Abstract Decompression, anatexis and the clockwise granulite-grade P–T evolution of high-grade rocks of Prydz Bay reflect late collisional extension that occurred c. 530 Ma in the Prydz Belt. Rapid cooling of the mid-crust high-grade terranes of the Prydz Belt was achieved during c. 517-486 Ma by tectonically driven exhumation along dextral ductile shear zones in which late tectonic partialmelt bodies were emplaced. Instead of a model of polyphase metamorphism and deformation for the basement-and-cover sequences in Prydz Bay, we apply an accretionary one, i.e. an accretionary wedge with allochthonous blocks, to interpret the tectonic history in the Late Neoproterozoic of the Prydz Belt. SHRIMP U–Pb dates and Nd isotopic data available for both Prydz Bay and the Grove Mountains are used to explain amalgamation of the high-grade terranes in the Prydz Belt. This demonstrates that the assembly of the East Antarctic Craton was completed in the Pan-African event, and the East Antarctic Craton is a Pan-African-age collage rather than a keystone of East Gondwana during the Neoproterozoic.

Abstract The East Antarctic Shield consists of a variety of Archaean and Proterozoic–Cambrian high-grade terranes that have distinct crustal histories and were amalgamated at various times in the Precambrian-Cambrian. High-grade Pan-African tectonism at 600–500Ma is recognized from four distinct belts: the Dronning Maud Land, Lützow-Holm Bay, Prydz Bay and Denman Glacier Belts. These high-grade belts juxtapose distinct Mesoproterozoic and Neoproterozoic crustal provinces (Maud, Rayner and Wilkes), the Rauer Terrane, and have also marginally affected Archaean cratonic remnants in the Napier Complex and southern Prince Charles Mountains. The Wilkes Province experienced its principal tectonothermal events prior to 1130Ma and was not affected by the younger events that characterize the Maud Province (1150 and 1030–990Ma), the Rayner Province (990–920Ma) and the Rauer Terrane (1030–990Ma). These differences between the isotopic/event records of the basement provinces now separated by the Pan-African belts require that the older provinces were not formerly parts of a continuous ‘Grenville’ belt as proposed in the SW US-East Antartic model. East Antarctica was not a single unified crustal block within either East Gondwana or Rodinia until the Cambrian, which is now demonstrated to be the key phase of high-grade and ultrahigh-temperature (UHT) metamorphism associated with supercontinent assembly. The high-grade Pan-African tectonism is characterized by extensive infracrustal melting, clock-wise P–T paths, rapid post-peak exhumation along isothermal decompression paths to shallow- or mid-crustal levels by 500 Ma and the generation, at least locally, of UHT conditions. A significant flux of heat from the mantle into the deep and initially overthickened crust is required to produce these observed metamorphic effects. Whilst the thermal evolution can be explained by models that invoke the removal of most of the lithospheric mantle following crustal thickening and prior to rapid extension of the remaining crust, these one-dimensional models are inconsistent with present crustal thicknesses of 25–35km in the Pan-African domains of the East Antarctic Shield.

Abstract India and East Antarctica collided during assembly of the Rodinia supercontinent at around 1 Ga. Granulites related to this orogeny are exposed in the Eastern Ghats Province (EGP) in India, and these are believed to have been contiguous with granulites of the Rayner Province in East Antarctica at that time. In the Indian segment, we describe a shear zone between the EGP and the Rengali Province to its north along which strongly foliated bands of garnetiferous quartzofeldspathic gneisses, khondalites and charnockites are intercalated. The foliation is consistently east–west trending and subvertical, with downdip intersection lineations. Maximum asymmetry in horizontal sections and textural analysis using electron backscattered diffraction (EBSD) analysis confirm that the transport vector during shearing was horizontal. The shear zone is interpreted as a dextral strike-slip fault that operated under greenschist-facies conditions, juxtaposing 1 Ga EGP granulites with 2.8 Ga cratonic granulites to the north. The corresponding region in East Antarctica is represented by the Rauer Group, where intercalations between 2.8 and 1.0 Ga, vertically orientated lithologies, are observed alongside 0.5 Ga shear zones. These features in the Rauer Group can be correlated with those in the Rengali Province, further supporting existing palaeogeographical reconstructions of Gondwana.