Structure and mineralization in the Lebowa granite suite: Insights from high-resolution 2D reflection seismic method

Abstract

Rare Earth Elements (REEs) are critical metals that occur in various geological systems including granitic systems. The Lebowa Granite Suite (LGS) of the Bushveld Complex (South Africa) is known as an A-type granitic suite and hosts polymetallic mineralization including tin, fluorine and REE mineralization. High-resolution reflection seismic surveys were conducted to understand the structural architecture and mineralization within the farm boundaries of Blokspruit and Ruigtepoort in the LGS in the North West Province. Two-dimensional (2D) reflection seismic results show that the LGS is approximately 5 km thick in the western portion of the Bushveld Complex and is intruded by dolerite sills of the Umkondo large igneous province. The REE mineralization is structurally controlled and hosted within actinolite intrusive bodies. REE mineralization is associated with NW-SE and NE-SW trending faults, which acted as conduits for ore-forming fluids. In seismic sections, fault zones are delineated as highly attenuated seismic signatures that crosscut strong amplitude seismic horizons. Near the highly attenuated zones are high amplitude reflector packages (HARPs), which correspond to the actinolite intrusive bodies. We demonstrate the value of using the reflection seismic method as an effective and efficient exploration strategy to explore for geological structures that control REEs mineralization, and its potential to become a core component for mineral exploration in hard rock environments.