Australian Proterozoic Tectonics: Evolution of the Musgrave and Arunta Provinces

Project Details

The Proterozoic was a time of dramatic change in Earth tectonics regimes, marking the transition from Archaean style tectonics to modern day “plate tectonics”. The transitionary period is characterised by the development of complex and still poorly understood tectonic systems. In Australia Proterozoic terrains span much of the spectrum observed globally, from narrow belt-like terrains with short histories and voluminous I-type magmatism to systems with long-lived histories characterised by protracted high heat and repeated episodes of crustal differentiation.

Two of the most important terrains in the Australian Proterozoic are the Arunta and Musgrave Blocks in central Australia. The Musgrave Block and its apparent extension into the Albany Fraser Province constitute the only major Grenvillian-aged (1300-1000 Ma) orogenic system in Australia. The global Grenvillian system is a key element in global supercontinent reconstructions and has been the subject of a vast number of studies focused on its tectonic evolution. In the Australian context, the Musgrave-Albany Fraser system has been interpreted as recording the collisional assembly of the Southern and Northern Australian Cratons, an interpretation consistent with its apparently younger crustal growth and orogenic events compared to the surrounding continental regions. However in comparison with many other Grenvillian-aged orogenic systems, the geological evolution of the Musgrave-Albany Fraser belt is poorly known.

Existing data suggest that the Musgrave Block may have been initiated as a system of offshore island arcs that underwent collision at ~1600 Ma. Sparse data also imply that Musgrave Block was the site of intracratonic basin development at around 1400 Ma prior to the onset of a ~200 Ma of tectonism broadly linked to global Grenvillian-aged events. However our understanding of the tectonic evolution of the Musgrave Block is still in its infancy. By taking advantage of the unprecedented access opportunity negotiated by the South Australian Mineral Resources Group, this project will significantly enhance the understanding of the Australia's Grenvillian-aged tectonic system.

The project has several aims:

1. To constrain the provenance of metasedimentary rock sequences.
2. To constrain the timing, evolution and distribution of the major orogenic events in the Musgrave Block.
3. To build on the existing geochemical, isotopic and age datasets relating to the major felsic magmatic suites in the Musgrave Block.

The Arunta Block is the type of example of a long-lived tectonic system dominated by high heat flow and unusually enriched granitic rocks. Recent tectonic models have highlighted that the Arunta Block may have evolved at or near an active plate margin associated with the North Australia Craton. However there has been comparatively little work undertaken to evaluate such tectonic models in the context of the geological record. This project will concentrate on understanding the stratigraphic, structural, metamorphic and magmatic evolution of the southern Arunta Block over the key interval 1800-1600 Ma ago. This interval is characterised by a number or regional high-T to low medium-P metamorphic events, as well as basin development and rifting.

A significant amount of field work in a well-exposed terrain with laboratory work focussed on developing a geochronologic framework and constrained models for the thermobarometric evolution of the terrain and its interplay with the magmatic rocks systems is required as part of this project. The project will involve collaboration with the Northern Territory Geological Survey and will be both a field and laboratory based program. Both the Arunta and Musgrave projects will be linked with existing Industry associated projects currently being undertaken by the Continental Evolution Research Group (CERG) in the Gawler Craton and Curnamona Province. This research will form a major collaborative program to create a tectonic synthesis for the southern Australian Proterozoic and its connections with the North Australian Craton. This synthesis will form a key element in developing models for the evolution of the Australian Proterozoic in general, and will generate key datasets to enhance mineral exploration programs.

Supervisors