Extreme Value Theory Modeling of Geochemical Anomalies: Block Maxima Approach
Emmanuel Ayitey *
Department of Mathematics and ICT, Adiembra Senior High School, P. O. Box 16, Takoradi, WR, Ghana and Department of Mathematics Science, University of Mines and Technology, P. O. Box 237, Tarkwa, WR, Ghana.
Christiana C. Nyarko
Department of Mathematics and ICT, Adiembra Senior High School, P. O. Box 16, Takoradi, WR, Ghana and Department of Mathematics Science, University of Mines and Technology, P. O. Box 237, Tarkwa, WR, Ghana.
Henry Otoo
Department of Mathematics and ICT, Adiembra Senior High School, P. O. Box 16, Takoradi, WR, Ghana and Department of Mathematics Science, University of Mines and Technology, P. O. Box 237, Tarkwa, WR, Ghana.
Micheal Affam
Department of Geological Engineering, University of Mines and Technology P. O. Box 237, Tarkwa, WR, Ghana.
*Author to whom correspondence should be addressed.
Abstract
Mineral shortages can be avoided if the mineral industry accurately predicts mineral deposits, which is critical given the importance of minerals in Ghana's economy. The goal of this dissertation was to use the block maxima (BM) approach of Extreme Value Theory (EVT) to accurately predict gold (Au) concentration and the time period of occurrence of these geochemical anomalies in Ghana's Wassa-Amenfi region. The information was based on a time series of daily gold concentrations collected between 2010 and 2018 by Ghana's geology and survey department. The shape parameter estimates from the analysis indicated that the Fréchet family of GEV distributions was a good fit for the dataset. The GEV model was used to forecast the occurrence of anomalies every 2, 5, 10, 20, 50, and 100 years. According to the findings, an extreme Au of 31.06 was expected to occur once every 5 years in Wassa-Amenfi.
Keywords: Extreme value theory, generalized extreme value distribution, geochemical anomalies, part per billion