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《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]

卷:

第37卷

期数:

2015年第05期

页码:

52-70

栏目:

基础地质与矿产地质

出版日期:

2015-09-15

文章信息/Info

Title:

Petrogenesis of Early and Late Paleozoic Plutons in Sanchakou Area of East Tianshan and Their Implications for Evolution of Kangur Suture Zone

文章编号:

1672-6561(2015)05-0052-19

作者:

王超; 陈斌; 马星华; 鄢雪龙

1. 北京大学 地球与空间科学学院，北京 100871； 2. 北京大学 造山带与地壳演化教育部重点实验室，北京 100871； 3. 合肥工业大学 资源与环境工程学院，安徽 合肥 230009； 4. 中国地质科学院矿产资源研究所 国土资源部成矿作用与资源评价重点实验室，北京 100037； 5. 万宝矿产有限公司，北京 100053

Author(s):

WANG Chao;  CHEN Bin;  MA Xing-hua;  YAN Xue-long

1. School of Earth and Space Sciences, Peking University, Beijing 100871, China; 2. Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education, Peking University, Beijing 100871, China; 3. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, Anhui, China; 4. MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China

关键词:

花岗岩; 壳幔岩浆混合; 古生代; 岛弧; 康古尔缝合带; 构造演化; 东天山; 新疆

Keywords:

granite;  crust-mantle magma mixing;  Paleozoic;  island arc;  Kangur suture zone;  tectonic evolution;  East Tianshan;  Xinjiang

分类号:

P581

DOI:

-

文献标志码:

A

摘要:

对东天山地区三岔口矿岩体和三岔口东岩体的成因及构造背景进行探讨。三岔口矿岩体为一套花岗闪长岩-闪长岩体，形成于443 Ma，为晚奥陶世岩浆作用产物。三岔口矿岩体具有轻稀土元素及大离子亲石元素富集、高场强元素亏损的特征，表明其形成于岛弧环境，高放射成因Nd(ε_Nd(t)=6.6~7.5)和低初始N(⁸⁷Sr)/N(⁸⁶Sr)值(0.703 69~0.703 89)表明岩浆混合中的基性端元很可能起源于俯冲带亏损的岩石圈地幔，幔源岩浆底侵导致下地壳部分熔融，并与生成的花岗质熔体混合形成中酸性岩浆。三岔口东岩体为一套花岗岩-花岗闪长岩-闪长岩体，侵位时代约为322 Ma，属于中亚造山带碰撞后岩浆作用的产物。三岔口东岩体同样具有岛弧岩浆特征，富集轻稀土元素及大离子亲石元素，亏损高场强元素，但其岛弧特征继承自其下地壳源区的性质，东天山地区下地壳主要是早古生代形成的深埋弧岩浆岩拼贴而成的。三岔口东岩体同样由壳幔岩浆混合作用形成，其基性端元可由区内同期基性—超基性岩体模拟。三岔口矿火山弧岩浆组合的确立可将康古尔地区俯冲作用的时间追溯至奥陶纪。晚石炭世早期，康古尔缝合带区域构造由挤压向拉伸转换，三岔口东岩体对应区域的后碰撞构造演化阶段。

Abstract:

The petrogenesis and tectonic setting of Sanchakou deposit pluton and East Sanchakou pluton in East Tianshan area were discussed. Sanchakou deposit pluton consists mainly of granodiorite-diorite, and LA-ICP-MS zircon U-Pb dating results indicate that Sanchakou deposit pluton forms at 443 Ma and is the product of Late Ordovician magmatism. This pluton exhibits island arc setting with the characteristics of enrichment in light rare earth element (LREE) and large ion lithophile element (LILE), and depletion in high field strength element (HFSE). High ε_Nd(t) (6.6-7.5) and low initial N(⁸⁷Sr)/N(⁸⁶Sr) (0.703 69-0.703 89) suggest that the mafic end-member during magma mixing could have been originated from a young lithospheric mantle source, which is previously metasomatized by subduction zone melts/fluids in Early Paleozoic. Underplating of mantle-derived basaltic magma leads to partial melting of lower crust. Mixing of basaltic magma and the resultant crustal granitic melt forms the intermediate and acid magma. East Sanchakou pluton is mainly made up of granite-granodiorite-diorite, and LA-ICP-MS zircon U-Pb dating results suggest that this pluton is emplaced at about 322 Ma and is the product of post collisional magmatism of Central Asian orogenic belt. This pluton also exhibits island arc setting with the characteristics of enrichment in LREE and LILE, and depletion in HFSE, but the island arc setting characteristics are probably inherited from the lower crust source, which is dominated by Early Paleozoic deep island arc magmatite. This pluton is also formed by the mixing of crustal-mantle magma, and its mafic end-member can be simulated by the homochronous mafic-ultramafic pluton in East Tianshan area. The establishment of volcanic arc magmatic assemblage of Sanchakou deposit pluton shows that the subduction time in Kangur area can date back to Ordovician. Region tectonic transforms extrusion into extension at the early Late Carboniferous, East Sanchakou pluton is corresponding to the stage of regional post-collisional structural evolution.

参考文献/References:

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备注/Memo

备注/Memo:

收稿日期:2015-05-07
基金项目:国家305项目(2011BAB06B04-2);国家自然科学基金项目(41202033)
作者简介:王超(1987-),男,河北衡水人,理学博士研究生,E-mail:wangchaopku@126.com。
通讯作者:陈斌(1964-),男,安徽全椒人,教授,博士研究生导师,理学博士,E-mail:binchen@pku.edu.cn。

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更新日期/Last Update: 2015-09-28