High-resolution airborne gravity imaging over James Ross Island (West Antarctica)

James Ross Island (JRI) exposes a Miocene-Recent alkaline basaltic volcanic complex that developed in a
back-arc, east of the northern Antarctic Peninsula. JRI has been the focus of several geological studies because it
provides a window on Neogene magmatic processes and paleoenvironments. However, little is known about its internal
structure. New airborne gravity data were collected as part of the first high-resolution aerogeophysical survey flown over
the island and reveal a prominent negative Bouguer gravity anomaly over Mt Haddington. This is intriguing as basaltic
volcanoes are typically associated with positive Bouguer anomalies, linked to underlying mafic intrusions. The negative
Bouguer anomaly may be associated with a hitherto unrecognised low-density sub-surface body, such as a breccia-filled
caldera, or a partially molten magma chamber.