We present an oxygen isotope and petrologic study of four voluminous, zoned ash-flow sheets of the Southwestern Nevada Volcanic Field (SWNVF): Topopah Spring (TS, .1200 km3, 12.8 Ma), Tiva Canyon (TC, 1000 km3, 12.7 Ma), Rainier Mesa (RM, 1200 km3, 11.6 Ma), and Ammonia Tanks (AT, 900 km3, 11.45 Ma). The d18O values of quartz, sanidine, sphene, magnetite, and zircons in rhyolites and latites of...

New analytical and experimental data constrain the storage and equilibration conditions of the magmas erupted in 1912 from Novarupta in the 20th century’s largest volcanic event. Phase relations at H2O+CO2 fluid saturation were determined for an andesite (58.7 wt% SiO2) and a dacite (67.7 wt%) from the compositional extremes of intermediate magmas erupted. The phase assemblages, matrix melt com...

Archean volcanic rocks in the mafic-dominated, ca. 2.66–2.69 Ga Point Lake and Beaulieu River belts, Slave Province, Northwest Territories, are significant in demonstrating the facies that characterize specific portions of pillow volcanoes or seamounts, irrespective of tectonic setting. Three distinct localities mapped in detail display facies consistent with: (1) proximal, deep-water, (2) medi...

Abstract The episode of widespread organic carbon deposition marked by peak black shale sedimentation during the Palaeoproterozoic is also reflected in exceptionally abundant graphite deposits this age. Worldwide anoxic/euxinic sediments were preserved as a deep crustal reservoir both carbon, and sulphur accompanying pyrite, commonly >1 wt %. carbon- sulphur-rich crust interacted with mafic ...

Zircon ages and trace element compositions from recent silicic eruptions in the Lassen Volcanic Center (LVC) allow for an evaluation of the timing and conditions of rejuvenation (reheating and mobilization of crystals) within the LVC magmatic system. The LVC is the southernmost active Cascade volcano and, prior to the 1980 eruption of Mount St. Helens, was the site of the only eruption in the C...

TheEmeishan large igneous province contains a diverse assemblage of igneous rocks includingmildly peralkaline granitic rocks ofA-type affinity. The granitic rocks from the Panzhihua, Baima andTaihe plutons are temporally, spatially and chemically associatedwith layeredmafic-ultramafic intrusions. Electronmicroprobe analyses of themajor and accessoryminerals along with major and trace element da...

The ~1.08 Ga anorogenic, A-type Pikes Peak batholith (Front Range, central Colorado) is dominated by coarsegrained, biotite±amphibole syenogranites and minor monzogranites, collectively referred to as Pikes Peak granite (PPG). The batholith is also host to numerous small, late-stage plutons that have been subdivided into two groups (e.g. Wobus, 1976. Studies in Colorado Field Geology, Colorado ...

Mafic volcanism accounts for 80% of magmas erupted on Earth. Although the majority these eruptions are effusive to Strombolian and fountain-fed, large explosive mafic do occur. This work uses deposits pyroclast textures from 12.6 ka Curacautín ignimbrite eruption Llaima volcano constrain conditions that drove this extrapolate findings provide insights into promote large-volume, elsewhere. The (...