Application Of Singular Value Decomposition And Bi-dimensional Empirical Mode Decomposition To Extract Aeromagnetic Anomalies Related To Mineralized Granites

Southeast yunnan is located at the confluence of the Yangtze block,cathaysia block and sanjiang fold belts,where the geological evolution process is complex and the magmatic activity is intense.There are three tin polymetallic metallogenic belts,include gejiu,bozhushan and dulong,with huge resource potential.In order to obtain more objective and more accurate reveals the deep geological structure features in the study area and its relation with the spatial distribution of the mineralization,Singular Value Decomposition(SVD)and Bi-dimensional Empirical Mode Decomposition(BEMD)methods were applied to the data of 1:20 0000 aeromagnetic pole in this paper.Combining with the metallogenic geological background of gejiu-bozhushan-duolong ore concentration field to obtain the ore-controlling factors which can provide reference for further ore prospecting in this area.(1)The low-pass filtered images decomposed by BEMD and SVD methods reveal the deep geological structure and geological features of the research area.The regional background field reflects the overall distribution of the deep weak magnetic basement(kunyang rock,yaoshan rock)and ferromagnetic basement(dahongshan rock).The superposition of positive and negative magnetic anomalies in the south China landmass area indicates that there are larger magmatic body in the depth.The tin-tungsten ore deposit in the ore concentration area is located in the negative magnetic anomaly area,which indicates that it has a close spatio-temporal relationship with the granitic body,which is the main ore-controlling factor in the study area.(2)The band-pass filtered images extracted by BEMD method reflects the geological structure and geological features of medium depth.The overall distribution of the middle-depth granitic body in the gejiu-bozhushan-duolong tin-tungsten polymetallic ore concentration area in the study area is revealed,the middle-depth granitic body is larger than the exposed,and is controlled by the deep major faults around it,which provide a channel for the upward migration of the ore-bearinghydrothermal fluid.The mineralization of tin and tungsten in the study area has close spatial relationship with granite.(3)The high-pass filtered images decomposed by BEMD and SVD methods reveal the shallow geological structure and geological features.The tin and tungsten deposits in the region are mostly located in the positive magnetic anomaly area surrounding a trap negative anomaly.It is inferred that positive magnetic anomaly is caused by the mineralization of skarn alteration in the contact metasomatism zone formed around granite.Therefore,the contact metasomatism zone formed by granites and carbonate rocks is a favorable area for mineralization.(4)The contact metasomatism zone characterized by positive magnetic anomalies that surrounding a trap negative anomaly is an important marker for the exploration of tin and tungsten deposits.The magnetic anomaly information extracted by BEMD and SVD methods show that there are concealed granites favorable for mineralization in mengzi-pingbian region(A),shiping-jianshui region(B),and north maguan region(C),and there is a certain burial depth in region A.