Fault trace-oriented singularity mapping technique to characterize anisotropic geochemical signatures in Gejiu mineral district, China

Abstract

Mineralization is complex and controlled by various non-linear geo-processes. Geochemical signatures of mineralization-favored spaces inherited from multiple geo-processes are consequently anisotropic. Singularity index mapping technique efficient in identifying heterogeneity of geochemical signatures had been utilized to recognize geochemical anomalies in many cases. As an example of interdisciplinary collaboration, this paper using a newly proposed fault trace-oriented singularity index mapping technique intends to characterize hydrothermal mineralization-associated anisotropic geochemical signatures. In the case study, fault traces in the Gejiu mineral district, China are divided into segments with equal length. Centered by fault segments, a set of rectangular windows are defined to estimate singularity index. Variations of geochemical signatures along the vertical direction of fault traces are characterized. The fault trace-oriented singularity indices assigned to their corresponding fault segments term faults as positive, negative and regular fault segments to qualitatively and quantitatively explain interrelations between fault structures and hydrothermal fluids or mineralization. In comparison with frequently employed fault properties (e.g., length, density, types, etc.), the new fault attributes (i.e., positive, negative, and regular fault segment) are applicable to describe variations of physical–chemical reactions between ore-forming fluids and wall rocks along fault traces that benefit the interpretation to metallogenic mechanism. The newly proposed method can be considered as a supplement to the formerly introduced square window-based isotropic singularity index mapping technique.