The Role of Structural Geology in Exploration Risk Assessment

Nov 18th 2016: Dr. Patricia F. Allwardt

Dr. Susan Kidwell - William Rainey Harper Professor of Geosciences, University of Chicago

Sponsored by John-Paul Zonneveld and Atlas

Dead shells do tell tales: Evaluating human impacts using the youngest fossil record

Biologists and the public increasingly appreciate the many ways that humans interact with natural systems, mostly to the detriment of wild species and habitats. However, data are difficult to acquire for more than a few select species and for the past several decades to centuries that are needed to recognize change, discriminate between natural and human drivers, and establish natural baseline conditions. Field work, experiments, and modeling are revealing that death assemblages - the actively accumulating shells and bones encountered in present-day seabeds and landscapes - are remarkably reliable sources of historical ecological information at precisely these scales despite the perils of skeletal destruction and 'time-averaging'. Paleontologists are now testing this approach in a large range of settings to develop it as a standard method for the toolkit of conservation biologists and environmental managers. Such studies turn uniformitarianism upside-down - we are applying earth science methods to very young fossil records to better understand modern-day biota. The effort to get a mechanistic understanding of death assemblage preservation is, however, also yielding insights relevant to deep-time records and to the long-term burial and recycling of biogenic carbonates.

http://geosci.uchicago.edu/people/susan-kidwell/

Understanding Variability in Glacier Behavior in a Changing Climate

March 31, 2017: Dr. Ellyn Enderlin

Talk abstract:

Over the last two decades, atmospheric and oceanic warming have driven increases in surface meltwater runoff and iceberg discharge from the Greenland Ice Sheet. Although spatial and temporal variations in surface meltwater runoff can largely be explained by changes in air temperature, the link between iceberg discharge variability and climate change is relatively poorly understood.
The over-arching goal of my research is to develop an improved understanding of the relative influence of changing air and ocean temperatures as well as the internal controls of glaciers, such as geometry, on iceberg discharge. Using remotely-sensed ice thickness and velocity observations, I've shown that spatial and temporal variations in iceberg discharge have resulted in large variability in the contribution of individual glaciers to sea level rise since 2000. My ongoing research projects use a combination of in situ and remotely sensed data to investigate potential explanations for the observed variability. In this presentation I will focus on one aspect of my ongoing research projects: ice-ocean interactions. Specifically, I will show how repeat stereo satellite images can be used to quantify spatial and temporal variations in glacier submarine melting. I will also show how a variety of remotely sensed datasets can be combined to assess the influence of changing ice-ocean interactions on iceberg discharge and the freshwater fluxes from the mélange of icebergs, bergy bits, and sea ice in Greenland's glacial fjords. The results of these ongoing analyses support the need for the continued development of novel observational techniques and interdisciplinary research efforts to improve predictions of glacier change and the associated impacts on the Earth system.

Biography:

Ellyn Enderlin is a Research Assistant Professor at the University of Maine. She completed her Ph.D. research under the supervision of Dr. Ian Howat (Glacier Dynamics Group, Byrd Polar and Climate Research Center) in 2013. Since then, she has been working at the University of Maine Climate Change Institute. Ellyn's research projects focus on combining remotely-sensed and in situ observations and numerical ice flow modeling to develop a better understanding of the environmental triggering mechanisms and internal controls of marine-terminating glacier behavior (i.e., glacier dynamics). Ellyn is particularly interested in glacier-ocean interactions, namely submarine melting and iceberg calving, and how changes in these interactions influence the rate of mass loss from the fast-flowing glaciers that drain the Greenland and Antarctic ice sheets. Ellyn is co-chair of the US national committee for the Association of Polar Early Career Scientists (USAPECS). For more information about Ellyn Enderlin, visit her website: https://sites.google.com/site/ellynenderlin/home.

Cratonic surface histories, kimberlites, and mantle dynamics

Dr. Rebecca Flowers - University of Colorado

The Grace Anne Stewart Speaker Series is excited to announce Dr. Rebecca Flowers as our distinguished speaker for the fall of 2017. Dr. Flowers will be visiting the department Oct. 26-27, with her keynote address at noon on Friday the 27th.

