Improved detection of anomalous catchment basins by incorporating drainage density in dilution correction of geochemical residuals

Abstract

In exploration for mineral deposits using stream sediment samples, a phenomenon known as dilution of metal content originating from mineralized sources should be taken into account. Dilution occurs when stream sediments originating from upstream mineralized and non-mineralized areas are mixed during transport and deposition. In the sample catchment basin approach, dilution correction is accomplished by employing Hawkes's equation (1976). Catchment area size is the correction factor used in the Hawkes's equation to correct geochemical residuals for dilution. However, the upstream area of each stream sediment sample is representative of the hydrological response and dilution capability of a drainage basin. In the present research, the Hawkes's equation was modified by incorporating drainage density of catchment basin to correct geochemical residuals for dilution. The existing and new equations were applied to stream sediment data from Iran. The results were compared using known occurrences of Au mineralization as validation points. This showed the superiority of the new technique using drainage density as a factor for correcting geochemical residuals against dilution.

Geochemistry of stream sediments from Eséka area (SW Cameroon): implications for surface process assessment and precious metals (Au, Pd, and Pt) exploration

“…The comparison of Au, Pt, and Pd contents in stream sediment of this study compared to other studies shows that these elements are lower than those recorded in Abiete-Toko Gold District, South Cameroon (Nono et al, 2021) and in Giyani area, South Africa (Sadeghi et al, 2015) with recorded content in percentage values. It should recalled that concentrations of precious metals (e.g., Au, Pd, and Pt) in stream sediments are below the detection limit in general (Bellehumeur & Jébrak, 1993;Bellehumeur et al, 1994) and even low contents in stream sediments can reveal the presence of valuable ore in their sources (Bonham-Carter et al, 1987;Parsa et al, 2017;Shahrestani & Mokhtari, 2017). The results reveal that rocks and weathering profiles around certain sampling points (Figs.…”

“…Rare-earth elements are used as powerful markers of fundamental geochemical processes due to their similar physicochemical properties (Leybourne & Johannesson, 2008). According to several authors (e.g., Shahrestani & Mokhtari, 2017;Shahrestani et al, 2020), the geochemistry of stream sediments is the most effective tool in the preliminary geochemical exploration of mineral deposits.…”

“…Conversely, concentrations of precious metals (e.g., Au, Pd, and Pt) in stream sediments are always below the detection limit due to their heterogeneous distribution in their source areas (Bellehumeur & Jébrak, 1993;Bellehumeur et al, 1994). Even low contents in stream sediments can reveal the presence of valuable ore in their sources (Bonham-Carter et al, 1987;Parsa et al, 2017;Shahrestani & Mokhtari, 2017). In some rivers of Eséka region, alluvial gold is worked by artisanal miners since November 2017 and the primary source of the gold is not yet identified, as well as the alluvial extend.…”