Wed 21st November @ noon, Rm 312.222

Abstract:

The Wyoming province consists of Precambrian rocks that are exposed in the Laramide uplifts in the Rocky Mountains of Wyoming.  The province records a long history with rocks dating back to 3.4 billion years ago (Ga) and xenocrystic zircon grains dating to ca. 3.9 Ga.  Lu/Hf ratios on some of the xenocrystic zircons indicate an ancestry that goes back into the Hadean.  The earliest granitic rocks at 3.4 Ga are tonalitic.  Potassium-rich plutons, indicative of granites derived from crustal melting, were emplaced 3.3 Ga, indicating that evolved continental crust in the Wyoming province had formed at that time.  The majority of the province is composed of variably deformed granitic plutons that were emplaced 2.85 Ga, 2.7 Ga., and 2.62 Ga.  Like Phanerozoic continental arc magmas, these plutons contain contributions from both continental and juvenile components.  The formation of early continental crust in the Wyoming province may explain why the Wyoming province records the earliest Himalayan-type orogeny on Earth at 2.7 Ga.  This is evinced by high T granulite metamorphism (>900°C, >10 kbar), juxtaposition of rocks with >3 Ga zircon grains against paragneisses that were juvenile at the time, and post metamorphism leucogranites emplaced in an extensional environments.

Wed 14th November @ noon, Rm 312.222

Abstract:

Large igneous provinces (LIP) are the manifestations of mantle plume activities, i.e. the rise of hot deep mantle materials. Mantle plumes play crucial roles in Earth’s tectonic and geodynamic evolution, climatic changes, and mass extinction events.  Two competing theories exist about the origin and operation of mantle plumes: (1) the fixed model where plumes (or superplumes) are anchored to the core deep in the mantle, and (2) the dynamic model where the formation and evolution of plumes and superplumes are link to large scale mantle convection and supercontinent cycles. The current global LIP record appears to show a cyclic nature following that of the supercontinent cycle. However, this LIP record is predominantly a continental record due to the destruction of oceanic LIPs (O-LIP) as part of the oceanic crust for much of Earth’s earlier history. Establishing the O-LIP record will enable us to evaluate if LIP intensity in the oceanic realm has remained semi-constant over geological time as some have suggested or followed similar cycles to the continental LIP record. Here we show that O-LIP basalts possess distinct elemental and isotopic compositional distributions that allow us to statistically discriminate O-LIP volcanic rocks from MORB, arc basalts, and continental-LIP basalts. We applied such a filter system to identify O-LIP from the global ophiolite records. Together with the geotectonic and age variations for each such record, we have started to establish a GIS-based global O-LIP record.

Short bio:

 Luc Doucet comes from Bourg-en-Bresse, a small town in France famously known for its blue-white-red tricoloured chickens. After a Ph.D. in St Etienne, France on mantle petrology, he moved to Brussels, Belgium to apply the “non-traditional” stable-isotope systematics on mantle and crustal rocks to study the formation of both oceanic and continental lithosphere (Kerguelen LIP and Siberia and Kaapvaal). March 2018, he moved to Perth to join the Earth Dynamics Research Group, in which he tries to figure out about oceanic large igneous provinces in the geologic record.

 

Wed 7th November @ noon, Rm 312.222

Abstract:

The Desert Fireball Network (DFN) is a continental scale facility dedicated to observing meteorite dropping events. The DFN is expanding overseas to become part of the Global Fireball Observatory (GFO), with partnerships established with 14 other institutions, and cameras already deployed and running in the USA, Canada, UK and Morocco.

The DFN alone, over its 3 million km² viewing area observes ~1.5 fireballs every night brighter than -1.5 mag. Reducing these data has produced a set of over 1000 fireball orbits. The Global Fireball Observatory already generates 4.5TB of data per night, managed by the small team here at Curtin. Mass modelling of these events is ongoing, though it is estimated that there are multiple candidates that could have resulted in a meteorite on the ground. The observation and recovery of the latest meteorites will be discussed.

Recent development of the FireOPAL systems in partnership with Lockheed Martin is also providing a unique imaging observatory for SSA satellite and debris tracking.

 

Short bio:

Dr. Eleanor Sansom completed her undergraduate and masters degree in geophysics at Imperial College London. She joined the Desert Fireball Network team in Perth, Australia in December 2012 and completed her PhD. in early 2017 after developing novel techniques for determining the masses of fireball meteoroids. Eleanor is currently the Desert Fireball Network Science Lead and continues to increase the accuracy of the team’s predictions of where meteorites may have fallen, as well as diving into the large orbital dataset being produced by the DFN – a mine of information including mass flux of incoming material and can provide information on asteroid families for impact hazard mitigation.

