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现代地质 ›› 2006, Vol. 20 ›› Issue (1): 141-150.

• 岩石学与矿床学 • 上一篇    下一篇

新疆东准噶尔北部青格里河下游花岗岩类的时代及地质意义

周刚1,2,张招崇3,谷高中2,杨文平2,何斌2,张小林2,罗世宾2,王祥2,贺永康2   

  1. 1中国地质科学院地质研究所,北京100037;2新疆地质矿产局第四地质大队,新疆阿勒泰836500;
    3中国地质大学地质过程与矿产资源国家重点实验室,北京100083
  • 收稿日期:2005-11-16 修回日期:2005-12-25 出版日期:2006-01-20 发布日期:2006-01-20
  • 作者简介:周刚,男,高级工程师,博士研究生,1966年出生,矿物、岩石、矿床学专业,主要从事区域地质和矿产勘查工作。
  • 基金资助:

    国家“305”项目(2001BA609A-07-02);国家自然科学基金项目(40572047);教育部新世纪优秀人才支持计划(NCET-04-0728);科技部“973”项目(2001CB409807);新疆维吾尔自治区1∶5万区域地质矿产调查项目(XJQD2003-03)

Dating of Granitic Plutons and Its Geological Implications in the Lower Reaches of the Qinggeli River in the Northern Part of East Junggar, Xinjiang

ZHOU Gang1,2, ZHANG Zhao-chong3, GU Gao-zhong2, YANG Wen-ping2, HE Bin2, ZHANG Xiao-lin2, LUO Shi-bin2, WANG Xiang2, HE Yong-kang2   

  1. 1 Institute of Geology, China Academy of Geological Sciences, Beijing100037,China;
    2 No.4 Geological Team of Xinjiang Bureau of Geology and Mineral Resources, Altay, Xinjiang836500, China;
    3 State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing100083, China
  • Received:2005-11-16 Revised:2005-12-25 Online:2006-01-20 Published:2006-01-20

摘要:

选取新疆东准噶尔北部青格里河下游一带乌图布拉克、阿热勒托别和哈旦逊岩体等具一定规模的3个代表性岩体,通过全岩Rb-Sr等时线同位素定年,确定了研究区内玛音鄂博断裂南侧花岗岩类的形成时代分别为(334.1±9.5) Ma、(300±9) Ma和(280±12) Ma,其初始87Sr/86Sr比值分别为0.704 33、0.704 35和0.703 84。结果表明研究区内花岗岩分别形成于华力西中晚期的不同阶段。乌图布拉克岩体形成于早石炭世,为碰撞造山作用晚期的钙碱性花岗岩,可能是早泥盆世富Nb玄武岩部分熔融的产物;结合前人厘定的板块俯冲时间(408~376 Ma),推测西伯利亚板块与哈萨克斯坦—准噶尔板块的碰撞时限为376~334 Ma。阿热勒托别岩体形成于后碰撞拉张环境,可能是形成于岛弧环境的中基性火山岩部分熔融的产物;哈旦逊岩体虽然也形成于后碰撞拉张环境,但拉张程度更高,属于与岩浆底侵作用有关的花岗岩类。

关键词: Rb-Sr等时线年龄, 花岗岩类, 碰撞, 底侵, 东准噶尔北部, 新疆

Abstract:

Three representative plutons, Wutubulak, Areletuobie and Hadansun, in the lower reaches of the Qinggeli river in the northern part of East Junggar, Xinjiang were chosen for Rb-Sr isochron dating.The results show that the formation-ages of granitic plutons in the southern side of the Mayin'ebo fault in the researched area are (334.1±9.5) Ma, (300±9) Ma and (280±12) Ma with the initial 87Sr/86Sr ratios of 0.70433, 0.70435 and 0.70384, respectively, and that they were generated at different stages of middle-late Variscan Movement. The Wutubulak pluton, which formed at Early Carboniferous, belong to calc-alkaline series, was likely produced by partial melting of the Early Devonian Nb-enriched basalts during post-collisional event. In combination with the previously assumed plate subduction time (408-376 Ma), the collision of Siberian Plate  with Kazakstan-Junggar Plate can be limited within the range of 376-334 Ma. The Areletuobie pluton formed in an extensional setting subsequent to post-collision, and it is inferred to be generated by partial melting of intermediate-basic volcanic rocks that might form in an island arc setting. Although the Hadansun pluton also formed in an extensional environment of post-collision, it might be related to magma underplating under a strong extensional environment

Key words: Rb-Sr isochrone age, granitoid, collision, underplating, northern part of East Junggar, Xinjiang

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