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
Diamonds in ophiolite: recycling deep mantle into supra-subduction zones. This project aims to investigate whether the discovery of diamonds in oceanic rocks, known as ophiolites, is a global phenomenon. Even half a century after the introduction of plate tectonic theory, significant knowledge gaps remain regarding the fate of subducted lithosphere and Earth processes deep within the mantle. This project will use Australasian examples to test the hypothesis that diamonds are ubiquitous in the ma ....Diamonds in ophiolite: recycling deep mantle into supra-subduction zones. This project aims to investigate whether the discovery of diamonds in oceanic rocks, known as ophiolites, is a global phenomenon. Even half a century after the introduction of plate tectonic theory, significant knowledge gaps remain regarding the fate of subducted lithosphere and Earth processes deep within the mantle. This project will use Australasian examples to test the hypothesis that diamonds are ubiquitous in the mantle and occur widely in ophiolites. Results will have major implications for our understanding of how ocean crust grows and how rocks in the upper mantle form, as well as providing insight into how organic carbon is cycled from the seabed deep into the mantle before being returned back to Earth's surface.Read moreRead less
Continents in the Mantle Transition Zone? Sediment Recycling and the Geochemical Fertilization of the Deep Mantle. Because of its intrinsic compositional buoyancy, continental crust has traditionally been considered to be unsubductable in the denser underlying mantle. Yet some ocean island basalts carry a geochemical signature of recycled continental material in their plume source in the deep mantle. This project will reconcile this paradox through high-pressure experiments that will simulate su ....Continents in the Mantle Transition Zone? Sediment Recycling and the Geochemical Fertilization of the Deep Mantle. Because of its intrinsic compositional buoyancy, continental crust has traditionally been considered to be unsubductable in the denser underlying mantle. Yet some ocean island basalts carry a geochemical signature of recycled continental material in their plume source in the deep mantle. This project will reconcile this paradox through high-pressure experiments that will simulate subduction of continental sediments into the deep mantle. These experiments will provide the first empirical constraints on the role of sediment-derived fluids in mantle metasomatism and the origin of economically-rich potassic magmas, and the nature of the ultrarefractory continental component that ultimately reaches the plume source for ocean-island basalts.Read moreRead less
Resolving the influence of intraplate orogenesis on continental margin tectonics. Novel, multi-dating of continental sedimentary rocks will be undertaken to examine the effects of a high sediment flux from an enigmatic, major mountain-building event on a distant continental margin. This will expand our understanding of the range of tectonic influences between continental interiors and margins and onshore resource potential.
Pyrite: a deep-time capsule of ocean chemistry and atmosphere oxidation. Surprisingly little is known about trace element trends in past oceans, even though these data are vital for interpreting the evolution of the Earth's atmosphere, evolutionary pathways of marine life and cycles of major mineral deposits. Using laser-based analysis of sedimentary pyrite in deep marine rocks, this project aims to produce, for the first time, temporal variation curves for 25 trace elements in seawater over the ....Pyrite: a deep-time capsule of ocean chemistry and atmosphere oxidation. Surprisingly little is known about trace element trends in past oceans, even though these data are vital for interpreting the evolution of the Earth's atmosphere, evolutionary pathways of marine life and cycles of major mineral deposits. Using laser-based analysis of sedimentary pyrite in deep marine rocks, this project aims to produce, for the first time, temporal variation curves for 25 trace elements in seawater over the last 3.5 billion years. Preliminary research has validated the technique and demonstrated major changes in certain trace elements over geologically short periods. Outcomes will assist the minerals industry in the discovery of new deposits of zinc, copper, gold and iron ore in Australia.Read moreRead less
Down under down under: using multi-scale seismic tomography to image beneath Australia's Great Artesian Basin. Seismic arrays will be deployed in the Great Artesian Basin to image the crust and mantle using distant earthquake and ambient noise sources. This will answer fundamental questions about the tectonic evolution of eastern Australia and elucidate the structure of a region containing significant deep Earth resources.
The biogeochemical cycling of gold: development of innovative strategies in exploration. Doctor Southam's application of fundamental geomicrobiology to mineral exploration and mineral processing will enhance Australia's leadership in the global mining industry. The use of natural processes to develop biotechnological innovations will result in more sustainable mining practices.
Deep and smelly: exploring the roles of pressure and sulphur in hydrothermal metal transport. Hot, salty fluids carry metals in the Earth's crust and are responsible for the formation of Australia's mineral wealth. This project combines exciting new experiments with molecular-level simulations to predict metal transport, providing a sound basis for improving mineral exploration models and sustaining discovery of new deposits.
Magnetite and metal-rich sulphides in arc magmas. Ascending magmas cool and crystallise a variety of minerals. Triggering sulfide deposition which hosts base and precious metals is a critical point in magma evolution. This research will explore the role of magnetite as this trigger and its potential as a tracer of this process.
The link between cratonic roots, redox state, and mantle geodynamics. This project aims to understand the role of Earth's redox state on the geodynamic evolution of continental cratonic roots. Cratonic roots form strong, buoyant rafts upon which Australia's oldest crust and mineral deposits survived. Cratons preserve a record of planetary-scale chemical shifts, including the rise of surface oxygen, but it is unclear how these redox shifts themselves affected lithospheric processes. This project ....The link between cratonic roots, redox state, and mantle geodynamics. This project aims to understand the role of Earth's redox state on the geodynamic evolution of continental cratonic roots. Cratonic roots form strong, buoyant rafts upon which Australia's oldest crust and mineral deposits survived. Cratons preserve a record of planetary-scale chemical shifts, including the rise of surface oxygen, but it is unclear how these redox shifts themselves affected lithospheric processes. This project integrates new developments in geochemistry, geophysics, and geodynamics, to map the geochemical state and structure of cratonic roots, aiding mineral exploration, and also shedding light on the processes that modify, mineralise, and sometimes destroy cratonic roots.Read moreRead less