Wed 31st October @ noon, Rm 312.222

Abstract:

Sedimentary basins are sensitive recorders of both tectonic and surface processes, and generate relatively strong geophysical signals. As such they can be used to help to define past tectonic processes in regions of poor exposure, for example beneath the ice-sheets of Antarctica. Here we analyse some of the sedimentary basins of eastern Wilkes Land, which in geological terms can be considered part of Australo-Antarctica.  Geophysical modelling, erosion modelling and landscape restoration methods are employed, seeking to better understand their original geometry, formation process, and subsequent erosion.  From this, several distinct basins (and sub-basins) are defined each of which has a different inferred style of formation and erosive history. New geochronological constraints allow some inferences to be made as to the age of the sedimentary rocks, and so further constrains the tectonic setting of their formation, as well as providing further knowledge on Gondwanan geology.  Our erosion mapping also provide a strong indication of past ice sheet configurations and processes and helps to understand offshore depositional sites.

 

Short bio:

 Alan Aitken comes from Edinburgh (in Scotland), and came the long way around to Perth to take up a position at the UWA, where he has been employed as Goodeve Lecturer in Geophysics since 2012.  His research encompasses a wide range of topics and scales, but can be summarised as the use of geophysics to resolve the importance of earth processes to society as controlling factors for natural resources and environmental change, in particular through the use of gravity and magnetic methods to understand buried geology. He teaches widely across the UWA geosciences curriculum, and administers the Geology Honours and Master of Geoscience courses.

Wed 10th October @ noon, Rm 312.222

Abstract:

Magmatic sulfides hosted by mafic/ultramafic rocks are the largest resource of Ni and platinum group elements (PGE) on the planet. The genesis of these deposits by magmatic processes of sulfide saturation, enrichment and fractionation are well constrained. However, there are some Ni and PGE deposits that occur as hydrothermal deposits. These have puzzled economic geologists for years due to the largely immobile behaviour of Ni and PGE in hydrothermal fluids and most have loosely assumed a connection with magmatic sulfides, but that link is, as yet, unproven. By using Zeiss’ automated mineralogy to fully quantify a suite of samples that represent the alteration and destruction of magmatic sulfides under specific geologic conditions, it is apparent that this process liberates significant Ni, Cu, Fe, S and Pd to a fluid phase, such that it becomes a viable source of these metals into hydrothermal fluids, and whilst causing the death of the magmatic ore deposit, it has the potential to rise again and become one of these enigmatic hydrothermal Ni and PGE deposits.

Short bio:

Dr David Holwell is an Associate Professor working as an economic geologists at the University of Leicester in the UK. He received a BSc (Hons) in Geology at Durham University and a Masters in Mining Geology from the Camborne School of Mines. His did his PhD at Cardiff University on the world class PGE deposit of the Platreef in South Africa. He has worked for SRK Exploration as a consultant exploration geologist and his research work focusses on the nature and genesis of precious and base metal ore deposits, helping to develop better exploration models. Most recently, this work has expanded into the field of technology metals, including major UK-government grants for work on tellurium and selenium; metals essential for the solar industry, and resources in demand for the growing electric car markets.

Wed 22nd August @ noon, Rm 312.222

Abstract:

The rare earth elements (REE) are widely studied by petrologists and mineralogists, as valuable petrogenetic tools. But they are also vital raw materials for a wide range of modern technology; in particular, Nd is an essential component of NdFeB permanent magnets that are widely used in wind turbines and in the motors of electric cars. Other uses of the REE include catalysts, phosphors for lighting, ceramics, and in specialist glass. Despite their diverse use in many industrial sectors and consumer products, almost all of the world’s production of the REE comes from a group of mines in China. Since 2010, this concentration of supply has led to the REE being considered as critical metals, and has driven substantial exploration and research; but few new mines have successfully begun production.

The REE are found throughout the Earth’s crust but the highest concentrations are typically found in association with alkaline igneous rocks and carbonatites, or in magmatic-hydrothermal deposits. They can also be concentrated by low-temperature processes, in heavy mineral sands and in deposits formed by lateritic weathering of REE enriched protoliths. Deposits of the REE are characterised by exceptionally wide-ranging and varied mineralogy, with over 50 minerals being considered as potential REE ore minerals, although only a small proportion of those have been exploited commercially. This complex mineralogy has significant implications for the mining and processing of REE ores, and represents one of the key challenges that must be overcome to enable new REE mines to succeed.

