Remote Sensing Structural Interpretation And Refined Extraction Of Alteration Information In Pulang Copper Mine, Yunna

Based on the scientific research cooperation project of Yunnan Copper Mineral Resources Exploration and Development Co.,LTD.,Study on Metallogenic Model and Prospecting Direction of Typical porphyry Deposits in the "Sanjiang" Metallogenic Belt in Southwest China--Remote Sensing Geological Interpretation,this paper uses Landsat-8,Worldview-Ⅱ,Hyperion and other remote sensing data.The interpretation of geological structure information,alteration information extraction and mineral mapping of Pulang super large porphyry copper mine are carried out.The geological structure and alteration information obtained by remote sensing is verified by combining with geological and geochemical exploration data and field survey results.The main research contents are as follows:(1)Landsat8 data were used to extract the line-ring tectonic pattern of Pulang mining area and its peripheral areas;The wire-ring structure of Pulang mining area was extracted by Worldview-Ⅱ.The Pulang mining area is located in the south of the Pulang-Sonuo ring structure,and the Pulang-Sonuo intermediate acid intrusive rock belt is located in the ring structure.It is speculated that the ring structure is formed by the deep magma chamber and the dome structure formed by magma upward invasion.Secondary equiaaxial ring structures are developed in Pulang mining area.Such ring structures are related to protruding rock branches,dykes,depressions between protruding rock masses and alterations of surrounding rock caused by rock mass invasion.(2)Principal component analysis method(Crosta)was used to extract the information of iron staining and hydroxyl alteration in the region,and threshold method was applied to combine the characteristics of the study area,and density segmentation was carried out on the information of alteration like alteration anomalies in the study area,and the distribution map of iron staining and hydroxyl alteration anomalies was obtained.The anomaly information of iron stain is distributed in the vicinity of the North-South fault and the NW fault,while the anomaly information of hydroxyl group is distributed in the vicinity of the North-South fault,east-west fault and the NW fault,and mostly distributed in the edge of the ring structure.The alteration information near the first mining area and the dense area of line and ring structure is strong.(3)The hyperspectral data Hyperion was used to map the minerals in Pulang mining area and its peripheral areas,and the alteration information was refined to identify the minerals directly related to mineralization,such as mica(sericite),sphalerite,galena,chlorite,limonite and malachite.The high temperature magnetite is identified in the east of Pulang mining area,which is distributed zonely along the NNW fault,and only sphalerite is distributed in the area of non-porphyrite rock exposed southward.In the west of the mining area,there are a lot of saponite,opal and zinc montmorillonite,along with a lot of galena.This also indicates that large areas of porphyrite mass in the eastern Pulang area emerged from the surface and developed high temperature hydrothermal alteration.In the west,the medium acid rock mass is hidden and developed medium and low temperature hydrothermal alteration.Refined mineral mapping can distinguish the hydroxyl minerals formed by weathering of the Quaternary system from those formed by alteration.For example,there is a large amount of hydroxyl alteration information on some slopes in the north of the mining area,but the weathering in this area is strong,and it is impossible to determine whether the alteration is caused by weathering or weathering.Fine mineral mapping identifies it as opal.This is of great help to the screening of true and false anomalies and the causes of false anomalies.(4)The correlation analysis of line and ring structure with iron stain and hydroxyl alteration anomaly information shows that the intersection density of linear structure has the highest correlation with iron stain and hydroxyl alteration anomaly information.(5)The remote sensing prospecting mark was established to delineate three prospects in the north,east and southeast of Pulang mining area and its peripheral areas.