Research Interests: Dr. Flowers focuses on understanding how deep Earth and surface processes are coupled over hundreds of millions of years. She employs field observations, geochronology, and thermochronology to address a wide variety of research problems. In particular, she has recently employed (U-Th)/He geochronology to the study of kimberlite emplacement ages, the age of formation of the Grand Canyon, and the reconstruction of large impact basins.

Biography: Dr. Flowers is an Assistant Professor at the University of Colorado, Boulder. She completed her Ph.D. at MIT and a postdoc at Caltech, before serving as a Humboldt Research Fellow at the University of Tubingen, Germany. She has received various awards, including the prestigious NSF CAREER award for junior faculty, and has served on both the EarthScope and Mineralogical Society of America Distinguished Lecturer programs.

Exploring Planetary Differentiation through an Isotopic Lens

Dr. Anat Shahar, Carnegie Institution of Washington

February 9, 2018

The Grace Anne Stewart Speakers Series is excited to announce that Dr. Anat Shahar from the Carnegie Institute will be visiting our Department February 9. She will be delivering a keynote address at noon, but we invite all members of the department to chat with her over lunch or to sign up for a private meeting.

Abstract:

Planetary differentiation occurred at high temperature, high pressure, varying oxygen fugacity and on bodies with varying compositions. The specific conditions at which bodies differentiated can be probed and the chemical fingerprints of that differentiation can be found in stable isotope ratios measured today in natural samples. Experiments are key to understanding the mechansims behind the fractionations seen in nature as the pressure, temperature and compositional space can be interrogated systematically. In this talk I will focus on how pressure, temperature and composition affect the partitioning of isotopes between metal and silicate. In particular I will focus on whether experiments can explain the isotopic signatures found in rocks on Earth and if the light element in the core has left a fingerprint on the isotopic ratios in the mantle.

Biography:

Dr. Shahar received her PhD at UCLA and is currently a Staff Scientist at the Geophysical Laboratory at the Carnegie Institution of Washington. She is a Fellow of the Mineralogical Society of America and has received numerous awards including excellence in teaching awards and the prestigious Clarke Medalist from the Geochemical Society.

Ecological Networks: The Impacts of Invasion on Paleocommunity Dynamics

Dr. Carrie Tyler

March 16, 2018

The Grace Anne Stewart Speakers Series is excited to announce that Dr. Carrie Tyler from Miami University (Oxford, Ohio) will be visiting our Department March 16. She will be delivering a keynote address at noon, but we invite all members of the department to chat with her over lunch or to sign up for a private meeting. Please email the stewartspeakerseries@gmail.com for more information.

Abstract:

The fossil record documents dramatic ecosystem changes that can be used to understand how and why past ecosystems have changed. But can we use paleocommunities as an analog for modern communities? In this talk, after assessing the reliability of the fossil record, we will examine the effects of invasion on marine paleocommunities by comparing modeled food web structure, stability, and resilience during the Late Ordovician. We find that the growing consensus is that skeletal remains and fossil assemblages can be used to evaluate changes in ecosystems today. Thus, our findings have important consequences for conservation and management efforts, as they suggest that (1) invasion led to destabilization and loss of resilience, and (2) that functional richness may play a more critical role in long-term ecosystem stability and persistence than biodiversity.

Biography:

Dr. Tyler is an Assistant Professor at Miami University in Oxford, Ohio. She received her Ph.D. in Geosciences at the Virginia Tech and completed a post-doctoral fellowship at the Florida Museum of Natural History, University of Florida. She currently holds two NSF grants investigating the biotic interactions of echinoids, and modelling community complexity and stability through periods of biotic escalation and community disturbance.

Research Interests:

Dr. Tyler is a palaeobiologist, conducting research which investigates processes governing the distribution, palaeoecology, and evolution of marine invertebrates, the role of taphonomy and the fidelity of the fossil record in the development of macro-evolutionary and macro-ecological models, the application and development of quantitative palaeontological methods, morphometrics and functional morphology of marine invertebrates, and ecosystems response to and recovery from perturbation.

