Paleozoic siliciclastic rocks from northern Victoria Land (Antarctica): Provenance, timing of deformation, and implications for the Antarctica-Australia connection

• Published in: Geological Society of America Bulletin
• Main Authors: Di vincenzo G, Grande A, ROSSETTI, FEDERICO
• Other Authors: Di vincenzo, G, Grande, A, Rossetti, Federico
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Victoria Land; Transantarctic Mountains; Bowers; Robertson Bay; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/11590/118836; https://doi.org/10.1130/B31034.1

Paleozoic sequences exposed along the Transantarctic Mountains in Antarctica and in southeastern Australia are segments of a formerly contiguous accretionary orogen that developed along the eastern margin of Gondwana. The margin underwent amalgamation and eastward accretion in the early Cambrian to Early Ordovician Ross-Delamerian orogen and in the Ordovician to Carboniferous Lachlan orogen. Northern Victoria Land plays a key role in many geodynamic reconstructions because it has long been considered the along-strike continuation of Australia in Antarctica; however, the correlation between lithotectonic units in Antarctica (Wilson, Bowers, and Robertson Bay terranes) and those in southeastern Australia (Glenelg, Grampians-Stavely, and Stawell zones), as well as the presence of Lachlan-aged tectono-metamorphic events in northern Victoria Land, are still uncertain. 40Ar-39Ar laser experiments on detrital and syndeformational white micas from low-grade siliciclastic rocks of northern Victoria Land, in conjunction with mineral-textural analysis and whole-rock geochemical and Nd isotope data, are used to constrain provenance and the timing of deformation, and to assess analogies with correlative structural zones in southeastern Australia. Detrital white micas of the western lithotectonic unit (Wilson terrane) yielded an age pattern dominated by late Cryogenian to Ediacaran ages (650–550 Ma), closely matching those of turbidites from the Australian Kanmantoo Group. Detrital white micas from the easternmost lithotectonic units (Bowers terrane and Robertson Bay terrane) yield indistinguishable age patterns, strikingly in agreement with those available for the western subprovince of the Lachlan orogen in Australia, which are dominated instead by younger ages with a dominant Ross orogen fingerprint (550–480 Ma). Deposition of siliciclastic detritus in the three lithotectonic units most likely occurred synchronously in the early–middle Cambrian, and the different signatures suggest that detritus was supplied from different ...