| 新疆东天山旱草湖环状岩体锆石U-Pb年龄、地球化学特征及成因 |
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| 引用本文： | 王伟,孟勇,王凯,宿晓虹,余吉远,吕舜,郭周平,全守村.新疆东天山旱草湖环状岩体锆石U-Pb年龄、地球化学特征及成因[J].地质通报,2019,38(5):777-789. |
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| 作者姓名： | 王伟 孟勇 王凯 宿晓虹 余吉远 吕舜 郭周平 全守村 |
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| 作者单位： | 自然资源部岩浆作用成矿与找矿重点实验室/中国地质调查局西安地质调查中心, 陕西 西安 710054;长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064,长安大学, 陕西 西安 710064 |
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| 基金项目： | 中国地质调查局项目《中国大地构造演化和国际亚洲大地构造图编制》（编号：DD20190364）和《新疆东天山1：25万沁城幅区调（修测）》（编号：1212011120473） |
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| 摘 要： | 以新疆东天山旱草湖地区中酸性环状岩体为研究对象,进行LA-ICP-MS锆石U-Pb年龄和全岩地球化学研究,探讨其成因和地质意义。结果表明,侵入英云闪长岩的最老年龄为275.0±2.9Ma(MSWD=4.8),侵位时代为二叠纪。岩体Al_2O_3含量为14.46%～17.05%,A/CNK为0.93～1.09,属准铝质和弱过铝质系列,较富集K_2O,MgO含量较低,为0.71%～2.84%,Mg~#值为33.3～48.6。微量元素高Sr、低Y,Sr含量为217×10~(-6)～740×10~(-6),Y含量为4.26×10~(-6)～21.4×10~(-6),Sr/Y值为16.87～145.07,富集大离子亲石元素Rb、Sr、Ba,亏损高场强元素Nb、Ta、Ti。稀土元素配分模式图呈现平坦右倾的轻稀土元素富集、重稀土元素亏损,表明岩体来源于石榴子石和金红石较稳定而斜长石不稳定的区域,属于角闪岩相向榴辉岩相过渡阶段,可能是同时期底侵的产物。地球化学特征表明岩体不是一期岩浆事件结晶分离演化的结果,不同岩性的岩体之间没有发生结晶分离。部分熔融程度和新生幔源组分的不同导致了旱草湖环状花岗质岩体的形成,二叠纪旱草湖地区存在较强烈的中酸性岩浆活动,是东天山二叠纪构造-岩浆演化的响应。
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| 关 键 词： | 新疆 东天山 旱草湖 中酸性环状岩体 锆石U-Pb年龄 地球化学 |
| 收稿时间： | 2017/6/5 0:00:00 |
| 修稿时间： | 2017/7/18 0:00:00 |
Zircon U-Pb ages, geochemical characteristics and petrogenesis of ringed pluton in the Hancaohu area, eastern Tianshan Mountains of Xinjiang |
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| WANG Wei,MENG Yong,WANG Kai,SU Xiaohong,YU Jiyuan,L&#; Shun,GUO Zhouping and QUAN Shoucun.Zircon U-Pb ages, geochemical characteristics and petrogenesis of ringed pluton in the Hancaohu area, eastern Tianshan Mountains of Xinjiang[J].Geologcal Bulletin OF China,2019,38(5):777-789. |
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| Authors: | WANG Wei MENG Yong WANG Kai SU Xiaohong YU Jiyuan L&#; Shun GUO Zhouping and QUAN Shoucun |
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| Institution: | Key Laboratory for the Study of Focused Magmatism and Giant ore Deposits, MNR/Xi''an Center of Geological Survey, CGS, Xi''an 710054, Shaanxi, China;Chang''an University, Xi''an 710064, Shaanxi, China,Chang''an University, Xi''an 710064, Shaanxi, China,Chang''an University, Xi''an 710064, Shaanxi, China,Chang''an University, Xi''an 710064, Shaanxi, China,Chang''an University, Xi''an 710064, Shaanxi, China,Chang''an University, Xi''an 710064, Shaanxi, China,Chang''an University, Xi''an 710064, Shaanxi, China and Chang''an University, Xi''an 710064, Shaanxi, China |
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| Abstract: | Choosing the Hancaohu intermediate-acid annular pluton distributed in East Tianshan Mountains of Xinjiang as the study object, the authors used LA-ICP-MS zircon U-Pb isotope chronology and geochemical characteristics to study the petrogenesis and geological significance of the pluton. The results indicate that the age of the earliest intrusive tonalite pluton is 275.0 ±2.9Ma (MSWD=4.8), suggesting that its emplacement epoch is Permian. The Al2O3 of the ringed pluton is 14.46%~17.05%, and A/CNK is 0.93~1.09, suggesting metaluminous and weak peraluminous series. The rocks are enriched in K2O, and their MgO content is 0.71%~2.84% and Mg# value is 33.3~48.6. Their trace elements are high in Sr and low in Y, the content of Sr is 217×10-6~740×10-6, that of Y is 4.26×10-6~21.4×10-6, and Sr/Y ratio is 16.87~145.07. They are enriched in LILEs(Rb, Sr, Ba) and depleted in HFSEs(Nb, Ta, Ti). They are characterized by LREE enrichment and HREE depletion, implying that they were formed in an area with stable garnet, rutile and unstable plagioclase, belonging to the transitional stage from amphibolite facies to eclogite facies; they were probably formed by underplating in the same period. The variation of main elements and race elements content and discontinuous LREE/HREE show that the pluton was not formed by crystallization evolution of one magmatic event, and the plutons of different lithologies are not separately crystallized from each other. Comprehensive analyses show that the lithospheric extension after Permian collision in Huangshan-Jingerquan area caused asthenosphere mantle upwelling and lithosphere delamination. The lithosphere vertical accretion at the boundary of the underplating crust and mantle induced the partial melting and produced high K calc-alkaline magma. With the instant intrusion of the magma, the difference of partial melting and newly formed mantle source components led to the formation of Hancaohu granitic pluton. It is shown that there was violent intermediate-acid magmatism in the Hancaohu area in Permian, and it was the response to tectonic-magmatism evolution in Permian in East Tianshan Mountains. |
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| Keywords: | Xinjiang East Tianshan Mountains Hancaohu intermediate-acid annular pluton zircon U-Pb ages geochemistry |
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