Age of volcanism, intrusion, and mineralization in the Thomas Range, Keg Mountain, and Desert Mountain, western Utah
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Abstract
Twenty-six new age determinations by the fission-track method establish a chronology for volcanism, intrusion, and mineralization in the Thomas Range, Keg Mountain, and Desert Mountain, in western Utah. The fission-track ages confirm D. R. Shawe's three-fold classification of igneous rocks. The oldest group of rocks consists of flows, agglomerates, and some ash-flow tuffs that were deposited 38-39 m.y. ago. The middle group contains widespread rhyolitic ash-flow tuffs that originated from local volcanic centers 30-32 m.y. ago. A dike emplaced along the probable ring-fracture zone of the Keg caldera about 31 m.y. ago indicates that caldera collapse occurred soon after eruption of ash-flow tuffs. Rocks believed to belong-to the middle group also were intruded by the quartz monzonite of Desert Mountain 27-30 m.y. ago. Little or no igneous activity took place within the next 20 m.y., during which time the region was strongly broken by Basin-and-Range faulting. Rhyolites of the youngest group were extruded 8-10 m.y. ago in the Keg Mountain area and 6-7 m.y. ago in the Thomas Range. The beryllium-fluorite mineralization at Spor Mountain occurred after the rhyolitic volcanism in the Thomas Range.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Age of volcanism, intrusion, and mineralization in the Thomas Range, Keg Mountain, and Desert Mountain, western Utah |
| Series title | Journal of Research of the U.S. Geological Survey |
| Volume | 3 |
| Issue | 5 |
| Year Published | 1975 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Reston, VA |
| Description | 8 p. |
| First page | 597 |
| Last page | 604 |
| Country | United States |
| State | Utah |
| Other Geospatial | Thomas Range, Keg Mountain, Desert Mountain |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |