The Geological Setting And Fractal Analysis Of Geochemistry In Southern Part Of Sanjiang Region, Southwestern China

Multiphase mineralization is widely developed and superimposed in the samedistrict in Sanjiang ore belt. The complexity of the geological setting and the varietyof the deposit types bring difficulty for the application of traditional methods indelineating the regional geochemical anormaly and describing the elementaldistributions in single deposit. In this paper, based on the systematic analysis ofgeological setting and the variety of mineralization, several fractal models andprobability statistics were used to analyze ore-forming elemental distribution, aimingto indicate the ore-controlling factors.According to multifractal model and probability statistics, the elementaldistributions in different geological unit and catchment basin are depicted, and thecharacteristics of mineralization in different units are clarified. It is revealed that thesingularity of Cu is high in Yidun continental arc and Simao block; and that of Auare high in Jinshajiang-Ailaoshan suture zone and Tengchong terrene. This studysupports and enriches the understanding of geological prospecting laws.Several methods, of which the fundamental principles are systematicallydiscussed, including probability distribution methods, concentration-area model,spectrum-area model and singularity index, are combined to extract geochemicalanomalies in different geological units and catchment basins. Due to the differencesbetween the principle of each method, most of the anomalies derived from variousmethods are different. However, the anomalies, with high coincide to the deposits(ore occurrences), can be obtained by combining the results. Based on this analysis,we delineated several targets in the study area, including Au-Ag-Pb-Hg in Ailaoshaosuture, Pb-Zn-Ag in Simao block and Pb-Zn-Ag and Sn-Cu in Tengchong block,which is instructive for mineral prospecting.The self-similar model and multifractal model are selected to analyzeore-forming elemental distributions in Beiya multi-type gold metallic deposit,Pulang porphyry copper-molybdenum deposit and Mengman hot spot gold deposit.It is revealed that the fractal parameters of elemental distributions in deposits withvarious genetic types are different. The mineralization in these deposits are mainly controlled by the fault system in contact area and the expansion and contractionstructure of magma, the alteration zone and the NW trending, respectively. Moreover,the elemental distributions in multi-type deposit are more heterogeneous than thoseon the other two deposits.In this paper, fractal models are systematically applied in different scales,including region and single deposit. The comparative of these analyses can providemore effective information about the characteristics of elemental distribution. It ishelpful for understanding the metallogenesis and enriches the application of fractalmodel.