Evaluation of Geological Structure on Potash Solution Mining in the Dallol Depression: Case Study of Circum Minerals, Dallol Depression, Northern Ethiopia

Abstract

ABSTRACT This study aims to assess the geological challenges associated with potash solution mining in the active rift of the Dallol Depression and to propose an optimised borehole design for Circum Minerals Limited. An integrated approach combining satellite image interpretation, field observations, borehole data, and seismic images was utilised to produce detailed geological and structural maps and to characterise subsurface evaporite sequences. The seismic images and borehole logs acquired by the company were interpreted to demarcate subsurface features, whereas three‐dimensional models derived from multiple well logs and fence diagrams enhanced stratigraphic interpretation. The nearest neighbour polygon method was used to estimate the total potash deposits of the concession area. The high‐resolution seismic data were interpreted in conjunction with the subsurface geological map generated from borehole data using Rockworks 15 software. The borehole data indicated that the stratigraphic sequences of the evaporite deposits (salt deposits and muddy salt) consist of clastic materials, upper halite, marker beds, sylvinitite member, upper carnallitite member, bischofitite member, lower carnallitite, kainitite member, lower halite unit, and a basal clastic unit. The evaporite sequence in general, and the upper halite and bischofitite members in particular, show two distinct thickening trends: towards the rift‐axis and towards the rift center. The total potash resource is estimated at approximately 18.81 billion tons, of which 3.57 billion tons remain unexploited due to the effects of fault confinements. The existing borehole designs limit the company's total extraction capacity. To improve recovery both from intact and fault‐bounded potash deposits, this study recommends the addition of 16 systematically located boreholes, considering the deposit geometry and resource distributions, to enhance potash recovery and promote sustainable mining practises.