The Matusevich aeromagnetic anomaly over Oates Land, East Antarctica

The "Matusevich Anomaly" is a high-amplitude and linear aeromagnetic feature imaged over Oates Land, East Antarctica. Interpretation of this anomaly provides new geophysical insight into the Wilson Terrane. We compare aeromagnetic signatures, ground susceptibility data and geology to investigate the potential sources for the Matusevich Anomaly. This comparison indicates that mylonitic hornblende-bearing Granite Harbour Intrusives or meta-ultramafic rocks and metabasites of the Wilson Metamorphic Complex could cause the anomaly. The magnetic bodies located directly beneath the Matusevich Glacier lack a prominent gravity signature. Hence, an intermediate rather than ultramafic bulk composition of the magnetic sources is more likely, at least for the Exiles Nunataks segment of the Matusevich Anomaly. Modelling suggests that magnetic intrusions, at least 8-km thick, and possibly as much as 14-km thick, are required to fit the Exiles Nunataks segment of the Matusevich Anomaly. These magnetic intrusions may reveal buried magmatic arc crust emplaced along the Exiles fault system. This segment of buried arc crust is an important imprint of Ross-age subduction. Mafic/ultramafic bodies flank the arc on both sides, as indicated by approximately coincident gravity and aeromagnetic anomalies. If these bodies represent remnants of oceanic crust, then the Matusevich Glacier might conceal not only a major fault, but also a former suture zone.