Evaluation of volcanic and hydrothermal fluxes to the surface environments is important to elucidate the geochemical cycle of sulphur and the evolution of ocean chemistry. This paper presents S/(3)He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur flux of 100 Gmol/y at MOR. The S/(3)He ratios of h...

Older and younger granitoids are widespread throughout the basement rocks of NE Egypt. Therefore, they are played a significant role in the evolution of the Pan-African crust. The Wadi El Sheikh-Gabal Saint Katherine area comprise three distinctive magmatic granitoid suites, namely: (1) calc-alkaline older quartz monzodiorite-tonalite suite (COG), (2) calcalkaline younger monzogranite suite (CY...

the makran subduction zone in southeastern iran and southern pakistan is where the oceanic crust of the arabian plate (oman sea) is subducting beneath eurasia. compared to other subduction zones in the world, the makran subduction zone has some unusual features, including different seismicity patterns in its eastern and western parts. also, the quaternary volcanoes in the eastern part of makran...

Hydrothermal precipitates associated with active vents in the eastern Manus back-arc basin, Papua New Guinea, are among the most gold rich yet discovered on the modern sea floor. The volcanic rocks associated with this mineralization were investigated to determine if they are sufficiently enriched in gold to account for the gold content of the sulfides by simple leaching and to determine whethe...

Andean volcanism occurs within the Andean Volcanic Arc (AVA), which is the product of subduction of the Nazca Plate and Antarctica Plates beneath the South America Plate. The AVA is Earth’s longest but discontinuous continental-margin volcanic arc, which consists of four distinct segments: Northern Volcanic Zone, Central Volcanic Zone, Southern Volcanic Zone, and Austral Volcanic Zone. These se...

New geochemical data including Sm/Nd isotopic data show evidence for an early Paleozoic arc/back-arc complex in the Nashoba terrane of southeastern New England. The Nashoba terrane lies between rocks of Ganderian affinity to the northwest and Avalonian affinity to the southeast. It consists of early Paleozoic mafic to felsic metavolcanic and metasedimentary rocks that were intruded by intermedi...

Three tectono-magmatic systems create volcanism in Central America; the volcanic front, a weak secondary front and the back-arc. Most magma output occurs at the volcanic front along narrow lines of historically active composite volcanoes in strikeslip/extensional settings. Lavas have strong slab signature, are water-rich and plagioclase and pyroxene phyric. A sporadic secondary front occurs abo...

Sedimentologic, stratigraphic, and geochronologic data from strata of early Mesozoic age in the central Mojave block elucidate the paleogeographic and tectonic evolution of the magmatic arc in the southern U.S. Cordillera. A sequence of calcareous siltstone, volcaniclastic conglomerate, tuff, and quartzose sandstone records the transition from shallow-marine rocks of the Fairview Valley Formati...

[1] The Talkeetna arc is one of two intraoceanic arcs where much of the section from the upper mantle through the volcanic carapace is well exposed. We reconstruct the vertical section of the Talkeetna arc by determining the (re)crystallization pressures at various structural levels. The thermobarometry shows that the tonalites and quartz diorites intruded at 5–9 km into a volcanic section esti...

Wrangellia Superterrane. The Paleozoic to Mesozoic Wrangellia superterrane (Insular terrane) consists of intraoceanic volcanic assemblages and basement rocks of the Peninsular, Wrangellia, and Alexander terranes (Plafker et al, 1994). The magmatic-arc assemblages of the Peninsular terrane appear to have been built upon the Wrangellia composite terrane prior to the midCretaceous and include: 1) ...