GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 1.3 GNGTS 2024 Joint inversion of gravity and magnetc data of the Cornubian Batholith (South-West UK) G. Maurizio 1 , C. Braitenberg 1 1. Department of Mathematcs, Informatcs and Geosciences (MIGe), University of Trieste, Trieste, Italy, The Inversion of the gravity and magnetc potental felds is a useful method to detect and identfy a concealed crustal body. Depending on its physical propertes and geometry, the positve or negatve anomalies in the gravity and magnetc felds are detectable with appropriate instrumentaton. The grav-mag method is a powerful tool in mineral exploraton, used in frst instance due to the natural 2D coverage of the data acquisiton. The combinaton of magnetc and gravity datasets guarantees reliability to the inversion results and increases the probability that the detected bodies are realistc geological elements, resolving the ambiguity problem of the single feld inversion result (Sampietro et al., 2022; Maurizio et al., 2023). The Cornubian Batholith is a large early Permian granitc body in the south-west peninsula in Great Britain and is the post-collisional result of the Variscan orogeny. It is placed on the peninsula extending in west-southwest directon of-shore and is composed by six main plutons outcropping and cutng the upper Paleozoic coverage (Willis-Richards and Jackson, 1989). The fve on-land plutons have been individually studied and it has been observed that each one has a distnctve mineralogy (Simons et al. 2016). The Cornubian Batholith has an important mining history, since from Prehistoric period. The ore felds were imposed in three distnct stages referred to as pre-, syn-, and post-batholith stages, in relaton to the emplacement of the Cornubian Batholith (Willis- Richards and Jackson, 1989). Most of the mineralizaton took part simultaneously with the formaton of the batholith, while remaining mineralizaton occurred with the thermal and tectonic evoluton of the region (Willis-Richards and Jackson, 1989). Actve mines are stll present and are operatve. The main actvity in the area involves kaolin extracton, but several studies have shown its potental for Tin, Lithium and Tungsten producton (Romer and Kroner, 2016; Simons et al., 2017), and for the exploitaton of geothermal energy (Beamish and Busby, 2016; Reinecker et al., 2021). To perform the inversion, we use the jif3d framework (Moorkamp et al., 2011) which is a jupyter collecton of scripts for joint inversion of diferent datasets, in this case gravity and magnetc feld measurements. Inversion was performed considering variaton of informaton (Moorkamp, 2022): this means that the algorithm searches a one-to-one relaton between the investgated propertes. The inversion minimizes the misft between observed and calculated felds and reduces the variaton of informaton. At the end we obtain a model with density and susceptbility values that ft the observatons and show correspondence between the two propertes.