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Scientific Investigations Report 2009–5014

Scientific Investigations Report 2009–5014

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Table 3. Lithology, thickness, extent, and water-bearing characteristics of hydrogeologic units in the upper Humboldt River basin, northeastern Nevada.­­

[Abbreviations: ft, foot; Fm, formation]

Rock or
stratigraphic unit
Lithology Thickness and
Younger basin-fill deposits Quaternary Alluvium and glacial moraines Sorted and interbedded clay, sand, and gravel along stream flood plains. Poorly sorted to unsorted clay, silt, sand, gravel, and boulders of alluvial fans and moraines. Deposits of flood plains probably do not exceed a few tens of feet in thickness. Moraines and deposits of alluvial fans probably range from hundreds to more than 1,000 ft thick. Together with older basin-fill deposits, comprise shallow water-table aquifers and deeper confined aquifers. Permeability highly variable depending on lithology.
Older basin-fill deposits Quaternary and Tertiary Older alluvium of stream terraces (Coats, 1987, p. 70), sedimentary deposits of the Miocene and Pliocene Elko Basin (Wallace and others, 2008, p. 59–62), and limestone, conglomerate, sandstone, shale, and tuff of Oligocene to Paleocene age (Coats, 1987, p. 51–62). Poorly consolidated deposits of fluvial and lacustrine origin. Includes deposits of alluvial fans, stream flood plains, and shallow lakes. Deposits commonly are tuffaceous and are extensively interbedded with volcanic rocks. Total thickness including interbedded volcanic rocks ranges from less than 500 ft mostly along basin margins to more than 5,000 ft in a deep and narrow structural basin that extends from southern Huntington Valley to northern Marys River Area (fig. 3). Together with younger basin-fill deposits, comprise shallow water-table aquifers and deeper confined aquifers. Permeability highly variable depending on lithology.
Volcanic rocks Tertiary Volcanic rocks Ash-flow and air-fall tuffs, lava flows, and domes. Compositions include basalt, andesite, dacite, latite, and rhyolite (Coats, 1987, pl. 1 and p. 51–67). Extensively interbedded with older basin-fill deposits. See above for composite thickness. Mostly impede ground-water flow because tuffs weather to clay and because of interbedded fine-grained lake deposits. Presence of perennial streams in watersheds underlain by these rocks also indicates low permeability.
Crystalline rocks Cambrian and Jurassic Metamorphic rocks Metamorphic rocks include marble, schist, and gneiss. They are metamorphosed carbonate and clastic sedimentary rocks of Paleozoic age in the central and northern Ruby Mountains and Elko Hills. Thickness of metamorphic rocks probably similar to nearby unmetamorphosed carbonate and clastic sedimentary rocks of Paleozoic age. Granitic rocks extend to great depths and can be much more extensive than indicated by outcrop area. Impedes the movement of ground water.
Tertiary and Jurassic Granitic intrusive rocks Granite and granodiorite in the central Ruby Mountains and alaskite in the southern Independence Mountains.
Clastic sedimentary rocks Devonian to Ordovician Woodruff Fm
Valmy Fm
Vinini Fm
Shale, siltstone, sandstone, quartzite, chert, and marine volcanic rocks. Structurally overlie along the Roberts Mountains thrust various units of carbonate rocks. Thickness about 2,000 ft in the Snake Mountains, 9,000 ft in northern Independence Mountains, 4,700 ft in the Pinyon Range, and 4,000–10,000 ft in the Ruby Mountains (Coats, 1987, p. 10–13 and 29–34). Generally impedes movement of ground water. Presence of perennial streams in watersheds underlain by these rocks also indicates low permeability.
Carbonate and clastic sedimentary rocks Permian, Pennsylvanian and Mississippian Edna Mountain Fm
Schoonover Fm
Diamond Peak Fm
Chainman Shale
Webb Fm
Shale, sandstone, sandy limestone, conglomerate, and chert. Depositionally overlie various units of carbonate rocks Thickness at least 20,000 ft in the Ruby Mountains, 10,000 ft in the Pinyon Range and Snake Mountains, and about 4,000 ft in the Independence Mountains. An oil well penetrated 4,500 ft of carbonate rocks from the Devils Gate Limestone to the Hanson Creek Formation at the north end of the Pinon Range (Coats, 1987, p. 13–47). Comprise carbonate-rock aquifers generally beneath basin-fill aquifers. High permeability due to solution widening of fracture zones. Absence of perennial streams in watersheds even partly underlain by these rocks indicates high permeability.
Permian to Cambrian Phosphoria Fm
Strathearn Fm
Moleen Fm
Tomera Fm
Ely Limestone
Joana Limestone
Pilot Shale
Devils Gate Limestone
Nevada Formation
Lone Mountain Dolomite
Roberts Mountains Fm
Hanson Creek Fm
Eureka Quartzite
Pogonip Group
Windfall Fm
Dunderberg Shale
Hamburg Dolomite
Secret Canyon Shale
Geddes Limestone
Eldorado Dolomite
Pioche Shale
Prospect Mountain Quartzite
Intervals of limestone and dolomite interrupted by thinner intervals of shale, quartzite, and conglomerate. All units rarely present in a single mountain range. Underlie entire study area, but are concealed over large parts of mountain ranges by various units of clastic sedimentary rocks.

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