Predictive modeling and comparative evaluation of geostatistical models for geochemical exploration through stream sedim
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ORIGINAL PAPER
Predictive modeling and comparative evaluation of geostatistical models for geochemical exploration through stream sediments Muhammad Ahsan Mahboob 1,2 & Turgay Celik 3 & Bekir Genc 1 Received: 29 June 2020 / Accepted: 22 September 2020 # Saudi Society for Geosciences 2020
Abstract Geochemical exploration of stream sediments is an important step for the identification of areas of interest with potential mineralization, particularly in the early stages of mineral exploration. A total of 407 sample points for 15 different geochemical traces were collected from Central Wales and classified into two groups: a training group consisting of 285 samples and a testing group consisting of 122 samples. Geospatial characterization of each parameter at stream level was performed using two different prediction models; the inverse distance weighting and the geostatistical kriging. Several variations of the IDW model was applied based on the power function and the number of the sample points, and the best one selected based on “root mean square prediction error” statistic. The same statistic was also used in the best-fitted semivariogram models including the circular, spherical, exponential and Gaussian for each geochemical parameter in Kriging. Finally, the mineral prospectivity map of the area was developed based on the geochemical accumulation index (GAI) using multivariate overlay analysis. The experimental results show that there is no single method that can be used independently to predict the spatial distribution of geochemical elements in streams. Instead, a combinatory approach of IDW and kriging is advised in order to generate more accurate predictions. The mineral prospectivity map based on GAI showed that most of the mineral-enriched streams were found in northwest, northeast, and south part of the study area which was also confirmed with the existing mining activities in the region. Keywords Geochemical mineralization prediction . Geostatistics . Stream sediments . Geographic information systems . Spatial modeling . Mineral exploration
Introduction Stream sediments usually result from the erosion and transportation of soil and rock remnant, and other materials present upstream of the sampling locations within a basin (Merritt et al. 2003). Thus, stream sediments are considered to be representative of the geochemistry of the rocks present in the
Responsible Editor: Murat Karakus * Bekir Genc [email protected] 1
School of Mining Engineering, University of the Witwatersrand, Johannesburg, South Africa
2
Sibanye-Stillwater Digital Mining Laboratory (DigiMine), Wits Mining Institute (WMI), University of the Witwatersrand, Johannesburg, South Africa
3
School of Electrical and Information Engineering, University of the Witwatersrand, Johannesburg, South Africa
upstream drainage basin. Usually, stream sediments are the primary sampling source for geochemical exploration, primarily in areas where distinct drainage systems exist due to the l oc a l t op o g r a p hy ( F l e t c h e r 1 9 9 7 ; S al
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