Doctor of Philosophy

dissertationDiagenetic variables (e.g., microbial influence, sediment composition and fluid chemistry) are investigated to determine the effects on iron redox reactions and iron (oxyhydr)oxide nucleation, cement textures, mineralogy and chemistry. Three individual examinations are conducted in the Colorado Plateau, USA: 1. reservoir fluid chemistry in a natural fossil CO2 reservoir in the Jurassic Navajo Sandstone exposed in Justensen Flats in the northern San Rafael Swell, 2. concretion formation in the reactive, volcaniclastic Jurassic Brushy Basin Member of the Morrison Formation, and 3. comparative microbial influences in the precipitation of iron (oxyhydroxides) in a modern Ten Mile Graben spring system and the Brushy Basin Member. Bulk geochemistry in a lithologically controlled, iron (oxyhydr)oxide reaction front in Justensen Flats shows that the precipitating fluid in the reservoir was likely a CO2- and hydrocarbon-charged fluid and that CO2 injection into a saline reservoir would result in dolomite precipitation and significantly reduce porosity. Chemical and physical concretion comparisons in the Brushy Basin Member show that reactants are moving via fluid flow in porous host rocks and producing uniform concretion morphologies and mineralogies. In reactive Brushy Basin Member claystone and siltstone lithofacies, reactants are being sourced from abundant ashes reacting with groundwater to create localized diagenetic microenvironments and produce variable concretion mineralogies and morphologies. Variability of fluids on regional to outcrop scales and lithologically controlled fluid flow and cement precipitation in permeable reservoirs furthers the science of carbon capture and sequestration. Comparison of modern and 100ka microbial iron (oxyhydr)oxides in tufas at the Ten Mile Graben spring system shows that biosignatures exhibit some degradation and recrystallization on millennial time scales, although biotic features are clearly recognizable. Microbial fossils in the Brushy Basin Member are associated with macroscopic biotic features such as charophyte molds. Biogenic iron (oxyhydr)oxides in modern tufas and Jurassic rocks exhibit two distinct elemental suites that function as biosignatures: 1. C, Fe, and As, and 2. C, S, Se. Biogeochemical markers provide diagnostics for depositional environment, fluid chemistry and potential microbial fossils and/or biosignatures to aid in the exploration of similar iron- and clay-rich sediments on Mars in Gale Crater

Magmatic Intrusions into the Sulfur-Rich Carmel Formation on the Colorado Plateau, USA: Implications for the Mars 2020 Mission

We report on basaltic dikes in the Colorado Plateau, which crosscut sulfate bearing sediments and compare this to Martian basalts and basaltic sediments in contact with sulfate mineralizations

Alteration and Oxidiation of an Olivine Lamprophyre Dike from Southern Utah, USA: An Analog for Mars

We report on oxidized basaltic dike intrusions on the Colorado Plateau as analog for Martian basalt oxidation

Magmatic intrusions into sulfur-rich sediments on the Colorado Plateau: an analog for Mars exploration

Mafic magmatism is a prevalent geologic process on Earth, and is a principal source of subsurface geologic change and energy influx on postNoachian Mars. While rare on Earth, the intrusion of mafic magmas into sulfur-rich soils and rocks is expected on Mars due to the observation of widespread high sulfur concentrations in Martian soils. On Mars, soils have been found to be rich in sulfur. Respectively, soil samples from Gusev Crater and Gale Crater contain between 4-8 weight percent, and 4-7 weight percent SO3, though ammounts[sic] as high as 31 weight percent have been measured in Gusev crater. With widespread sulfur-rich sediments and evidence of magmatism both ancient and young, mafic intrusions into rocks and sediments bearing significant quantities of sulfur species is expected on Mars. Processes associated with the magmatic intrusion of a sulfur-rich host, including degassing and alteration, may provide the requisite energy and nutrients for biological activity.On Earth, well exposed mafic dikes intrude the sulfur-rich sedimentary formations of the Jurassic San Rafael Group. Approximately 200 dikes, sills, and breccias can be found in proximity to the San Rafael Swell in Utah, and represent an Earth analog for a scenario of mafic magma intruding sulfur-rich sediments. Here we will investigate such an analog; a mafic dike intruding the sulfur-rich Jurassic Carmel Formation of the San Rafael Group

Super-orbital re-entry in Australia - laboratory measurement, simulation and flight observation

