Wed 27th November @ noon, Rm 312.222

Abstract:

The accretion of planets and their thermochemical evolution, the formation of the Moon, cratered landscapes, and the origin of habitable environments and atmospheres, are consequences of hypervelocity collisions of asteroids and comets with planetary bodies including the Earth. Impacts may be considered as one of the most fundamental processes in the solar system and it is a key question whether stochastic impacts of large bodies (giant collision) may have significantly changed the course of the evolution of individual planets or whether the evolution of planets was more or less determined after its formation. The presentation comprises examples of multi-scale numerical modelling, laboratory impact experiments and morphological and geophysical observations on the Moon to disentangle the collision history of the inner solar system and to quantify the role of impacts in the formation and early evolution of the Earth-Moon system.

 

Short bio:

Kai Wünnemann is Professor for “Impact and Planetary Physics” at Museum für Naturkunde (MfN) and Freie Universität (FU) Berlin. He is the deputy head of the Science Programme “Evolution and Geoprocesses” and head of the section “Impact and Meteorite Research” at MfN.

He has been studying impact processes for more than 20 years by numerical modelling, laboratory experiments, and geophysical exploration to improve our understanding of the collision history of planets and its implications for the evolution of lithospheres and biospheres. He is one of the lead developers of the iSALE software (http://www.isale-code.de) that is used by more than 200 users around the world to simulate impact and shock wave processes on all scales. He used different methodological approaches to study several craters on Earth and planetary surfaces during his PhD thesis at the University of Münster (2001), as postdoc at Imperial College London and University of Arizona (2002-2005), and as senior researcher and head of the Meteorite Impact Research section at the Museum für Naturkunde (MfN) in Berlin (since 2006).

Wed 20th November @ 11 am, Rm 312.222

Abstract:

The talk discusses how water modulates crustal temperatures during continental arc magmatism. It proceeds to show the role that hydrous basaltic arc magmas have in exsolving water during fractionation and underplating at the Moho, and consequently on melting the overlying crust.  A holistic petrological model is presented that focusses on the role of water through the subduction factory, from slab to surface, and how it facilitates the formation of continental crust.

 

Short bio:

Professor WJ Collins began his work on A-type granites at ANU with Bruce Chappell, before moving to La Trobe University for a PhD on Archean granites with Prof Allan White. A post-doc on high-grade Proterozoic terranes in central Australia ensued with Prof. Ron Vernon at Macquarie University before moving to the University of Newcastle as a lecturer. He moved to James Cook University as a Professor before returning to Newcastle as Director of the NSW Institute for Frontiers Geoscience. He became a Curtin Professorial Fellow last year.

Wed 23rd Octover@ noon, Rm 312.222

Abstract:

The Basin and Range Province of the western United States has been influential in the development of ideas concerning the extension of continental crust. New structural, geophysical and geochronological data from several field sites in eastern California, southern Nevada, Utah and southeastern Idaho call into question the role of regional detachment faults in engendering large-scale extension of the upper crust. Our data are instead consistent with the now-40-year-old interpretation of Proffett (1977) in the Yerington district, Nevada, that mid- to late Cenozoic extension was accommodated in brittlely deformed rocks by moderately to steeply inclined normal faults that tilted to lower dip during deformation, and were cut by one or more generations of younger, more favorably oriented faults. The application of critical Coulomb wedge theory to the still-contentious Sevier Desert detachment of west-central Utah implies a friction coefficient as low as 0.13. Our data have profound implications for the interpretation of detachment faults in other extensional and passive margin settings.

 

Short bio:

Nicholas Christie-Blick is a professor at Lamont-Doherty Earth Observatory, on sabbatical leave in Perth until June, 2020. His research deals with sedimentation processes, crustal deformation, and deep-time Earth history, with particular reference for the last several years to the low-angle normal fault paradox. He was an undergraduate at Cambridge (1974), and completed his PhD at the University of California, Santa Barbara with John Crowell (1979). He is best known in Australia for his work on the Ediacaran Period, with a new project under way in the Flinders Ranges of South Australia.

