Year: 2025 | Month: December | Volume: 12 | Issue: 12 | Pages: 793-814
DOI: https://doi.org/10.52403/ijrr.20251281
Lithostructural Controls on Orogenic Gold at the Kiesta C Deposit, Sabodala-Massawa District, Senegal
Ibrahima Dia1, Ibrahima Sow1
1Polytech Diamniadio, Amadou Mahtar Mbow University, Dakar, Senegal.
Corresponding Author: Ibrahima Dia
ABSTRACT
Orogenic gold deposits in the Sabodala–Massawa district cluster along crustal-scale shear corridors, but deposit-scale controls on fluid focusing and ore-shoot geometry remain weakly constrained. At the Kiesta C deposit, we test how shear-corridor architecture, jogs and bends, and rheology contrasts at felsic intrusive contacts govern permeability creation, reactivation, and gold distribution. We integrate deposit-scale mapping and pit-wall structural analysis with oriented core logging, petrography, alteration–vein classification, stereographic analysis, and 3D integration of downhole assays. High-grade shoots plunge steeply to the SE, parallel to intersection lineations defined by anastomosing NE–SW shear zones, second-order splays, and intrusive contacts. Gold grades are highest where shear bends and step-overs coincide with albitized quartz–feldspar porphyry and foliated diorite margins, which we interpret to have stiffened and embrittled wall rocks near the brittle–ductile transition, sustaining cyclic crack–seal permeability. A two-stage alteration pattern is recognized: early sericite–carbonate–silica–pyrite halos hosting disseminated Au, overprinted by inner albite–silica–carbonate–tourmaline domains cut by quartz–tourmaline stockworks that host the highest grades. Vein textures and overprinting relationships support repeated brittle failure and sealing of fracture networks during late re-activation of the shear corridor. We propose a conceptual model in which the three-dimensional connectivity of shear corridors, intrusive margins, and brittle fractures—rather than any single “syn-gold” structure—primarily controls ore-shoot continuity and plunge. This framework yields a set of structurally driven, field-based exploration criteria that are applicable within the Sabodala–Massawa district and transferable to analogous orogenic corridors in the Mako Belt.
Keywords: Orogenic gold systems; Mako Belt; shear corridors; albitization; quartz–tourmaline veins; brittle–ductile transition; ore-shoot geometry; Sabodala-Massawa.
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