Antarctica in the Gondwana Supercontinent

The fit of the large continental blocks within Gondwana is well established (e.g. Lawver et al., 1998) as three continents, Australia, India and Africa, fit well against the present-day rifted margins of Antarctica (Fig. 7.3). In contrast, due to considerable uncertainty over the number and position of some of the microplates within the West Antarctic region (e.g. Dalziel and Elliot, 1982; Storey, 1996; Storey et al., 1998), the Gondwana reconstruction is less well constrained along the Transantarctic margin of East Antarctica. In this region, the Ellsworth-Whitmore Mountains crustal block, Antarctic Peninsula, Thurston Island and Marie Byrd Land (subdivided into west and east portions, Divenere et al., 1996) are generally accepted as the main West Antarctic microplates, but other minor microplates (i.e. The Haag Nunatak, Berkner and Filchner microplates) are also used in reconstructions (e.g. De Wit et al., 1988). On the basis of palaeomagnetic data, geometry and geological constraints (particularly the presence of a large proportion of subduction-related rocks), the main West Antarctic microplates are generally retained in approximately their present location along the palaeo-Pacific margin of Gondwana in most models (e.g. Lawver et al., 1992). To obtain their Gondwana pre-break-up positions, both the Antarctic Peninsula and the Thurston Island block (Grunow et al., 1991) are rotated anticlockwise from their present-day position with respect to East Antarctica, the two microplates of Marie Byrd Land are restored along a strike-slip fault (Divenere et al., 1995), and Campbell Plateau, Chatham Rise, and North and South Islands of New Zealand can be reconstructed to Marie Byrd Land.

Figure 7.3: (A) Gondwana tight fit reconstruction (Early Jurassic). (B and C) Major initial stage in the break-up of Gondwana: (A) initial rifting stage (Late Jurassic); (B) change in the Gondwana break-up stress regime from dominantly north-south between east and west Gondwana to dominantly east-west with the two-plate system being replaced by a multiple-plate system (Early Cretaceous) (after Fitzgerald, 2002, with permission from the Royal Society of New Zealand). AP, Antarctic Peninsula; TI, Thurston Island; MBL, Marie Byrd Land; CR, Chatham Rise; CP, Campbell Plateau; SNZ, Southern New Zealand; NNZ, northern New Zealand; LHR, Lord Howe Rise; WS, Weddell Sea. Continent and microplate positions are from Lawver et al. (1992, 1998) with other information from Storey (1996).

Detailed information about the different reconstructions and tectonic scenarios for Antarctica in Gondwana can be found in Lawver et al. (1998) and Larter et al. (2002).

We will here focus on the major Antarctic geological constraints, key regions and datasets which represent a well-established basis for reconstructing the southern continents in Gondwana.

In this context, our review will also face some controversial aspects, which are presently under debate, concerning the reconstruction of the main phases during the amalgamation of the supercontinent. The geological evolution of the Antarctic continent is reviewed considering two main time periods: (i) c. 600-450 Ma, covering the processes which were active immediately before and during the amalgamation of Gondwana; and (ii) c. 450-180 Ma, including all the major events that occurred after the final stage of Gondwana amalgamation to the time immediately before the break-up phase.

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