Gilsonite exploration by using electrical resistivity tomography with multi-electrode gradient array: Acase study in Rionegro (Colombia)

Abstract

Subsurface exploration using geophysical methods has increased the prospective economic possibilities for new non-metallic minerals and other raw materials such as solid hydrocarbons. In this paper, we show results of electrical resistivity tomography (ERT) carried out by using the multi-electrode gradient array, and conducted with the main purpose ofmapping thehighresistivity anomalies relatedto the presence of solid hydrocarbons bodies. ERT profiles were interpreted trough considering the gilsonite evidence on rocky outcrops in the La Luna Formation (Ksl) and their respective lithological contact with the Bocas Formation (Jb). This study concludes that,both on thesurface and in the subsurface, in the stratification plane of La Luna Formation, the gilsonite is a tabular and oblique shape, and the contact Ksl-Jb is faulty with an almost vertical inclination.However,different structural processes have contributed to theirregularformation and massive body of gilsonite. Finally,the study concludes that resistivity tomographies represent a reliable alternative for preliminary exploration stages. Sincethe cost of the methodisrelatively low in Colombia, it also serves as aneconomically viable alternative for small exploratory projects.