Structurally controlled fluid flow: High-grade silver ore-shoots at Martha epithermal mine, Deseado Massif, Argentina

► Structure of high-grade silver ore-shoots at Martha Mine is described. ► The geometry of ore-shoots at Martha Mine suggests a first-order structural control on their location and orientation.► Controls on permeability and fluid flow during epithermal vein formation are analysed. ► Mineralisation, and presumably hydrothermal fluid flow, was concentrated on a step-over zone developed between two NW trending structures. ► Hydrothermal ascending fluids took advantage of vein intersections and were also channelized along preferred opening areas within individual veins.