Antarctica and supercontinent evolution: historical perspectives, recent advances and unresolved issues

Abstract

The Antarctic rock record spans some 3.5 billion years of history, and has made important contributions to our understanding of how Earth's continents assemble and disperse through time. Correlations between Antarctica and other southern continents were critical to the concept of Gondwana, the Palaeozoic supercontinent used to support early arguments for continental drift, while evidence for Proterozoic connections between Antarctica and North America led to the 'SWEAT' configuration (linking SW USA to East Antarctica) for an early Neoproterozoic supercontinent known as Rodinia. Antarctica also contains relicts of an older Palaeo-to Mesoproterozoic supercontinent known as Nuna, along with several Archaean fragments that belonged to one or more 'supercratons' in Neoarchaean times. It thus seems likely that Antarctica contains remnants of most, if not all, of Earth's supercontinents, and Antarctic research continues to provide insights into their palaeogeography and geological evolution. One area of research is the latest Neoproterozoic-Mesozoic active margin of Gondwana, preserved in Antarctica as the Ross Orogen and a number of outboard terranes that now form West Antarctica. Major episodes of magmatism, deformation and metamorphism along this palaeo-Pacific margin at 590 -500 and 300-230 Ma can be linked to reduced convergence along the internal collisional orogens that formed Gondwana and Pangaea, respectively; indicating that accretionary systems are sensitive to changes in the global plate tectonic budget. Other research has focused on Grenville-age (c. 1.0 Ga) and PanAfrican (c. 0.5 Ga) metamorphism in the East Antarctic Craton. These global-scale events record the amalgamation of Rodinia and Gondwana, respectively. Three coastal segments of Grenville-age metamorphism in the Indian Ocean sector of Antarctica are each linked to the c. 1.0 Ga collision between older cratons but are separated by two regions of pervasive Pan-African metamorphism ascribed to Neoproterozoic ocean closure. The tectonic setting of these events is poorly constrained given the sparse exposure, deep erosion level and likelihood that younger metamorphic events have reactivated older structures. The projection of these orogens under the ice is also controversial, but it is likely that at least one of the Pan-African orogens links up with the Shackleton Range on the palaeo-Pacific margin of the craton. Sedimentary detritus and glacial erratics at the edge of the ice sheet provide evidence for the c.

Peak and post–peak development of UHT metamorphism at Mather Peninsula, Rauer Islands: Zircon and monazite U–Th–Pb and REE chemistry constraints

“…Given its present position the evolution of the Rauer Terrane is critical to understanding the amalgamation of East Antarctica, and particularly the relative importance of 1000 and 530-510 Ma tectonothermal events in weld-ing together the various Archaean and Proterozoic crustal blocks (Zhao et al, 1995;Hensen and Zhou, 1995;Carson et al, 1996;Hensen and Zhou, 1997;Fitzsimons, 2000;Harley, 2003;Carson et al, 2007;Wang et al, 2007;Kelsey et al, 2007Kelsey et al, , 2008Boger, 2011;Harley et al, 2013). The Mather Paragneiss detrital zircon age spectra (upper intercepts of 2800-2400 Ma) and the protolith zircon age of the host tonalitic orthogniess (3268 ± 4 Ma) obtained in this study are consistent with the previously reported zircon dates from Archaean orthogneisses of the Rauer Islands, and confirm that the host orthogneiss surrounding the UHT paragneisses are Archaean in protolith age.…”

“…Timing of UHT metamorphism and tectonic implications Placing a strong time constraint on the UHT event in the Mather Paragneiss is critical for models of the development of the Rauer Islands, the Prydz Belt and the amalgamation of East Antarctica (Harley et al, 2013). The first indication that these paragneisses might record an event distinct in age from the Prydz Tectonic Event was reported by Zhou (1995, 1997), who obtained a 600 Ma Sm-Nd garnet-whole rock isochron for Mather Paragneiss SH/88/218.…”

“…The Prydz Belt of SE Prydz Bay is polymetamorphic (Wang et al, 2008;Liu et al, 2009;Grew et al, 2012Grew et al, , 2013Harley et al, 2013;Liu et al, 2013). It preserves a complex record of latest Mesoproterozoic to early Neoproterozoic magmatism, sedimentation and granulite facies tectonism (Wang et al, 2008;Liu et al, 2009;Grew et al, 2012) (Table 1) that is broadly comparable to tectonothermal events in the Rayner Complex to the west (Liu et al, 2013).…”

Pan–African granulites of Madagascar and southern India: Gondwana assembly and parallels with modern Tibet

“…Equivalent units in Madagascar are the Antongil Domain, with 3.3-3.1 Ga tonalite intruded by 2.6-2.5 Ga granite (Tucker et al,Figure 3. Cratons (>0.9 Ga) and Pan-African orogens (0.7-0.5 Ga) of Gondwana (modified from Gray et al, 2008;Meert and Lieberman, 2008;Harley et al, 2013 1999; Schofield et al, 2010), and the Masora Domain with similar protoliths but a stronger Pan-African overprint discussed further below (Tucker et al, 2011a;Key et al, 2011;Ichiki et al, 2015). Although Indian and African sides of the orogen both record 2.6-2.5 Ga magmatism, they are set apart by major magmatic events at 3.5-3.0 Ga in the former, and at 2.1-1.8 Ga and~1.0 Ga in the latter.…”

Early Palaeozoic continental growth in the Tasmanides of northeast Gondwana and its implications for Rodinia assembly and rifting

“…It has been considered sourced from East Antarctica from rocks now buried under the ice sheet Saeed, 2008, 2011). Extensive Pan African belts are considered to underlie icecovered East Antarctica, based on rock systems exposed at the continental periphery, and is consistent with a Pacific-Gondwana population in zircon eroded from the Antarctic interior and deposited at the continental margins (Harley et al, 2013). Alternatively a much more distant source has been suggested involving the collision belt of East and West Gondwana along the East African Orogen (Squire et al, 2006;Maidment et al, 2013).…”