Structural evolution of the Lanterman Metamorphic Complex, northern Victoria Land, Antarctica

Abstract

The metamorphic rocks of the Lanterman and Salamander Ranges in northern Victoria Land, termed the Lanterman Metamorphic Complex, are composed predominantly of semipelitic metasediments and subordinate pelitic, calcareous and conglomeratic metasediments, and mafic schists of presumed volcanic origin. Intrusive rocks include metamorphosed basic dikes, metatonalites, and Granite Harbour Intrusives. Talc schists occur as small pods in highly deformed zones in the eastern Lanterman Range and separate zones of distinct structural and metamorphic character. In the western terrane, amphibolite facies metamorphism accompanied the development of a steeply dipping schistosity (S1) and a vertical mineral elongation lineation. Bedding (So) was transposed within S1. Subsequent deformation during retrograde metamorphism resulted in mesoscopic crenulate structures (F2 and F3) in S1. The development of S1 and its crenulation is regarded as part of a continuous deformation cycle broadly coeval with the emplacement of the Granite Harbour Intrusives during the early Paleozoic Ross Orogeny. In the eastern terrane, in which no intrusives occur, greenschist facies metamorphism accompanied the development oflarge-scale upright folds in metaconglomerates. So is not transposed in the axial schistosy which is subvertical, trends NNW, and contains a near-vertical lineation defined by pebble elongation. Juxtaposition ofthe two contrasting terranes probably accompanied the emplacement of the talc schists during the Ross Orogeny. © Crown copyright 1985.