Alteration Information Extracting Of Remote Sensing Image And Metallogenic Prognosis For The Xiongcun Cu-Au Distrcit, Xietongmen County, Tibet

Xiongcun ore concentration area is located in the middle of Gangdise metallogenic belt on the southern margin of Lhasa terrane,Tibet.It has excellent metallogenic geological conditions and huge resource potential.On the basis of field geological survey,this paper comprehensively analyses the data of soil geochemical survey and rock geochemical survey in Xiongcun mineral concentration area,extracts soil geochemical characteristics and rock geochemical characteristics by geostatistical method,and then delineates the prospecting target area in combination with metallogenic geological conditions,and finally carries out engineering verification.Through the research of this paper,the following achievements and understandings have been achieved:?1?Xiongcun Formation(J_1-2x)is the main outcropping stratum in Xiongcun ore concentration area.Faults are well developed in the ore-concentrated area,and structural fissures provide migration channels and ore-hosting space for ore-forming elements.The magmatic activity in the ore-concentrated area is intense and characterized by multi-stage intrusion.The intrusive rocks occur in the form of stocks or branches.The main ore-bearing porphyries are Early-Middle Jurassic amphibole quartz diorite porphyries and middle-late Jurassic amphibole quartz diorite porphyries with eyeball-like quartz phenocrysts.Ore-bearing porphyry intrudes into volcanic-sedimentary rocks of Xiongcun Formation and forms porphyry copper-gold?silver?mineralization in tuff near the top and contact zone of porphyry.?2?By comparing the traditional statistical method,EDA method and content-area analysis method,it is concluded that EDA method is more suitable for the study of elements in soil geochemical survey in mineral concentration areas,and content-area fractal method is more suitable for the study of elements in rock geochemical survey in mineral concentration areas.Mathematical and statistical characteristics of the contents of measured elements in soils and rocks show that the elements of Cu,Au,Ag,Pb,Zn in soils and Cu,Au,Ag,Pb,Zn,Mo,As,Sb and W in rocks are highly differentiated,especially the possibility of enrichment and mineralization of Cu,Au and Ag is high,which is basically consistent with the mineralization characteristics found in mineralization areas.?3?Multivariate statistical analysis shows that the elements in soil can be divided into F1 factor?Cu-Au?and F2 factor?Ag-Pb-Zn?.The elements in rock can be divided into four categories:F1 factor?Cu-Au-Ag-Mo?,F2 factor?Co-Ni?,F3 factor?Pb-Zn-Mn?and F4 factor?As-Sb-W?.By comparing the anomaly maps of element superposition combination and factor combination,it is more reasonable to define element combination anomaly by factor combination anomaly method.?4?Based on the anomalous map of various factors combination of soil and rock,combined with metallogenic geological conditions and prospecting indicators,six prospecting target areas I-1,I-2,I-3,II-1,II-2 and II-3 were delineated in the ore concentration area.The prospecting targets of I-1,I-2 and I-3 are located in the range of No.1,No.2 and No.3 orebodies respectively,which are in good agreement with the discovered orebodies.It shows that the method of factor combination anomaly is effective and reasonable in delineating prospecting targets.New orebodies have been found in the prospecting target areas II-1 and II-2.Among them,the average grade of copper in the prospecting target area II-1 is 1.26%,the average grade of Au is3.22×10^-6,the average grade of Ag is 564.13×10^-6,the average grade of Pb is 3.75%,and the average grade of Zn is 2.03%.The average grade of copper in the prospecting target area II-2 is 0.74%,and the average grade of Au is 1.43×10^-6,belongs to skarn type ore body.