Analysis of lithogeochemical data using log-ratio transformations and C-A fractal to separate geochemical anomalies in Tak-Talar, Iran

Abstract

While classical approaches of interpreting geochemical data may have failed owing to some reasons, a new generation of approaches and methods enable us to identify exact mineralization sites, when they would be particularly coupled with new methods for classification anomalies. Geochemical data, as a part of the composition data, has a closed numerical system that decreases or increases of one element affect other elements. In this study, to fulfill detailed analysis of composition data, 131 lithogeochemical samples were collected from Tak-Talar, located in the southeast of Iran, and were analyzed with ICP-OES and fire assay methods, and then examined using the family of log-ratio transformations, centered log-ratio (CLR) transformation. To discriminate anomalies from the background, concentration-area fractal was used, in which results showed gold and copper anomalies in the northeast and central parts of the study area were well coordinated with siliceous and oxide hydrothermal veins, mineralization outcrops, faults, and alteration zones. Then obtained mineralization sites were compared with deep samples from trenches that show the results are in agreement with each other. To investigate the paragenesis of elements, multivariate methods such as cluster analysis and robust factor analysis were also performed. The results present that elements such as Cu, Pb, As, Sb, Ag, Mo, and Au were associated together which was completely consistent with the genesis of the ore deposit (epithermal and porphyry). Related findings were integrated to determine anomalies that were prioritized, in terms of intensity and area, by C–A fractal for important elements. It can be expected these results may be useful for geochemical exploration and studying deposits with various mineralization phases.