Subglacial imprints of early Gondwana break‐up as identified from high resolution aerogeophysical data over western Dronning Maud Land, East Antarctica

Abstract

Determining the location and geometry of possible subglacial rifts in western Dronning Maud Land is a key element to address processes leading to early Gondwana break‐up. However, previous geophysical investigations did not lead to unambiguous delineation of rift structures over this region. We interpret high‐resolution airborne radar and aerogravity data to image subglacial rift structures. Subglacial topography, free‐air and Bouguer gravity maps, coupled with 3D inverse gravity models, image a rift–rift–rift triple junction at the intersection of the Jutulstraumen ice stream and the Pencksökket glacier. These continental rifts were associated with alkaline and tholeiitic intrusions, minor dyke swarms and flood basalts of Jurassic age, but not with huge volumes of Karoo magmatism, such as that which characterizes the southern Africa conjugate margin. The western Dronning Maud Land triple junction may be linked to the Karoo mantle plume and represents an early stage of magmatism and rifting during Gondwana break‐up.

New geophysical compilations link crustal block motion to Jurassic extension and strike-slip faulting in the Weddell Sea Rift System of West Antarctica

“…35 mantle plume which gave rise to the extensive Karoo-Ferrar LIP (Elliot, 1992;Elliot and Fleming, 2000;Ferraccioli et al, 2005a;Jourdan et al, 2005;Riley et al, 2005). The interpreted Jurassic magmatism beneath Berkner Island may follow the trace of the inherited Gondwanide Orogen that has been inferred to continue north of the Pensacola…”

“…1 and 2a) (Elliot, 1992;Elliot and Fleming, 2000;Ferraccioli et al, 2005a;Jourdan et al, 2005;Riley et al, 2005). This dominantly mafic event has been linked with the impact of a mantle plume between South Africa and East Antarctica, potentially a key driver for Gondwana breakup (Fig.…”

New aeromagnetic view of the geological fabric of southern Dronning Maud Land and Coats Land, East Antarctica

“…Hence, aero-geophysical data play a key role in extrapolating the sparse geological information into the interior of East Antarctica for purposes of developing a reliable tectonic model. Several onshore aeromagnetic surveys (Golynsky et al, 1996(Golynsky et al, , 2002Ferraccioli et al, 2005aFerraccioli et al, , 2005bShepherd et al, 2006;Riedel et al, 2013) were conducted in DML to better constrain and understand the Gondwana pre-break-up geology (older than~180 Myr). In this context, an important discovery by Riedel et al (2013) identified, among other magnetic anomalies, a linear NE-SW trending anomaly in central DML (Fig.…”

The surficial and subglacial geomorphology of western Dronning Maud Land, Antarctica

“…At some localities within the Kirwan Escarpment, less resistant shales and sandstones of Permian age (the Amelang Plateau Formation) have been deposited onto the basement Precambrian metamorphic rocks (Aucamp, Wolmarans, & Neethling, 1972;Faure & Mensing, 2011). Jurassic tholeiitic basalts are also present within the sequence, and correspond in age with the main phase of Karoo volcanism in southern Africa (Duncan, Hooper, Rehacek, Marsh, & Duncan, 1997;Ferraccioli et al, 2005). These basalts are referred to as the Kirwan Volcanics and are widespread at the Vestfjella and in some parts of the Heimefrontfjella (Faure & Mensing, 2011).…”

“…WDML consists of several nunatak groups that form a broad escarpment and several smaller subglacial mountain ranges, and these have been modified extensively by tectonic, fluvial and glacial processes dating back to continental rifting in the Late Mesozoic (Ferraccioli, Jones, Curtis, & Leat, 2005;Näslund, 2001). These processes, however, are currently not well constrained spatially or chronologically.…”