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    广东莲花山断裂带韧性剪切带变形特征及其与成矿的关系

    The deformation characteristics of ductile shear zone and its relationship with mineralization in Lianhuashan fault zone, Guangdong Province

    • 摘要: 莲花山断裂带是中国东南陆缘重要的NE向构造带。该断裂带不仅是区域上重要的二级构造单元分界线,也控制着广东省最重要的锡铜多金属成矿带。前人研究表明,莲花山断裂带内的韧性变形与锡铜多金属成矿关系密切,但对于莲花山断裂带内的韧性变形展布特征及其对成矿作用的贡献,还存在着较多争议。本次研究,通过对莲花山断裂带进行大比例尺的矿田构造填图,实测典型地质剖面等手段,结合拉伸线理产状的测量和显微构造的观察,认为断裂带内的韧性变形由自北向南一系列近NE60°走向的剪切带雁列展布而成,各剪切带之间呈大致平行展布。在韧性变形之后,这些雁列状的剪切带又被30°走向的脆性断层所切割。莲花山断裂带内的韧性变形控制着矿体的形态和规模,后期岩浆-热液活动利用先存韧性剪切带的空间,成矿元素在韧性变形的裂隙中沉淀富集成矿。莲花山断裂带内找矿勘探工作部署应该围绕断裂带内韧性变形的区域,并注意韧性变形附近次一级的容矿裂隙。

       

      Abstract: The Lianhuashan fault zone is an important NE-trending tectonic belt on the southeastern continental margin of China. It is not only an important boundary of secondary tectonic units but also controls the most important tin-copper polymetallic metallogenic belt in Guangdong Province. Previous studies show that the ductile deformation in Lianhuashan fault zone is closely related to the tin-copper polymetallic mineralization. However, there are still some disputes about the distribution of ductile deformation and its contribution to mineralization in Lianhuashan fault zone. In this study, by means of large-scale structural mapping and typical geological profiles of the Lianhuashan fault zone, in combination with the measurement of tensile lineation attitude and the observation of microstructure, the authors have reached the conclusion that the ductile deformation in the fault zone was formed by a series of in-situ shear zones striking nearly 60° in N-S direction, which are roughly parallel to each other. After ductile deformation, these shear zones were cut by brittle faults striking 30°. Ductile deformation controls the shape and scale of orebodies in Lianhuashan fault zone. In the late magmatic and hydrothermal activities, the space of preexisting ductile shear zone was utilized to precipitate and enrich metallogenic elements in the cracks of ductile deformation. The ore-prospecting work in Lianhuashan fault zone should be arranged around the ductile deformation area and should pay attention to the ore-hosting fractures near the ductile deformation.

       

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