Identification and mapping of lithogeochemical signatures using staged factor analysis and fractal/multifractal models

To identify geochemical signatures related to deposit-type sought, staged factor analysis (SFA), fractal and multifractal methodologies were utilized to process the lithogeochemical data in the Laochang district, Yunnan province, SE China. In this study, 13 elements, includingW, Mo, Pb, Zn, Ag, As, Bi, Hg, Sb, Sn, Cu, Cd and Mn, were analyzed in 825 rock samples. A centred logratio (clr) transformation was applied to address the closure problem of geochemical data. The results clearly demonstrate that SFA greatly assisted with not only interpretation of geochemical zonation patterns genetically related to intrusions, but also extraction of multi-element associations signature of the mineral deposit-type sought. The geochemical distribution patterns can be characterized by multifractal parameters such as singular exponent alpha, as well as tau"(1) and Delta alpha, which are effective for depicting the spatial heterogeneity signatures of geochemical data. Through geochemical mineralization prospectivity indices (GPMI) and C-A model, the results illustrate that element distribution signatures are greatly influenced by fault density. The integrated methods are useful for identifying significant multi-element anomalous signature and generating reliable target areas for further prospecting.