PhD Research Opportunities – The School of Earth,
Environmental and Biological Sciences
Investigating the Early-Mid Miocene igneous record of the Gulf of California (Mexico). The Gulf of California is a young example of a continental rift developed close to an active continental margin. Most continental-scale rifts that proceed to sea floor spreading develop in association with large volume igneous activity, however, the role of magmatism and the igneous record are commonly overlooked in understanding rift evolution. It has been widely presumed that Gulf of California rift developed rapidly beginning ~12 Ma, but new studies are challenging these previous models and suggesting a much earlier history to rifting and volcanism. Importantly, volcanism across the region may provide important records on the timing of the switch from wide to narrow rift modes. This PhD project will reinvestigate the mid-Miocene igneous record around the Gulf of California, but principally in Baja California to test this new conceptual model. The Project will involve field studies (stratigraphy, physical volcanology) and sampling for analytical research (petrology, whole-rock geochemistry, geochronology) to understand the origin, timing and evolution of magmas during this apparent switch in rift modes.
Sedimentary rocks are a key recorder of tectonic events. This fundamental Australia-based research will take new approaches to establish a finely tuned record of orogenic processes deforming the continental interior and how sediment loading from this mountain building event may have affected extension and magmatism at the continental margin. This project will examine the Late Devonian to Early Carboniferous (~380-320 Ma) continental sedimentary record across central and eastern Australia as this time slice records widespread rift basin development in northeastern Australia, intraplate orogenic events in central Australia (Alice Springs Orogeny), the progradation of a major sheet of cratonic-derived quartz-rich sand spreading outwards across Australia, and the initiation of Late Paleozoic glaciation. Mutliple dating techniques applied to the detrital minerals will be a key component of this project, revealing both the igneous and high-grade metamorphic history (from U/Pb zircon and rutile ages), and the recent tectonic and exhumation history (using lower temperature thermochronometers) of the source region. These new data will provide new insights into the relationship and timing of sedimentation and deformation. We are looking for a student with previous experience in field mapping, stratigraphy/sedimentology, sedimentary petrology and/or geochronology.
Iron nodules (pisoliths) are a common feature of many soils and weathering pro?les in the tropics and subtropics of Australia and around the world. Magnetic and non-magnetic soil Fe nodules commonly occur together in the same soils, where the magnetic nodules are distinguished by their high maghemite and hematite content. Previous research suggests that magnetic nodules form by intense heating of non-magnetic Fe nodules in topsoils during high-intensity bushfires. However magnetic nodules commonly occur deep within the soil or weathering profile, leading some authors dismiss thermal transformation of other Fe oxides. Alternative explanations which have been proposed include slow oxidation of ferrous solutions or formation via ferrihydrite in the presence of high concentrations of P, citrate or other organic ligands. This project will undertake a detailed geochemical, mineralogical and morphological comparison of magnetic and non-magnetic nodules in order to determine the mode of formation of magnetic Fe nodules in various environmental settings.
The project investigates the impact of stored energy on the deformation of rocks up to large strains and rotations. The successful candidate will employ numerical and physical modelling to examine the energy budget and mechanics of two-phase deformation (inclusions in a matrix) to large strains and rotations. She/he will explore the relevance of stored energy for fault formation and rock rheology.
The project will recover cores through the Holocene reef sequence (0-10 ka) in two reefs (Heron and One Tree) in the southern Great Barrier Reef (GBR) and reconstruct reef growth (i.e. geomorphological development), sea level and palaeoclimate histories. The applicant will participate in both phases of the coring campaigns in the southern Great Barrier Reef, and work closely with the other national and international partners in the project We are looking for a student with previous experience in carbonate sedimentology, coral reef biology, geochemistry and geology.
Study of Eoarchean terranes (4.0 Ga-3.6 Ga) has provided invaluable information on the early Earth including; the requirement for early formed proto crust and complementary depleted mantle. Nevertheless, all presently recognised localities that contain lithologies older than ~3.6 Ga have been subjected to at least amphibolites facies metamorphism. Geochemical evidence indicates that it is highly likely that pre 3.7 Ga crust is present in the Pilbara, but as of yet none have been definitively recognised. Furthermore, the Pilbara Craton contains abundant basaltic sequences that have been subjected to no more than lower greenschist facies metamorphism.
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