构造透镜体中成矿雏形断裂的形成过程

以应力-应变曲线峰值为界,岩石破坏可分为 2个阶段,前阶段发育为雏形断裂,后阶段发育成宏观断裂。雏形断裂是一种特殊的断裂形式,在自然界中少见宏观断裂。与宏观断裂不同的是,雏形断裂既无断层面,又无碎裂岩,仅由小（微）裂隙组成。裂隙通常互不连通,总体具优选方向,且集中成透镜状裂隙群。裂隙群中部裂隙最发育,往边部渐趋消失。透镜状裂隙群之间呈雁列式排布,易发育和保存于构造透镜体弱应变域中。主要变形机制有液压致裂和应力腐蚀。形成前经历过微裂隙闭合、弹性变形和微裂隙生长扩容 3个阶段。以 2个中型金矿床为实例,研究了这一新发现的成矿构造的地质特征,认为变形分解、液压致裂和构造泵吸三者相互耦合,在雏形断裂形成与成矿过程中发挥关键作用。雏形断裂发育阶段可以形成独立的工业矿体。

FORMATION OF METALLOGENIC EMBRYO-FAULTS IN TECTONIC LENS

 According to the dividing line of peak value of stress/strain curve,lithofraction may be divided into two phases which the former develops embryo-fault and the latter forms macro-fault. Embryo-fault is a kind of special fracture types that are much less than macro-faults in nature. Compared with macrofault, embryo-fault only consists of minute fissures and micro-fissures without fault surface and cataclasite. Fissures don't link each other, have whole preferred orientation and assemble a series of fissure lens. Fissures grow mostly in the center of fissure group and in going outwards disappear gradually. The fissure lens group, in en echelon arrangement, is ease to be developed and conserved in the weak strain domain of tectonic lens. The primary deformation mechanism of embryo-fault is hydrofracture and stress corrosion, and its formation experiences three stages：microfissure closure, elastic deformation and microfissure growth dilation. On the basis of two medium-size gold deposits, authors study the geological feature of the metallotectonics discovered newly, realizing that the coupling between deformation partitioning, hydrofracturing and tectonic pumping plays a key part in the formation of embryo-fault and its mineralization. The orebodies may form in the forming process of embryo-fault.