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

Journal Article · Sat Oct 01 04:00:00 EDT 1994 · Geological Society of America, Bulletin

DOI:https://doi.org/10.1130/0016-7606(1994)106<1304:ECVITM>2.3.CO;2· OSTI ID:145660

Sawyer, D A; Hudson, M R ^[1]; Fleck, R J; Lanphere, M A ^[2]; Warren, R G; Broxton, D E ^[3]

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1. Geological Survey, Denver, CO (United States)
2. Geological Survey, Menlo Park, CA (United States)
3. 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, Journal Name: Geological Society of America, Bulletin Journal Issue: 10 Vol. 106; ISSN BUGMAF; ISSN 0016-7606
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
40 CHEMISTRY
58 GEOSCIENCES
AGE ESTIMATION
ARGON 39
ARGON 40
CALDERAS
COMPILED DATA
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MAGMA
MASS SPECTROSCOPY
MIOCENE EPOCH
NEVADA
RADIOACTIVE WASTE DISPOSAL
STRATIGRAPHY
TUFF
VOLCANIC ROCKS
Yucca Mountain Project