Mining waste environments: globally significant and growing biogeochemical hotspots ,

Dr. Lesley Warren, Lassonde Institute of Mining, University of Toronto

November 23, 2018

Talk abstract: Globally, extractive industries are estimated to produce 7.2 billion tons of waste and use 7-9 billion m of water; creating one of the fastest growing and least well studied biogeochemical contexts on the planet. Tailings, containing reactive sulfur, iron, nitrogen and carbon compounds, represent the largest global mining environmental liability. Currently, it is difficult for mines to design tailings impoundments or develop effective management and reclamation approaches, because the microbial processes that generate impacts remain a black box. However, as mining landscapes continue to grow world-wide, the fundamental lessons learned in these contexts are also required to better inform our understanding of global biogeochemical cycling. Here, I will present results from both metal and oil sands mining contexts, where we have begun to address this knowledge gap through the joint application of genomics and geochemistry. Research to date provides fascinating glimpses of extensive and often surprising biogeochemical cycling within these environments, as well as distinctive microbial communities that interactively shape biogeochemical outcomes.

Research interests Dr. Warren holds the Claudette MacKay-Lassonde Chair in Mineral Engineering and is the director of the Lassonde Institute of Mining. She is an applied geochemist and molecular microbiologist. Her main focus is applying emerging molecular biological techniques to mining contexts to explore the roles of bacteria in affecting water quality. This research information produced develops new tools to enhance environmentally sound practices in the mining industry.

71 (combined) years as a woman in the field: Perspectives as student, academic, industry, and government geoscientists

Dr. Chris Schneider and Dr. Georgia Hoffman

Tuesday April 3rd, 2018, 5PM, ESB 1-23

Professional Development Seminar:
71 (combined) years as a woman in the field: Perspectives as student, academic, industry, and government geoscientists
The Grace Anne Stewart Speaker Series will be holding a discussion-based question-and-answer session about what it is like to be a woman and a professional geoscientist. The guest speakers will be Georgia Hoffman and Chris Schneider and the seminar will be held in ESB 1-23 at 5 pm on Tuesday, April 3rd. This session will count as Professional Development hours for graduate students who attend. Please email the stewartspeakerseries@gmail.com for more information.

Biographies:
Chris Schneider received B.A. degrees in geology and archaeology from the University of Minnesota in 1999 and a Ph.D. in geology from the University of Texas at Austin in 2003. After that, she spent 5 years in postodoctoral positions and visiting assistant professorships at Cornell College, Appalachian State University, California State University at Bakersfield, University of California, Davis, and Colorado College. On moving to Canada, she worked three years at the Alberta Geological Survey as a carbonate stratigrapher, leaving that job to return to teaching by becoming sessional for one semester at the University of Alberta. Chris is currently a geological specialist for Beryl Mining Company, currently under contract to Suncor, and is an adjunct professor in Earth and Atmospheric Sciences. Chris's research includes geohazards and carbonate stratigraphy beneath the oil sands, mass extinction survivorship with relevance to creating successful marine protected areas, and climate change effects on marine intertidal ecosystems.

Georgia Hoffman received a B.A. in geology from the University of Pennsylvania in 1970. She then moved to Alberta and began an M.Sc. in geology at the University of Alberta, but when a summer job mapping coal deposits in the foothills turned into a permanent job, she began a career in industry. She has worked for a variety of mining companies, energy companies, and consulting companies, and in 1995 she completed an M.Sc. in Biological Sciences (Paleobotany) at the U of A. Most recently, she has worked for Beryl Mining Company under contract to Suncor, and for Aeon Paleontological Consulting Ltd.

Winter 2019 Talk: Tungsten-182 anomalies in terrestrial rocks: Evidence for core-mantle chemical interaction?

Dr. Hanika Rizo, Carleton University

Friday, March 15th, 2019 - Explore the world of extinct isotopes in terrestrial rocks

