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Thermal and Compositional Evolution of the Mid-Miocene Searchlight Magmatic System (Nevada, USA) as Recorded in Zircon
Thesis - Campus Access Only
Master of Science (MS)
Geochemistry, geochronology, Ti-in-zircon, trace element, volcanics, Zircon
The middle Miocene Searchlight pluton (~17-15.8 Ma) in southern
Nevada, USA, located in the Colorado River Extensional Corridor, has an
extensive spatially and temporally associated volcanic record. Regional
extension has rotated a large crustal block ca. 90° to expose a 12-13 km section
of crust that included parts of the Searchlight pluton and its volcanic cover in the
adjacent Highland Range. Recent geochronology and geochemistry of the
pluton and volcanic strata have shown that the construction of the Searchlight
magma system was piecemeal. We examined the growth and dynamics of the
Searchlight magma system using zircon trace elements from U/Pb age-dated
plutonic and volcanic rocks. Zircon trace element indices for magmatic
temperature and evolution, including Ti, Hf, Th, U, Th/U, Yb/Gd, and Eu/Eu*,
showed a strong correlation to rock type and age. The Searchlight magmatic
system has recorded a complex solidification history, a progression from a
trachyandesitic to rhyolitic composition with time, and clear cogenetic links
between some of the plutonic and volcanic rocks.
Johnson, Brent Michael, "Thermal and Compositional Evolution of the Mid-Miocene Searchlight Magmatic System (Nevada, USA) as Recorded in Zircon" (2014). Master's Theses. 4468.