Episodic caldera volcanism in the Miocene southwestern Nevada volcanic field. Revised stratigraphic framework, {sup 40}Ar/{sup 39}Ar geochronology, and implications for magmatism and extension
- Geological Survey, Denver, CO (United States)
- Geological Survey, Menlo Park, CA (United States)
- Los Alamos National Lab., NM (United States)
The middle Miocene southwestern Nevada volcanic field (SWNVF) is a classic example of a silicic multicaldera volcanic field in the Great Basin. More than six major calderas formed between >15 and 7.5 Ma. We summarize major revisions of the SWNVF stratigraphy that provide for correlation of lava flows and small-volume tuffs with the widespread outflow sheets of the SWNVF. New laser fusion {sup 40}Ar/{sup 39}Ar isotopic ages are used to refine and revise the timing of eruptive activity in the SWNVF. The use of high-sensitivity mass spectrometry allowed analysis of submilligram-sized samples with analytical uncertainties of {approximately}0.3% (1 {sigma}), permitting resolution of age differences as small as 0.07 Ma. These results confirm the revised stratigraphic succession and document a pattern of episodic volcanism in the SWNVF. 95 refs., 6 figs., 3 tabs.
- DOE Contract Number:
- AI08-91NV11040
- OSTI ID:
- 145660
- Journal Information:
- Geological Society of America, Bulletin, Vol. 106, Issue 10; Other Information: PBD: Oct 1994
- Country of Publication:
- United States
- Language:
- English
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