斑岩型矿床容矿裂隙的成矿流体压裂改造及其脉体特点

斑岩型矿石中脉体穿切关系普遍而复杂。斑岩型矿床容矿初始裂隙之间具有程度不同的连通关系,成矿作用过程是成矿组分在既有的裂隙中迁移、充填和沉淀的过程。在多期成矿过程中,如果没有构造应力的改造,似乎不应该出现大量脉体的多期穿切关系。然而不仅是斑岩型矿床,其他与热液活动有关的矿床中均可出现大量脉体的相互穿切现象。针对此种现象,运用水力压裂机理,探讨了成矿流体对初始裂隙的压裂改造作用,认为成矿阶段多期流体活动可以形成与流体活动期次和强度相匹配的无数期新生压裂裂隙,同时可极大地扩展容矿空间的规模和范围。成矿流体压裂改造裂隙也是斑岩型矿床容矿裂隙的重要成因类型。由于流体活动的多期性和压裂裂隙生长的快速性,相比构造活动对脉体的改造,流体压裂成因裂隙所导致的脉体穿切关系更为常见。这些观点较好地解释了斑岩型矿床中频繁而复杂的脉体穿切和错断关系。

Ore-forming fluid fracturing treatment of ore-bearing fractures and the characteristics of the related veins in porphyry deposits

Veins in porphyry deposits are well developed and their crosscutting relationship is complex. The initial fractures, where the veins fill in, are connected in varying degrees. Mineralization is a process of migration, filling and precipitation of ore-bearing fluid in the existing fractures. During the multi-stage mineralization, if there is no structural stress transformation, it seems that there should not be a large number of multi-stage cutting of veins. However, a large number of veins, which intersect each other, are widely found in porphyry deposits and other hydrothermal deposits. Based on the mechanism of hydraulic fracturing, this paper discusses the fracturing effect of ore-forming fluid on fracture forming. The multi-stage fluid activities result in the well-developed fractures by ore-forming fluid fracturing, which greatly expand the scale and scope of the ore-bearing space. This kind of fractures is an important genetic type of ore-bearing fractures in porphyry deposits. Due to the multistage fluid activities and the rapidity of fracture growth, the cross-cutting between the veins and fractures caused by the fluid fracturing is more common than that caused by the transformation of structural activities on veins. These viewpoints can well explain the frequent and complex cutting and faulting of veins in porphyry deposits.