New Insights Into Western Antarctic Peninsula Magmatism From Joint Inversion of UAV Magnetic and Gravity Data

The Antarctic Peninsula is a unique sector of the circum-Pacific continental margin arc where subduction ceased due to a series of ridge-trench collisions, preserving a relatively un-deformed magmatic arc. This region, therefore, has the potential to provide key insights into how subduction systems behave during their final stages. However, the remote nature of the region means that both geological and geophysical data coverage is often sparse, limiting the ability to interpret its tectonic evolution. Here we present a new analysis of gravity and magnetic data collected from a Windracers Ultra Uncrewed Aerial Vehicle (UAV). The survey targeted a 75 × 25 km region where the Antarctic Peninsula bends and magnetic signatures change, which has been attributed to the onshore influence of adjacent oceanic transform faults running approximately orthogonal to the Peninsula. Using joint inversion of magnetic and gravity data based on a “Variation of Information” approach, we show the region is dominated by two large intrusions, of likely granodiorite composition. Our data indicate little evidence for structural control on magma emplacement, however, coincident imagery suggests that after magma emplacement the region was subject to significant deformation approximately parallel to the Peninsula margin. We interpret these features in terms of the processes occurring as subduction ceased.