The Geometric Characteristics Of Fault Structure And Its Constraints On Mineralization In The Yangla Mining Area, Northwestern Yunnan

Yangla Copper Deposit,lies in the middle piece of the Jinsha River plate suture belt,belongs to Paleo Tethys tectonic zone,which is the most important copper deposit of China.So far,Yangla copper mine has attracted many scholars to study,and have made many achievements.But the shortage is that the study of the structure of this region is not enough.This paper focuses on faults of this area,by using the traditional analysis method and some new methods,such as curvature analysis of fault surfaces?fractal characteristics of faults.It is expected to fill some gaps in the study of tectonics in the Yangla area and provide the basis for actual production.The main results obtained as follows:1?The results of curvature analysis of fault surfaces illustrate faults of Yangla Deposit are relatively flat and got small change,the derived structures,such as tensile fractures and joints,are concentrated in the range of 5m.In the process of tectonic evolution,the faults in the mining area show a gradual process,which has slight transformation and inheritance to the early faults,and the damage is small.2?Based on the fractal analysis of fracture,the complexity of fault in the Linong ore section is higher than in the Jiangbian ore section and,the same as surfaces than underground.and the complexity of the NE trending faults is relatively high,which is positively correlated with the distribution of ore bodies in the mining area.It also shows that the faults is still activating slowly.In the mining are,the regional distribution of the high information dimension is NE-SW,which is consistent with the distribution of the fault and the ore body.The ore-bodies has been found is almost distributed in the range of information dimension greater than 1.2,it can be concluded that the value of information dimension can be used to determine the distribution of ore bodies,and the prospecting direction of A and B two in the peak area of information value.Thus,the A prospecting directions is delineated in the peak area of the information dimension.3?Based on the regional tectonic evolution and the calculation of the conjugate shear joints in the mining area,it is concluded that the direction of the maximum principal stress in the mining area has undergone three major changes:SN?EW(?1=76°)?NE-SW(? 1=230°),corresponding to the extrusion direction of the early Hercynian?late-Hercynian to Indosinian and Yansha periods to Himalaya periods.Forming the early NE tectonic belt,the early EW tectonic belt,the near SN tectonic belt,the late NE tectonic belt and the late EW tectonic belt.Its constraints on metallogenetic and ore control are as follows:? The faults and interlayer crushing zones of the late-Hercynian to Indosinian are ore-bearing-fault-structure.The distribution of ore bodies presents a branch and complex phenomenon along with the width of the fracture zone.The ore bodies is often controlled by fault and rock-bodies,the contact form between rock-body and ore-body is mostly normal fault contact;?In Yanshan periods and Himalaya periods,the tectogenesis destroys the ore bodies into chipping that is contained within the crushing zone and causes the interlayer crushing zones turn to NNW direction.Most of the late NE trending and EW trending faults formed the ore breaking phenomenon,the ore bodies was broken into a step shape,and the fault fault distance was mostly within 10m.