Transport network and flow mechanism of shallow ore-bearing magma in Tongling ore cluster area |
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基金项目: | the National Natural Science Foundation of China,the Fostering Plan Fund for Beyond-Cen- tury Excellent Talent of the Ministry of Education,the Science and Technology Key Item of the Ministry of Education,the Special Plan of Science and Technology of the Ministry of Land and Resources |
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摘 要: | The Tongling area is one of the most important ore cluster areas in the middle to lower Yangtze River metallogenic belt. The ore-forming process in Tongling region was mainly resulted from the me- dium-acidic magma intrusion activity during Yansha- nian epoch1―4]. Lots of research of the structure sys- tem and intrusion series were carried out in recent decades and the following aspects were mainly fo- cused on: (1) Accurate determination of the petrologic structure, chemical composition a…
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收稿时间: | 6 August 2005 |
修稿时间: | 20 December 2005 |
Transport network and flow mechanism of shallow ore-bearing magma in Tongling ore cluster area |
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Authors: | DENG Jun WANG Qingfei HUANG Dinghua WAN Li YANG Liqiang GAO Bangfei |
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Institution: | 1. State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing 100083, China;Key Laboratory of Lithosphere Tectonics and Lithoprobing Technology of Ministry of Education, China University of Geosciences, Beijing 100083, China 2. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China 3. School of Mathematics and Information Science, Guangzhou University, Guangzhou 510405, China |
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Abstract: | Abundant studies revealed that shallow intrusions of the Yanshanian epoch resulted in the mass mineralization of the Tongling
region. Various evidences showed there existed a concealed magma chamber at −10 km depth in the middle part of this region
during Yanshanian epoch, from which the ore-forming magma was generated and then transported to the superficial layer. Yet
the transport network and flow mechanism of the shallow ore-bearing magma, the key problem associated with ore-forming process,
was relatively little focused on. Integrate analysis of structural mechanics, statistical fractal and geological facts suggested
that NE trending high-angle fold-related thrust faults and the tessellated basement ones served as the main pathways for the
shallow magma’s transporting, moreover, the saddle void spaces among adjacent strata in the folds upon this fault system provided
the place for magma’s emplacement. So the folds in the upper part and faults in the lower part of the upper crust constituted
the fluid’s transport and emplacement network. During the deformation of geologic body with multi-layer structure, the layers
in the upper part tended to fold when received the jacking stress from the lower part, while the lower one inclined to fault
undergoing loads of the upper part. And the producing probability of this structure assemblage was highly increased in the
condition, such as in the Tongling area, that the mechanic rigidity of the lower layers was stronger than that of the upper
ones. For the pre-existence of fluid-conducting network, the top magma with high volatile in the magma chamber transported
rapidly to the superficial layer in dyking pattern, located in the void spaces of folds, filled and reconstructed them. The
sudden drop of pressure caused the fluid unmixing from the magma and mass ore-forming elements concentration. Pulse activity
of the dyking may be the principal reason why magmatic bodies in the Tongling area were spatially-temporally concomitant and
limited flux in chemical compositions. |
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Keywords: | Tongling structural network magma intrusion fractal dyke |
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