Application of petrophysically and geologically guided inversion to aeromagnetic and drilling data for investigation of magnetite ore in Pocheon, Korea

Abstract Around Pocheon, Korea, geological and geophysical investigations have been performed for the magnetite ore deposits within the Gonamsan intrusion. In 2022, a new ore body was identified by drilling operations based on the interpretation results of drone-based aeromagnetic survey data, and its three-dimensional shape was constructed based on the interpretation sections of drilling cores. By utilizing these data, the objective of this study is to investigate the deterministic framework which can roughly estimate the potential resources of the ore deposit from aeromagnetic survey data. Conventional geophysical inversion has limitations in delineating the boundaries of anomalous bodies, since it suffers from a non-uniqueness problem, especially for potential field data (Wei and Sun in Geophysics 86:G133–G158, 2021). Furthermore, some parts of the aeromagnetic data used in this study were collected at a higher altitude, resulting in an increment of the uncertainties of the inversion results. Astic and Oldenburg (Geophys J Int 219:1989–2012, 2019) proposed petrophysically and geologically guided inversion (PGI), which is able to provide statistical criteria of boundaries from the Gaussian mixture model (GMM) including petrophysical and geological prior information. Based on the PGI framework, we define parameters of GMM from susceptibility information of drilling cores around the new ore body and perform PGI of both maintaining the original GMM and updating it during the inversion process. We interpreted PGI results based on the property and probability of original and learned GMM, and the volume of the isolated ore bodies was consistent with the volume of our target magnetite deposit. This case study demonstrates the potential of the PGI as an analytical tool for quantitative potential resources’ estimation of ore bodies in mineral exploration.