Zircon is a unique, although not exactly perfect, chronometer mineral and "time capsule" that preserves information about the earliest history of the Earth. The set of tools for extracting this information includes U-Pb dating, Lu-Hf isotopic tracing, trace element concentrations, oxygen isotope composition, Ti concentrations thermometry, and imaging of the internal grain structure. Veracity of this information, however, deteriorates, if the grain is internally heterogeneous, and various isotopic and chemical analyses sample domains of different age, origin, and degree of alteration. The goal of this project is developing methodology for extracting comprehensive and accurate information about the origin of the zircon's host rock while circumventing the effects of heterogeneity. The student will use a combination of ion microprobe techniques, imaging, and precise isotopic analysis of U, Pb and other elements separated from zircon grain fragments, to refine the ways of getting a comprehensive genetic information from zircon. This methodology will be applied to the earliest terrestrial zircons, and, after optimisation, to other important detrital zircon populations throughout the Earth's history.

In recent times, tomographic imaging techniques have enabled seismologists to produce detailed three-dimensional maps of Earth structure from large seismic datasets. Traditional methods of seismic tomography often rely on iterative non-linear inversion schemes and represent structure by a regular grid of parameters. However, iterative inversion schemes may converge to local minima and regular parameterizations are inconsistent with non-uniform distributions of data. The aim of this project is to introduce a suite of new computational tools to seismic tomography in order to overcome these problems. The important requirement of defining a continuous medium from an irregular distribution of nodes placed only where they are required by the data can be satisfied using natural neighbour interpolation. We envisage the use of a fully non-linear search technique to solve the inverse problem, e.g. the locally developed neighbourhood algorithm. Finally, the forward problem of calculating model predictions can be rapidly solved using grid-based wavefront tracking schemes such as the fast marching method. The use of direct search methods in seismic tomography is computationally expensive, but the project will have ready access to a powerful 128-node supercomputer. A background in computational mathematics is recommended.

Contact the supervisor directly for more information.

To find clues to major events of the past, the Biogeochemistry Group at ANU studies molecular fossils of biological lipids (biomarkers) that can be preserved in sediments and sedimentary rocks. Using biomarkers, we study extremely ancient and strange ecosystems such as sulphidic oceans that once existed to the north of Australia billions of years ago, or modern environments such as salt lakes in Australia's outback. We elucidate environmental cataclysms that caused major mass extinctions, fluctuations of geochemical cycles that may have triggered the first emergence of complex life, and human induced environmental catastrophes such as the salinization of lakes and the pollution of estuaries. If you are looking for a project that combines aspects of geology, chemistry, biology and environmental sciences, and you are interested in topics such as the origin and early evolution of life, climate change, organic chemistry, microbiology or environmental genomics, then you can join one of our current projects or bring your own ideas to the group.

Contact the supervisor directly for more information.