Geology of the region between the Matusevich and Tucker Glaciers, north Victoria Land, Antarctica

Abstract

An outline is given of the geology of the region between the Matusevich and upper Tucker Glaciers in north Victoria Land, Antarctica. The Rennick Glacier lies along a major structural break between high-grade metasediments and plutonic rocks to the west and low-grade metasediments to the east. The regional strike of foliation in both groups of metasediments is north-west. West of the Rennick Glacier, the basement complex consists of high-grade, regionally metamorphosed Precambrian paragneiss and schist of the Wilson Group intruded and migmatised by granite, granodiorite, tonalite, and pegmatites of the Granite Harbour Intrusives. East of the Rennick Glacier, the Robertson Bay Group, a thick late Precambrian geosynclinal sequence of interbedded greywacke and cleaved argillite, extends throughout the Admiralty Mountains to the Robertson Bay — Tucker Glacier area. In the Bowers Mountains, the Bowers Group, an infaulted dominantly shallow-water sequence of interbedded basic volcanics, volcanic-derived argillite, greywacke, limestone, sandstone, and conglomerate probably overlies the Robertson Bay Group. Both groups have undergone low-grade regional metamorphism up to low greenschist facies. Strong north-west folding of both groups in mid-Paleozoic time was followed by post-tectonic intrusion of the Robertson Bay Group by Devonian granite and granodiorite plutons of the Admiralty Intrusives. In the upper Rennick Glacier, Devonian rhyolitic lavas unconformably overlie the Granite Harbour Intrusives. Jurassic Ferrar Group basalt and dolerite are interbedded with, and intrusive into quartzitic and feldspathic sandstone of the Beacon Group, which unconformably overlie a peneplaned surface of older rocks. Post-Jurassic faulting has tilted large blocks of the sequence up to 15°.