Geochemical criteria of the gold content of the Tom-Yaya interfluve weathering crusts

Abstract

Relevance. Gold-bearing weathering crusts are widespread in the Tom-Yaya interfluve, but the criteria for predicting their gold content, including geochemical ones, have not been adequately developed. Aim. To identify the geochemical features of the weathering crusts of the Tom-Yaya interfluve to resolve issues of predicting their gold content. Object. Weathering crusts from the rocks of the Paleozoic basement of the Tom-Yaya interfluve. Methods. The chemical composition of weathering products was determined by ICP-mass spectrometry. Core samples of 36 wells for 20 elements were analyzed. The results obtained were processed in the statistical analysis software package Statistica. The main parameters of the distribution of chemical elements in the profiles of gold-bearing and non-gold-bearing weathering crusts were calculated, discriminant and factor analyzes were carried out. Results. Statistically significant differences in the chemical composition of the weathering profile zones were established. In weathering of non-gold-bearing rocks, the removal of P, Mn, Co, Ni, Zn and the accumulation of Cr, Mo, Ag, Sn, Sb, Hf, Tl, Pb, Bi occur with the indifferent behavior of Au, As, Fe, Cu. Gold-bearing weathering crusts are formed in mineralized zones and are initially enriched in Au, As, W, Sb, and, to a lesser extent, Cu, Zn, Pb, Bi, Tl, Hf, Sn. The average content of gold and most satellite elements (except Pb) decreases during the weathering of mineralized zones, but the dispersion increases many times, as a result of which areas of secondary enrichment in gold and satellite elements Sb, As, Ag, Sn, Tl, Co, Cu, Zn, Cd, Bi appear within the zones of hydrolysis and hydration. Geochemical associations characteristic of residual weathering crusts are largely preserved in redeposited crusts, where As, Sb, W, Cd, Ag, Sn, and Hf are accumulated together with gold.

Keywords

• gold
• residual weathering crust
• redeposited weathering crust
• geochemical criteria
• Tom-Yaya interfluve