| 大兴安岭中生代伸展造山过程中的岩浆作用 |
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| 引用本文： | 邵济安,张履桥,牟保磊.大兴安岭中生代伸展造山过程中的岩浆作用[J].地学前缘,1999,6(4):339-346. |
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| 作者姓名： | 邵济安 张履桥 牟保磊 |
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| 作者单位： | 1. 北京大学,北京,100871
2. 内蒙古地质研究所,呼和浩特,010020 |
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| 摘 要： | 概括地介绍了大兴安岭中生代伸展造山过程，重点讨论了晚中生代火山岩、深成岩的岩石学及同位素地球化学特征：存在一套板内拉张环境下的Ａ 型花岗岩，火山岩为一套钾质粗面质岩石，大多数花岗岩和火山岩具有低的Ｎ（８７Ｓｒ）／ Ｎ（８６Ｓｒ） 值（０７０４ ～０７０８） 和正的ε（Ｎｄ ，ｔ） （１ ～４） 值，据此认为这是底侵作用形成的一套壳 幔混熔岩浆的产物，结合岩浆喷发与侵位过程中的伸展构造分析，认为这是大陆内部伸展造山的重要证据。此外，笔者还在该区发现早中生代的一套幔源镁铁质堆晶岩和侵入岩、早 中侏罗世及早白垩世的基性岩墙群、早白垩世（１３０ ～１２０ Ｍａ） 超基性的角闪岩、玻基橄辉岩和碱性橄榄玄武岩。由此可以证明，大兴安岭晚中生代的花岗岩 火山岩活动只是伸展背景下的岩浆演化的一个阶段。
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| 关 键 词： | 陆内造山 伸展造山 底侵作用 岩浆作用 大兴安岭 |
| 修稿时间： | 1998年10月5日 |
Magmatism in the Mesozoic extending orogenic process of Da Hinggan MTS |
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| Shao Ji''''an.Magmatism in the Mesozoic extending orogenic process of Da Hinggan MTS[J].Earth Science Frontiers,1999,6(4):339-346. |
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| Authors: | Shao Ji'an |
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| Abstract: | This paper explains briefly the Mesozoic extending orogenic process of Da Hinggan Mts , concentrating especially in petrologic and geochemical features of the late Mesozoic volcanic and plutonic rocks. There exists a suite of intraplate A type granites formed in an extensional environment. The volcanic rocks are potassic and trachytic. The granites and volcanic rocks have low N ( 87 Sr)/ N ( 86 Sr) values (0 704～0 708) and positive ε (Nd, t ) values (1～4). All of these are suggested as the results from the crust mantle miscible magma, which is created by underplating These rocks, analyzed jointly with the extending structures formed in the process of magmatic eruption and emplacement, can be considered as an important evidence of intracontinental extending orogeny Moreover, other evidences have been found by the authors in the area, including early Mesozoic mantle source mafic cumulate complex and intrusive rocks, Lower—Middle, Jurassic and Lower Cretaceous basic swarm dykes, and ultramafic hornblendite, limburgite, and alkaline olivine basalts of the Lower Cretaceous (130～120 Ma) Thus it is demonstrated that the late Mesozoic granite volcanic rock activity in the Da Hinggan Mts is only a stage of the whole magmatic evolution in an extensional settings |
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| Keywords: | intracontinental orogeny extending orogeny underplating magmatism Da Hinggan Mts |
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