Genesis of pyroxenite veins in supra-subduction zone peridotites:Evidence from petrography and mineral composition of Egiingol massif(Northern Mongolia)

作     者：Anas A.Karimov Marina A.Gornova Vasiliy A.Belyaev Aleksander Ya.Medvedev Nikolay V.Bryanskiy Anas A.Karimov;Marina A.Gornova;Vasiliy A.Belyaev;Aleksander Ya.Medvedev;Nikolay V.Bryanskiy

作者机构：A.P.Vinogradov Institute of Geochemistry Siberian Branch of Russian Academy of SciencesIrkutskFavorskogo str.1A 664033Russia 

出 版 物：《China Geology》 (中国地质（英文）)

年 卷 期：2020年第3卷第2期

页      面：299-313页

学科分类：070904[理学-构造地质学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：The reported study was funded by RFBR according to the research project(18-35-00535) IGC State Assignment Project(0350-2019-0008) 

主　　题：Pyroxenite vein Boninite Partial melting Melt-rock interaction Supra-subduction zone peridotite Egiingol massif Dzhida terrain Central Asian Orogenic Belt Northern Mongolia 

摘      要：Swarms of orthopyroxenite and websterite veins are found within Egiingol residual SSZ peridotite massif of Dzhida terrain(Central Asian Orogenic Belt,Northern Mongolia).The process of Egiingol pyroxenite veins formation is investigated using new major and trace element analyses of pyroxenite minerals,calculations of closure temperatures and composition of equilibrium *** pyroxenites show abundant petrographic and geochemical evidence for replacement of the residual peridotite minerals by ortho-and clinopyroxene due to melt-rock *** of peridotite olivines are found in pyroxenites,Cr#of spinel increases from peridotites to pyroxenites,and compositions of ortho-and clinopyroxene change from peridotite to *** authors show that calculated equilibrium melts for investigated pyroxenites are very similar to compositions of boninite lavas from the Dzhida ***,formation of pyroxenite veins most likely resulted from percolation of boninite melts through the Egiingol *** veins formed at first,followed by websterite ***,the authors assume that pyroxenite veins represent the channels for boninitic melts migration in supra-subduction environment.