| Title | Preliminary Structural Analysis of a Fractured Granite Targeted for Geothermal and Lithium Brine Extraction |
|---|---|
| Authors | Samuel Grainger, David McNamara, Elisabetta Mariani, Robin Shail, Chris Yeomans, Will McKenzie |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | The Porthgwarra-Land’s End Fault Zone (PLFZ) in Southwest England provides a surface analogue for steeply dipping faults in the subsurface that host geothermal brines enriched in dissolved lithium. These structures host geothermal waters and are targeted at depths of 2–5 km for heat and/or power and lithium production due to their elevated permeability relative to the surrounding host rock. Using integrated field observations and systematic fracture data collection, this study addresses the structural architecture and inferred permeability of the PLFZ. In the study area, the PLFZ comprises four principal strands with fault cores composed of gouge, mechanical and hydrothermal breccias, and epithermal quartz–hematite veins. Kinematic indicators preserved on fault surfaces and in fault rocks suggest distinct episodes of oblique-slip and strike-slip displacement. Fracture data reveal a heterogeneous and anisotropic permeability structure. The fracture-dense damage zone promotes fault-parallel flow and sealed fault cores act as barriers to cross-fault fluid flow. These findings provide a preliminary understanding of the influence of fault architecture on permeability anisotropy in a granite-hosted geothermal reservoir. The results provide a field-scale analogue of a subsurface target for geothermal and critical-metal exploration in the Cornubian Batholith and may be applied to similar projects worldwide. |