Geochemical Data Processing And Ore Prospecting Evaluation In Dajiacuo-nanongle Area,Western Gangdese

The Gangdese metallogenic belt is an important copper-polymetallic metallogenic belt in China.Most of the deposits in the area reflect the characteristics of chemical anomalies on the traditional geochemical anomaly map as “ high,large and complete ”.However,in the dajiacuo-nanongle area in the western section of the Gangdese metallogenic belt,the geological conditions are complex,the volcanic rock coverage of the Linzizong group is serious,and the geochemical abnormality is weak.Previously,many geological-geochemical exploration works have been carried out in the dajiacuo-nanongle area,and prospecting has made periodic progress.Therefore,it is necessary to screen out the weak anomalies with metallogenic potential under the special geological conditions of the dajiacuo-nanongle area,so as to provide favorable targets for the mineral geological investigation.The main research content of this paper is to analyze the 1:500000 geochemical data of volcanic rock area in the western Gangdese(dajiacuo-nanongle area)respectively by the traditional mean standard deviation method,C-A method and “connotation of the geological method”,compare the advantages and disadvantages of these methods,determine the optimal method,and analyze comprehensively according to the abnormal characteristics,known deposits(points)and geological characteristics Then,the target area is further optimized,and the anomaly verification is carried out first in the target area,then the location of hydrothermal center is predicted by combining the new technology of short wave infrared spectrum and geological investigation,and finally the mineralization is checked through the exploration groove.The lower limit of anomaly determined by the traditional method is higher,less anomaly,scattered distribution.The anomaly area is generally overlapped with the known ore point,and the weak anomaly is difficult to display.Under special geological conditions,it has certain limitations;However,the lower limit value of low anomaly in C-A method is smaller,and the area of anomaly delineated is larger.The phenomenon of whether there is ore anomaly or not and whether there is ore anomaly but there is no ore usually occurs,which is not conducive to reducing the workload and optimizing the target area;the above two methods are based on mathematical statistics For the purpose of seeking the best lower limit of abnormality.No matter what specific value the lower limit of abnormality is determined to,the final effect of its mapping has not substantially changed,only the size of the abnormal area,and the position of the abnormality has not changed.The “connotation of the geological method” objectively endows the data with geological connotations,optimizes and combines the original data to form anomalous intensity values of elements,and then draws anomaly maps,especially the complexity map of the elements is qualitatively different from it,In particular,under the special geological conditions of the dajiacuo-nanongle area,the “ connotation of the geological method ” has more advantages than the other two methods,and can quickly screen out weak anomalies with metallogenic potential.According to the anomaly characteristics reflected by the element complexity map and combined with the anomaly characteristics of the deposit type,the target area is optimized by the similarity analogy method,6 metallogenic prospect areas and 18 prospecting target areas are divided,and the target areas of dajiacuobei lead zinc silver copper prospecting and nanongle lead silver gold prospecting are selected for verification,which have achieved good results.In each target area,different degree of mineralization has been found,and the prospecting prospect is good.