Characteristics Of Host Structures And Tectonic Stress Field Of Copper-molybdenum Mine,Matou, Chizhou, Anhui Province

Matou copper-molybdenum, Chizhou city, Anhui province, north margin of lower Yangtze plate, which located in the joint part of the middle and lower Yangtze fracture and sag zone and the Caledonian orogenic belt of south Anhui. From Sinian to Quaternary, the strata are well developed but the Middle-Lower Devonian and parts of the Lower Carboniferous. NNE trending folds and fractures formed after Indosinian epoch, together with other structures formed during Late Indosinian epoch, Yanshanian epoch, and Himalayan epoch established the grid tectonic framework of the study area.The magmatism is intense in the area. Cu and Mo Occurrence rock mass developed in internal or external contact zone of granodiorite porphyry and Fentou formation of Middle Siluric which controlled by fissure concentrated zones of the rock mass and surrounding rock.This paper studied the fracture and joint structure and analyzed the development characters of ore-bearing structures and the Cu-Mo Occurrence Conditions. A statistics of attitudes of the host joints was made systematically by stereographic projection and so on. We draw the horizontal projection map, cross-section map and distribution graph of tectonic stress field during the metallogenic period. The main results achieved and understanding are as follows:1The N-S to NNE-SSW trending Xifengmiao-Matou sinistral strike-slip faults manifest the trending of the maximum principal stress axis(σ1)is NNE and the trending of the minimum principal stress axis (σ3) is NWW, the dip angle is nearly horizontal. The middle principal stress axis (σ2) is nearly vertical. F1as the route ways of the Matou copper-molybdenum mine initial tension joint developed in the end of the F1as the ore-bearing structures, The dominant attitudes are285°∠87°, which manifest the azimuth of the maximum principal stress axis (σ1) is15°and the azimuth of the minimum principal stress axis (σ3) is105°, the intermediate principal stress axis (σ2) is nearly vertical. Ore-bearing joints and mineral transfer structures were controlled by the same tectonic stress field.2Indosinian movement and Yanshan movement significant impact the structures of the study area, and the metallogenic happened in late Yanshan period. In Indosinian period, the mainly structure stress field is N-S compression and the trace of the structures are more or less parallel. In Yanshan period, the orientation of the compression structure stress field changed from NW-SE to NNE gradually developing a series of from NNE to NE trending faults. The Xifengmiao-Matou fault invaded by the granodiorite-porphyry produced edge stress concentration, which caused the tension joints.3F1deep fracture is the route ways of the ore solution, and the tension joints formed at the end of F1is the ore-bearing structures. The quality and shape of the mineralized bodies is positively correlated with the degree and scope of the extend joint, and that can help us prospecting.