Geochemical associations and their spatial patterns of variation in soil data from the Marrancos gold-tungsten deposit: a pilot analysis

Abstract

This paper discusses the results of a soil geochemical exploration survey in the environs of the Marrancos gold-tungsten deposit, dealing with 144 samples of topsoil, analysed for 53 chemical elements. At this initial stage of the project the main objectives were: (1) to identify associations between chemical elements; (2) to estimate spatial patterns of variation for such associations in the surficial materials. The associations were established using principal component analysis (PCA). Variography was used to obtain the theoretical model of spatial continuity of each variable. These models were used in the interpolation method (kriging) selected to estimate surficial dispersion patterns. The results of PCA and PCA mapping indicate distinct distribution patterns for the metals related to the primary mineralogical or geochemical association, as identified for this deposit. Based on the results, six of the 53 chemical elements studied were selected to estimate spatial patterns of dispersion in the topsoil. This approach allows the recognition of the geochemical signature of the deposit, and the selection of several target areas for follow-up work. Several sites were selected for water sampling (surficial and groundwater), and the soil samples to be used in partial extractions are now defined.