Morphometric and Terrain Analyses of A Mineralized Zone: Isolating the Signatures of Neotectonics, Fluvial Processes, and Opencast Mining

Detailed information on the geo-environmental conditions of a mineralized zone is required for sustainable exploitation of natural resources, and there is a need to isolate geo-environmental impacts of mining from natural occurrences. This study proposes an assemblage of simple basin-scale terrain modeling techniques to isolate tectonic-induced geo-ecological conditions from mining-induced geo-ecological changes in a mineralized zone of the Ilesa schist belt, southwestern Nigeria. To model and evaluate the signatures of past tectonic events and the impacts of mining, hypsometric parameters, bifurcation ratio and asymmetry factor (A.F.) were computed while change detection analysis of HAND models (for 1950 and 2018) was undertaken. Morphometric analyses showed that the landform evolution of the study area had been greatly influenced by the past tectonic activities. Six hydro-ecosystems (montane forest, hillslope forest, low hill forest, low-lying forest, riparian forest and river valley) were delineated. Between 1950 and 2018, the sizes of riparian, low-lying, hillslope, low hill and montane forests had reduced by 42%, 29%, 23%, 20% and 1%, respectively. Whereas in the same period, river valley had increased by 38%. Topographic change detection analysis revealed that the terrain status of 40% of the mineralized zone remained unchanged between 1950 and 2018. In the same period, 37% of the study area had witnessed a decrease in absolute height while the remaining 23% had an increase in absolute height. The outcome of this study suggests that the proposed methodology is suitable for the development of geo-environmental impact assessment protocol for a mineralized zone, particularly in poor countries.