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A Reassessment of Paleogeographic Reconstructions of Eastern Gondwana: Bringing Geology Back Into the Equation

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A Reassessment of Paleogeographic Reconstructions of Eastern Gondwana: Bringing Geology Back Into the Equation Gondwana Research 24 (2013) 984–998 Contents lists available at ScienceDirect Gondwana Research journal homepage: www.elsevier.com/locate/gr GR focus review A reassessment of paleogeographic reconstructions of eastern Gondwana: Bringing geology back into the equation L.T. White a,b,⁎, G.M. Gibson c, G.S. Lister b a Southeast Asia Research Group, Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey TW200EX, United Kingdom b Research School of Earth Sciences, Building 61, Mills Road, The Australian National University, Canberra 0200, Australia c Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia article info abstract Article history: In recent years several tectonic reconstructions have been presented for Australia–Antarctica break-up, with Received 6 December 2012 each putting the Australian plate in a different location with respect to Antarctica. These differences reflect Received in revised form 14 June 2013 the different datasets and techniques employed to create a particular reconstruction. Here we show that Accepted 25 June 2013 some of the more recent reconstructions proposed for Australia–Antarctica break-up are inconsistent with Available online 1 July 2013 both our current knowledge of margin evolution as well as the inferred match in basement terranes on the fl fi Handling Editor: M. Santosh two opposing conjugate margins. We also show how these incorrect reconstructions in uence the t of the Indian plate against Antarctica if its movement is tied to the Australian plate. Such errors can have a major Keywords: influence on the tectonic models of other parts of the world. In this case, we show how the position of the Antarctic plate Australia plate can predetermine the extent of Greater India, which is (rightly or wrongly) used by many Australian plate as a constraint in determining the timing of India–Asia, or India–Island Arc collisions during the closure of Break-up Tethys. We also discuss the timing of Australia–Antarctica break-up, and which linear magnetic features Indian plate are a product of symmetric sea-floor spreading versus those linear magnetic features that result from rifting Paleogeography of a margin. The 46 Ma to 84 Ma rotational poles previously proposed for Australia–Antarctica break-up, and confined to transitional crust and the continent–ocean transition zone, more likely formed during earlier stages of rifting rather than during symmetric sea-floor spreading of oceanic crust. So rotation poles that have been derived from magnetic anomalies in such regions cannot be used as input in a plate reconstruction. A new reconstruction of the Australia–Antarctica margin is therefore proposed that remains faithful to the best available geological and geophysical data. © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. Contents 1. Introduction .............................................................. 985 2. Geological Criteria used to evaluate reconstructions of eastern Gondwana ................................. 985 2.1. Piercing points between the Australian and Antarctic plates .................................... 985 2.2. Piercing points between the Indian and Antarctic plates ...................................... 986 3. Reconstructing eastern Gondwana before break-up ........................................... 986 3.1. Australia–Antarctica ....................................................... 986 3.2. Impact of Australia–Antarctica (mis)fits on the Indian plate .................................... 987 4. The initiation of sea-floor spreading between Australia and Antarctica ................................... 989 4.1. The timing of break-up according to interpretation of sea-floor magnetic anomalies ......................... 989 4.1.1. Australian margin ................................................... 989 4.1.2. Antarctic margin .................................................... 990 4.2. Stratigraphic record ....................................................... 991 5. Comparison of Australia–Antarctica reconstructions at the time of break-up ................................ 992 6. Reconstructing the South Tasman Rise ................................................. 993 7. Reconstructing Australia–Antarctica break-up: A clean slate ....................................... 994 ⁎ Corresponding author at: Southeast Asia Research Group, Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey TW200EX, United Kingdom. Tel.: +44 1784 276638; fax: +44 1784 434716. E-mail address: [email protected] (L.T. White). 