ABSTRACT
Understanding the dynamics of suturing and cratonisation and their implications are vital in estimating the link between the lithospheric mantle architecture and geothermal resources. We propose new interpretations of the Western Arabian Shield's geodynamic styles and geothermal anomalies. In this work, features of the crust and mantle were interpreted from geophysical modeling to unravel the structural dynamics between the Arabian Shield and the Red Sea rift, as well as the influence of these mechanisms on the uplift of the Cenozoic basalts. Estimates of the lower crust thermal properties were also achieved. Spectral properties of the potential field were used to define the Curie isotherm, heat fluxes, geothermal gradients, radiogenic heat production, Moho configuration, and lithosphere-asthenosphere boundary. Results show new structural styles, micro-sutures, and significant thermal anomalies. The defined geothermal patterns were inferred to be due to localized initiation of tectonic and asthenospheric disequilibrium during the rifting episodes within the Red Sea. Also, magma mixing is initiated by the northward migration of magma from the Afar plume towards the Western Arabian Shield which drives local mantle melts beneath the western Arabia, thereby providing the pressure field required for magma ascent. The ascendant magma flow provides the heating source of geothermal reservoirs within the Western Arabian Shield. However, there are indications that during the episodes of rifting within the Red Sea and/or ancient Pan-African activities, the mixing process may have been altered resulting in crustal thinning and creating pathways of ascendant magma flow along the MMN volcanic line. Integrating geophysical and geothermal models indicated new zones of suturing and extensional tectonics between the amalgamated terranes. The geodynamic interpretation shows a new redistribution of terranes and continuous compressional and transtentional movements within the Arabian Shield.
ABSTRACT
The geophysical-based integrated electrical conductivity (IEC) and the groundwater hydraulic confinement-overlying strata-depth to water table (GOD) techniques were used to assess vulnerability levels of aquifers and the extent of aquifer protection in Abi, Nigeria. The IEC indices was generated from constrained one dimensional (1D) inversion of vertical electrical sounding (VES) and two dimensional (2D) electrical resistivity tomography (ERT) data, acquired randomly in the area. The GOD indices were sourced from existing geologic data within the area. Results showed that IEC values vary from <0.1 S in the weakly protected areas to >2.0 S in the strongly protected areas. The GOD indices vary from <0.3 in the lowly vulnerable areas to 0.6 in the highly vulnerable areas. Thus, the groundwater resources in the area need to be properly managed for sustainability and such management practices have been suggested.
