Greenschist Facies Metamorphic Zircon Overgrowths as a Constraint on Exhumation of the Brooks Range Metamorphic Core, Alaska

Origin and tectonic evolution ofthe metamorphic sole beneath the Brooks Range ophiolite, Alaska

Structural field relations, petrologic and geochemical studies, and radiometric age aualysis of metamorphic rocks at the base of the Brooks Range ophiolite provide a record of the time, tectonic setting, and initial conditions of ophiolite emplacement during the Middle Jurassic western Brookian orogeny. The metamorphic sole of the Misheguk, Siniktanneyak, and Avan Hills ophiolite bodies is tran...

The metamorphism and exhumation of the Himalayan metamorphic core, eastern Garhwal region, India

[1] Geothermobarometric together with microand macro-structural data indicate ductile flow in the metamorphic core of the Himalaya in the Garhwal region of India. Peak metamorphic pressure and temperature increase dramatically across the Main Central Thrust (MCT) from !5 kbar and !550°C in the Lesser Himalayan Crystalline Sequence (LHCS) to !14 kbar and !850°C at !3 km above the MCT in the Grea...

Fast Cooling and Exhumation of the Valhalla Metamorphic Core Complex, Southeastern British Columbia

High-grade, migmatitic paragneisses (820°C, 8 kbar peak conditions) of the Valhalla metamorphic core complex experienced the retrograde net transfer reaction (ReNTR): garnet + melt + K-feldspar = sillimanite + biotite + plagioclase during cooling and crystallization of the melt, resulting in an increase in the Fe/(Fe + Mg) of both garnet and biotite at their margins. Diffusion profiles generate...

Cretaceous and Eocene U-Pb Zircon Migmatite Ages from the East Humboldt Range Metamorphic Core Complex, Nevada

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Oceanic- and continental-type metamorphic terranes: Occurrence and exhumation mechanisms