JULY 2005, GSA TODAY ABSTRACT The subduction factory processes raw materials such as oceanic sediments and oceanic crust and manufactures magmas and continental crust as products. Aqueous fluids, which are extracted from oceanic raw materials via dehydration reactions during subduction, dissolve particular elements and overprint such elements onto the mantle wedge to generate chemically distinc...

The straightforward but unexpected relationship presented here relates crustal thickness to magma type in the Izu-Ogasawara (Bonin) and Aleutian oceanic arcs. Volcanoes along the southern segment of the Izu-Ogasawara arc and the western Aleutian arc (west of Adak) are underlain by thin crust (10-20 km). In contrast those along the northern segment of the Izu-Ogasawara arc and eastern Aleutian a...

The incipient island-arc system of southern Central America (Cretaceous early Oligoccne) is characterized by thick turbidite systems. which mainly filled inner fore-arc troughs. Outcrop data show four. second-order depositional sequences in the deep-water sedlments. The formation of these depositional sequences is strongly related to the morphotectonic evolution of the island-arc system. Each d...

Abstract Arc volcanic rocks erupted above oceanic subduction zones generally have heavy molybdenum (Mo) isotopic compositions, which are attributed to contributions from slab–derived fluids with isotopically Mo at subarc depths. Given that mafic igneous light compositions been rarely identified, it is unclear where isotope reservoirs reside, as these must exist due through geologic time. We pre...

Sumatra Island and its surroundings, Indonesia, are one of the most active tectonics in world. The Aceh-Andaman earthquake, destructive earthquakes world, occurred there. It has attracted many earth scientists to apply various methods, including seismic tomography, understand island’s subsurface structure tectonic system. This study is first delineate imaging beneath island surroundings using a...

The present-day distribution patterns of the cicadas of Wallacea, New Guinea, and the West Pacific reflect the extremely complex geotectonic history of that area. The patterns found in two unrelated monophyletic groups of cicadas (Insecta, Homoptera, Cicadoidea), the subtribe Cosmopsaltriaria and the tribe Chlorocystini with its sister tribe Prasiini, are analysed and related to data from the g...

Oceanic island basalts have a large range in dO values (4·5– INTRODUCTION 7·5‰) compared with the assumed primordial mantle values A 1996 conference on ‘shallow level processes in ocean (5·5–6·0‰) and with mid-ocean ridge basalts (5·7 ± 0·2‰). island magmatism’ drew attention to the controversy that Some Hawaiian tholeiitic basalts have low O values (4·6–5·2‰), is developing on the possible ext...

Variations of oxygen isotope ratios in arc-related lavas can constrain trace-element enrichment in a mantle source being fluxed by addition the contributions of subducted crustal igneous rocks, sediments, and of aqueous fluid. Comparison of this model with observed variations fluids to the sub-arc mantle. We have measured oxygen isotope in the geochemistry of lavas from the Vanuatu–Fiji–New Cal...

Back-arc basins in continental settings can develop into oceanic basins, when extension lasts long enough to break up the lithosphere and allow mantle melting that generates new crust. Often, basement of these is not only composed crust, but also exhumed mantle, fragments intrusive magmatic bodies, a complex mid-ocean ridge system characterised by distinct relocations spreading centre. To bette...