Structural evolution of Dronning Maud Land (East Antarctica) and significance for links with the East African and Kuunga orogens

In Dronning Maud Land (DML), East Antarctica, a ca. 620-500 Ma mobile belt dissects the continent. This ca. 1000 km wide orogen has been linked to the East African Orogen on the one hand and relationships to the Kuunga orogen were suggested on the other. The mobile belt reworks mainly Grenville-age crust. The foreland hinterland boundaries are clearly defined in the Heimefrontjella (western DML) and in eastern DML (Sor Rondane), both as major dextral transpression zones. The mobile belt is characterized by medium to high-grade metamorphism between ca. 620 - 500 Ma

Detailed Seismic Bathymetry Beneath Ekstrom Ice Shelf, Antarctica: Implications for Glacial History and Ice-Ocean Interaction

The shape of ice shelf cavities are a major source of uncertainty in understanding ice-ocean interactions. This limits assessments of the response of the Antarctic ice sheets to climate change. Here we use vibroseis seismic reflection surveys to map the bathymetry beneath the Ekstrom Ice Shelf, Dronning Maud Land. The new bathymetry reveals an inland-sloping trough, reaching depths of 1,100 m below sea level, near the current grounding line, which we attribute to erosion by palaeo-ice streams. The trough does not cross-cut the outer parts of the continental shelf. Conductivity-temperature-depth profiles within the ice shelf cavity reveal the presence of cold water at shallower depths and tidal mixing at the ice shelf margins. It is unknown if warm water can access the trough. The new bathymetry is thought to be representative of many ice shelves in Dronning Maud Land, which together regulate the ice loss from a substantial area of East Antarctica. Plain Language Summary Antarctica is surrounded by floating ice shelves, which play a crucial role in regulating the flow of ice from the continent into the oceans. The ice shelves are susceptible to melting from warm ocean waters beneath them. In order to better understand the melting, knowledge of the shape and depth of the ocean cavity beneath ice shelves is crucial. In this study, we present new measurements of the sea floor depth beneath Ekstrom Ice Shelf in East Antarctica. The measurements reveal a much deeper sea floor than previously known. We discuss the implications of this for access of warm ocean waters, which can melt the base of the ice shelf and discuss how the observed sea floor features were formed by historical ice flow regimes. Although Ekstrom Ice Shelf is relatively small, the geometry described here is thought to be representative of the topography beneath many ice shelves in this region, which together regulate the ice loss from a substantial area of East Antarctica