| The geotectonic location of the study area is located in the stress area where the North China Plate,the Yangtze Plate,and the Tethys Ancient Ocean Plate collide.The Huixian-Liangdang northern metallogenic belt,where the study area is located,has strong magmatic activity and developed fault structures at various stages,which is one of the important gold metallogenic areas in the Western Qinling Mountains.The thesis mainly relies on 1:10000 soil geochemical surveys in the Huojishan region of the Western Qinling.A total of 1030 soil geochemical exploration samples were collected to study Au,Ag,Cu,Pb,Zn,W,Sn,Mo,and Bi in the study area.Data of 12 kinds of element content such as,As,Sb and Hg are used as the object,and the combination of elements is divided by correlation analysis,cluster analysis and factor analysis to study the characteristics of element spatial changes.The fractal and multifractal theories are introduced.The content-area(C-A)model,multifractal filtering technology(S-A),and local singularity index method are used to determine the lower limit of each single element anomaly.This threshold is used for interpolation to perform single element anomaly extraction and Parsing.Based on the analysis of single element anomaly fractal,the factor-pan Kriging model was used to quantitatively analyze the spatial difference of geochemical exploration data in the study area.Figure and space quantitative combination 3D distribution map.The multi-fractal filtering technique is used to draw the background of the factor score and the anomaly map,so that the background and the anomaly are separated,and the hidden element combination anomaly information of each factor is effectively extracted.Based on the geological background,single element and combined element anomaly characteristics,the classification and evaluation of geochemical element anomalies in the study area were made.Get the following achievements and understanding:(1)Through the analysis of regional geological background and field geological survey,the geological characteristics of the study area are mainly as follows: regional faults and fold structures are more developed,mainly based on faults.There are three faults,F1,F2 and F3,and there are ductile shear zones spreading along the north-east direction.The area with dense gold anomalies is obviously controlled by the fault structure.(2)Statistics of variation coefficients and element combination relationships were analyzed based on geochemical data.As,Bi,Au,Sb,Pb,and Ag elements were strongly enriched in the soil in the study area,and W,Sn,Hg,and Mo elements were enriched.distributed.The elements Bi,Ag,Mo,Hg,Sb,As,Pb,Au,and W have a strong differentiation and migration ability,showing a strong differentiation distribution,which is extremely conducive to the migration of rich ores.Multivariate statistical analysis showed that the F1 factor accounted for the largest variance contribution rate,33.133%,which represented the Au-Ag-Pb-Zn-Sb element combination.(3)The comparative analysis results of extracting abnormal information based on fractal theory show that: the C-A model does not need to remove the extreme values of elements.The extracted abnormalities are mostly distributed in high background areas,but there are certain limitations in the extraction of weak abnormal areas.The S-A model and the singularity index can well extract the changing background anomalies.The S-A model can filter out the background values at different scales and extract the local anomaly information,making up for the deficiency of the C-A model,but the edge area anomalies cannot be effectively extracted.The local singularity index method can perform local deep level extraction based on the above two methods,and is a powerful tool for identifying weak geochemical anomalies.The comparative analysis of the three fractal methods provides strong evidence for the analysis of deep-level geochemical anomalies in the study area.(4)The factor-Pan Kriging model analyzes the spatial structure of each combined element and reasonably expresses the geochemical combination anomaly information in the study area.Factor score contour maps and spatial quantitative combination 3D distribution maps depict element abnormalities from multiple angles.The multi-fractal filtering technology(S-A)extracts anomalies of combined elements,which can provide an important reference for target area delineation.(5)A total of 8 prospecting prospects were identified,including 1 grade ? anomaly(?-1),2 grade ? anomalies(?-1,?-2),and 5 grade ? anomalies(?-1,(III-2,III-3,III-4,III-5).Among them,?-1,?-1 and ?-2 are important prediction areas for ore prospecting potential.And propose further work. |
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