Prince Charles Mountains
Location & geology
Antarctica, a continent which covers an area of some 14 million km2, is largely (~98%) covered with ice. Scattered bedrock exposures occur only as permanently ice-free dry valley areas, islands and/or coastal outcrops, and mountain ranges, nunataks and massifs extruding through the ice cap. The Prince Charles Mountains represent one such region of bedrock exposure located in the southern part of MacRobertson Land, East Antarctica. They are exposed in a huge (600 by 300 km) depression in the East Antarctic continental ice cap formed as a result of ice drainage along the the Lambert graben through the the Lambert glacier - Amery Ice Shelf region.
The Transantarctic mountains, stretching for ~3500 km across the Antarctic continent from the Ross Sea to the Weddell Sea, mark the geological and geographical boundary between West and East Antarctica. Geologically, West Antarctica represents an accretion of individual continental blocks whereas East Antarctica is dominated by a single ancient Precambrian craton. This craton or continental shield, the East Antarctic Shield, once formed a central part of the Gondwanan supercontinent.
The Prince Charles Mountains comprise a series of nunataks, mountain peaks and flat-topped massifs, up to ~3230 m high, which constitute the largest and most well exposed cross-section of the East Antarctic Shield. Outcrops, ranging in age from Archaean to Eocene or younger, include basement Proterozoic and minor Archaean rocks of sedimentary and igneous origin which were metamorphosed and deformed at ~1000 ma. Subsequent intrusion by Cambrian granites, pegmatites, aplites and alkaline dykes at ~500 to 600 ma was accompanied by a second thermal event and followed by the deposition of Permo-Triassic sediments. Further intrusion, and minor extrusion, of basic alkaline igneous rock types occurred during the Mesozoic and Cenozoic.
Subdivision of the Prince Charles Mountains into northern and southern sections occurs in the region of Mount Willing and is based on the geology of the area as much as the geography. Whereas the southern Prince Charles Mountains are considered to represent an Archaean terrane, comprising both Archaean and Proterozoic basement metamorphic rocks, the northern Prince Charles Mountains are considered to represent part of the Proterozoic mobile belt of the East Antarctic Shield. In addition, metamorphic grade associated with the 1000 ma event, increases northwards from greenschist and lower amphibolite facies in the southern Prince Charles Mountains through upper amphibolite to lower granulite facies in the northern Prince Charles Mountains.