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西南天山乌什县晚三叠世镁铁-超镁铁质层状杂岩体年代学及地球化学研究
引用本文:胡朝斌,李培庆,辜平阳,陈锐明,查显锋,庄玉军.西南天山乌什县晚三叠世镁铁-超镁铁质层状杂岩体年代学及地球化学研究[J].地质力学学报,2016,22(4):1015-1031.
作者姓名:胡朝斌  李培庆  辜平阳  陈锐明  查显锋  庄玉军
作者单位:中国地质调查局西安地质矿产研究所, 西安 710054;中国地质大学地球科学与资源学院, 北京 100083;中国地质调查局西安地质矿产研究所, 西安 710054;中国地质调查局西安地质矿产研究所, 西安 710054;中国地质调查局西安地质矿产研究所, 西安 710054;中国地质调查局西安地质矿产研究所, 西安 710054
基金项目:中国地质调查局地质调查项目“特殊地质地貌区填图试点”(DD20160060)、“新疆1:5万喀伊车山口等3幅艰险区试点项目”(12120114042701)、“东昆仑成矿带木孜塔格铅锌铜金多金属矿调查评价区地质矿产调查”(DD20160002)
摘    要:镁铁-超镁铁质层状杂岩体被认为是岩石圈伸展的重要标志之一,携带有丰富的地幔信息,是研究地幔物质组成、深部地质作用的绝佳对象。西南天山乌什县北巴勒的尔喀克沟地区新发现的镁铁-超镁铁质岩体具有层状杂岩特征,获得辉长岩锆石U-Pb年龄为224±4 Ma,属于晚三叠世。岩石地球化学分析显示富水、富碱、轻稀土富集、重稀土亏损以及明显富集Th、U、Nb、Ta、La、Ce不相容元素等特征,指示其源自于含水的富集型地幔源区,是石榴石二辉橄榄岩较低程度部分熔融的产物。其原生岩浆可能为富铁、钛的高镁玄武质岩浆,岩石系列主要受分离结晶作用控制,同化混染作用影响小。该期岩浆活动于南天山洋盆闭合、板块的碰撞造山活动之后的陆内造山阶段,代表了板块拉伸背景下幔源岩浆演化的产物,指示西南天山地区在三叠纪末可能存在一期岩石圈伸展事件。

关 键 词:西南天山  镁铁-超镁铁质  层状杂岩
收稿时间:2016/9/12 0:00:00

GEOCHRONOOGICAL AND GEOCHEMICAL STUDY OF THE LATE TRIASSIC LAYERED MAFIC-ULTRAMFIC INTRUSIONS IN BEISHAN AREA OF WUSHI COUNTY, SOUTHWEST TIANSHAN
HU Chao-bin,LI Pei-qing,GU Ping-yang,CHEN Rui-ming,ZHA Xian-feng and ZHUANG Yu-jun.GEOCHRONOOGICAL AND GEOCHEMICAL STUDY OF THE LATE TRIASSIC LAYERED MAFIC-ULTRAMFIC INTRUSIONS IN BEISHAN AREA OF WUSHI COUNTY, SOUTHWEST TIANSHAN[J].Journal of Geomechanics,2016,22(4):1015-1031.
Authors:HU Chao-bin  LI Pei-qing  GU Ping-yang  CHEN Rui-ming  ZHA Xian-feng and ZHUANG Yu-jun
Institution:Xi''an Center of Geological Survey, Xi''an 710054, China;School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;Xi''an Center of Geological Survey, Xi''an 710054, China;Xi''an Center of Geological Survey, Xi''an 710054, China;Xi''an Center of Geological Survey, Xi''an 710054, China;Xi''an Center of Geological Survey, Xi''an 710054, China
Abstract:Layered Mafic-ultramafic intrusions, which carry abundant information of mantle and provide an excellent approach to probe the mantle material composition, plate tectonic and deep geological process, are generally considered to be an important symbol of lithosphere extension, We discovered a suit of layered Mafic-ultramafic intrusions in Southwest Tianshan area, and obtained the zircon U-Pb age of gabbros of 224±4 Ma. These rocks are characterized by the enrichment of LREE, H2O, Na2O+K2O and incompatible elements such as Th, U, Nb, Ta, etc., and depleted in HREE. They might be derived from enriched mantle, which is formed by low degree partial melting of garnet lherzolite. The primary magma may be high Mg basaltic magma which was rich in iron and titanium and mainly controlled by the fractional crystallization. This magam in the continental orogenic stage was actived in the environment of intracontinent orogen after the closure of the South Tianshan ocean and post collisional orogeny, which derived from mantle in the envirnment of extensional environment. We can concluded that the Southwest Tianshan area was under an extensional tectonic seting during late Triassic.
Keywords:Southwest Tianshan area  mafic-ultramafic  layered intrusions
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