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Type: Theses
Title: Thermo-mechanical evolution of orogeny in the Musgrave Province
Author: Walsh, Alec Keith
Issue Date: 2015
School/Discipline: School of Physical Sciences
Abstract: The architecture of orogens, the physical record of deformation and metamorphism, and the duration and rates at which orogeny progresses is intimately linked with thermomechanical state of the lithosphere and it’s evolution and modifi cation during orogenesis in polymetamorphic terrains. This thesis presents an integrated study that investigates the structural, metamorphic and geodynamic features of the Musgrave Province to understand the interplay between orogenesis and the temporal and spatial changes in lithospheric rheology. The metamorphic record in the Musgrave Province is dominated by Grenvillian-aged (1270–1100 Ma) ultra-high-temperature metamorphism which was characterised by > 80 Myr of metamorphic temperatures of approximately 1000 °C. The duration of such extreme conditions resulted in extremely residual crust which had major implications for the style of reworking in the younger Ediacaran–Cambrian intraplate Petermann Orogeny. Crustal thickening during intraplate orogeny occurred at ~ 600 Ma and resulted in the development of a thick-skinned foreland fold-thrust belt. Loading of the lithosphere caused the development of an extremely deep and narrow flexural foreland basin in which syn-orogenic sequences were buried to depths of ~10 km. The architecture of the foreland implies that intraplate deformation was localised into a region of dramatically weakened lithosphere, which could have developed in response to the initial distribution (and burial) of heat producing layers in the mid-crust. In the deep-crustal core of the orogen, migmatites from the western part of the orogenic system which record peak metamorphism between 600 and 570 Ma and long-lived pervasive deformation (> 40 Myr), represent a comparatively warm and weak portion of crust. To the east, discrete and brittle deformation occurred in comparatively strong lithosphere and but is accompanied by a similar record of elevated metamorphic temperatures (>600 °C) which span 590 to 530 Ma. Observed variations in deformational response independent of temperature or duration highlights the important role of other factors, such as availability of fluids, might have in facilitating reduction in strength and localise deformation in residual lithosphere. Ultimate re-strengthening of the Petermann Orogen lithosphere was achieved during progressive removal of the orogenic heat production during erosion, enabling the preservation of a puzzling record of intraplate orogeny.
Advisor: Kelsey, David Edward
Hand, Martin Phillip
Dissertation Note: Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Physical Sciences, 2015.
Keywords: intraplate orogeny
metamorphism
Central Australia fold-thrust belt
foreland basin
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
DOI: 10.4225/55/582d3e659c9f9
Appears in Collections:Research Theses

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