Extraction Of Geochemical Anomalies And Delineation Of Ore-finding Targets For Pb-Zn And Sn-W Polymetallic Mineralization In Tengchong Block,Southwestern China

With the decrease of surface mine,the prospecting for concealed orebodies become more and more important.Mineral exploration had entered into the prospecting stage with the characteristic of information prospecting.The effective extraction of mineralization abnormal information is very crucial in the evaluation of mineral resources.Geochemical exploration has a strong position in mineral exploration.Recognition and evaluation of geochemical anomalies caused by ore bodies is critical in geochemical exploration activities.It has a direct impact for further exploration and decision-making.Factor analysis is a statistical analysis method for reduce the dimensionality of the data.All of the original variables concentrated into a few variables which are uncorrelated.These new variables can be an explanation for the inherent relationship between the original variables.With the occurrence of geological processes,the material composition of the geological body will occur migration and produce a new distribution relationship.The combination of elements can be used as an indicator of specific mineralization or rock.This paper attempts to use the factor analysis method to deal with the geochemical data from stream sediment survey at scale of 1:200,000.Then,rock-forming element groups characterizing geological units and faults associated with mineralization and ore-forming element groups were established by factor analysis.Geological data is not simple linear data.It has nonlinearity and nonstationarity due to the complexities and multi-stages of geological processes and the heterogeneous composition and texture of geological bodies.Bi-dimensional empirical mode decomposition(BEMD)is the development of empirical model decomposition(EMD)in two-dimensional data.It is an adaptive method for analysis of nonlinear and non-stationary data.This paper attempts to decompose the scores of the ore-forming element groups into different intrinsic mode functions with different frequencies by BEMD.Then,identify the ore-finding targets and high background zones favorable mineralization.We can draw the following conclusions:(1)The geochemical data can be concentrated into a few variables which are uncorrelated by factor analysis.These new variables can respect most information of the original data.Some of these variables might provide clearly geological and mineralized significances for interpretation..(2)In the basis of the main factors generated by factor analysis,each main factors standing for specific geologically mineralized features can be further decomposed into different two dimensions intrinsic mode functions with different frequencies and a residual function.Some functions among them may provide more specific ore-finding information than factors for identifying ore-finding targets.(3)It has been illustrated by our studies that BEMD combined with factor analysis can be effectively applied in extracting the geochemical association components characterizing different types of mineralization and the geological factors associated with mineralization.