The geochemical role of iron in basaltic magmatism and planetary differentiation: an experimental study. The amount of Fe in primitive terrestrial basalts is surprisingly variable. The reasons for this are poorly understood, but could include melting of Fe-enriched refertilized mantle sources, increasing partitioning of FeO into the melt with depth of melting, or oxidation of some FeO to Fe2O3. An experimental investigation of the effects of Fe both as 2+ and 3+ on the partial melting of model ....The geochemical role of iron in basaltic magmatism and planetary differentiation: an experimental study. The amount of Fe in primitive terrestrial basalts is surprisingly variable. The reasons for this are poorly understood, but could include melting of Fe-enriched refertilized mantle sources, increasing partitioning of FeO into the melt with depth of melting, or oxidation of some FeO to Fe2O3. An experimental investigation of the effects of Fe both as 2+ and 3+ on the partial melting of model mantle material should help resolve this problem, while also providing the fundamental thermodynamic data needed to calibrate a general model for upper mantle phase relations.Read moreRead less
Understanding the deep mantle: experimental petrology at very high pressures. The great processes that shape the Earth at its surface, including plate tectonics and continental drift, can only be understood by appreciating how the interior of the Earth works. However, studying the deep Earth is difficult because of the enormous pressures and temperatures involved. This research proposes to simulate conditions in the Earth's lower mantle (that is, below 670 km in depth) by making use of an Austra ....Understanding the deep mantle: experimental petrology at very high pressures. The great processes that shape the Earth at its surface, including plate tectonics and continental drift, can only be understood by appreciating how the interior of the Earth works. However, studying the deep Earth is difficult because of the enormous pressures and temperatures involved. This research proposes to simulate conditions in the Earth's lower mantle (that is, below 670 km in depth) by making use of an Australian invented diamond-based ceramic, to double the pressure at which experiments can be performed. The information gained from this fundamental research will help predict how giant ore bodies form. The development of the high-pressure apparatus will also aid material scientists in their quest for novel materials.Read moreRead less
Water storage in the earth's mantle - understanding the process of OH incorporation in olivine. The amount of water in the Earth's mantle is thought to be sufficient to replace the surface oceans more than ten times. Whether this water exists in a fluid, melt, or mineral is important for understanding a range of mantle properties. The entire upper mantle water budget may be accommodated at defect sites in the mineral olivine. However, defects found in natural olivine do not correspond to thos ....Water storage in the earth's mantle - understanding the process of OH incorporation in olivine. The amount of water in the Earth's mantle is thought to be sufficient to replace the surface oceans more than ten times. Whether this water exists in a fluid, melt, or mineral is important for understanding a range of mantle properties. The entire upper mantle water budget may be accommodated at defect sites in the mineral olivine. However, defects found in natural olivine do not correspond to those produced
experimentally. Therefore, previous conclusions on water storage in the mantle are questionable. To address this problem the mechanism of water incorporation in olivine will be investigated using experimental petrology and spectroscopy.Read moreRead less
The Earth's Deep Carbon Cycle. The climate change debate has focused scientific attention on Earth’s exogene carbon-cycle. However, Earth has another, much deeper carbon-cycle which is poorly understood. In addition to exerting a profound influence on atmospheric greenhouse gas concentrations over time scales from thousands to billions of years, it is critically important in many processes in the Earth’s deep mantle. The major means by which the deep carbon-cycle is replenished is via subduction ....The Earth's Deep Carbon Cycle. The climate change debate has focused scientific attention on Earth’s exogene carbon-cycle. However, Earth has another, much deeper carbon-cycle which is poorly understood. In addition to exerting a profound influence on atmospheric greenhouse gas concentrations over time scales from thousands to billions of years, it is critically important in many processes in the Earth’s deep mantle. The major means by which the deep carbon-cycle is replenished is via subduction of carbonate-bearing oceanic crust. The project proposes a high-pressure experimental and field-based program to understand the fate of this carbonate during its journey from the exosphere, through subduction zones and into the deep mantle.Read moreRead less
The seismic significance of water and partial melting in planetary interiors. Novel laboratory techniques will be used to measure the influence of dissolved water on the seismic properties of the deep interiors of Earth and Moon. The outcome will be new insight into the crucial role of water in the formation and subsequent evolution of our dynamic planet and its more quiescent moon.
