GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 3.1 GNGTS 2024 Airborne and Ground IP: an integrated approach for exploraton F. Daut 1 , A. Viezzoli 2 , G. Fiandaca 1 1 The EEM Team for Hydro & eXploraton, Dep. of Earth Sciences A. Desio, Università degli Studi di Milano, Via Botcelli 23, Milano (Italy) 2 Emergo s.r.l., Via XX Setembre 12, Cascina (Pisa), Italy Introducton The Iberian Pyrite Belt (IPB) is one of the oldest and stll actve mining districts in the world. In the last decade, a renewed mining actvity and scientfc research have led into a wealth of new data and new geological hints for explorers and for the academic community, making the IPB one of the most important and dynamic mining districts in Europe (Inverno et al, 2015). In this region, the great number of diferent signatures related to the ore body and to its vectors call for an integrated use of complementary geophysical methods. The sulfdes targets show contrast in both density and electrical propertes, and historically gravity has played a crucial role for exploring in the IPB. These methods have been later accompanied by EM methodologies, both airborne and ground, given their high sensitvity to conductve targets (Menghini et al, 2022). With this contributon we will focus on an applicaton of a novel modelling approach that aims to properly extract the Induced Polarizaton (AIP) efects from the Airborne Electromagnetc (AEM) data. The AEM survey has been acquired in the IPB for mineral exploraton to localize the VMS deposit. Afer the AIP modelling, we will show a comparison between the airborne chargeability and some overlapping ground IP models from the same area. This comparison aims to beter understand the potental in the use of AIP for exploraton and to atempt an improvement in the defniton of the sensitvity feld of the airborne technique, as well as its relatonships with ground IP. Then, a joint inversion between the two methods will be presented. Inductve Induced Polarizaton - theory and modelling It is known and accepted that the Electromagnetc methods are sensitve to Induced Polarizaton efects (AIP) when acquired over a polarizable medium (Kratzer and Macnae, 2012; Viezzoli et al., 2013). From a physical point of view, the polarizaton processes generate currents in the ground (polarizaton currents) with an opposite directon respect to the pure EM currents (eddy currents) that proceed downward with a difusive regime. These efects generate a distorton of the recorded electromagnetc signal which ofen culminate in its change of sign at late tmes when the halfspace is partcularly polarizable. In general, the distortons generated from IP have two signatures in the EM data: a faster decay (respect to the purely resistve forward response) and/or negatve voltages. Under these conditons, the standard EM modelling, which does not account for