Wed 2nd October @ noon, Rm 312.222

Abstract:

Deep marine sediments host ~2.9 × 10²⁹ microbial cells, equivalent to up to 3.6% of the total living biomass on the planet with Archaea accounting for ~37% of that population. These subsurface microbial communities are generally considered to be structured through in situ environmental conditions such as the availability of electron acceptors and donors, porosity and sediment lithology. Yet, recent studies have shown that a subset of subseafloor microbial communities were present at the time of deposition and formed a genetic archive originally referred to as “the Paleome” and reflect the paleo-depositional environment. However, additional highly resolved profiling of subseafloor microbiomes are required to substantiate this claim. In this talk I will show that up to 15% of subseafloor bacterial communities in the Arabian Sea subsist through fermentation but originated from the overlying water column during the last glacial interglacial cycle where they were involved in denitrification during periods of strong oxygen minimum zone conditions. This fraction of subseafloor Bacteria underwent weak postburial selection and therefore formed a living long-term genomic record of the paleodepositional environment. To explore the global potential of sedimentary Archaea to also record changes in the paleodepositional environment, we performed a highly-resolved 16S rDNA survey of subseafloor archaeal communities in up to 140 kyr-old sediments of the northern Red Sea covering the last six Marine Isotope Stages (MIS) when alternating glacial low stands and interglacial highstands caused drastic changes in sea level and salinity in the Red Sea. Our results revealed a strong significant response of subseafloor archaeal communities to changes in paleodepositional conditions associated with MIS stages and their transitions and only a moderately significant response to changes in sediment lithology. This suggest that a substantial part of the subseafloor archaeal communities would have been present at the time of deposition and that they no longer play a highly active role in the cycling of sedimentary organic matter. This claim was substantiated by the parallel finding that the majority of buried archaeal lipid biomarkers (GDGTs) that comprise the TEX₈₆ paleothermometry were derived from ancient marine Thaumarchaeota and not from e.g. methanogenic archaea that were identified from the Red Sea paleome.

 

Short bio:

Associate Prof. Marco Coolen is a geomicrobiologist who is best known for his studies on ancient DNA signatures preserved in lake and marine sediments to reconstruct terrestrial and aquatic ecosystem responses to long-term climate variability or to more recent human environmental impact. In addition, Coolen studies the activity, limitations, and evolution of the deep biosphere and is exploring to what extent microbes buried in the geologic record can form long-term genomic records of ecosystem-climate interactions. He is also using similar technologies to study the diversity and functioning of active microbes in modern environments such as the role that bacteria play in human gallstone formation, the functioning of Shark Bay microbial mats, and the degradation of oceanic plastic waste as well as industrial-derived persistent organic pollutants.

Wed 25th September@ noon, Rm 312.222

Abstract:

In this talk I will present two case studies that show the insights novel stable isotopes can provide us when studying the evolution of planet Earth.

The first will use neodymium stable isotopes to discuss planetary formation. As a geologist there is no more fundamental question than what the Earth is made from?  About 15 years ago pioneering work using 142Nd showed that the Earth is distinct from chondritic meteorites the supposed building blocks of planet Earth and threw into question the long-standing chondritic Earth hypothesis.  A possible solution to this offset is the so called sulfide matte.  Here I will discuss using the newly developed Nd stable isotope system to investigate this solution.

In the second example I will use molybdenum stable isotopes to constrain the volume of crust on the early Earth. Estimates of the volume of the earliest crust based on zircon ages and radiogenic isotopes remain equivocal. Stable isotope systems, such as molybdenum, have the potential to provide further constraints but remain underused, due to the lack of complementarity between mantle and crustal reservoirs. Mo isotope data for Archean komatiites and Phanerozoic komatiites and picrites and demonstrate that their mantle sources all possess sub-chondritic signatures complementary to the super-chondritic continental crust. These results confirm that the present-day degree of mantle depletion was achieved by 3.5 billion years ago and that the Earth has been in a steady state with respect to molybdenum recycling. Mass balance modelling shows that this early mantle depletion requires the extraction of a far greater volume of mafic-dominated proto-crust than previous thought, more than twice the volume of the continental crust today, implying rapid crustal growth and destruction in the first billion years of Earth’s history.

 

Short bio:

Alex McCoy-West studied geology (to MSc) at Victoria University of Wellington (New Zealand) and then completed a PhD at the Australian National University.  These projects focused on using a combination of igneous petrology and radiogenic isotope geochemistry.  Following this he moved to Durham University (UK) to undertake postdoctoral research developing novel stable isotope systems.  Alex is now based at Monash University where he is focused on understanding the early Earth. His main research interests centre around using novel-stable isotopes to constrain various aspects of planetary evolution.