Core-mantle chemical interaction is a topic that has been hotly debated for decades. While physical (e.g. thermal) interactions across the core-mantle boundary suggest chemical exchange is also expected, it is generally assumed that the Earth's core has been chemically isolated since its formation. This is because unequivocal geochemical evidence for this exchange has been difficult to find. The short-lived 182Hf-182W isotope system (t1/2=8.9 Ma) has always been considered to have potential to provide evidence for this process. This is because the W concentration and 182W isotopic composition of the core and the mantle can be assumed significantly different. Since W is siderophile and Hf is lithophile, core-mantle differentiation led to significant differences in the W concentration of these reservoirs. Since this differentiation occurred during the lifetime of the Hf-W system, the extinct isotope 182Hf decayed into 182W entirely in the mantle, leaving the core with an unradiogenic 182W isotopic composition. Thus, any core material "leaking" into the mantle could be detected in the 182W isotopic composition of magmas associated with deep mantle plumes. In this seminar, I will present and discuss 182W data for Hadean and Archean mantle-derived rocks that together with 182W data recently obtained in ocean island basalts, might provide the most compelling evidence to date that mantle plumes carry a core geochemical signature.

Research Interests: Hanika's research interests are primarily focused on early earth geochemical processes. Hanika uses extinct isotopic systems, 182Hf-182W and 146Sm-142Nd, to understanding the timing and extent of metal segregation into earths core, the crystallization of earths magma ocean, and the effect of meteoritic bombardment on the silcate earth between 4.5 and 3.9 Ga.

Fall 2019 Talk: The Carbonaceous Chondrite Record of Icy Planetesimals

Dr. Myriam Telus, University of California, Santa Cruz

Friday, October 18, 2019
Atlas Talk: Noon, Tory 3-36
Meet the Speaker: 1PM, Tory 3-36

Abstract

Carbonaceous chondrites show evidence for significant water-rock alteration that is thought to have occurred within ice-rich planetesimals. In this presentation, I will review our current understanding of the formation and evolution of icy planetesimals. In particular, I focus on my recent work on understanding the composition and formation conditions of Ca-carbonates in CM chondrites (Telus et al., 2019, GCA). These minerals formed via direct precipitation from the fluid and/or water-rock interactions in the parent asteroid. To understand the formation conditions of carbonates in CM chondrites, the C and O isotopic composition of Ca-carbonates and the O isotopic composition of magnetite were measured. I also discuss whether our data support current carbonaceous chondrite parent body models and how this work relates to current asteroid exploration missions.

November 22, 2019: Industry and Government Panel Discussion and Networking Session

Featuring Guest Speakers:

• Astrid Arts, Cenovus Energy
• Karen Fallas, Geological Society of Canada
• Dr. Gabrielle Gascon, Environment and Climate Change Canada
• Sheri Gilmour, Stantec Consulting Ltd.
• Dr. Carolyn Relf, Yukon Geological Survey

12:00 - 1:00 pm; Tory 3-36
ATLAS talk with Dr. Carolyn Relf: Evaluating Yukon's Geothermal Potential

5:00 - 6:30 pm; Tory 3-36
Industry and Gov't Panel: Diversity and Professional Development in the
Geosciences (PD hour for Grad. Students))

6:30 - 8:30 pm; Faculty Club
Networking Session, Wine & Cheese

Linking Deep Earth Processes and Surface Systems

July 2, 2020, Dr. Sally Gibson Webinar

Abstract: My research is inspired by a passion to understand how large-scale geodynamic processes in Earth’s deep interior impact on its surface systems. This has involved petrographic and geochemical analysis of samples collected during field campaigns in Large Igneous Provinces (Paraná-Etendeka, Deccan and Tertiary North Atlantic Igneous Provinces), continental rift zones (Rio Grande, Baikal, East Africa) and ocean islands (Galápagos and Trindade) together with studies of mantle xenoliths and kimberlites. Much of the ongoing activities of my research group unify these long-held interests, and focus oncombining micro-scale observations with in-situ analyses of volatiles in basalts and mantle xenoliths to improve constraints on the global cycling of elements that are vital to life and our planet’s habitability. One of the major goals is to quantify the concentrations and distributions of H 2 O, F, Cl, Li, and CO 2 in Earth’s subcontinental mantle so that we can place more robust constraints on the role that this large and ancient reservoir plays in modulating the flux of volatiles from its deep interior to its atmosphere via volcanism. Our findings suggest that the re-mobilisation of volatiles stored in pyroxene-rich regions of the lithospheric mantle -- e.g. during the formation of Large Igneous Provinces in the geological past and continental rift zones at the present-day -- may be a particularly important driver of environmental change.

download poster (pdf)

