Testing absolute plate reference frames and the implications for the generation of geodynamic mantle heterogeneity structure

Shephard 2012 agegrids vels 140-1Absolute reference frames are a means of describing the motion of plates on the surface of the Earth over time, relative to a fixed point or frame. Multiple models of absolute plate motion have been proposed for the Cretaceous-Tertiary period, however, estimating the robustness and limitations of each model remains a significant limitation for refining both regional and global models of plate motion as well as fully integrated and time dependent geodynamic models. Here, we use a novel approach to compare five models of absolute plate motion in terms of their consequences for forward modelled deep mantle structure since at least 140 Ma. … Read more…

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Constraining the Jurassic extent of Greater India: Tectonic evolution of the West Australian margin

2011GC003919-p1a-1We present the Indian Ocean plate tectonic model accompanying the study of Gibbons et al., (2012). This work details the first regional-scale tectonic model of the breakup of East Gondwana. Our model shows that the breakup of East Gondwana started with the migration of a continental sliver, Argoland, in the Late Jurassic and was followed by breakup between Greater India and Australia-Antarctica in the Early Cretaceous, involving spreading reconfigurations, which left several sunken continental plateaus of Indian crust on the Australian plate. New evidence from seafloor off northwest Australia also shows that the majority of Greater India reached only about halfway up the West Australian margin, to the Wallaby-Zenith Plateaus. … Read more…

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Insights on the kinematics of the India-Eurasia collision from global geodynamic models

Image 002We present the input plate motion models and results from the study by Zahirovic et al. (2012) on the India-Eurasia collision using linked kinematic and geodynamic models.

Two end-member scenarios of the India-Eurasia collision were tested. The conventional model invokes long-lived Andean-style subduction along southern Eurasia until continental collision between a maximum extent Greater India and Lhasa at ~60 Ma. … Read more…

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Full-fit, palinspastic reconstruction of the conjugate Australian-Antarctic margins

AusAntCThick47Ma-1Despite decades of study the pre-rift configuration and early rifting history between Australia and Antarctica is not well established. The plate boundary system during the Cretaceous includes the evolving Kerguelen-Broken Ridge Large Igneous Province in the west as well as the conjugate passive and transform margin segments of the Australian and Antarctic continents. … Read more…

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Dynamic subsidence of eastern Australia during the Cretaceous

Dynamic Subsidence of Eastern Australia Matthews et al (2011)During the Early Cretaceous Australia’s eastward passage over sinking subducted slabs induced widespread dynamic subsidence and formation of a large eperiogenic sea in the eastern interior. Despite evidence for convergence between Australia and the paleo-Pacific, the subduction zone location has been poorly constrained. Using coupled plate tectonic-mantle convection models, we test two end-member scenarios, one with subduction directly east of Australia’s reconstructed continental margin, and a second with subduction translated ~1000 km east, implying the existence of a back-arc basin. Our models incorporate a rheological model for the mantle and lithosphere, plate motions since 140 Ma and evolving plate boundaries. While mantle rheology affects the magnitude of surface vertical motions, timing of uplift and subsidence depends on plate boundary geometries and kinematics. … Read more…

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