Fracture analysis of the lithium-bearing Cligga Head granite: Impacts on critical mineral mobilisation and fluid flow

Abstract

Fracture systems within low-permeability crystalline granitic rocks are critical pathways for fluid flow within these bodies. Constraining the sequence of mineralisation in fracture sets is key to effectively determining the mineral potential and exploitability of rare and critical metals within granite bodies. This study presents the results of a field fracture analysis at the greisen-bearing, lithium-rich Cligga Head granite—a satellite granitic body of the Cornubian Batholith in southwest England. Field mapping of the well-exposed granite body, younging tables and scanning electron microscopy (SEM) are used to develop a temporal model for the evolution of fractures in the Cligga Head granite. Seven fracture sets with varying mineral infill were identified. These fractures exhibit a sequence of cross-cutting relationships that broadly correspond to regional lineament trends — associated with the Variscan Orogeny. As high-quality granite exposure in the region is limited, detailed fracture analysis of satellite granite bodies like Cligga Head provides valuable context for regional critical mineral exploration.