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Implications for the Supercontinent Cycle Geoscience Frontiers 8 (2017) 1431e1445 HOSTED BY Contents lists available at ScienceDirect China University of Geosciences (Beijing) Geoscience Frontiers journal homepage: www.elsevier.com/locate/gsf Research Paper Contemporaneous assembly of Western Gondwana and final Rodinia break-up: Implications for the supercontinent cycle Sebastián Oriolo a,*, Pedro Oyhantçabal b, Klaus Wemmer a, Siegfried Siegesmund a a Geoscience Center, Georg-August-Universität Göttingen, Goldschmidtstraße 3, 37077 Göttingen, Germany b Departamento de Geología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay article info abstract Article history: Geological, geochronological and isotopic data are integrated in order to present a revised model for the Received 13 May 2016 Neoproterozoic evolution of Western Gondwana. Although the classical geodynamic scenario assumed Received in revised form for the period 800e700 Ma is related to Rodinia break-up and the consequent opening of major oceanic 6 January 2017 basins, a significantly different tectonic evolution can be inferred for most Western Gondwana cratons. Accepted 11 January 2017 These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and Available online 20 February 2017 Handling Editor: R.D. Nance recorded subduction with back-arc extension, island arc development and limited formation of oceanic crust in internal oceans. This period was thus characterized by increased crustal growth in Western Keywords: Gondwana, resulting from addition of juvenile continental crust along convergent margins. In contrast, BrasilianoePan-African Orogeny crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana. Neoproterozoic The Río de la Plata, Congo-São Francisco, West African and Amazonian cratons collided at ca. 630 Collisional tectonics e600 Ma along the West Gondwana Orogen. These events overlap in time with the onset of the opening Pannotia of the Iapetus Ocean at ca. 610e600 Ma, which gave rise to the separation of Baltica, Laurentia and Metacratonization Amazonia and resulted from the final Rodinia break-up. The East African/Antarctic Orogen recorded the Introversion-extroversion subsequent amalgamation of Western and Eastern Gondwana after ca. 580 Ma, contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin. However, the Kalahari Craton was lately incorporated during the Late EdiacaraneEarly Cambrian. The proposed Gondwana evolution rules out the existence of Pannotia, as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia. Additionally, a combination of intro- version and extroversion is proposed for the assembly of Gondwana. The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the supercontinent cycle, as supercontinent amalgamation and break-up do not necessarily represent alternating episodic processes but overlap in time. Ó 2017, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/). 1. Introduction which was extended to South America, Australia and Antarctica by Wegener (1915). The term Gondwana was first used in the geological literature to The amalgamation of Gondwana started at ca. 630 Ma and refer to a plant-bearing series in India and was afterwards extended to ca. 550e530 Ma, when subduction along its proto- extended to the Gondwana system (Feistmantel, 1876; Medlicott Pacific margin was already established (Dalziel, 1997; Cordani and Blanford, 1879, and references therein). Based on similarities et al., 2003; Meert and Torsvik, 2003; Cawood, 2005; Collins and in the PaleozoiceMesozoic geological and fossiliferous record of Pisarevsky, 2005; Cawood and Buchan, 2007). Likewise, Pannotia India and other continental masses, Suess (1885) proposed the was considered as a Late Neoproterozoic “short-lived” supercon- existence of a supercontinent and coined the name Gondwanaland, tinent that included Laurentia and Gondwanan domains, prior to Gondwana final configuration (Powell and Young, 1995; Dalziel, 1997). On the other hand, the break-up of Rodinia took place in e * Corresponding author. two phases at ca. 800 700 Ma and after ca. 600 Ma, being the later E-mail addresses: [email protected], [email protected] (S. Oriolo). coeval with the timing of Gondwana assembly (Cordani et al., 2003; Peer-review under responsibility of China University of Geosciences (Beijing). Cawood, 2005; Li et al., 2008). Late Neoproterozoic paleogeography http://dx.doi.org/10.1016/j.gsf.2017.01.009 1674-9871/Ó 2017, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC- ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1432 S. Oriolo et al. / Geoscience Frontiers 8 (2017) 1431e1445 thus resulted from major geodynamic processes that might be a whereas the Congo Craton in Africa exhibits several distinct Meso- priori linked to the evolution of Rodinia, Pannotia and/or Gond- proterozoicmagmaticeventsatca.1.50,1.38and1.10Ga(Ernst et al., wana (Fig. 1). 