Integrated Geophysical Approach for REE Exploration: a Case Study Using MASW, P-Wave Tomography and Reflection Seismic

Abstract

Summary Rare Earth Elements (REEs) play a crucial role in modern technological advancements and green energy transition. We present an integrated geophysical approach using a single seismic dataset combining multichannel analysis of surface waves (MASW), P-wave first-arrival tomography and reflection seismic for exploration of shallow-seated REE deposit hosted within the Lebowa Granite Suite (LGS) of the Bushveld Igneous Complex (BIC). To image the REE deposits of the LGS, four 2D seismic profiles (from 3 to 7.5 km long) were acquired using dense source-receiver spacing with a total length of 21 km. Preliminary reflection seismic processing results show good quality seismic images of deeper structures, while thick weathering appears to have an adverse effect on the near-surface portion of the stacks. This effect was overcome via combination of P-wave first-arrival tomography and MASW. For the MASW purposes, longer reflection seismic spreads were split into lateral sliding windows individually optimized for different profiles to achieve desired depth of penetration while reliably capturing surface wave dispersive behaviour. Both MASW and P-wave tomography results complement each other showing velocity anomalies that correspond to structures seen on the stacked seismic sections, attributed to hydrothermal alternations of the BIC that enriched the granites with REEs.