A multi-method approach to study the geodynamic evolution of eastern Dronning Maud Land in East Antarctica by integrating geophysical data with surface geology
Planet Earth has not always been as it appears today. Since billions of years, continents have been drifting continually caused by lateral variations of mantle density resulting in convection. Analyzing the movement of lithospheric plates back in eartha s history is essential for the determination of the shape of ancient supercontinents. It further provides paleogeographic information and is vital for biogeographic and climate studies. Whereas the break-up of the former extensive landmass of Gondwana can be reconstructed fairly well by analyzing seafloor-spreading anomalies of the oceanic crust, the amalgamation of Gondwana still needs to be understood in more detail. This is because oceanic crust, that rarely exceeds 180 million years in age, does not provide any direct evidence for the amalgamation of Gondwana in Late Neoproterozoic/Early Palaeozoic times as well as for older supercontinent cycles. East Antarctica, once centerpiece of Gondwana, can be considered a rather stable region as it has not been affected by orogenic processes since the Early Paleozoic except for its Palaeo-Pacific margin. Furthermore, the Antarctic plate is mainly surrounded by mid-ocean ridges and features continental rift systems widely related to the break-up of Gondwana. Therefore, exposed regions that can be found in Sor Rondane, East Antarctica, are well suited for studying the formation and break-up of Gondwana as well as preceding collision and break-up processes. Sor Rondane is situated in eastern Dronning Maud Land and exposes the contact zone of crustal blocks of different origin and architecture. Therefore, it is considered to be a site of at least one suture between East and West Gondwana. This study examines the final amalgamation and break-up history of Gondwana by investigating Sor Rondane and adjacent regions. To answer those questions, a detailed understanding of the crustal architecture is essential. This encompasses the number of involved crustal fragments, the location of their boundaries and their geological evolution. Moreover, this comprises the structural and metamorphic evolution as well as the shallow crustal dynamics of Sor Rondane. Due to the extensive ice-coverage of this region, the study of exposed rocks by various geological methods was combined with regional aerogeophysical investigations. In the austral summers 2010/11 and 2011/12, structural field work and geological sampling were executed by the Federal Institute for Geosciences and Natural Resources (BGR). Additional airborne geophysical surveys were flown in collaboration with the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI), between 2010 and 2015. The data set includes ice-penetrating radar, aeromagnetic and aerogravity measurements. These combined geological and geophysical data sets are used to analyse the structure and composition of rock units and enable to map units beneath the ice not accessible to geological methods. For instance, fault systems may correlate with magnetic lineaments gained from aeromagnetic anomaly data. These can be tracked over large distances underneath the ice and thus facilitate interpretations at a larger scale
