剪切应变异常带近等距控矿模式——以粤西河台金矿为例

A Nearly Equidistant Ore-Controlling Model for Shear-Strain Anomaly Belts: An Example of the Hetai Gold Deposit in Western Guangdong Province

本文研究了河台金矿富矿体的分布规律并对河台金矿与富矿体有关的热液成矿期进行了构造-流体成矿数值模拟研究。研究表明,河台金矿的富矿体在平面上表现为左阶近等距的分布规律;剖面上也表现为近等距的分布规律,并都有北东向侧伏的规律。其中,据统计,河台金矿云西矿床相邻品位富集中心在侧伏方向上的距离为85~179m;河台金矿高村矿床相邻品位富集中心在侧伏方向上的距离为62~302m。剪切应变异常带是有利于发生剪切滑动与成矿的扩容区,且本区数值模拟产生的平面剪切应变异常带具有与富矿体分布特征一致的左阶近等距性。由此提出,剪切滑动之前剪切应变异常带的近等距性决定了剪切滑动后矿体的近等距性。以上控矿模式称为剪应变异常带近等距控矿模式。剪切应变异常带对矿体的控制可能形成于剪切应变异常带形成期的剪切滑动控矿及剪切应变异常带形成之后的微裂隙扩张控矿。将该模式控制的近等距性的矿体进行矿体统计分析预测,有望实现一定的找矿效果。

In order to provide a scientific basis for prospecting at depth,this paper studies the distribution character of bonanzas and carries out numerical simulations on hydrothermal metallogenic epoch after mylonitization in the Hetai gold deposit of western Guangdong Province. The results show that bonanzas are distributed in left step and nearly equidistant on plane,also nearly equidistant on a vertical section,and dipping northeast. It is 85 ~ 179m to the adjacent bonanza in dipping direction in the Yunxi deposit,and 62 ~ 302m to the another one in pitching direction in the Gaocun Deposit. The anomalous belts of shear strains by numerical simulations are the places favorable for sliding and mineralization in the Hetai gold deposit. These anomalous belts of shear strains are also left step and nearly equidistant,same as the distribution character of bonanzas. The near equidistance of the anomalous belts of shear strains before shear sliding controlled the near equidistance of ore bodies after shear sliding. This is called the nearly equidistant ore-controlling model with anomalous belts of shear strains. Such controlling was probably determined by shear sliding when the shear strains anomalous belts were forming and by micro crack expansion after the shear strains anomalous belts had formed. Applying this model to statistical analysis and prediction of ore bodies in the deposits would help improve the effect of ore-search efforts.