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引用本文:菅坤坤1 魏燕霞2 施 彬3 刘 力4 王 星1 袁 璋1. 东昆仑造山带中灶火地区早中生代镁铁质岩墙群的成因及地质意义[J]. 中国地质, 2015, (5): 1457-1470.
JIAN Kun-kun1,WEI Yan-xia2,SHI Bin3,LIU li4, WANG Xing1, YUAN Zhang1. Petrogenesis and geological significance of the Early Mesozoic mafic dyke swarms in Zhongzaohuo area, East Kunlun orogenic belt[J]. Geology in China, 2015, (5): 1457-1470(in Chinese with English abstract).
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东昆仑造山带中灶火地区早中生代镁铁质岩墙群的成因及地质意义
菅坤坤1 魏燕霞2 施 彬3 刘 力4 王 星1 袁 璋1
作者单位
菅坤坤1 魏燕霞2 施 彬3 刘 力4 王 星1 袁 璋1 1. 陕西省地质调查中心陕西 西安 7100162. 中国水利水电第三工程局有限公司陕西 西安 7100163.中国地质科学院地质研究所北京 1000374. 湖北省地质调查院湖北 武汉 430034 
摘要:
提要:东昆仑造山带中灶火地区镁铁质岩墙群以闪长玢岩为主,含少量闪斜煌斑岩、辉绿玢岩及辉绿岩,LA-ICP-MS锆石U-Pb年代学指示该套岩墙群结晶侵位年龄为(249±1)Ma。稀土元素含量整体较高,富集轻稀土元素(∑REE=99.9×10-6~173.9×10-6 ,(La/Yb)N=3.5~9.3);微量元素表现出富集大离子亲石元素(LILE),亏损高场强元素(HFSE)的特征;源区分析表明,镁铁质岩浆为俯冲洋壳析出的流体交代富集地幔的结果,且在岩石成因中部分熔融起到主导作用,地壳混染和分离结晶作用对岩浆成分分异起到的作用有限。构造环境分析表明,岩石的形成与俯冲作用有关,结合区域构造演化认为镁铁质岩墙群的成因为:早三叠世,在古特提斯洋向北俯冲的环境下,俯冲板片释放的流体交代富集地幔,诱发地幔部分熔融形成镁铁质岩浆,受弧后伸展的动力学背景影响,岩浆最终上升侵位形成镁铁质岩墙群。
关键词:  东昆仑造山带  镁铁质岩墙群  锆石U-Pb年代学  俯冲带流体
DOI:
分类号:
基金项目:中国地质调查局地质调查项目(1212010918021)资助。
Petrogenesis and geological significance of the Early Mesozoic mafic dyke swarms in Zhongzaohuo area, East Kunlun orogenic belt
JIAN Kun-kun1,WEI Yan-xia2,SHI Bin3,LIU li4, WANG Xing1, YUAN Zhang1
Abstract:
Abstract: The Zhongzaohuo mafic dyke swarms in East Kunlun are principally composed of dioritic porphyrite with minor lamprophyre, porphyritic diabase, and diabase. The LA-ICP-MS zircon U-Pb dating indicates that the mafic dykes were emplaced at (249±1) Ma. The mafic dykes are enriched in LILE and depleted in HFSE. The rocks have higher total REE,with slightly enriched LREE (∑REE=99.9×10-6~173.9×10-6 ,(La/Yb)N=3.5~9.3). Source region analysis shows that mafic magma resulted from the fluid from subducted ocean crust and the mantle metasomatism, and partial melting played a dominant role in magma evolution,while crustal contamination and fractional crystallization played a limited role in magmatic differentiation. Tectonic setting analysis shows that the formation of the rocks was related to subduction; in combination with the tectonic evolution of East Kunlun, the authors hold that the formation process of mafic dyke swarms in this paper is as follows: in early Triassic, as the result of northward subduction of Paleo-Tethys Ocean, fluids from the subduction slab were dehydrated and mantle peridotite experienced metasomatism, which promoted the mantle peridotite partial melting into mafic magma; the magma was affected by the dynamic background of the back-arc extension, and then it migrated upward to the upper crust along the fissures to form the mafic dykes.
Key words:  enced metasomatism, which promoted the mantle peridotite partial melting into mafic magma  the magma was affected by the dynamic background of the back-arc extension, and then it migrated upward to the upper crust along the fissures to form the mafic dykes.