矿体的侧伏规律及其地质意义

Regularity and geological significance for lateral trending of orebodies

断裂控制的二维板式矿体中,矿体赋存空间的最小单位为透镜状裂隙,或称为一个成矿构造单元,第一世代的透镜状裂隙群呈雁列状排列,经递进变形逐渐为第二世代的桥构造连接,形成一条完整的成矿波形断裂.提出了单侧伏和复侧伏的概念,认为雁列成矿透镜状裂隙群彼此平行,其侧伏为单侧伏;雁列成矿裂隙群通过桥构造连通成一条波形控矿断裂,其侧伏为复侧伏.提出了主动侧伏和被动侧伏的概念,认为矿体的倾伏方向与破裂面上主剪应力的方向一致为主动侧伏,否则为被动侧伏.实例研究表明矿体的侧伏向与成矿期的动力学之间具有密切的成因联系.强调解析成矿构造形成时的动力学过程,对确定隐伏矿体的侧伏规律具有十分重要的地质意义.

In the two-dimensional tabular orebodies controlled by fractures, the smallest unit for ore-controlling space is lens-like fractures, or a metallotectonic unit. The first generations of lens-like fractures, at an echelon arrangement, are linked up through the second generations of bridge structures to form gradually a comprehensive wavy fracture by progressive deformation. From the concepts of single lateral-trending and composite lateral-trending, the single lateral-trending shows the lateral trending of series of echelon lenticular fractures paralleled reciprocally. The composite lateral-trending indicates the lateral trending of an ore-controlling wavy the fracture, which consists of echelon fracture groups connected by bridge structures. Furthermore, based on above concepts, the concepts of the active lateral trending and passive lateral trending are suggested in this paper. The former implies that the plunging trending is identical with the direction of main shear stress on the fracture plane, but the latter is not. Some case studies indicate that the lateral trending of orebodies has close relation to the dynamics during mineralization epoch. Further study on the dynamic process for the formation of metallostructures is very significant in confirming the lateral trending of buried orebodies.