| 拉脊山-化隆变质核杂岩构造及其隆升机制探讨 |
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| 引用本文： | 张旺生,冯光胜,高山,孙林华.拉脊山-化隆变质核杂岩构造及其隆升机制探讨[J].地球科学,2003,28(4):407-413. |
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| 作者姓名： | 张旺生 冯光胜 高山 孙林华 |
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| 作者单位： | 中国地质大学地球科学学院, 湖北武汉 430074 |
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| 基金项目： | 中国地质调查局“民和县幅 1∶2 5万数字地质填图项目”(No .2 0 0 2 13 0 0 0 0 16) . |
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| 摘 要： | 中祁连拉脊山、化隆地区的变质核杂岩是由韧性变形的太古宙、元古宙化隆群变质岩系组成核; 由脆-韧性变形和经受了低压变质的中、上寒武统和岩体组成中间层; 由脆性变形和未变质的下白垩统组成盖层.变质核杂岩的组成与结构显示了对称伸展和隆升的特征.23~ 32Ma是快速隆升的时期.主剥离断层剪切位移量约25~ 27km, 并根据矿物对计算, 变质核杂岩的伸展变质温度约625~ 630℃, 变质深度约20km, 变质压力约为0.63GPa, 属偏低压型区域热流变质作用.从青藏高原热壳、热幔、厚壳的演化历史及构造隆升活动来看, 认为拉脊山、化隆变质核杂岩是地幔热隆引起地壳伸展的典型实例, 是研究青藏高原岩石圈结构和高原隆升的重要窗口.
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| 关 键 词： | 变质核杂岩 热隆 伸展构造 拉脊山 |
| 文章编号： | 1000-2383(2003)04-0407-07 |
| 收稿时间： | 2003-04-18 |
Metamorphic Core Complex Structure and Uplifting Mechanism in Lajishan-Hualong Area |
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| ZHANG Wang-sheng,FENG Guang-sheng,GAO Shan,SUN Lin-hua.Metamorphic Core Complex Structure and Uplifting Mechanism in Lajishan-Hualong Area[J].Earth Science-Journal of China University of Geosciences,2003,28(4):407-413. |
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| Authors: | ZHANG Wang-sheng FENG Guang-sheng GAO Shan SUN Lin-hua |
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| Abstract: | This paper studies the metamorphic core complex in Lajishan-Hualong area, middle Qilian. Its core consists of Archeozoic and Proterozoic Hualong Group metamorphic complexes undergoing ductile deformation, with its median layers, Middle-Upper Cambrian and mass of magmatic rocks undergoing plastic deformation of low-pressure metamorphism, and overlayers, Lower Cretaceous experiencing minor brittle deformation without metamorphism. The composition and texture of the metamorphic core complex show features of symmetrical extension and uplifting and a rapid uplifting period within 23 to 32 Ma and displacement quantity of normal denudational faults about 25-27 kilometres. The mineral pair calculation measures its extensional metamorphic temperature about 625-630 ℃, the metamorphic depth about 20 km and the metamorphic pressure about 0.63 GPa, which shows that it should belong to a regional thermal current metamorphism of low-pressure type. In the light of long run thermal crustal, thermal mantle, thick crustal evolution and tectonics upwelling of the Qinghai-Tibet plateau, the Lajishan-Hualong metamorphic core complex can be considered as a typical example of crust extension caused by thermal upwelling of mantle. The Lajishan-Hualong area can, therefore, become a window to look into the structure and tectonic upwelling of the Qinghai-Tibet plateau lithosphere. |
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| Keywords: | metamorphic core complex thermal upwelling extensional tectonic Lajishan |
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