Delineation of deep prospecting targets by combining factor and fractal analysis in the Kekeshala skarn Cu deposit, NW China

摘要

Three-dimensional visualization, factor analysis, and fractal/multifractal modeling are combined to study the geochemical data of borehole primary halo in the Kekeshala mining area in Northwestern China to screen exploration targets. First, based on the borehole spatial database comprising collar, survey, geology, and sample tables, 3D borehole primary halo samples are extracted. Their 3D block model is then constructed by spatial interpolation. Second, sample factor analysis of the borehole primary halo mainly includes four factors: F1 consists of Ag-Cu-Sn combination, F2 consists of Pb-Zn combination, F3 consists of As-Sb combination, and F4 consists of Mo-W combination. Moreover, 3D geochemical zoning is conducted for the samples. Third, based on the 3D block model of the primary halo, the F1 factor score is further modeled by Concentration-Volume (C-V) fractal model. Furthermore, based on the fractal fitting line's four segments obtained from the inflection points, geochemical barren host rocks, weakly deep prospect, moderately deep prospect, and highly deep prospect are extracted. Results indicate the following: (a) the F1 factor embodies the main metallogenic process or stage, which can be used as a comprehensive indicator of the spatial aggregation of major metallogenic elements in the study area; (b) the C-V fractal model can effectively determine the F1 factor deep prospect threshold of the skarn-Cu deposit in Kekeshala; and (c) the moderately and highly deep prospects of the F1 factor can well reflect the favorable geological conditions of metallogenesis and be used as the basis for delineating the prospecting target. Therefore, the fractal deep prospect of the geochemical F1 factor of the borehole primary halo has a good application effect in deep prospecting and prediction, which can be effectively used to explore the depth and edge of known deposits.