Structural history and tectonic evolution of the boundary between the Wilson and Bowers terranes, Lanterman Range, northern Victoria Land, Antarctica

Abstract

The boundary between the Wilson and Bowers terranes is one of the major tectonic discontinuities of northern Victoria Land (Antarctica) and is referred to as the Lanterman Fault Zone by most authors. Fieldwork carried out in this area indicates that the structural evolution of this boundary is polyphase and four main tectonic phases can be recognized: (1) west over east thrusting of Ross age (i.e. around 500 Ma), coeval with amphibolite and amphibolite–greenschist facies transition metamorphism; (2) sinistral strike-slip shearing, coeval with greenschist facies metamorphism; this event may belong to the Ross Orogeny or may represent evidence of the Borchgrevink Orogeny (i.e. around 360 Ma); (3) large-wavelength folding of late-Ross or Borchgrevink age; (4) Cenozoic brittle tectonics, expressed by small to km-scale structures, with dextral strike-slip displacement. Evidence for this structural evolution is not confined to a single tectonic lineament, but occurs throughout the area close to the boundary between the Wilson and Bowers terranes. It follows that the docking of the Wilson and Bowers terranes was complex and polyphase and it is not possible to define a single tectonic setting for the Lanterman Fault Zone, since it was the site of contrasting tectonic regimes at different times and at different structural levels.