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引用本文:赵一珏1 杨经绥2 刘仕军1 刘飞2 田亚洲2. 新疆中天山巴仑台闪长岩成因及其地质意义[J]. 中国地质, 2015, (5): 1228-1241.
ZHAO Yi-jue1, YANG Jing-sui2, LIU Shi-jun1, LIU Fei2, TIAN Ya-zhou2. The origin of the Baluntai diorite in Central Tianshan Mountains, Xinjiang, and its geological significance[J]. Geology in China, 2015, (5): 1228-1241(in Chinese with English abstract).
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新疆中天山巴仑台闪长岩成因及其地质意义
赵一珏1 杨经绥2 刘仕军1 刘飞2 田亚洲21,2
1. 云南地矿国际矿业股份有限公司,云南 昆明 650051;2. 大陆构造与动力学国家重点实验室地幔研究中心,中国地质科学院地质研究所,北京 100037
摘要:
提要:巴仑台闪长岩反映的大洋俯冲信息为对比乌瓦门蛇绿岩与西侧长阿吾子和东侧库米什蛇绿岩的关系,探讨南天山洋的洋-陆演化过程具有重要意义。闪长岩具高碱和高铝特征,(Na2O+K2O)=4.14%~7.05%,Al2O3为14.62%~17.35%,为一套高钾钙碱性系列岩石,(La/Yb)N平均10.46,以富集轻稀土元素和大离子亲石元素(如K、Rb、Ba、Pb等)、亏损Nb、Ta、Ti等高场强元素为特征,形成于岛弧环境。闪长岩LA-ICP-MS锆石U-Pb年龄为(430.1±1.1)Ma,锆石εHf(t)=-12.7~-7.6,二阶段Hf模式年龄TDM2为1895~2219 Ma,指示巴仑台闪长岩为早志留世南天山洋北向俯冲,导致中天山古老结晶基底部分熔融形成。
关键词:  锆石U-Pb年龄  Hf同位素  巴仑台闪长岩  乌瓦门蛇绿岩  中天山南缘缝合带
DOI:
分类号:
基金项目:国土资源部公益性行业科研专项(201011034)资助。
The origin of the Baluntai diorite in Central Tianshan Mountains, Xinjiang, and its geological significance
ZHAO Yi-jue1, YANG Jing-sui2, LIU Shi-jun1, LIU Fei2, TIAN Ya-zhou2
1. Yunnan Geology and Mineral Resources International Mining Industry Co., Ltd., Kunming 650051, Yunnan, China, 2. CARMA, State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
Abstract:
Abstract: Studies of petrology and geochemistry indicate that the Baluntai diorite is the high-K calc-alkaline diorite. The rocks, which have the data Na2O+K2O=4.14%-7.05%, Al2O3 =14.62%-17.35%, (La/Yb)N with an average of 10.46, are characterized by enrichment of large ion lithophile elements (LILE, such as K, Rb, Ba, and Pb) and light REE but depletion of high field strong elements (HFSE, like Nb, Ta, and Ti),and were probably produced in an island arc settings. LA-ICP-MS zircon U-Pb dating shows that the Baluntai diorite was formed at (430.1±1.1)Ma. In-situ zircon Hf analyses show that zircons from Baluntai diorite have εHf(t) values from -12.7 to –7.6 and tDM2 model ages of 1895 Ma to 2219 Ma. Combined with Hf isotope analytical results and regional geological data, it is held that the Baluntai diorite resulted from partial melting of the Tianshan crystalline basement in response to northward subduction of South Tianshan Ocean during the Early Silurian. The isotopic ages of the Baluntai diorite body represent the upper age limit of the Wuwamen ophiolite.
Key words:  zircon U-Pb dating  Hf isotope  Baluntai diorite  Wuwamen ophiolite  southern central-Tianshan suture zone