Arc magmas are distinguished from those of other tectonic settings by several first order characteristics; 1) they tend to be realtively differentiated with even the most mafic rocks in a suite typically ≥50% SiO2, 2) they typically contain high H2O contents and 3) they have distinctive trace element signatures. The “standard” model for arc petrogenesis involves melting of a mantle wedge, preco...

Anorthite megacrysts from twelve volcanic centers of the Kurile Island Arc were analyzed by the ion microprobe for concentrations of: Li, Be, B, F, Mg, P, Cl, K, Ti, Fe, Co, Rb, Sr, Y, Zr, Nb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, and Pb. These 1–2-cm megacrysts are mainly found as early phenocrysts in basalts, but are also present in andesites, rhyolites and hybrid rocks from almost every studied vo...

the halak abad prospect occurs in the northeastern part of central iran zone (sabzevar structural zone). in this investigation, geochemical evolution, age and source of part of northeastern iran magmatic arc (intrusive bodies) in halak abad area in the khorasan razavi province has been studied. the exposed rocks consist of volcanic rocks with andesite and dacite nature, limestone, plutonic rock...

the shahabad gabbroic intrusion, with nw-se trend cropped out at the boundary of zagros and sanandaj-sirjan zones is composed of olivine gabbro, orthogabbro and troctolite. plagioclase, clinopyroxene and olivine are the main minerals; and magnetite, titanomagnetite and serpentine are minor and secondary minerals. microprobe analyses of the minerals show that plagioclase is labradorite, pyroxene...

Back-arc extension has been well documented in subduction plate tectonic regimes. However, the reasons why back-arc extensions are associated with some systems but not others have remained elusive. Here, spatio-temporal variations composition of Cenozoic basalts northeast Asian continental margin used to constrain mechanism for episodic extensions. Using geochemical data sensitive affinity, we ...

the deep internal structure of the crust can be determined using appropriate seismic and electromagnetic methods. the natural source magnetotelluric (mt) method is the most suitable electromagnetic technique for probing into the deep crust. a long period magnetotelluric data set obtained in the southern chilean andes is investigated in this paper. dimensionality analysis shows that the data may...

The Grenada back-arc basin is located between the Aves Ridge, which hosted remnant Early Paleogene “Great Caribbean Arc,” and Eocene to Present Lesser Antilles Arc. Several earlier studies have proposed different modes of opening for this basin, including N-S E-W directions. main aim study constrain circumstances leading basin. Three combined wide-angle reflection seismic profiles were acquired...