This talk will provide an overview of currently-known REE deposits, summarise some recent and ongoing research carried out on their geology and mineralogy, and discuss the implications for successful mining of these deposits to meet global demand for the REE. This research has been carried out by a large team of collaborators across three major projects: EURARE, funded by the European Union’s Framework Programme 7; SoS RARE, funded by the UK’s Natural Environment Research Council; and HiTech AlkCarb, funded by the European Union’s Horizon 2020 Research and Innovation Programme.

Short bio:

I’m a Principal Geologist at the British Geological Survey, where I’ve worked for almost 18 years. After a PhD in alkaline igneous rocks and rare earth element mobilisation, and a short stint as a geologist for the Scottish government, I joined BGS in early 2001, initially as a mapping geologist. I met Pete and many other Curtin colleagues whilst I was working on geological mapping projects in the Highlands and Madagascar! In 2010, when China restricted export quotas on the rare earth elements, I shifted the focus of my research back into that area. I have since been the BGS lead on three major grant-funded projects looking at the geology of rare earth element resources, and that’s what I’ll talk about at Curtin. I am also interested in the geology of other ‘technology metal’ resources, particularly lithium in pegmatites.

Wed 8th August @ noon, Rm 312.222

Abstract:

Partial melting and the segregation and migration of melt are the fundamental processes governing the formation and chemical differentiation of Earth’s lithosphere. These processes can be constrained using a combination of melt modelling, using new thermodynamic activity models which now allow the precise modelling of the melting of both ultramafic (mantle) and mafic (basalt) sources; and through empirical observations, such as geochemical and isotopic measurements, particularly within accessory minerals. These approaches will be deployed in tracing the conceptual chemical evolution of planet Earth: (a) charting how the chemistry of Earth’s first primary crust reflects that of mantle from which it was extracted; (b) the generation and geodynamic of Earth’s early continental crust; (c) the evolution and differentiation of that crust; and (d) the genesis of economically crucial mineral deposits hosted by highly evolved melts.

 

Short bio:

Nick Gardiner is a Research Fellow at CET-Curtin Node under the Timescales of Mineral Systems theme. He has a BA in geology from the University of Oxford, a MSc in geochemistry from the University of Leeds, and then returned to Oxford to complete a DPhil in isotope and metamorphic geochemistry. After a number of years working in the global commodities markets (JP Morgan, Merrill Lynch), he returned to Oxford (and academia) in 2013, and joined Curtin in 2015. His current research focuses on using geochemical tools to constrain magmatic-metamorphic processes notably: (a) petrogenetic controls on granite-hosted mineral deposits; (b) the growth and development of Earth’s early continental crust; (c) Hf isotope systematics applied to crustal evolution studies; (d) talking about himself in the third person. He moves to Monash in September.

Wed 27th June @ noon, Rm 312.222

Abstract:

An increasing number of tectonic studies rely on U-Pb ages of detrital zircon to identify sediment source regions.  Such studies can be confounded if zircon ages reflect original primary sources rather than final, proximal sources. Such is the case with ~ 1 Ga Grenville zircon in North America – detrital grains are found in abundance thousands of kilometres from known exposed sources. This is likely a result of the incredible zircon fertility of Grenville age plutons (i.e. granitoids with very high Zr abundance).

To test further the utility of detrital accessory minerals we examined zircon and apatite from plutons exposed in a series of inselbergs, i.e. sediment point sources, in SE California. For zircon from granitic bedrock 80% yield dates of 74 Ma; 20% are Proterozoic xenocrysts. Detrital zircon ages overlap those of the bedrock, but show a different age frequency; in all sediment size fractions there is > 50% of Proterozoic grains. To determine if apatite was a more faithful recorder of provenance we analysed grains from both bedrock and alluvium for Sr isotopic composition. The ⁸⁷Sr/⁸⁶Sr ratio of detrital apatite largely overlap those of bedrock apatite but some analyses are significantly more radiogenic implying an exotic component.  Single apatite crystals from both bedrock and alluvium were also analysed for (U-Th)/He.  The average cooling date for bedrock apatite is 21.8 Ma. Approximately 80% the detrital grains overlap the bedrock values demonstrating the value this technique to provenance studies. However, ~ 20% of the cooling dates are ≥ 30 Ma also implying exotic sources.  Because sediment was collected in a single watershed contained entirely within the granite these apatite grains are potentially of aeolian origin. A similar origin could also explain the enigmatic detrital zircon U-Pb age distributions.  These results suggest considerable caution in interpreting provenance, particularly if relying on single mineral studies.

