Geochronologic-petrochemical studies of the Hongshishan mafic-ultramaflc intrusion,Beishan area,Xinjiang(NW China):petrogenesis and tectonic implications
作者单位：Key Laboratory of Mineral ResourcesInstitute of Geology and GeophysicsChinese Academy of Sciences State Key Laboratory of Lithospheric EvolutionInstitute of Geology and GeophysicsChinese Academy of Sciences Department of Earth ScienceUniversity of GhanaP.O.Box LG 58Legon-AccraGhana Research School of Earth SciencesThe Australian National UniversityBuilding 61Mills Road ActonCanberraACT 0200Australia
会议名称：《中国科学院地质与地球物理研究所2012年度（第12届）学术年会》
会议日期：2013年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：financially supported by the Knowledge Innovation Programme of the Chinese Academy of Sciences (Grant KZCX2-YW-107) Nature Science Foundation of China (Grant 41030424) Chinese State 305 Programme(Grant 2006BAB07B03-01)
关 键 词：Beishau eastern Tianshan fractional crystallization mafic-ultramafic intrusions mantle plume
摘 要：The Hongshishan mafic-ultramafic intrusion(SIMS zircon U-Pb age 286.4±2.8 Ma) consists of dunite,clinopyroxene peridotite,troctolite,and *** elements display systematic *** elements have identical distribution patterns,including flat rare-earth element(REE) patterns with positive Eu anomalies and enrichments in large ion hthophile elements(LILE) but depletions in Nb and Ta,indicating fractional crystallization as a key factor in magmatic evolution. Petrologic and geochemical variations in drill core samples demonstrate that minor assimilation and progressive magma mjectioiis were closely associated with Ni-Cu *** balance estimates and Sr-Nd isotopes reveal that the Hongshishan parental magmas were high-Mg and low-Ti tholeiitic basalts and were derived from a lithospheric mantle source that had been modified by subducted slab metasomatism before partial melting. Southward subduction of the Palaeo-Tianshan-Junggar Ocean is further constrained by a compilation of inferred subduction-induced modifications of mantle sources in mafic-ultramafic intrusions distributed in the eastern Tianshan-Beishan *** the regional positiveεNd(t) granites,high-Mg and low-Ti basaltic magmas(mafic-ultramafic intrusions),and slightly later high-Ti basalts in NW China suggests that their petrogenesis could be attributed to Permian mantle plume activities.