Zealandia in Antarctica: early Paleozoic basement in Marie Byrd Land, West Antarctica and possible connections to its Gondwana neighbours

Abstract

The early Paleozoic geology of New Zealand and evidence for the wider continental mass of Zealandia are reviewed in this contribution, especially with regard to the record of detrital zircon chronology. U-Pb age populations are reported from three new samples of siliciclastic and volcaniclastic sandstones in late Cambrian to Ordovician Swanson Formation, which constitutes the basement in the Ford Mountains and Edward VII Peninsula of western Marie Byrd Land, West Antarctica. Comparison with previously published data shows the same prominent age groups: 480–700 Ma (Early Ordovician to late Neoproterozoic) and 900–1100 Ma (early Neoproterozoic to late Mesoproterozoic). These are related respectively to ultimate sources formed during earliest Gondwana and late Rodinia supercontinental assembly. They conform to a common and widespread pattern seen in early Paleozoic basement throughout the Western Province of Zealandia and which continues over much of the Campbell Plateau of New Zealand, as well as other parts of West Antarctica and South America. South Zealandia is conjectured to have extensive Mesoproterozoic and late Neoproterozoic-Cambrian igneous/metamorphic basement which supplied sediment to earliest Paleozoic basins over a wide region, including western Marie Byrd Land, which is considered as an integral part of Zealandia. It may also have provided late Neoproterozoic and Cambrian sediment to contemporary sedimentary basins in adjacent North Victoria Land (East Antarctica) and the central Transantarctic Mountains. Eastward continuation of any Zealandia continental margin into the Weddell Sea area is very uncertain but essentially comparable early Paleozoic sediment provenance in southern South America at least confirms the continuity of Rodinia and Gondwana assembly processes.