Potential fields characterization of inaccessible areas: multiscale analysis of the West Antarctic Rift System

Abstract

We used potential field data to help unravel the geological characteristics of the West Antarctic rift system, one of the largest and least known rift systems on our planet. A comprehensive understanding of this region is lacking, as it is covered by the West Antarctic Ice Sheet (WAIS), which reaches thicknesses of over 3 km. Aeromagnetic and aerogravity datasets collected by the British Antarctic Survey (Ferraccioli et al., 2007) were analyzed via a multiscale analysis (Fedi et al., 2015) useful for identifying the main structural lineaments, i.e., contacts, dykes, sills, volcanic bodies and intrusions in the Pine Island Glacier catchment of WAIS. Our results reveal that several regions are characterized by contact-type sources associated to fault systems bordering major magma-rich rift basins, like the Pine Island Rift, Byrd Subglacial Basin, and Bentley Subglacial Trench, as well as those associated with Pine Island glacier tributaries, which lie at high angle wrt to the glacier trunk and rift basins. Furthermore, we identified magmatic sources near or off-rift zones, such as the edges of the Bentley Subglacial Basin, which allow a better understanding of the sub-ice depth of the magmatic sources. In addition, our results provide new information about the main magmatism trends and their average depths. We thus showcase that potential field anomalies allow a better comprehension of the West Antarctic Rift System regional geology, tectonic architecture and magmatic patterns. This research opens interesting scenarios about the extent and position of magmatic sources and on how they contribute towards shaping the sub-ice topography within this sector of the rift system, which in turn is a primary control on ice sheet flow in this highly dynamic and potentially unstable sector of WAIS. In conclusion, potential field analysis with a multiscale approach emerges as a pivotal tool and provides valuable insights into continental rifting processes, especially in inaccessible areas such as West Antarctica, where there are only very few geological outcrops.