Investigating fluid-rock interaction at the hand-specimen scale via ITRAX

Abstract

Abstract Accessing geochemical compositions on the hand-specimen scale provides important clues towards understanding fluid-rock interaction in mineralization. In this study, we used the ITRAX core scanner to detect the geochemical composition of a hand specimen obtained from Yangshan skarn-type Iron deposits in China. In order to investigate fine-scale nature of element immigration during the fluid rock interaction, the discrete wavelet leader transform combined with log-cumulants was utilized to calculate the multifractal spectrum which can describe the degree of the irregularity and heterogeneity of the geochemical distributions. The present results show that the iron, manganese, aluminum, europium, silicon and calcium are multifractally distributed with different singularity spectra. Among them iron and manganese hold narrower singularity spectrum than other elements, indicating that their distributions are more regular or homogeneous. By comparing the multifractal characteristics between the vein area and the wall-rock area, we show that the distributions of the strongly affected sections (near the vein area) would be more homogeneous than those of the weakly affected sections. This fact demonstrates that the fluid-rock interaction (isomorphism between Fe2+ and Mn2+) homogenized the nature stochastic distribution of original hydrothermal systems. The multifractal characteristics described by the first two log-cumulants provide a valid way to investigate the intensity of fluid-rock interactions through measuring the heterogeneity of geochemical distributions on the hand-specimen scale.