Water is an important volatile component in andesitic eruptions and deep-seated andesitic magma chambers. We report an investigation of H2O speciation and diffusion by dehydrating haploandesitic melts containing 62.5 wt.% water at 743–873 K and 100 MPa in cold-seal pressure vessels. FTIR microspectroscopy was utilized to measure species [molecular H2O (H2Om) and hydroxyl group (OH)] and total H...

Abstract The South Eastern Futuna Volcanic Zone (SEFVZ; 50 km × 80 km) is located in the NW of Lau back-arc basin at northern boundary and YAO microplates. Fatu Kapa an area (∼15 10 diffuse volcanic activity center SEFVZ intersection two axes with fracture zone. At this place, volcanic, tectonic, hydrothermal activities are enhanced. most differentiated series whole region found area. Based on ...

Pillow lava rims from the Mesoarchean Barberton Greenstone Belt in South Africa contain micrometer-scale mineralized tubes that provide evidence of submarine microbial activity during the early history of Earth. The tubes formed during microbial etching of glass along fractures, as seen in pillow lavas from recent oceanic crust. The margins of the tubes contain organic carbon, and many of the p...

Recycled subducted ocean crust has been traced by elevated 187Os/188Os in some studies and by high nickel and low manganese contents in others. Here, we show that these tracers are linked for Quaternary lavas of Iceland, strengthening the recycling model. An estimate of the osmium isotopic composition of both the recycled crust and the mantle peridotite implies that Icelandic Quaternary lavas a...

We report the oxygen isotope composition of olivine and orthopyroxene phenocrysts in lavas from the main magma types at Mt Shasta and Medicine Lake Volcanoes: primitive high-alumina olivine tholeiite (HAOT), basaltic andesites (BA), primitive magnesian andesites (PMA), and dacites. The most primitive HAOT (MgO [ 9 wt%) from Mt. Shasta has olivine dO (dOOl) values of 5.9–6.1%, which are about 1%...

The Emperor Seamount-Hawaiian island chain is thought to originate from melting of a heterogeneous mantle plume, but the composition of the plume has always been inferred from the compositions of the erupted lavas. It has been suggested that recycled (i.e. previously subducted) basaltic oceanic crust (with or without sediments) is part of this plume and responsible for the enriched isotopic com...

Introduction: Deconvolution of thermal emission spectra from Mars orbiting spacecraft, in-situ analysis of martian rocks by Mars Pathfinder, Spirit and Opportunity rovers, as well as investigation of martian meteorites, all point towards a wide magmatic diversity at the surface of the planet. Compositions varying from olivine-rich basalt to high-silica granite / rhyolite through basaltic andesi...