Anomaly identification in soil geochemistry using multifractal interpolation: a case study using the distribution of Cu and Au in soils from the Tongling mining district, Yangtze metallogenic belt, Anhui province, China

Interpolation between existing data points is necessary in order to construct contours and surfaces to determine spatial variations and anomalies within soil geochemical datasets. In this study we focus on the mature Cu and Au Tongling mining district, in Anhui province, eastern China. Copper and Au concentrations in both topsoil (A horizon) and deep soil (C horizon) were used to compare Kriging and multifractal Kriging interpolation methods. In order to separate anomalous samples from background concentrations, anomaly thresholds for Cu and Au soil concentrations were calculated for the Tangling mining district using a scattergram of contoured elemental concentrations versus number of mineral deposits contained in each contour. The anomaly threshold for Cu was 56.23 mg.kg(-1); a contour constructed for this value contains the majority of the known Cu deposits within the Tongling mining district while also indicating other potentially prospective areas.