2013). Despite being almost coeval with the timing of Rodinia as- Two end-member processes were proposed for the formation of sembly, the youngest event comprises gabbroenorite dykes that supercontinents, namely introversion and extroversion, depending resulted from intraplate magmatism (Ernst et al., 2013). on whether internal or external oceans of a supercontinent are A different situation can be observed in the Kalahari Craton, closed to form the next one, respectively (Fig. 2; Nance et al., 1988; which presents an ArcheanePaleoproterozoic nucleus surrounded Hartnady, 1991; Hoffman, 1991; Murphy and Nance, 2003, 2005, by Late Mesoproterozoic mobile belts. The northern (present co- 2013; Mitchell et al., 2012; Evans et al., 2016). Internal oceans ordinates) SinclaireGhanzieChobe Belt recorded arc-related mag- comprise juvenile crust that forms after break-up of the previous matism resulting in collision and subsequent post-collisional supercontinent and external ocean crust predates the previous magmatism at ca. 1.1 Ga (Kampunzu et al.,1998; Becker et al., 2006). supercontinent (Murphy and Nance, 2003, 2005). In terms of To the southwest, collision-related deformation and meta- paleogeography, introversion implies that the location of a super- morphism in the Namaqua Belt has been placed at ca. 1.20e1.18 Ga continent is the same of its predecessor, whereas the successor is (e.g., Miller, 2008; Colliston et al., 2015; Cornell et al., 2015), located in the opposite hemisphere in the case of extroversion although extension in a back-arc setting was alternatively consid- (Mitchell et al., 2012). In the particular case of Gondwana, an ered for this major tectonothermal event (Bial et al., 2015a, b). The extroversion model has been typically considered (Hoffman, 1991; southeastern margin of the Kalahari Craton, in turn, is bounded by Murphy and Nance, 2003, 2005, 2013; Evans et al., 2016). the Natal Belt, which recorded accretion of island arc complexes Based on a review of geological, geochronological and isotopic (e.g., Thomas, 1989; Jacobs and Thomas, 1994; Spencer et al., 2015). evidences, a revised model for the Neoproterozoic evolution of On the other hand, the Umkondo LIP intruded the Kalahari Craton Western Gondwana is presented in this work. Relationships with at ca. 1.1 Ga (Hanson et al., 2004) and was correlated with coeval Rodinia break-up and the evolution of the Terra Australis Orogen intraplate extensional magmatism in the Congo Craton (Ernst et al., are discussed, and implications for the supercontinent cycle are 2013). In contrast, Becker et al. (2006) interpreted this intrusion as analyzed as well. the result of post-collisional processes. Although it seems to be clear that the Río de la Plata, West African 2. Pre-Gondwana configuration and Congo-São Francisco cratons were not part of Rodinia (Fig. 1a), the position of the Kalahari Craton is still uncertain. However, even if Many contributions attempted to elucidate Late Mesoproter- being part of Rodinia, the Kalahari Craton might already rift away at ozoiceEarly Neoproterozoic paleogeography (e.g., Powell et al., ca. 700 Ma (Jacobs et al., 2008). Rifting at ca. 800e700 Ma gave rise 1993; Dalziel et al., 2000; Kröner and Cordani, 2003; Pisarevsky to the opening of a major oceanic basin between Laurentia and et al., 2003; Tohver et al., 2006; Li et al., 2008; Evans, 2009), eastern Gondwanan cratons and was succeeded by a second rifting which represents a key point to understand the history of Gond- event starting after ca. 610e600 Ma (Fig. 1a) that triggered the wana amalgamation. The assembly of Rodinia took place at ca. opening of the Iapetus Ocean between Laurentia, Baltica and Ama- 1.1e1.0 Ga and, although most authors agree on the fact that the zonia (e.g., Cawood et al., 2001; Meert and Torsvik, 2003; Li et al., Amazonian Craton was part of Rodinia (Dalziel et al., 2000; Tohver 2008). In any case, most reconstructions do not consider Meso- et al., 2006; Li et al., 2008; Evans, 2009), the participation of other proterozoic connections of the Congo-São Francisco and Kalahari western Gondwanan blocks is still under discussion. Kröner and cratons (e.g., Cordani et al., 2003; Meert and Torsvik,
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