Plutonic Rocks from the Cape Roberts Hinterland: Wilson Piedmont Glacier, Southern Victoria Land, Antarctica

P.J. Forsyth*, N. Mortimer & I.M. Turnbull

Institute of Geological and Nuclear Sciences, Private Bag 1930, Dunedin - New Zealand

Received 10 December 2001; accepted in revised form 2 July 2002
 

Abstract - Previous geological mapping of the inland Dry Valleys area of South Victoria Land identified a number of 1-10 km-size granitoid plutons, and assigned them to calc-alkaline (DV1a), adakitic (DV1b) and monzonitic (DV2) suites. In the adjacent coastal Wilson Piedmont Glacier area, mapping hitherto consisted of regional reconnaissance or local structural and chemical studies.  Our new mapping of this part of the Ross Orogen shows that most Wilson Piedmont granitoid rocks can be assigned to plutons and suites previously recognised in the inland Dry Valleys.  We have mapped and clarified the boundaries of the previously-described Bonney, Denton, Avalanche Bay, Gonville and Caius, Swinford, Harker and Brownworth plutons.  Some new plutons are recognised, namely Evans, Discovery, Flint and Coleman. DV1a and DV1b plutons are mostly foliated, while DV2 rocks are unfoliated. We outline three major swarms of Vanda dikes, eastward continuations of those mapped in the Dry Valleys. Mafic to intermediate intrusive bodies are more extensive in the Wilson Piedmont than in the Dry Valleys, and their geochemistry suggests they are petrogenetically related to the DV1a granitoid suite.

*Corresponding author (j.forsyth@gns.cri.nz)