Wed 18th September @ noon, Rm 312.222

Abstract:

The meteorite Allende fell in 1969 in Mexico, and remains one of the most heavily studied meteorites to date. Due to the large volume of material that fell, many different analyses have been carried out on the meteorite as technology has developed all over the world. Allende is a carbonaceous chondrite (CV subclass) that is presumed to originate from the same parent asteroid that all CV chondrites came from. Allende has undergone a relatively small amount of thermal and aqueous alteration when compared with many other meteorites, therefore textures observed in this rock may be considered relatively primitive. Extensive investigation of the various meteoritic components, i.e. chondrules, matrix grains, and calcium-aluminium inclusions, using EBSD, led to finding some of the first evidence of the process of asteroid compaction in this meteorite. Low-porosity components, i.e. chondrules, show a very small amount of crystal-plastic deformation when compared with small matrix grains, which would have been highly porous prior to compaction. These findings align with modelling predictions of impact-induced compaction as the driver for asteroid compaction. Further fabric analyses of the small matrix grains across a large area revealed an asymmetrical flattening of the matrix grains against low-porosity objects, such as chondrules, and enabled the direction of compaction to be estimated. Finally, we used EBSD data from 3 CV chondrites, including Allende, to compare matrix grain morphology and crystallography. Grain size, shape and alignment were assessed and considered in the context of the differing thermal and aqueous alteration that each meteorite has experienced based on prior work. At present, it is not common to measure the chondritic matrix grain sizes and shapes during classification. This approach may be a useful tool in the future for quantifying the physical properties of meteoritic matrices. The comparison across and between different meteorite classes may allow for patterns to be observed and correlated with accretionary or alteration processes, leading to a better understanding of how the chondritic parent bodies evolved.

 

Short bio:

Lucy is a postdoctorate researcher working with Prof. Gretchen Benedix in the Space Science and Technology Centre (SSTC), here at Curtin. The focus of her postdoc is investigating Martian meteorites to gather a better understanding of the formation and origin of these rocks on the Martian surface, using electron backscattered diffraction (EBSD). She completed her PhD in Planetary Geology in 2017 exploring early impacts in the solar system, and found evidence of deformation induced by impacts, also using EBSD techniques. She is a passionate science outreach advocate and enjoys sharing her love of science with the public.

Fri 9th August @ 11 am, Rm 312.222

Abstract:

Generated by a dynamo process in the Earth’s liquid iron outer core, the global geomagnetic field surrounds and protects our entire planet creating a bubble in interplanetary space. The chaotic nonlinear nature of this geodynamo process leads to the magnetic field being highly variable on a range of timescales and the shortest of these can be observed directly by networks of observatories and satellites. For longer timescale variations, we must turn to palaeomagnetic records made possible by the extreme ferromagnetic stability of ferrous grains occurring naturally in many rocks. This talk will focus on how Earth’s magnetic field has changed through geological time and the variations that appear to have occurred on the very longest timescales (tens to thousands of millions of years).  It will present recent key palaeomagnetic observations and new modelling results that support strong inter-relations between the different parameters used to characterise magnetic field behaviour. This joint observation-modelling approach promises to provide fundamental new insights into the operation of the geodynamo through geological time and its sensitivity to changing conditions in Earth’s core and lowermost mantle.

 

Short Bio:

Andy Biggin is Professor of Palaeomagnetism at the University of Liverpool in the UK. He works in the Geomagnetism Lab in the School of Environmental Sciences where he has worked since obtaining an Advanced Fellowship from the Natural Environment Research Council (NERC) in early 2009. He got his BSc in geophysics from Liverpool in 1997, his PhD in palaeomagnetism from Kingston (Surrey, not Jamaica) in 2001, and since then has worked as a post-doc in UNAM (Mexico), Montpellier (France), and Utrecht (the Netherlands). Between contracts, he also worked for the Bradford and Bingley financial services company for a couple of years before the big crash (coincidence?). Andy’s research is based around the study of the ancient geomagnetic field through its record preserved in rocks and archaeological materials. He is particularly interested in understanding if, when, and how long term variations in the field’s behaviour tie in with simultaneous changes in conditions in the Earth’s core and mantle. In his spare time, Andy enjoys reading, gaming, eating/drinking out, watching rugby league (Leeds Rhinos in particular) and spending time with his son and with his wife – an English teacher and arts graduate who has little to no interest in geomagnetism.

