Hydrogen Isotopic Compositions of Pyroxenes in Nushan Peridotite Xenoliths, SE China
Hydrogen isotopic compositions of pyroxenes in peridotite xenoliths from the Nushan volcano, Anhui Province, SE China have been obtained using an ion probe (Cameca 1270). D/H ratios are constant within a single grain and among the different grains from the same sample. The lack of correlation between the D/H ratios and the hydrogen contents indicates that the hydrogen isotopic compositions are inherited from their mantle source. Combining with the δD values of coexisting amphiboles, it is inferred that the Nushan mantle experienced at least a two-stage metasomatic event.One was responsible for formation of amphiboles with extremely variable δD values, and the other was probably responsible for the high δD values (up to -20‰) of some clinopyroxenes from peridotites, clinopyroxene and mica megacrysts. High δD values point to a subduction-related fluid being involved in one metasomatic event. The primary δD values (-90‰ to -140‰) of the Nushan pyroxenes, together with data gleaned from the literature, suggest that the D/H ratios of the nominally anhydrous mineral reservoir might have differed from that of the other mantle hydrogen in being relatively depleted in D.
作 者： Yu Huimin XIA Qunke E.Deloule YANG Xiaozhi 作者单位： Yu Huimin,XIA Qunke,YANG Xiaozhi(CAS Key Laboratory of Crust-Mantle Materials and Environments,School of Earth and Space Sciences,University of Science and Technology of China,Hefei,Anhui 230026,China)E.Deloule(CRPG-CNRS,BP20,54501 Vandoeuvre Cedex,France)
刊 名： 地质学报（英文版） SCI 英文刊名： ACTA GEOLOGICA SINICA 年，卷(期)： 2005 79(3) 分类号： P5 关键词： hydrogen isotope pyroxene peridotite ion probe mantle composition Nushan Anhui