东准噶尔柳树泉地区橄榄辉石角闪石岩年代学、矿物学特征及其地质意义  

Geochronology and Mineralogy of Olivine Pyroxene Hornblendite in Liushuquan Area of East Junggar,China and Their Geological Implications

作　　者：赵庆华 黄岗[2,3] 白建科 陈涛[3] 徐岩 ZHAO Qing-hua;HUANG Gang;BAI Jian-ke;CHEN Tao;XU Yan(School of Architectural Engineering and Intelligent Construction,The Open University of Henan,Zhengzhou 450046,Henan,China;School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;Shaanxi Geology and Mineral Research Institute Co.,Ltd.,Xianyang 712000,Shaanxi,China;Xi'an Center of Geological Survey,China Geological Survey,Xi'an 710054,Shaanxi,China)

机构地区：[1]河南开放大学建筑工程与智能建造学院,河南郑州450046 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]陕西地矿区研院有限公司,陕西咸阳712000 [4]中国地质调查局西安地质调查中心,陕西西安710054

出　　处：《地球科学与环境学报》2022年第3期413-430,共18页Journal of Earth Sciences and Environment

基　　金：中央返还两权价款资金项目(A15-1-LQ05);中国地质调查局地质调查项目(DD20160006);陕西省青年科技新星项目(2019KJXX-078)。

摘　　要：在新疆东准噶尔造山带南缘的柳树泉地区新发现了超镁铁质岩体,岩性为橄榄辉石角闪石岩。采用LA-ICP-MS锆石U-Pb定年获得其锆石年龄为(410.9±3.5)Ma,形成时代为早泥盆世。岩相学特征表明,橄榄辉石角闪石岩主要造岩矿物为角闪石、橄榄石、单斜辉石,含少量的斜方辉石和斜长石,副矿物为铬铁矿、尖晶石、磁铁矿等。电子探针分析结果显示,橄榄石属于贵橄榄石系列,单斜辉石主要为富钙透辉石,斜方辉石为古铜辉石,角闪石为钙镁角闪石和镁角闪石。矿物化学特征揭示柳树泉岩体的母岩浆为演化程度较低的高镁拉斑玄武质岩浆,且母岩浆成分具有高Mg、Ni的特点,岩浆结晶时具有较高氧逸度(△NNO+0.9~△NNO+1.8)和含水量(5.1%~7.0%)。综合研究认为,柳树泉地区橄榄辉石角闪石岩具有阿拉斯加型岩体特征,其母岩浆为受到俯冲带熔流体交代的地幔楔部分熔融形成的含水高镁拉斑玄武质岩浆,形成于弧前伸展的构造环境,揭示卡拉麦里地区存在早泥盆世洋壳俯冲作用,并经历了弧前扩张演化过程。The ultramafic rock is newly found in Liushuquan area on the southern margin of East Junggar orogenic belt,Xinjiang,and the lithology is mainly olivine pyroxene hornblendite.LA-ICP-MS zircon U-Pb age of the rock is(410.9±3.5)Ma,indicating that magmas emplace during Early Devonian.Petrographic characteristics show that the main rock-forming minerals of olivine pyroxene hornblendite are amphibole,olivine,clinopyroxene,and a small amount of clinopyroxene and plagioclase,and the accessory minerals are chromite,spinel and magnetite.The EPMA results show that olivine belongs to chaysolite series,clinopyroxene is calcium-rich diopside,clinopyroxene is bronzite,and amphiboles are tschemakite and magnesiohornblende.The mineralogical characteristics reveal that the parental magma of olivine pyroxene hornblendite is high-Mg porphyritic basaltic with low evolution degree and high contents of Mg and Ni,and has high oxygen fugacity(△NNO+0.9-△NNO+1.8)and water content(5.1%-7.0%)during crystallization.The comprehensive research shows that olivine pyroxene hornblendite in Liushuquan area is Alaska-type complex,and its parental magma is water-bearing high-Mg tholeiitic basaltic,and is formed by partial melting of mantle wedge metasomatized by subduction zone molten fluid,and is formed in forearc extensional tectonic setting,which reveals the existence of Early Devonian oceanic crust subduction and forearc extension evolution in Karamaili area.

关 键 词：橄榄辉石角闪石岩 锆石U-Pb年龄 矿物学 阿拉斯加型 早泥盆世 弧前扩张 东准噶尔 

分 类 号：P588.12[天文地球—岩石学] P571[天文地球—地质学]