Late-Ross Ductile Deformation Features in the Wilson Terrane of Northern Victoria Land (Antarctica) and Their Implications for the Western Front of the Ross Orogen

A.L. Läufer¹* & F. Rossetti²

¹Johann Wolfgang Goethe-Universität, Geologisch-Paläontologisches Institut, Senckenberganlage 32-34,
60054 Frankfurt a.M. - Germany
²Dipartimento di Scienze Geologiche, Universitá “Roma Tre”, Largo S. L. Murialdo 1, 00146 Roma - Italy

Received 6 November 2002; accepted in revised form 27 October 2003
 

Abstract - The northern Victoria Land sector of Antarctica is part of the Pacific end of the Transantarctic Mountains. Its early Palaeozoic geodynamic history is commonly attributed to the Ross Orogeny resulting from W-directed subduction of the palaeo-Pacific Ocean under the active continental margin (i.e. the Wilson Terrane) of Gondwana. Kinematic data on ductile deformation were collected in the greater Rennick Glacier area. The data indicate the presence of two late-Ross-age opposite-directed systems of ductile shear within the Wilson Terrane. High-grade metamorphic and migmatitic rocks are west- and eastward reversely displaced over low-grade metasedimentary rocks and shallow-level granitic intrusions. The shear zones are offset in a step-like pattern suggesting the presence of ENE trending right-lateral faults. The depicted structural pattern accounts for a close relationship to the Exiles and Wilson thrusts in Oates Land further N, which can be traced across Victoria Land from the Pacific coast to the Ross Sea. Accordingly, the western front of the Ross Orogen and thus its boundary towards the Proterozoic East Antarctic Craton is presumably located not much further W of the W-directed shear systems. It may best be interpreted as a fold-and-thrust belt where the intra-Wilson Terrane arc was detached and thrust westward onto the craton in Cambro-Ordovician times.


 
*Corresponding author (laeufer@em.uni-frankfurt.de)