1342-937X/$ – see front matter © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gr.2013.06.009 L.T. White et al. / Gondwana Research 24 (2013) 984–998 985 8. Implications for basin evolution along Australia's southern margin .................................... 996 9. Conclusions .............................................................. 996 Acknowledgments ............................................................. 996 References ................................................................. 996 1. Introduction 2004), eventually resulting in sea-floor spreading between India, Australia and Antarctica (Norvick and Smith, 2001). A plate tectonic reconstruction of the Earth is reliant on a series of It therefore follows that many of the rocks will have similar char- choices. The choices refer to which data sources, reference frames acteristics across each margin. This is demonstrated in the geological and/or time-scales are adopted for a particular reconstruction observations (e.g. mapping, petrology, geochemistry and geochronol- (e.g. White and Lister, 2012). These choices ultimately explain why ogy) that have been conducted over several decades along each mar- one plate reconstruction is different from another. gin (c.f. Fitzsimons, 2003; Boger, 2011; Gibson et al., 2013; Veevers, In this paper, we review existing reconstructions of the Australian 2012 and references therein) (Fig. 1). So any given plate reconstruc- plate with respect to the Antarctic plate and show how it is possible tion should position the plates in a manner that is consistent with to arrive at very different conclusions regarding the position of the these observations. We therefore used the Pplates reconstruction Australian and Indian plates within Gondwana and after its dispersal. software developed at the Australian National University to test In particular, we show how the adoption of different datasets and the validity of published reconstructions by examining how they rotational poles influence the position of these plates in various position conjugate geological terrane boundaries and key piercing reconstructions. We further test which of the existing reconstructions points that occur along the margins. for the break-up of eastern Gondwana are the most geologically plausible, and use this framework to develop a new reconstruction 2.1. Piercing points between the Australian and Antarctic plates for the evolution of this margin. We chose to review the reconstructions of Australia–Antarctica The best piercing points for reconstructions of Gondwana are because there is contention as to which of the published models is near-vertical, planar structures of the same age such as dykes or faults the best representation of available geophysical and geological data that formed after Gondwana coalesced and before it dispersed (e.g. Tikku and Cande, 1999, 2000; Whittaker et al., 2007, 2008; (i.e. between ~750 Ma and ~165 Ma) (Reeves and de Wit, 2000). Müller et al., 2008; Tikku and Direen, 2008; Williams et al., 2011; For the Australian–Antarctic margin these include the correlation of: Gibson et al., 2013). Much of the disagreement centers on: (1) which (1) the Neoproterozoic proto–Darling Fault (Australia) with its pro- reconstruction provides the best paleogeographic fit between the posed extension to an unnamed fault beneath the Scott and Denman two continents (c.f. Powell et al., 1988; Williams et al., 2011; Gibson Glaciers (Antarctica) (Harris, 1995; Fitzsimons, 2003; Boger, 2011), et al., 2013), (2) establishing when sea-floor spreading began between (2) the Paleozoic Avoca–Sorell fault system (Australia) with the the two plates (c.f. Tikku and Direen, 2008; Direen, 2011; Direen et al., Leap Year or the Lanterman faults (Antarctica) (Gibson et al., 2011, 2012) and (3) which fracture zones are considered to be conjugates of 2013), and (3) the Coorong Shear Zone (Australia) with the Mertz one another during the computation of Euler poles (c.f. Whittaker et Shear Zone (Antarctica) (Gibson et al., 2013). The Mertz Shear Zone al., 2007, 2008; Tikku and Direen, 2008; Williams et al., 2011). We had previously been correlated with the Kalinjala Mylonite Zone in examine each of these issues individually, first by discussing the South Australia but this interpretation is now considered less likely background to each problem, and by showing graphical examples following the discovery of meso-Archean crust east of the Kalinjala and potential solutions to each issue. Mylonite Zone (Fraser et al., 2010), indicating that the edge of the Please note that all Era, Period, Epoch, Stage and magnetic Delamerian orogeny occurred much further east than earlier sup- isochron ages reported in this paper refer to those in the most recent posed (e.g. Di Vincenzo et al. 2007; Goodge and Fanning, 2010). Fur- internationally recognized geological
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