| Abstract: | The Miocene Bruneau-Jarbidge and adjacent volcanic fields of the central Snake River Plain, southwest Idaho, are dominated by high-temperature rhyolitic tuffs and lavas having an aggregate volume estimated as 7000 km3. Samples from units representing at least 50% of this volume are strongly depleted in 18O, with magmatic feldspar ??18OVSMOW (Vienna standard mean ocean water) values between -1.4??? and 3.8???. The magnitude of the 18O depletion and the complete lack of any rhyolites with normal values (7???-10???) combine to suggest that assimilation or melting of a caldera block altered by near-contemporaneous hydrothermal activity is unlikely. Instead, we envisage generation of the high-temperature rhyolites by shallow melting of Idaho Batholith rocks, under the influence of the Yellowstone hotspot, affected by Eocene meteoric-hydrothermal events. The seeming worldwide scarcity of strongly 18O-depleted rhyolites may simply reflect a similar scarcity of suitable crustal protoliths. ?? 2005 Geological Society of America. |
| Genre: | Article |
| ProdID: | 70027561 |
| Citation Author: | Boroughs, S.; Wolff, J.; Bonnichsen, B.; Godchaux, M.; Larson, P. |
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| Citation End Page: | 824 |
| Citation Issue: | 10 |
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| Citation Language: | English |
| Citation Larger Work Title: | Geology |
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| Citation Number Of Pages: | 4 |
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| Citation Search Results Text: | Large-volume, low-??18O rhyolites of the central Snake River Plain, Idaho, USA; 2005; Article; Journal; Geology; Boroughs, S.; Wolff, J.; Bonnichsen, B.; Godchaux, M.; Larson, P. |
| Citation Start Page: | 821 |
| Citation Volume: | 33 |
| Citation Year: | 2005 |
| Type: | citation/reference |
| Text: | Large-volume, low-??18O rhyolites of the central Snake River Plain, Idaho, USA; 2005; Article; Journal; Geology; Boroughs, S.; Wolff, J.; Bonnichsen, B.; Godchaux, M.; Larson, P. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1130/G21723.1 |
| Date Other: | Sat, 1 Jan 2005 00:00 -0600 |
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