Geological Structure of Mac. Robertson Land (East Antarctica)



In East Antarctica, bedrock emerges from under the continental ice sheet in coastal hills and skerries or in mountain ranges within 200 km of the coast. However, the ice sheet in Mac. Robertson Land has been lowered by the Lambert Glacier to such an extent that mountain ranges up to 600 km inland are exposed. These bedrock exposures are the only direct access geologists have to the interior of East Antarctica. While the predominance of granulite facies rocks in the coastal areas give the impression that most of East Antarctica is underlain by such high-grade rocks, the presence of low-grade rocks in southern Mac. Robertson Land indicates that the interior of East Antarctica is probably a far more diverse terrain. The present book is one view of this interior: It summarizes the results that Soviet geoscientists obtained from field operations between 1966 and 1974 in Mac. Robertson Land. The territory covered by this study includes a coastal belt of granulite facies rocks and charnockites and the interior area (southern Prince Charles Mountains) of gneissic granites and metasediments and metavolcanics with greenschist to amphibolite facies. Soviet contributions to our present geological knowledge of these areas have been substantial, most notably the discovery of a banded iron formation at Mount Ruker in the southern Prince Charles Mountains. Moreover, the Soviets were the first to recognize the significance of the continental rift presently occupied by the Lambert Glacier and Amery Ice Shelf, and they have documented this rift by geophysical and geological observations.