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...

48 We model the ascent and eruption of lunar mare basalt magmas with new data on crustal 49 thickness and density (GRAIL), magma properties, and surface topography, morphology and 50 structure (Lunar Reconnaissance Orbiter). GRAIL recently measured the broad spatial variation 51 of the bulk density structure of the crust of the Moon. Comparing this with the densities of lunar 52 basaltic and pi...

Deep extensions of low seismic velocities in the mantle beneath volcanic centers are commonly attributed to high temperatures and have been used as a possible characteristic of hot plumes originating at the core-mantle boundary. To address this issue, we examine the effect of volatiles on melting to determine if regions of low seismic velocities may also be interpreted as regions of melting wit...

Crustally-derived granites may be generated in a variety of tectonic settings, but whatever the ultimate causse of heating crustal thickening, crustal extension, enhanced heat flux from the mantle, or magmatic advection by mantle-derived melts crustal melting likely occurs in a dynamic environment. Under these conditions deviatoric stress acting on an anisotropic crustal source region will lead...

We present a quantitative assessment of the thermal and dynamic response of an amphibolitic lower crust to the intrusion of basaltic dike swarms in an arc setting. We consider the effect of variable intrusion geometry, depth of intrusion, and basalt flux on the production, persistence, and interaction of basaltic and crustal melt in a stochastic computational framework. Distinct melting and mix...

The El Oro complex, southwestern Ecuador, is a tilted section of the metasedimentary Ecuadorian forearc, which was partially molten during Triassic time due to gabbroic magma emplacement. Pressure and maximum temperature estimates show that the metamorphic gradient during anatexis was 45 °C/km in the upper crust and 10 °C/km in the 7–8 km garnet-bearing migmatitic lower crust, controlled by bio...

Modern plate tectonic brings down oceanic crust along subduction zones where it either dehydrates or melts. Those hydrous fluids or melts migrate into the overlying mantle wedge trigerring its melting which produces arc magmas and thus additional continental crust. Nowadays, melting seems to be restricted to cases of young (< 50 Ma) subducted plates. Slab melts are silicic and strongly sodic (t...

The continental crust in the overriding plate of India-Asia collision zone southern Tibet is characterized by an overthickened layer felsic composition with underlying granulite-eclogite layer. A large data set indicates that this experienced magmatism from 245 to 10 Ma, as recorded Gangdese Batholith. Magmatism was punctuated flare-ups at 185−170, 90−75, and 55−45 Ma caused a combination exter...

The lower crust of the Mesozoic Sierra Nevada batholith was made up of high MgO, garnet-poor and low MgO, garnet-rich pyroxenites. Both groups are genetically linked and are collectively complementary to the mafic to intermediate Sierran plutons. High MgO pyroxenites represent high pressure cumulates from a mantle-derived hydrous basalt or basaltic andesite, resulting in derivative magmas havin...

The eucrites and diogenites are meteorites that probably originate from asteroid 4-Vesta. The upper part of the crust of this body is certainly composed of eucrites which are basaltic or gabbroic rocks. Diogenites are ultramafic cumulates whose relationships with eucritic lithologies are unknown. Here, we show that the orthopyroxenes of some diogenites display very deep negative Eu anomalies (E...