Rhyolite thermobarometry and the shallowing of the magma reservoir, Coso volcanic field, California
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Abstract
The compositionally bimodal Pleistocene Coso volcanic field is located at the western margin of the Basin and Range province ∼60 km north of the Garlock fault. Thirty-nine nearly aphyric high-silica rhyolite domes were emplaced in the past million years: one at 1 Ma from a transient magma reservoir, one at ∼0·6 Ma, and the rest since ∼0·3 Ma. Over the past 0·6 My, the depth from which the rhyolites erupted has decreased and their temperatures have become slightly higher. Pre-eruptive conditions of the rhyolite magmas, calculated from phenocryst compositions using the two-oxide thermometer and the Al-in-hornblende barometer, ranged from 740°C and 270 MPa (2·7 kbar; ∼10 km depth) for the ∼0·6 Ma magma, to 770°C and 140 MPa (1·4 kbar; ∼5·5 km) for the youngest (∼0·04 Ma) magma. Results are consistent with either a single rhyolitic reservoir moving upward through the crust, or a series of successively shallower reservoirs. As the reservoir has become closer to the surface, eruptions have become both more frequent and more voluminous.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Rhyolite thermobarometry and the shallowing of the magma reservoir, Coso volcanic field, California |
| Series title | Journal of Petrology |
| DOI | 10.1093/petrology/41.1.149 |
| Volume | 41 |
| Issue | 1 |
| Year Published | 2000 |
| Language | English |
| Publisher | Oxford University Press |
| Description | 26 p. |
| First page | 149 |
| Last page | 174 |
| Country | United States |
| State | California |
| Other Geospatial | Coso volcanic field |
| Google Analytic Metrics | Metrics page |