Aspects of the Structural Evolution and Magmatism in Western New Schwabenland, Antarctica
- Garry D. Mckenzie
Published Online: 21 MAR 2013
Copyright 1987 by the American Geophysical Union.
Gondwana Six: Structure, Tectonics, and Geophysics
How to Cite
Spaeth, G. (1987) Aspects of the Structural Evolution and Magmatism in Western New Schwabenland, Antarctica, in Gondwana Six: Structure, Tectonics, and Geophysics (ed G. D. Mckenzie), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM040p0295
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1987
Print ISBN: 9780875900643
Online ISBN: 9781118664483
Data and observations on rock units of the northern Kraul Mountains (Vestfjella) and the Ahlmann Ridge in western New Schwabenland (western Queen Maud Land) are presented. The numerous dolerite dikes of both regions, which are apparently of Mesozoic age, indicate crustal extension. The majority have been intruded parallel to observed or assumed major fracture zones which dissect this part of the western edge of the East Antarctic Shield. These dolerite dikes and related sills are chemically similar to the basaltic lava flows of the Kraul Mountains. For this reason and because of the relationship between the dikes and the Permo-Carboniferous sedimentary rocks (Beacon Supergroup), they are regarded as Mesozoic and equivalent to the Jurassic volcanic rocks of the Transantarctic Mountains and not upper Precambrian, as indicated on the Geologic Map of Antarctica, (1:5,000,000, Craddock (1972)). Paleomagnetic and radiometric dating studies are in progress. The results of recent geophysical investigations also suggest dissection of the crust of the Antarctic continent and shelf at the eastern edge of the Weddell Sea. This dissection, shown by fracture tectonics, may be related to the opening of the Weddell Sea and a failed rift during the fragmentation of Gondwana. Geochemical, petrographic, and structural investigations on presumed Mesozoic dolerite dikes and the basaltic-andesitic lavas of late Precambrian age on the Ahlman Ridge demonstrate the difference in age of these magmatic events. The phase of fracture tectonics, as shown by surface morphology and by the emplacement of the dolerite dikes, was preceded by at least two phases of deformation of the upper Precambrian platform sedimentary and volcanic rocks. One is inferred to be a compressive strain possibly connected with the Ross Orogeny.