| 摘要: |
| 造山前、造山和造山后（或碰撞前、碰撞和碰撞后）花岗岩是花岗岩研究的热门话题。但是，目前关于造山前、造山和造山后的概念存在模糊和矛盾的认识，为此提出了关于造山前、造山和造山后的概念和新的判别方法，并结合非洲、土耳其和巴西的某些实例进行了讨论。着重讨论了青藏高原与碰撞有关的花岗岩，指出青藏高原只存在造山前和造山2个阶段，不存在造山后阶段。认为青藏高原碰撞的时间大概在55Ma左右，25～3Ma的埃达克岩和淡色花岗岩是碰撞阶段形成的。青藏高原25～3Ma的花岗岩的特征暗示青藏高原在25Ma之前已经整体抬升，25Ma之后发育的伸展构造（藏南拆离系、大规模走滑断裂和南北向裂谷）是在青藏高原挤压的大背景下出现的，属于次级的派生构造，其并不能说明青藏高原已经进入伸展减薄和垮塌的碰撞后阶段。 |
| 关键词: 造山前、造山和造山后阶段 地壳厚度 花岗岩 青藏高原 |
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| Criteria for the recognition of pre-, syn-and post-orogenic granitic rocks |
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ZHANG Qi1, WANG Yuan-long1, JIN Wei-jun1, JIA Xiu-qin2, LI Cheng-dong31,2,3
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1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039, China;3. Tianjin Institute of Geology and Mineral Resources, Tianjin 300170, China
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| Abstract: |
| Pre-, syn-, and post-orogenic (pre-, syn- and post-collisional) granitic rocks are a hot topic of granite research. However, vague and contradictory views exist about the concepts of pre-, syn-, and post-orogeny. Therefore the authors present a new concept and discrimination method for pre-, syn-, and post-orogeny and discuss some case histories of Africa, Turkey and Brazil. The focus is on granitic rocks of the Qinghai-Tibet Plateau related to collision. They point out that only the pre- and syn-orogenic stages occurred on the Qinghai-Tibet Plateau. The collision on the Qinghai-Tibet Plateau took place at ~50 Ma. The 25-3 Ma adakite and leucogranite formed in the collision stage. The features of the 25-3 Ma granitic rocks imply that the Qinghai-Tibet Plateau had been uplifted wholesalely before 25 Ma, and the extensional tectonics (such as southern detachment system, large-scale strike-slip faults and N-S-striking rift) that developed after 25 Ma formed by compression in the syn-orogenic stage, rather than crustal extensional thinning and collapse in the post-orogenic stage. |
| Key words: pre-, syn- and post-orogenic stages crustal thickness granite Qinghai-Tibet Plateau |