 

Short bio:

Dr. Scott Samson is a Professor of Earth Sciences at Syracuse University, in Syracuse, NY, USA. His specialty is in radiogenic isotope geochemistry and U-Pb dating.  His interests include continental crustal formation, Neoproterozoic tectonics, sedimentary provenance, and felsic magmatic evolution.  He has published over 90 peer-reviewed papers, is a Fellow of the Geological Society of America, and winner of the Wasserstrom prize for postgraduate teaching.

Thurs 14th June @ noon, Rm 201.322

Abstract:

Here we consider the tectonic evolution of the Tso Morari schist dome, reporting some new map scale observations concerning the kinematics and sense of shear in the mantling carapace shear zones to this North Himalayan metamorphic core complex. We provide new 40Ar/39Ar geochronological data that date the operation of the major crustal shear zones that were in part responsible for the exhumation of these high-pressure rocks. These results suggest extreme extension at different stages of the exhumation and impact on the interpretation of the large-scale tectonic evolution of this terrane. Bulk rock geochemical analysis of the mafic rocks demonstrate that these were once ocean island basalts, although they are now eclogites that exhibit ultra-high-pressure parageneses. Lithosphere-scale extension on this scenario can be explained if compression during the accretion event led to the formation of back-thrusts that evolved into south-facing subduction zones. Roll back to the north would juxtapose Tso Morari against the Ladakh Batholith, at the same time extending and exhuming these high-pressure rocks. Roll back of a south-facing subduction zones also provides an explanation for the Eocene-Oligocene and Oligo-Miocene thermal pulses and/or extensional episodes experienced by these rocks, and perhaps defines the geodynamic scenario that caused the widespread development of metamorphic core complexes in the north-west Himalaya.

Short bio:

Marnie is the manager of the Argon Laboratory at ANU. She completed her PhD at Monash University. Her research interest are to determine when and how movement in the ductile zone of the Earth occur. Dating deformation and metamorphic events that occur at major zones of collision or extension during Earth’s history.  Dating deformation and movement zones using Ar/Ar geochronology within the framework of structural geology and microstructure.

Wed 23st May @ noon, Rm 312.222

Abstract:

Arguably, Nuna represents the first actual supercontinent. Many uncertainties still exist regarding its paleogeographic evolution. Especially considering the position of proto-Australia, a lack of robust paleomagnetic data prevent a well-defined picture for large intervals during the Paleo- to Mesoproterozoic. I present new paleomagnetic results from two sets of Australian sills with intrusion ages close to the proposed formation and breakup periods of Nuna. Paleomagnetic analysis yield two well defined paleopoles for the ~1.8 Ga Hart Dolerite and the ~1.3 Ga Derim-Derim sills. Comparison with other paleopoles from Nuna, mainly from Laurentia and the North China Craton (NCC), reveals a high degree of similarity, which led us to construct a common apparent polar wander path (APWP) for an updated core of Nuna between ~1.8 Ga and 1.3 Ga, consisting of Laurentia, Siberia, Baltica, proto-Australia and the NCC. A striking feature of this APWP is an overall steady but slow rotational movement of the supercontinent.  Superimposed, a much more rapid and irregular polar wander is visible. Based on the most recent paleomagnetic pole list, the breakup time for Nuna can be constrained between ~1.3 and ~1.2 Ga, manifested in relative motion between Laurentia, Australia and North China. We suggest an initial proto-SWEAT connection between Laurentia and Australia between 1.8 and 1.75 Ga, followed by a modified Nuna configuration for the 1.63 –1.3 Ga period. Nuna likely remained intact till ca. 1.3 Ga, when a broad intracontinental basin, bounded by Australia, the NCC and potentially Siberia, existed. Anisotropy of magnetic susceptibility suggests that the same magmatic event likely produced the Derim-Derim Sills and the Galiwinku dykes in Australia, and the Yanliao large igneous province in the NCC, originated from underneath the broad intracontinental basin.

Short bio:

Uwe Kirscher studied geophysics at the Ludwig- Maximilians University in Munich, Germany. He then did a PhD there working on the evolution of the Central Asian Orogenic Belt using paleomagnetic data. He is currently a research associate in Professor Li’s Laureate team working on paleomagnetic constraints for supercontinents.