Isotopic evidence for multiple recycled sulfur reservoirs in the Mangaia mantle plume

August 6, 2020: Dr. James Dottin III Webinar

Zoom link: https://zoom.us/j/92695930400

Abstract: Earth’s mantle is geochemically characterized with long-lived radiogenic isotopes of Sr, Nd, and Pb that define four geochemical endmember reservoirs (DMM, EM I, EM II, and HIMU). HIMU (High μ= ²³⁸U/²⁰⁴Pb) is a reservoir that is thought to form from the recycling altered oceanic crust that was carbonated upon mixing with the peridotitic mantle. Mangaia, an island in the Cook-Austral suite, is the type locality in the Pacific Ocean for HIMU that has also been shown to exhibit evidence for recycled anomalous sulfur of Archean origin. In this seminar, I will discuss a project in which I (and Co-authors) revisit Mangaia with high precision analyses of sulfide inclusions in olivine and pyroxene minerals separates and test for the prevalence Archean sulfur in the HIMU mantle source feeding Mangaia. We aim to constrain the nature of HIMU and use sulfur isotope compositions of Mangaia basalts to provide insight into of mixing of multiple melt sources. From the data we are able to highlight (1) a newly identified recycled endmember composition at Mangaia that is likely younger than the source linked to reservoir that hosts Archean sulfur and (2) isotopic disequilibrium among mineral separates from the same sample that suggests mixing of sulfur from two sources that were captured at different stages of crystallization.

download poster (pdf)

Enabling Inclusive Geoscience Field Experiences through Technology and Collaborative Strategies

September 9, 2020: Dr. Anita Marshall

The Grace Anne Stewart Speaker Series will be hosting our next webinar next week! We will be hosting Dr. Anita Marshall from the University of Florida on Wednesday, September 9 at 11:00AM MDT (18:00 GMT +1). Dr.Marshall is well known for her advocacy for disabilities in geoscience and will be speaking on Enabling Inclusive Geoscience Field Experiences through Technology and Collaborative Strategies. We highly recommend this seminar and discussion for both faculty and students in EAS. 

Frontiers of clumped isotopes in paleoceanography and paleoclimatology

October 8, 2020: Dr. Aradhna Tripati

Seasons in Titan's lower stratosphere

Thursday, January 21 at 11:00AM (MDT): Dr. Melody Sylvestre

Abstract:

Titan hosts a dense atmosphere mainly composed of nitrogen and methane. It features a rich photochemical activity mainly initiated by solar UV photons, which produces many hydrocarbons, nitriles and ultimately organic hazes. During its 29.5 years revolution around the Sun, Titan’s atmosphere undergoes significant seasonal and latitudinal variations of insolation which can affect its photochemistry and its dynamics.

The Cassini mission (2004-2017) allowed to monitor Titan’s atmosphere from its northern winter to its summer solstice. Mid-IR (9-17 microns) spectroscopic observations from the Cassini/CIRS measurements showed clear seasonal changes in temperature and abundance of photochemical species, especially in the upper stratosphere and mesosphere (120 – 600 km). However, seasonal changes in the lower stratosphere (50 – 120 km) are not well known.

In this seminar, I will present investigations of Titan’s lower stratosphere using Cassini/CIRS far-IR spectra (17 - 1000 microns). I will discuss the seasonal temperature and composition changes in this region and show how they can help us to understand chemical and dynamical processes of Titan’s atmosphere.

Past as prologue: how archives help us predict the fate of Earth’s ice sheets and the future of our discipline

Thursday, February 4 at 11:00AM (MDT): Dr. Benjamin Keisling

Abstract:
The Greenland ice sheet is losing mass at a rate that is unprecedented in the observational record, threatening accelerated sea-level rise in coastal areas around the globe. To understand the processes and mechanisms driving present day ice-loss, I look to the past by employing cosmogenic isotopes as an archive of ice-sheet change and use them to evaluate numerical ice-sheet model experiments. This demonstrates how critical archives are to contextualizing change and building a roadmap toward addressing ongoing crises like climate change. Then, to underscore this principle, I analyze conference reports and professional correspondence from the 1970s to problematize the popular understanding of why geoscience lacks diversity and offer archive-informed ways forward.