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...

High-magnesian andesite occurs at Hachimantai, northern Honshu, Japan. Disequilibrium zoning features indicate that the phenocryst minerals were derived from three different magmas. Chemical compositions and zoning profiles are accounted for by two-stage magma mixing: the first mixing occurred between a crystal-free basalt magma and a more differentiated olivine basalt magma; the second stage o...

Continental crust is too Si-rich and Mg-poor to derive directly from mantle melting, which generates basaltic rather than felsic magmas. Converting basalt to more felsic compositions requires a second step involving Mg loss, which is thought to be dominated by internal igneous differentiation. However, igneous differentiation alone may not be able to generate granites, the most silicic endmembe...

Several compositional features of sedimentary deposits can be used to reconstruct environmental conditions source areas. In this research, bulk X-ray diffraction mineralogy, heavy and clay mineral assemblages geochemistry obtained for modern the Cunene River its tributaries Caculuvar–Mucope are integrated with geological/geomorphological characteristics respective catchment areas evaluate what ...

Gabal El-Ineigi fluorite-bearing rare-metal granite with A-type affinity, located in the Central Eastern Desert of Egypt, is distinguished by its abundance large fluorite-quartz veins and mafic enclaves. Plagioclase (labradorite to oligoclase), Mg-rich biotite, hornblende are main components enclaves, significant amounts fluorite as essential phases, titanite Fe-Ti oxides (Nb-free rutile ilmeni...

In the Variscan Western Tatra granites hybridization phenomena such as mixing and mingling can be observed at the contact of mafic precursors of dioritic composition and more felsic granitic host rocks. The textural evidence of hybridization include: plagioclase-K-feldspar-sphene ocelli, hornblende- and biotite-rimmed quartz ocelli, plagioclase with Ca-rich spike zonation, inversely zoned K-fel...

[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...