Petrology of the Quaternary Volcanics of the Roosevelt KGRA, and Adjoining Area, Utah. Final Report, Volume 1

The Roosevelt KGRA (Known Geothermal Resource Aarea) located near Milford, Utah, is associated with a suite of quaternary silicic volcanics distributed for 15 km along the crest and western flank of the Mineral Mountains, a large tertiary granite batholith. The volcanics are high-silica rhyolites and occur as domes, flows and tuffs. Initial eruptions resulted in two flows of low viscosity, phenocryst-poor rhyolite. Later activity consisted of pyroclastic eruptions and the emplacement of at least 9 viscous domes. In addition to abundant glass the rhyolites contain alkali feldspar, plagioclase, biotite, iron-titanium oxides and small amounts of hornblende, allanite, apatite, zircon, sphene and topaz. Magmatic temperatures were about 700C and water fugacities ranged from 350 to 3450 bars. Based on water fugacity calculations it is concluded that there may have been one or more shallow magma chambers in the Mineral Range at depths of about 1.6 km

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Citation Date 1976-06-01T00:00:00

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Original ID 0c57e978-530f-40e0-aa44-acf7e493e855
Index Date 2014-01-23T17:58:02
Original Format ISO-USGIN
Original Version 1.2


Name Nash, W.P.
Organization Department of Gelogy and Geophysics, University of Utah, Salt Lake City, Utah (USA)

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North Bound 42.001618
South Bound 36.9979031
East Bound -109.0410581
West Bound -114.0529979