Fractal/multifractal analysis in support of mineral exploration in the Duolong mineral district, Tibet, China

Abstract

The study area, Duolong mineral district, Tibet, China is not a well-developed area but has received attention in recent years due to its considerable production of Cu-Au resources. This paper utilizes fractal/multifractal analytical techniques to gain insights to the geological environment, metallogenesis of ore deposits, as well as mineral exploration in this area. Porphyry Cu-Au mineralization related elements and fault-activity indicator elements from stream sediments geochemical data are integrated by log-ratio transformation-based principal component analysis, the results of which are further analyzed by singularity theory and spectrum-area model. Identified geochemical anomalies spatially coincident with structural framework are not only suggestive of the presence of mineralization but also suggest genetic relationship between mineralization and regional fault structures. The usefulness of the singularity theory and spectrum-area model, as two mature and effective geo-information extraction methods in the fractal/multifractal context, is compared based on their theoretical foundations and practical applications. It was found that, in the study area, the spectrum-area model is more effective for characterizing self-similar spatial patterns caused by specific geological processes, while the singularity theory can inform about geochemical behaviours of elements or element associations reflecting a series of geological processes. Compared to the results of the singularity technique, the results of spectrum-area modeling results, especially the geochemical background patterns, are more robust for interpreting structural framework and metallogenic background of the area. This study infers mesh-like structural control on porphyry mineralization, and identified background geochemical patterns of multi-element association by fractal/multifractal analyses further provide indirect and/or proxy geo-information of the mesh-like structure to support of mineral exploration in the Duolong mineral district.