An interdisciplinary approach to constructing models of the lithosphere across the Australia-Antarctica conjugate margin

• Main Authors: Reading, A, Halpin, J, Whittaker, J, Cracknell, M, Gal, M, Morse, P
• Format: Conference Object
• Language: English
• Published: . 2016
• Subjects: Earth Sciences; Geology; Tectonics; Antarctic; East Antarctica; Antarc*; Antarctica
• Online Access: http://ecite.utas.edu.au/110901

Terrane boundaries that define orogens separating the West and South Australian Cratons are evident in anumber of datasets, including geological, geochemical, geomagnetic anomalies, gravity anomalies andseismic tomography maps. Understanding this architecture is important in constraining the evolution ofProterozoic Australia. It also impacts on the lateral variations of rheology of the underlying lithosphere andasthenosphere of Australias former neighbour in Gondwana, East Antarctica, and hence on geothermal heatflux, glacial isostatic adjustment and other global climate system observables. Better understanding suchsystems has the potential to improve national preparedness and international resilience to global changessuch as sea-level rise. This research brings together diverse and disparate datasets that all inform, in different ways, the boundariesand deep structure of ancient cratons and orogens of western and southern Australia. These are constructedin the context of their disposition during the time of the southern hemisphere continents being configuredtogether in the Gondwana supercontinent, i.e. with the overprint of the Pan African orogeny. The datasets thatprovide the foundation for the new models are seismic tomography maps from Australia and Antarctica. Asthese are smoothed models, our methodology is to add terrane boundaries informed by the geology andgeochemistry of surface observations. We also incorporate information from airborne geophysics and remotesensed data. The methodologies used include changepoint detection and other informatics-basedapproaches. We thus extract new knowledge from the patterns and changes that occur across the layers inthis high-dimensional dataset. We also guide the reconstruction of these boundaries across continentalconjugate margin using well-informed plate-reconstructions, including recognition of the diverse Continent-Ocean-Boundary transitional crust along the Australian-Antarctic margin. We produce families of alternate models of the lithosphere, accessible through a visualisation framework.These provide focus for discussions on alternate tectonic hypotheses, and are also made available forcontinent scale rheological and seismological simulations. This approach allows a variety of information to beincluded in a single model, with differently constrained parts of the model being handled with quantitative rigor.Applications of the new candidate models include heat flux calculations, glacial isostatic adjustment studiesand will also be of value in sensitivity testing prior to new instrument deployments focussed on continentaldeep structure. Model suites will be made available to the research communities in interoperable data formats.