Magmatism in Antarctica and its relation to Zealandia

Abstract

Antarctica and Zealandia were once-adjacent blocks of Gondwana with a shared magmatic history during the Mesozoic and earlier. This is preserved in (a) shared Palaeozoic and Mesozoic Gondwana plutonism; (b) magmatism associated with syn-Gondwana breakup, including Jurassic-aged dolerite rocks of the Ferrar large igneous province, and igneous intrusions of similar isotopic affinity occurring on both continents coeval with Late Cretaceous rifting of Antarctica from Zealandia. The shared magmatic history continued post-Gondwana breakup through (c) the generation of oceanic crust and (d) eruption of diffuse alkaline magmatic province (DAMP) rocks. The DAMP encompasses magmatism from the Late Cretaceous to present day that shares isotopic and trace element characteristics over a (now) widely dispersed area of the southwest Pacific. This has been ascribed to either a previously contiguous mantle lithosphere with a shared, syn-Gondwana breakup history contributing to volcanic melts or to an isotopically distinct Antarctica–Zealandia asthenospheric mantle domain. The development of the Antarctic ice sheet after 34 Ma resulted in many volcanoes recording ice interactions that reveal many new details of Antarctica’s palaeoenvironmental history. Study of the volcanic history of Antarctica helps to advance understanding of the geological history of the region, including once-conjugate continents like Zealandia. © 2020, © 2020 The Royal Society of New Zealand.