Chemical and mineralogic trends within the Timber Mountain--Oasis Valley caldera complex, Nevada: Evidence for Multiple cycles of chemical evolution in a long-lived silicic magma system

Journal Article · Wed May 10 04:00:00 EDT 1989 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JB094iB05p05961· OSTI ID:6142520

Broxton, D E; Warren, R G; Byers, F M; Scott, R B

Rocks of the Miocene and Pliocene Timber Mountain--Oasis Valley(TM-OV) caldera complex in the southwest Nevada volcanic field are dominantlyrhyolites and quartz latites (trachytes). Minor basalticto dacitic rocks were erupted peripherally to the caldera complex and in themoat of the youngest caldera. We divided the petrologic evolution of thecaldera complex into a series of petrochemicalcycles based on systematic changes in rock chemistry, modal petrography, andmineral chemistry as a function of time. Each petrochemical cycle ischaracterized by periods of systematic differentitiation toward more siliceousor rhyolitic compositions. Breaks between cycles are generally abrupt andfollow either times of major ash flow tuff eruption or episodes of relativelymafic (basaltic to dacitic) volcanism.

• Research Organization: Los Alamos National Laboratory, Los Alamos, New Mexico(US); U.S. Geological Survey, Denver, Colorado
• OSTI ID: 6142520
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 94:B5; ISSN JGREA
• Country of Publication: United States
• Language: English

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58 GEOSCIENCES
580202* -- Geophysics-- Volcanology-- (1980-1989)
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FEDERAL REGION IX
GEOCHEMISTRY
GEOLOGY
GEOTHERMAL SYSTEMS
IGNEOUS ROCKS
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VOLCANIC REGIONS
VOLCANIC ROCKS