Airborne-based geophysical investigation in Dronning Maud Land, Antarctica

Abstract

Antarctica represents a key component in the investigation of the geological history and reconstruction of the supercontinents Rodinia and Gondwana. Remnants of the formation and disintegration of these former land masses can be found, although great uncertainties remain in the location of tectonic boundaries beneath the ice sheet of Antarctica due to general lack of outcrops and the limited amount of geological data. Space and airborne measurements are the only possibility to obtain comprehensive spatial data coverage of geophysical data over the extensive large polar areas.Common knowledge of the geological framework displays three major tectonic events which formed Dronning Maud Land (DML): the Grenvillian Orogen (1.1 Ga) build up Rodinia, the Pan-African-Antarctic Orogen (EAAO, 500 Ma) rose in the supercontinent Gondwana and finally the breakup of Gondwanaland, at around 180 Ma.During this work, as part of the VISA project (Validation, densification and nterpretation of satellite data for the determination of magnetic field, gravity field, ice mass balance and structure of the Earth crust in Antarctica using airborne and terrestrial measurements), four years of investigated airborne based data (2001-2005) are processed, compiled and interpreted. The methods of measurements are explained in the methodology chapter, focused on the complex computational and time-consuming processing, to handle topographic-, magnetic-, and gravity data.Finally, the thesis displays a compilation of a homogeneous database for the DML region from 14°W to 20°E and from 70°S to 78.5°S. Furthermore, comprehensive studies and techniques, such as wavelength-filtering, depth estimation routines, isostatic analysis and Curvature discussions, are applied for final geological interpretation.The presented maps display detailed boundaries of geologic and tectonic structures, which already have been suggested or discussed in recent literature, but have never been known to full extent, concerning detail, locations, boundaries and structures. With respect to earlier conducted geophysical investigations in DML, up to 85% of the gravity data and 65% of the magnetic data, presented in this thesis, cover unexplored regions and contribute therefore a large amount of new data to the Antarctic geological research.Old lithospheric boundaries between the Archaen Craton, the Grunehogna Province, and a Proterozoic to Early Paleozoic mobile belt, the Maudheim Province, were be interpreted on the basis of the new database and the use of isostatic and curvature analysis. Detailed mapping of thrust faults show the strike of major tectonic events. All of these observations constitute an integrated geological model, which is confirmed by recent seismologic-, seismic, - and geologic results.