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Encyclopedia of geology, five volume set, volume 1 5 (encyclopedia of geology series) ( PDFDrive ) 1848

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NEW ZEALAND Figure (A) Summary of the age ranges of New Zealand’s basement terranes (green, blue, brown, yellow), batholiths (red, orange), and metamorphic rocks (overprint stripes) Gondwana Sequence rocks are shown by letters: K, Kirwans Dolerite; T, Topfer Formation; P, Parapara Group; R, Reefton Group The terranes can be grouped into Eastern and Western provinces (B) One possible palaeogeo graphical reconstruction of south eastern Gondwana at about 120 Ma (the end of the convergent margin phase) The present day New Zealand coastlines are shown as white lines; the Alpine Fault and other faults are shown as white dotted lines (Reproduced with permission from Mortimer N (2004) New Zealand’s geological foundations Gondwana Research 7: 261 272 ß International Association for Gondwana Research.) were laid down and deformed towards the end of Cretaceous subduction These nine terranes make up the bulk of the New Zealand volcanosedimentary basement Smaller tectonostratigraphic units can be regarded as components of the larger terranes The Median Tectonic Zone is still used by some New Zealand geologists to describe a zone of terrane shards and igneous complexes of uncertain status and correlation that lies between the Brook Street and Takaka terranes (see Plutonic Rocks, below) Overlap Sequences Overlap sequences of varying ages can be recognized by their lesser deformation and metamorphism and distinctive petrofacies, as compared with older immediately underlying rocks Lateral correlatives are used to constrain models of terrane amalgamation and accretion The only New Zealand rocks that have been correlated with autochthonous Gondwanan sequences occur in two small outliers in northern South Island (marked G in Figure 2) Four units – the Reefton Group (marine Devonian), Parapara Group (marine Permian–Triassic), Topfer Formation (nonmarine Triassic), and Kirwans Dolerite (a Middle Jurassic low-titanium tholeiite sill intrusion) – indicate that the Buller and Takaka terranes had been accreted to Gondwana by the end of the Palaeozoic In North Island, a postulated Late Jurassic overlap sequence – the Waipa Supergroup, possibly sourced

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