Single‐element Anomaly Mapping from Stream Sediment Geochemical Landscapes Aided by Digital Terrain Analysis

Abstract

The identification of anomalies within stream sediment geochemical data is one of the fastest developing areas in mineral exploration. The various means used to achieve this objective make use of either continuous or discrete field models of stream sediment geochemical data. To map anomalies in a discrete field model of such data, two corrections are required: background correction and downstream dilution correction. Topography and geomorphology are important factors in variations of element content in stream sediments. However, few studies have considered, through the use of digital terrain analysis, the influence of geomorphic features in downstream dilution correction of stream sediment geochemical data. This study proposes and demonstrates an improvement to the traditional downstream dilution correction equation, based on the use of digital terrain analysis to map single‐element anomalies in stream sediment geochemical landscapes. Moreover, this study compares the results of analyses using discrete and continuous field models of stream sediment geochemical data from the Xincang area, Tibet. The efficiency of the proposed methodology was validated against known mineral occurrences. The results indicate that catchment‐based analysis outperforms interpolation‐based analysis of stream sediment geochemical data for anomaly mapping. Meanwhile, the proposed modified downstream dilution correction equation proved more effective than the original equation. However, further testing of this modified downstream dilution correction is needed in other areas, in order to investigate its efficiency further.

The Application of Portable X-ray Fluorescence (pXRF) for Elemental Analysis of Sediment Samples in the Laboratory and Its Influencing Factors

“…Stream sediment is one of the most commonly used sampling media in mineral resource exploration and environmental scientific research [1][2][3] since they represent large areas and particularly reflect the element background within specific catchment basins. The International Association of Geochemistry for Exploration conducted extensive research and discussion around sampling media and when conducting large-scale geochemical surveys across many countries, stream sediment was the most widely used sampling medium [4][5][6]. However, in areas with poorly developed water systems, such as deserts, particularly the Gobi desert, stream sediment is not an effective sampling medium.…”

Delineation of Integrated Anomaly with Generative Adversarial Networks and Deep Neural Networks in the Zhaojikou Pb‐Zn Ore District, Southeast China

“…As geochemical exploration searches for indicative elemental anomalies, instead of ore directly, elemental anomaly information has been visualised on a map once the chemical analytical results were obtained (Levinson, 1974). With interpolation of element concentration, geochemical anomaly maps are generally produced as concentration contours based on separation of background and threshold (Jang et al, 2021;Xiang et al, 2023). Methods for selection of a threshold mainly include: (i) comparison with published data, (ii) histogram, (iii) mean plus 2 (or 3) standard deviations, (iv) cumulative frequency on log probability plot, (v) comparison with the results of an orientation survey (Hawkes and Webb, 1962), (vi) geostatistics (Matheron, 1963), and (vii) fractal analysis (Cheng et al, 1994).…”