Wed 24th July@ noon, Rm 312.222

Abstract:

The Araçuaí orogen (SE Brazil) is one of the largest (350,000 km²) and long-lived (ca. 630 – 480 Ma) granitic province in the world. It was formed by the convergence between the Congo (Africa) and São Francisco (Brazil) cratons during the assembly of West Gondwana. Currently, two models are used to explain its origin. The first one suggests a long-lived pre-collisional subduction-related magmatism (630 – 580 Ma) followed by a collisional stage. The other model proposes a hot orogeny with a limited pre-collisional subduction. These models are mostly based on the investigation of the Galiléia batholith (15.000 km²), a weakly deformed, medium- to high-K calc-alkaline metaluminous body (0.97 < A/CNK < 1.07) characterized mostly by tonalites and granodiorites, and representing the core of this orogeny. Although these rocks have been extensively studied, the widespread coexistence of grossular-rich garnet and epidote, uncommon minerals in these type of granites, have never been investigated. A similar fate has been reserved for the geochronological and isotopic character of these rocks. In this talk I will present field, geochemical and isotopic results, these lasts obtained from garnets, zircons, titanite and apatite crystals. Garnet and epidote of magmatic origin suggest crystallization in a deep crust (≥ 25 km). Garnet crystals have δ¹⁸O values resembling a meta-igneous source and are characterized by a positive Eu/Eu* anomaly, in contrast to their granitic host. High-precision CA-ID-TIMS and LA-MC-ICPMS U-Pb zircon dating showed that for each sample, the age variability of magmatic zircon reach up to 50 Ma, spanning the entire lifetime of the batholith (ca. 630 – 580 Ma), with emplacement age at 581 ± 0.4 Ma. Together with their rather crustal εHf signature, we suggest that these granitoids were likely originated through a petrological cannibalism where each new magma batch was able to re-melt the former one up to batholith crystallization at 581 Ma. Titanites having ages of 576 ± 2 Ma suggest further 5 Myrs to cross the solidus while apatites showing different ages between the centre of the batholith (532 ± 17 Ma) and its easternmost part (510 ± 26 Ma) indicate different cooling histories. Overall, we suggest that the Galiléia batholith was assembled in the lower crust during the orogenic stages of the West Gondwana and experienced a slow cooling history (ca. 4 °C/Ma) consistent with models indicating that the Araçuaí orogen is a hot orogeny which experienced limited pre-collisional subduction.

 

Short bio:

Francesco Narduzzi was born in Italy in 1985. He obtained his BSc (2009) and MSc (2012) in mantle petrology at the Department of Geoscience of the University of Trieste. In February 2018, through a joint PhD agreement between the Department of Geology of the Universidade Federal de Ouro Preto, Minas Gerais, Brazil and the Department of Earth Science of the University of Stellenbosch, South Africa he obtained a double doctorate degree in Crustal Evolution and Natural Resources. Since November 2018 is a post doctorate fellow at the Instituto de Astronomia, Geofísica e Ciências Atmosféricas of the University of São Paulo, Brazil. Currently his main research regards the time constraints, redox conditions and sediment sources attending the Proterozoic rise of atmospheric oxygen in Brazil. Of his particular interest is the possible relationship between Proterozoic subaerial Large Igneous Provinces, Snowball Earth’s periods and the rise of atmospheric oxygen.

Wed 17th July @ noon, Rm 312.222

Abstract:

The Western Branch of the East African Rift System is known to have a thick lithosphere and sparse, alkaline volcanism associated with a metasomatized mantle source. Recent work investigating the relationship between Western Branch metasomatized mantle xenoliths and associated lavas has suggested that these metasomes are a significant factor in the evolution of the rift. Hydrous/carbonated fluids or silicate melts are potent metasomatic agents, however gaining insight into the source of a metasomatic agent proves challenging. Twenty-four silica-understaturated potassic lavas from the Virunga province in the Western Branch yield potential insight into metasomatic processes within their olivine hosted melt inclusions. These data are used in concert with B isotope analyses of associated metasomatized mantle xenoliths in an attempt to distinguish the driver of metasomatism in the area. Elevated volatile concentrations, anomalously negative B isotope ratios, and trace element evidence suggest two plausible sources of metasomatic agents – fluids evolved during paleo-subduction, and fluid exsolved from the melting of a mantle plume entraining old subducted material. These scenarios have implications for the long-term storage of volatiles within the lithosphere and may suggest prior metasomatism is a factor in driving rifting.

 

Short bio:

Born in Michigan, B.S. in Geology from Michigan State University in 2010, PhD in Geology from the University of Michigan 2015, Assistant Professor at the University of Puerto Rico. Other than playing around with rocks I enjoy making instruments out of kitchen utensils.