摘要
江西省德安县彭山锡矿田,是一个典型的高挥发份花岗岩底辟穹窿构造。穹窿面积约180km^2,构成穹窿的地层为晚元古代震旦纪及早古生代地层。穹窿核部有一中生代高挥发份花岗岩隐伏岩体,围岩中有大量极其发育的圆弧形层间重力滑动断层及滑裂岩带,并伴有大量以隐伏花岗岩体为中心的放射状裂隙及断层。些种隐伏的高挥发份花岗岩侵入体,具有强大的底辟上升刺穿能力,并伴有极其丰富的气液成矿热流体,有关的内生热液矿床,严格受层间重力滑动断层及滑裂岩带控制。
The Pengshan area in the northern part of De'an, Jiangxi Province, is an important prospect of Sn, As, Zn, Pb and fluorite. The author have studied typical deposits of Sn in detail and advanced a model named the 'high-volatile diapiric granite dome'. The mechanism for ore formation and ore-controlling factors are discuseds.
The Pengshan diapiric granite dome consists principally of four parts. The cryptical granite body of the continental crust anatectic type contains a great variety of pneumatolytic minerals such as topaz, fluorite and tourmaline. There are a great range of intense alterations and mineralizations dominated by skarnization, greisenization and silicification. There occur several large deposits of Sn, fluorite arsenopyrite and Pb-Zn. Thus, it shows that the granite body is enriched in the volatile components and hot ore fluids.
The dome structure described above is interpreted to have originated from the high-volatile anatectic granite intrusion into the overlying Sinian and lower Palaeozoic strata. The diapiric dome, which is disharmonious with the surrounding structures, covers three hundred sq km. A lot of radial faults and fissures were developed in the scope of the dome structure in the process of diapirism of the high-volatile granite, which led to the injection of ore-forming hydrothermal fluids into the country rocks. As a result, the incompentent beds or interface lying between different lithologies progressively changed into the lubricating layers or sliding surfaces. They were favourable for the formation of a lot of interlayer gravity-slide faults in the ring or curvic pattern and sliding fracture zones, and provided good ore-forming space, thus forming several stratiform hydrothermal deposits. The mechanism is comparable to the hovercraft mechanism as advocated by Voight (1972, 1973, 1974) or the model of interstatial fluid pressure as described by Hubbert and Rubey (1959).
出处
《地质论评》
CAS
CSCD
北大核心
1989年第2期127-135,共9页
Geological Review
