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Diachronous cleavage development in the Robertson Bay Terrane, Northern Victoria Land, Antarctica: Tectonic implications
Author(s) -
Dallmeyer R. D.,
Wright Thomas O.
Publication year - 1992
Publication title -
tectonics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.465
H-Index - 134
eISSN - 1944-9194
pISSN - 0278-7407
DOI - 10.1029/91tc02891
Subject(s) - terrane , diachronous , geology , bay , orogeny , tectonics , paleontology , cleavage (geology) , subduction , metamorphic rock , oceanography , fracture (geology)
The Robertson Bay terrane is the easternmost of three regional lithotectonic units comprising Northern Victoria Land. It is largely represented by a thick succession of Cambrian‐Ordovician distal turbidites (Robertson Bay Group), which has been folded into upright structures with development of an associated, regionally penetrative cleavage during maintenance of regionally uniform, low‐grade regional metamorphic conditions. Whole rock 40 Ar/ 39 Ar incremental‐release analysis of slate/phyllite documents diachronous cleavage development between ∼500 Ma (west) and 460 Ma (east) during the Ross orogeny. This systematic regional variation in age is consistent with tectonic models for the Ross orogeny that involve southwest directed subduction of the outboard Robertson Bay terrane beneath the Bowers terrane. Convergence rates of ∼0.4–1.0 cm/yr are suggested.