| Abstract: | Outflow sheets of the Hiko tuff and the Racer Canyon tuff, which together extend over approximately 16000 km2 around the Caliente caldera complex in southeastern Nevada, have long been considered to be products of simultaneous or near-simultaneous eruptions from inset calderas in the west and east ends, respectively, of the caldera complex. New high-precision 40Ar/39Ar geochronology and paleomagnetic data demonstrate that emplacement of the uppermost part of the Racer Canyon tuff at 18.33??0.03 Ma was nearly synchronous with emplacement of the single outflow cooling unit of the much larger overlying Hiko tuff at 18.32??0.04 Ma. Based on comparison with the geomagnetic polarity time scale derived from the sea-floor spreading record, we conclude that emplacement of the first of several outflow cooling units of the Racer Canyon tuff commenced approximately 0.5 m.y. earlier. Only one paleomagnetic polarity is found in the Hiko tuff, but at least two paleomagnetic reversals have been found in the Racer Canyon tuff. The two formations overlap in only one place, at and near Panaca Summit northeast of the center of the Caliente caldera complex; here the Hiko tuff is stratigraphically above the Racer Canyon tuff. This study demonstrates the power of combining 40Ar/39Ar and paleomagnetic data in conjunction with phenocryst compositional modes to resolve problematic stratigraphic correlations in complex ash-flow sequences where use of one method alone might not eliminate ambiguities. |
| Genre: | Article |
| ProdID: | 70019573 |
| Citation Author: | Gromme, S.; Deino, A. M.; Best, M. G.; Hudson, M. R. |
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| Citation End Page: | 35 |
| Citation Issue: | 1 |
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| Citation Language: | English |
| Citation Larger Work Title: | Bulletin of Volcanology |
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| Citation Number Of Pages: | 15 |
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| Citation Search Results Text: | Geochronologic and paleomagnetic evidence defining the relationship between the Miocene Hiko and Racer Canyon tuffs, eccentric outflow lobes from the Caliente caldera complex, southeastern Great Basin, USA; 1997; Article; Journal; Bulletin of Volcanology; Gromme, S.; Deino, A. M.; Best, M. G.; Hudson, M. R. |
| Citation Start Page: | 21 |
| Citation Volume: | 59 |
| Citation Year: | 1997 |
| Type: | citation/reference |
| Text: | Geochronologic and paleomagnetic evidence defining the relationship between the Miocene Hiko and Racer Canyon tuffs, eccentric outflow lobes from the Caliente caldera complex, southeastern Great Basin, USA; 1997; Article; Journal; Bulletin of Volcanology; Gromme, S.; Deino, A. M.; Best, M. G.; Hudson, M. R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1997 00:00 -0600 |
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