Identification Of Weak Geochemical Anomalies Of Stream Sediments In Xupu,Hunan Province

The Outline of the Fourteenth Five-Year Plan for National Economic and Social Development of the People's Republic of China calls for strengthening the evaluation of mineral resources and providing high-quality mineral exploration blocks.Hunan Province,as an area rich in non-ferrous metal resources,has superior metallogenic geological conditions.It is the primary task of geological work in this area to further find out the distribution of mineral resources.Stream sediment geochemical survey is an important means of regional investigation and mineral survey.It has remarkable prospecting effect and wide application scope.The main content of it is the identification and extraction of anomalies.With the development of mineral exploration,the evaluation and verification of the "high,large and complete" geochemical anomalies which are easy to be found have been basically completed.However,the large amount of data accumulated in the regional geochemical scanning in China still contain a large amount of unexcavated information,and it is necessary to adopt appropriate methods to extract the low and weak geochemical anomalies.In recent years,some scholars have put forward corresponding methods and discovered series of deposits in low and weak anomaly areas.Therefore,it is of great value to study and extract low and weak geochemical anomalies.Based on 1:200000 stream sediment geochemical data in Hunan Province,this paper analyzes the influence of lithologic background on the geochemical anomaly of stream sediments in depth,proposes a Gaussian mixture model based on factor score for lithology classification,and extracts the low and weak geochemical anomalies.Due to the existence of multiple populations,the element content distribution of geochemical data often presents skewness and multi-peaks.The unified background upper limit in the whole region may lead to the problem that the high background area is misjudged as anomaly,while the low and weak anomalies are ignored,which brings great trouble to geochemical exploration work.To separate different populations,weaken the influence of lithology background,this paper respectively from multiple elements and factor score two directions for research area to differentiate lithology,then for each type of the elements in the normal translation,3 s inspection after eliminating extreme value is used as the standardization,the standardization of data merged into a new data set,in order to extract the main oreforming elements in the study area,Cu,Pb,Sn,W Sb of geochemical anomalies,and compared with the traditional method.The results show that the stream sediments have the inheritance of the original rock chemical composition,and the element content distribution of the stream sediments roughly coincides with the geological units.The element combinations of the factors obtained from the factor analysis accord with the actual situation,and can be used for lithology division.The Gaussian mixture model can accurately complete lithologic classification,and the classification method can effectively suppress the lithologic background,enhance the original anomalies,and identify the low and weak anomalies.Compared with the multi-element method,the factor scoring method is more effective.The method proposed in this paper has obvious effect,simple operation and strong universality,which makes a certain supplement to the theoretical method of weakening the lithologic background of geochemical exploration anomalies,and provides a new idea for the identification of geochemical exploration anomalies.It has certain theoretical significance and practical value.