Arizona, Nevada, and California
Comments on Geologic Parameters
07 Top Seal Thickness:
Top-seal-thickness maps are lacking for the two principal hydrologic units in the Mojave Basin. Top seals for the deeply buried carbonate aquifers are a combination of upper Paleozoic marine shales, siliceous siltstone, and evaporites. The hydraulic conductivity of these noncarbonate rocks is commonly only 0.01 ft/d (Dettinger and others, 1995; Thomas and others, 1996). Although these noncarbonate seal facies are up to 200 ft (61 m) thick in north-central Nevada, they exhibit pinch-outs. Interbedded tuffaceous sediments and central-basin fine-grained sediments (lacustrine fill and playa) are the main seals for the Tertiary basin-and-range aquifers (Freethey and others, 1986; Harrill and others, 1988; Prudic and others, 1995).
Dettinger, M. D., Harrill, J. R., Schmidt, D. L., and Hess, J. W., 1995, Distribution of the carbonate rock aquifers and the potential for their development, southern Nevada and adjacent parts of California, Arizona, and Utah: U.S. Geological Survey Water-Resources Investigations WRI 91-4146, 100 p., 2 sheets.
Freethey, G. W., Pool, D. R., Anderson, T. W., and Tucci, Patrick, 1986, Description and generalized distribution of aquifer materials in the alluvial basins of Arizona and adjacent parts of California and New Mexico: U.S. Geological Survey Hydrologic Investigations Atlas HA-663, scale 1:500,000, 4 sheets.
Harrill, J. R., Gates, J. S., and Thomas, J. M., 1988, Major ground-water flow systems in the Great Basin region of Nevada, Utah, and adjacent states: U.S. Geological Survey Hydrologic Investigations Atlas HA-694-C, scale 1;1,000,000, 1 sheet.
Thomas, J. M., Welch, A. H., and Dettinger, M. D., 1996, Geochemistry and isotope hydrology of representative aquifers in the Great Basin region of Nevada, Utah, and adjacent states: U.S. Geological Survey Professional Paper 1409-C, p. C1-C100.