map ;28 cm. |
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| Citation Publisher: | U.S. Geological Survey, |
| Citation Series: | Open-File Report |
| Citation Series Code: | OFR |
| Citation Series Number: | 85-697 |
| Citation Search Results Text: | Water-table decline in the south-central Great Basin during the Quaternary Period; implications for toxic-waste disposal; 1986; OFR; 85-697; Winograd, I. J.; Szabo, B. J. |
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| Citation Year: | 1986 |
| Type: | citation/reference |
| Text: | Water-table decline in the south-central Great Basin during the Quaternary Period; implications for toxic-waste disposal; 1986; OFR; 85-697; Winograd, I. J.; Szabo, B. J. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/of/1985/0697/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/of/1985/0697/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey, |
