Small bodies of mantle-derived peridotites and other ultramafic rocks are commonly found in exhumed lower crustal units collisional orogens. They provide a direct record the complex evolution upper mantle before during an orogeny, therefore key markers geodynamic orogen. We report here discovery such peridotites, which occur as fragmented enclaves migmatites high-grade Variscan crust exposed Pe...

Petrographic and major element investigations of carbonates from seven drill cores recovered during IODP Expedition 357 on the Atlantis Massif (AM) provide information genesis carbonate minerals in oceanic lithosphere. Textural sequences mineralogical assemblages reveal three distinct types occurrences ultramafic rocks that are controlled by (a) fluid composition flow, (b) temperature, (c) pres...

baft ophiolite mélange is a part of naein-baft ophiolite (southeast of kerman province in iran). serpentinites from baft ophiolite mélange contain different types of spinels such as chromite, chromespinel, ferritchromite and magnetite which can reveal different stages of evolution in host serpentinites. the compositions of baft chromites show that they belong to podiform chromitites that may ha...

To constrain further the Mg isotopic composition of the Earth and chondrites, and investigate the behavior of Mg isotopes during planetary formation and magmatic processes, we report high-precision (±0.06& on dMg and ±0.07& on dMg, 2SD) analyses of Mg isotopes for (1) 47 mid-ocean ridge basalts covering global major ridge segments and spanning a broad range in latitudes, geochemical and radioge...

Peridotite xenoliths in arc volcanoes are very rare, usually small and remain poorly studied. Much of the earlier work focused on peridotites affected by re-crystallization, metasomatism and veining that took place shortly before the eruption of the host magmas; such lithologies may not be widespread in the mantle wedge.This study reports petrographic, major and trace element data for 17 large,...

rate’ of cpx and opx. Isobaric melting experiments show INTRODUCTION a > b, but the abyssal peridotite data suggest b > a, i.e. I recently showed (Niu, 1997) that proportions of residual opx would contribute more than cpx to the melt during minerals in abyssal peridotites (e.g. Dick, 1989; Johnson melting beneath ocean ridges. As abyssal peridotites et al., 1990; Johnson & Dick, 1992) exhibit s...