Chemical influences on the seismic structure of the Earth's upper mantle. This project aims to determine the sensitivity of the seismic properties of Earth’s upper mantle (to 400 km depth) to variations in the prevailing chemical environment. The unique capability of the ANU Rock Physics Laboratory for low-frequency measurement of wave speeds and attenuation will be exploited to clarify the newly discovered importance of redox conditions, and document the effect of varying proportions of the mos ....Chemical influences on the seismic structure of the Earth's upper mantle. This project aims to determine the sensitivity of the seismic properties of Earth’s upper mantle (to 400 km depth) to variations in the prevailing chemical environment. The unique capability of the ANU Rock Physics Laboratory for low-frequency measurement of wave speeds and attenuation will be exploited to clarify the newly discovered importance of redox conditions, and document the effect of varying proportions of the most abundant upper-mantle minerals olivine and pyroxene. The expected outcome will be a robust and comprehensive model to guide the interpretation of the complex architecture of the upper mantle, and thereby provide an improved understanding of the tectonic processes responsible for its evolution through geological time.Read moreRead less
Grain-boundary sliding in high-temperature ceramics: mechanical spectroscopy of high-purity magnesium oxide. The demise of elastic behaviour in materials stressed at sufficiently high temperature limits the usefulness of ceramics for structural applications, and is also responsible for reduced wave speeds and associated attenuation of seismic waves in the Earth's interior. Yet the nature of the transition in fine-grained materials tested at high temperature from elastic through anelastic to vis ....Grain-boundary sliding in high-temperature ceramics: mechanical spectroscopy of high-purity magnesium oxide. The demise of elastic behaviour in materials stressed at sufficiently high temperature limits the usefulness of ceramics for structural applications, and is also responsible for reduced wave speeds and associated attenuation of seismic waves in the Earth's interior. Yet the nature of the transition in fine-grained materials tested at high temperature from elastic through anelastic to viscous rheology remains poorly understood. Through a combination of mechanical testing by torsional forced oscillation/ microcreep methods of carefully fabricated and characterised specimens of polycrystalline MgO and associated micro-mechanical modelling we seek to clarify this fundamental and general aspect of high-temperature mechanical behaviour.Read moreRead less
Maximising accuracy and reliability of carbonate climate proxy archives. This project brings together expertise and cutting-edge methodology from different disciplines to identify the controls on the compositions of the shells and skeletons of marine organisms. The compositions of these materials are essential tools to reconstruct environmental conditions before modern climate records began. However, recent insights into how they form profoundly complicate and affect their interpretations.
The r ....Maximising accuracy and reliability of carbonate climate proxy archives. This project brings together expertise and cutting-edge methodology from different disciplines to identify the controls on the compositions of the shells and skeletons of marine organisms. The compositions of these materials are essential tools to reconstruct environmental conditions before modern climate records began. However, recent insights into how they form profoundly complicate and affect their interpretations.
The results will enable us to develop new, realistic models for the behaviour of chemical elements in these materials. This will significantly improve paleoclimate interpretations and provide critical benefit for protecting Australia’s marine resources in the future. Read moreRead less
Deep time in the deep Earth: using trace element diffusivities to constrain durations of deep Earth processes. Evaluation of deep Earth resources requires knowing how long geological processes took, some record of which is often preserved by gradients in the chemical compositions of minerals. Experiments at very high temperatures and pressures will determine how this evidence can be used to constrain the durations of a rich variety of geological processes.
The effects of local strain on the crystal chemistry of solid solutions. The concept of the solid solution, the substitution of one kind of atom for another in a crystal structure, is a central idea in both mineral sciences and solid state chemistry. Such atomic substitutions alter local crystal chemistry and hence always introduce strain into crystal lattices. In this project we aim to characterize this substitutional strain. Ultimately this should lead to a better understanding of the geologic ....The effects of local strain on the crystal chemistry of solid solutions. The concept of the solid solution, the substitution of one kind of atom for another in a crystal structure, is a central idea in both mineral sciences and solid state chemistry. Such atomic substitutions alter local crystal chemistry and hence always introduce strain into crystal lattices. In this project we aim to characterize this substitutional strain. Ultimately this should lead to a better understanding of the geological history of rocks, improvements in metal recovery from ores and to the design and synthesis of new materials.Read moreRead less