There are large uncertainties in the aerothermodynamic modelling of super-orbital re-entry which impact the design of spacecraft thermal protection systems (TPS). Aspects of the thermal environment of super-orbital re-entry flows can be simulated in the laboratory using arc- and plasma jet facilities and these devices are regularly used for TPS certification work [5]. Another laboratory device which is capable of simulating certain critical features of both the aero and thermal environment of super-orbital re-entry is the expansion tube, and three such facilities have been operating at the University of Queensland in recent years[10]. Despite some success, wind tunnel tests do not achieve full simulation, however, a virtually complete physical simulation of particular re-entry conditions can be obtained from dedicated flight testing, and the Apollo era FIRE II flight experiment [2] is the premier example which still forms an important benchmark for modern simulations. Dedicated super-orbital flight testing is generally considered too expensive today, and there is a reluctance to incorporate substantial instrumentation for aerothermal diagnostics into existing missions since it may compromise primary mission objectives. An alternative approach to on-board flight measurements, with demonstrated success particularly in the ‘Stardust’ sample return mission, is remote observation of spectral emissions from the capsule and shock layer [8]. JAXA’s ‘Hayabusa’ sample return capsule provides a recent super-orbital reentry example through which we illustrate contributions in three areas: (1) physical simulation of super-orbital re-entry conditions in the laboratory; (2) computational simulation of such flows; and (3) remote acquisition of optical emissions from a super-orbital re entry event

Radiation measurements in a simulated non-terrestrial atmosphere

A high-speed wind tunnel has been used to experimentally simulate the flow experienced by a capsule entering a planetary atmosphere. High speed photography showed that a steady test time of approximately 50 μs existed in the facility. Holographic interferometry has been performed to measure the twodimensional density distribution around a cylinder in the flow. A peak density ratio (density normalised by the free-stream density) of about 14 was observed. Emission spectroscopy allowed the characterisation of the conditions along the stagnation streamline in front of the capsule model. The results showed a temperature that varied between 8,500 K and 11,000 K in this region

Simulation of CO2–N2 expansion tunnel flow for the study of radiating bluntbody shock layers

A 25MJ/kg CO2–N2 expansion tunnel condition has been developed for the X2 impulse facility at the University of Queensland. A hybrid Lagrangian and Navier–Stokes computational simulation technique is found to give good correlation with experimentally measured shock speeds and pressure traces. The use of an inertial diaphragm model for describing secondary diaphragm rupture is found to estimate between 4% and 25% more CO2 recombination over the test time than the widely accepted holding-time model. The obtained freestream conditions are assessed for application to proposed bluntbody spectroscopy and subscale aeroshell experiments. The chemically and vibrationally excited freestream test gas is found to prevent exact thermochemical similarity from being achieved, and the strong radiation–flowfield coupling characteristic of Mars aerocapture conditions cannot be reproduced experimentally

Assessing Graduate Teaching Development Programs for Impact on Future Faculty

Long-term training programs for teaching assistants have greater impactTraining programs for university teaching assistants (TAs) improve the quality of teaching and learning. But a new HEQCO study of short and long-term training programs at two Ontario universities finds that while both make important contributions, long programs had a greater impact.Assessing Graduate Teaching Development Programs for Impact on Future Faculty was conducted at the University of Windsor and Western University, whose teaching and learning centres offer a wide range of TA training programs -- short, orientation-style conferences and longer, intensive workshops throughout the year.Project descriptionThe study used self-reported measures of TAs’ attitudes to teaching and teaching self-efficacy before and after each program, combined with focus group interviews four months after program completion. The goal was to assess and compare the impact of the programs and to link specific types of programming to measurable outcomes. FindingsTeaching development programs help improve the teaching effectiveness of new TAs in a variety of ways, according to the study. TAs felt better prepared for their role as instructors after participating in training. Both short (one-day events) and long programs (20-40 hours) contributed to increased teaching self-efficacy and to an increase in student-focused approaches to teaching. The focus groups found that when TAs began to teach on their own, they were able to apply the teaching techniques, course design principles and student-focused approaches to teaching that they learn in TA training programs. Participants in short programs emphasized concrete teaching techniques for facilitating discussions, marking, asking effective questions and becoming more familiar with expectations for the teaching assistant role. Participants in longer programs demonstrated greater confidence in using principles of course design and alignment and articulating learning outcomes, and showed a greater depth of reflection on teaching. Long programs also created communities of TAs from a variety of disciplines, where discussion about teaching continued beyond the end of the program. Participants also shared innovative teaching techniques or course design strategies with their peers and with faculty members. The study found that both programs make an important contribution – but do so in different ways. Short programs serve as a gateway to further teaching development, allowing new graduate students to learn a few very practical teaching strategies and better understand the benefits of further training. Longer programs allow participants to build community and strategically prepare for careers in teaching, whether inside or outside academia.The authors note that it is important for teaching centres and departments to clearly communicate the differences between the outcomes of orientation-style and more in-depth programs.Further researchAddition research could explore long-term changes in TAs’ approaches to teaching after training, as well as the impact of TA training on student learning, say the authors, complementing the self-report measures used in this study with observer and student ratings of TA teaching in real classroom settings. Other HEQCO studies that explore teaching and TA development include a report on two University of Toronto TA training programs, a study of Western University’s international TA training programs and an overview of the evolution of teaching and learning centres in Ontario colleges and universities.Authors of Assessing Graduate Teaching Development Programs for Impact on Future Faculty are Nanda Dimitrov, Ken Meadows, Erika Kustra, Theimann Ackerson, Laura Prada, Nick Baker, Pierre Boulos, Gayle McIntyre and Michael K. Potter