The links between large igneous provinces, continental break-up and environmental change: evidence reviewed from Antarctica

Abstract

Earth history is punctuated by events during which large volumes of predominantly mafic magmas were generated and emplaced by processes that are generally accepted as being, unrelated to 'normal' sea-floor spreading and subduction processes. These events form large igneous provinces (LIPs) which are best preserved in the Mesozoic and Cenozoic where they occur as continental and ocean basin flood basalts, giant radiating dyke swarms, volcanic rifted margins, oceanic plateaus, submarine ridges, and seamount chains. The Mesozoic history of Antarctica is no exception in that a number of different igneous provinces were emplaced during the initial break-up and continued disintegration of Gondwana, leading to the isolation of Antarctica in a polar position. The link between the emplacement of the igneous rocks and continental break-up processes remains controversial. The environmental impact of large igneous province formation on the Earth System is equally debated. Large igneous province eruptions are coeval with, and may drive environmental and climatic effects including global warming, oceanic anoxia and/or increased oceanic fertilisation, calcification crises, mass extinction and release of gas hydrates.This review explores the links between the emplacement of large igneous provinces in Antarctica, the isolation of Antarctica from other Gondwana continents, and possibly related environmental and climatic changes during the Mesozoic and Cenozoic.

New geophysical compilations link crustal block motion to Jurassic extension and strike-slip faulting in the Weddell Sea Rift System of West Antarctica

“…Gondwana breakup changed the global continental configuration, led to the opening of major oceanic gateways, likely triggered major shifts in the climate system and had significant impacts on the biosphere, hydrosphere and cryosphere (Storey et al, 2013).…”

Geology reviewed for the Falkland Islands and their offshore sedimentary basins, South Atlantic Ocean

“…A popular hypothesis for the generation of the Early Jurassic, Karoo magmatism that spanned the South African and Antarctic (Dronning Maud Land) segments of Gondwana, associated it with a mantle plume responsible for initiating the break-up of that supercontinent (e.g. Storey et al 1999); whilst the regional picture may well be more complicated, the involvement of a focused thermal anomaly is highly likely (Storey et al (2013). In contrast, the origin of the Ferrar igneous province remains unresolved.…”

“…Its linear outcrop parallel to the active, 'Pacific' margin of Gondwana (Fig. 4) invites an association with subduction, but the distance from the active margin is unusually large and other models have been proposed, as reviewed by Storey et al (2013).…”

“…There have been several attempts to address this issue which have invoked a variety of mechanisms. The rotation of small microplates during extension driven by doming above a Karoo thermal plume features in several interpretations as summarised by Storey et al (1999Storey et al ( , 2013 The tectonic history of West Antarctica is well beyond the scope of this review but, as a corollary for argument in favour of the rotation of a Falklands microplate, it is worth noting that there is good evidence for substantial anticlockwise rotation of the Ellsworth-Whitmore Mountains microplate (Grunow et al 1987;Randall & Mac Niocaill 2004). In the interpretation of Dalziel et al (2013) A representation of the Gondwana continental configuration in the Early Jurassic, immediately prior to the commencement of its break-up, simplified after Dalziel et al (2013, fig.…”

“…Fig. 4 shows a reconstruction of Gondwana incorporating rotation of a Falklands microplate back to a position off the SE coast of South Africa, based on illustrations in Dalziel et al (2013) and Storey et al (2013). It must be stressed that the underlying premise is not universally accepted but these authors, and others before them, accept 180° clockwise rotation of the Falklands microplate: 150° during the Late Jurassic fragmentation of Gondwana and a further 30° during opening of the South Atlantic…”