A. Eslami, G. Borghini, A. Montanini, G. Grieco, C. Marchesi
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引用次数: 2
Abstract
The Cheshmeh-Bid ophiolitic massif in the Khajeh-Jamali district (Southern Iran) is dominated by harzburgite-dunite tectonites locally intruded by orthopyroxenite dikes. These latter are composed of dominant coarse orthopyroxene with minor olivine, Cr-spinel, clinopyroxene and amphibole. Estimated equilibrium temperatures for Mg-hornblende and edenitic amphibole reveal a late stage magmatic origin. The Cheshmeh-Bid orthopyroxenites are characterized by very low Al2O3, CaO, Na2O and TiO2 abundances coupled to relatively high MgO and SiO2 contents. They display U-shaped REE patterns, selective LILE enrichment and positive Pb and Sr anomalies. The host harzburgites are highly refractory mantle residues resulting from fluid-assisted melting. Field observations and mineral assemblages suggest that the pyroxenites formed by melt injection along fractures within rather cold ambient harzburgites and chromitites at moderate pressure (P > 1 GPa). Based on bulk-rock compositions and mineral chemistry, we infer that the Cheshmeh-Bid orthopyroxenites originated from the intrusion and crystallization of hydrous Si-rich, low-Ca melts with a boninite signature in a suprasubduction environment. Fine-grained neoblastic domains developed in the pyroxenites in response to subsolidus ductile deformation and recrystallization, which were most likely related to the exhumation of the Cheshmeh-Bid ophiolite massif.
期刊介绍:
Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance.
Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.