湘中锡矿山锑矿床角砾岩及其与成矿关系研究

Breccias are common in the crust, especially in the fluid-saturated part of the crust, and many hydrothermal deposits are associated with breccias. In the past, geologists usually placed emphases on volcanic- and subvolcanic-related breccias, and those breccias occurring in epithermal deposits which share no obvious associations with magmatic activities,received relatively less attentions. The giant Xikuangshan antimony deposit, located in central Hunan, is a typical epithermal ore deposit, and is also an ideal location to study hydrothermal breccias. Since fragmented rocks and breccias are widespread in the Xikuangshan mining district, and those silicified breccias are closely connected with antimony mineralization. However, up to now no agreement has been reached on the origin of breccias occurring in this region. Genetic kinds of breccias and its formation periods, and formation mechanism of different breccias in the studied area are also still unclear. Therefore, by means of different discipline methods including economic geology, petrology, structure geology and geochemistry, integrated with some quantivtative analysis methods including fractal dimension analysis technique and numerical modelling technique, we attempt to ascertain the geological characteristics of different breccias and its temporal and spatial distribtuion regularities in the Xikuangshan region, and furthur reveal the origin of different breccias and its relationships with antimony mineralization. Some importances of this program can be summarized as follows: (1) it will help to reveal the ore genesis of the Xikuangshan deposit and the accumulation process of giant ores there; (2) it will help to promote the furthur understandings of breccias in epithermal deposits; (3) it will develop the low-temperature metallogenic theory, and provide theoretical guidances for the prospecting of simliar antimony deposits.

角砾岩在地壳中广泛分布，且很多热液矿床与角砾岩关系密切。过去人们对与成矿有关角砾岩的研究主要集中在与火山、次火山有关的角砾岩，对与岩浆活动关系不大的低温热液矿床中的角砾岩关注相对较少。湘中锡矿山超大型锑矿是一典型的低温热液型矿床，该矿破碎带及角砾岩十分发育，且角砾岩与成矿关系密切，是研究与低温热液成矿作用有关角砾岩的理想场所。目前该区角砾岩的研究程度较低，角砾岩的种类、形成期次和形成机制，仍不太清楚。本项目试图借助矿床学、岩石学、构造学和地球化学的研究方法，并结合分形理论和数值模拟等先进技术，通过研究其地质特征、时空分布和形成机制，来揭示锡矿山矿区角砾岩的成因以及角砾岩与成矿的关系。本项目的开展，将有助于深化对锡矿山低温热液锑矿的矿床成因和该区巨量矿石堆积过程的认识，对丰富和完善低温热液矿床中角砾岩的研究，促进低温热液成矿理论的发展，以及指导类似锑矿床的寻找与勘探，均具有十分重要的意义。

在自然界，角砾岩是普遍存在的，特别是在以脆性形变为主、流体饱和为特征的那部分地壳中，角砾岩最为常见。全球80%以上的金属矿床中均存在不同类型的角砾，因此，角砾岩被视为热液矿床、特别是脉型热液矿床中分布最为广泛的岩石组构，故一直是矿床学家关注的重点，但过去人们对与成矿有关角砾岩的研究，主要集中在与火山、次火山有关的角砾岩，对与岩浆活动关系不大的低温热液矿床中的角砾岩关注较少。.赋存于碳酸盐岩地层中的湘中锡矿山超大型锑矿床，被认为是典型的低温热液矿床，该锑矿区破碎带和角砾岩广泛分布，且角砾岩与锑成矿关系密切，是研究与低温热液成矿有关的角砾岩的理想场所。但前人对该矿角砾岩的研究程度较低，少量已有的研究也仅限于对角砾岩的野外观察和定性描述。.本项目借助岩石学、矿床学、构造学和地球化学的研究方法，对锡矿山矿区角砾岩的不同尺度角砾岩的特征、角砾岩的类型及时空分布特点、角砾岩与成矿的关系等方面进行了研究；并借助分形理论和数值模拟技术，重点研究了与成矿有关的角砾岩，探讨了该区与成矿有关的两类角砾岩的异同点，并揭示了该区与成矿有关角砾岩的形成机制，首次确认成矿流体的液压致裂作用是导致锡矿山矿区角砾岩形成的主要机制。本项目属首次对锡矿山矿区角砾岩进行了专题研究，划分出了该区不同类型角砾岩，明确了与成矿有关角砾岩的形成机制，这有助于深化对锡矿山矿区巨量矿石堆积过程的认识，对丰富和完善低温热液矿床中角砾岩的研究，促进热液成矿理论的发展，以及指导类似锑矿床的寻找，均具有十分重要的意义。