AESRC 2023

Title: "Orogenic equity, diversity, and inclusion in a supercontinent"

The Grenville Orogeny has historically played a prominent role in our understanding of Mesoproterozoic tectonics to the point it has become broadly synonymous with the global convergence associated with the assembly of Rodinia. Although the majority of workers interpret the tectonics of the Grenville Orogeny as a continental collision with Amazonia, there are several persistent alternatives that propose either that the Mesoproterozoic was characterized by an orogenic quiescence or stagnant lid. Constraining the geodynamic evolution of the Grenville Orogeny and tectonic regime of the Mesoproterozoic Era are key in understanding the evolution of plate tectonics on Earth.

In this presentation, I will discuss some of the recent attempts to constrain the geodynamics and tectonic regime of the Grenville Orogeny and the assembly of Rodinia. Topics of particular interest include the flaws in constraining crustal thickness with zircon trace elements, the proportion of sediment-derived granitoids as defined by oxygen isotopes, and the evaluation of terrane transfer during continental collision using Pb isotopes. All things considered, the Grenville Orogeny carries the hallmarks of a hot collisional orogeny with a relatively thin crust, substantial sediment-magma interaction, and the transfer of tectonically emplaced terranes.

Title: "Critical metal distributions in VMS deposits: The role of sulfide modification during hydrothermal activity, deformation, and metamorphism"

Critical minerals (CMs) are a diverse group of metals and minerals, characterized by important roles in modern and green technologies and potentially at-risk supply chains. Volcanogenic massive sulfide deposits host a variety of critical minerals (CMs) and other trace elements, but modification of sulfides during hydrothermal activity and subsequent deformation and metamorphism can significantly alter their primary distributions. This has major implications for exploration programs targeting CMs, and for their efficient extraction from primary ores and re-processed waste rock.

By combining in-situ microstructural and compositional mapping, we show that CMs are hosted by a range of different sulfides, and that these sulfides responded to deformation and metamorphism at greenschist-facies conditions in drastically different ways. Pyrite is largely unstrained, preserving primary hydrothermal textures, with both early CM-poor low-T pyrite and slightly later, high-T hydrothermal pyrite rich in Co and other CMs, which likely reflects a magmatic input during the main mineralization stage. Pyrrhotite is highly strained, with a moderate decrease in Co content linked to dynamic recrystallization and the local growth of cobaltite. Gallium and Ge occur in coarse hydrothermal sphalerite, but Ga was locally lost by diffusion along grain boundaries, and in sphalerite-free samples, Ga and Ge are hosted by synkinematic chlorite. Indium and Sn are concentrated in hydrothermal chalcopyrite, but it is not yet clear how they were affected by fluid-assisted remobilization of chalcopyrite into porphyroclast tails during deformation. Silver and Pb are concentrated along grain boundaries in dynamically recrystallized pyrrhotite and sphalerite, either introduced by fluids during deformation and/or expelled from the recrystallizing sulfides.

Title: "Trace metal cycling in the Great Lakes: sources, sinks, and biogeochemical controls"

The Environmental Engineering group in the department of Geological Sciences and Engineering at Queen's is working to improve our understanding of trace metal dynamics in the Great Lakes. The North American Great Lakes form a critically important yet complex, serially connected freshwater system. Disentangling the natural and anthropogenic drivers of water quality in the basin is important to manage and mitigate stresses imposed by e.g., climate change and urbanization. In this talk, I will present a high-level overview of our work on i) environmental baselines of metals and trace elements, ii) the biogeochemical processes underlying their spatiotemporal distribution patterns, and iii) potential imprints of human emissions in specific catchments. First, we collaborate with provincial and federal offices to aggregate long-term and basin-scale hydrodynamic and water quality monitoring data. From a selection of >20.000 entries, we recently developed mass-balance models to estimate metal loads carried by tributary rivers, connecting channels, and sedimentation. In addition, we performed field sampling in several Ontario catchments and used analysis of Cu stable isotopes to source-track anomalous metal loads. Finally, we are using metal occurrence in wastewater as a proxy for large-scale human emissions. Trace element analyses in effluent and sludge samples from >40 treatment facilities in the Great Lakes basin were combined with geospatial analyses of their respective sewersheds to assess human emissions and potential impacts from the tributary- to the basin scale. Overall, our work on trace metal biogeochemistry helps improve our understanding of the Great Lakes system and optimize surveillance and management strategies.

Title:“Coastal cliff rock stability and geotourist perceptions at Hopewell Rocks Provincial Park, New Brunswick"

Natural shoreline rock formations such as sea stacks, arches, and cliffs are unique geotourism destinations in Canada and globally. These formations, such as at Hopewell Rocks Provincial Park in New Brunswick, Canada, form when the rockmass erodes and becomes prone to partial or complete structural failure. Many geotourists visiting these formations (>250,000 per year at Hopewell Rocks) elevate the potential for failure events to cause casualties. Failure events always raise questions about the duration and extent of safety zone delineation and access control. This research aims to evaluate public safety risk of exposure to failure of these rock formations at the Park. This research draws on perspectives from rock mechanics, structural geology, and engineering geology to understand the geohazards and their instability behaviours, as well as insight from psychology and sociology that drive geotourism and human risk perceptions. To date, we have investigated two rockfall events at the Park: the 14 March 2016 Elephant Rock failure and the 5 September 2021 cliff rockfall near Lover’s Arch. We have also analyzed the stability of the Sentinel sea stack using geomechanical numerical models, with input from UAV-based photogrammetry and erosion records, to predict when this formation may become unstable. Lastly, we conducted a public survey and interviews with Park visitors to understand how they value the Hopewell Rocks, and risk perceptions on rock instability. The survey results show support for the idea that New Brunswickers have a strong positive connection to the Hopewell Rocks, and range of risk perceptions of personal safety balanced with a desire to preserve nature. This presentation will present a summary of these investigations and show a glimpse of our ongoing research at the Park.

Biography:

Dr. McLagan is the PI of the Fire, Earth, Water, Air Contaminant Biogeochemistry Lab (FEWA Lab) began as an Assistant Professor in Environmental Geochemistry in July 2022, jointly appointed between the Dept. of Geological Sciences and Geological Engineering and the School of Environmental Studies. Before this he worked as term-based lecturer at the University of Toronto, and as a researcher at the Technical University of Braunschweig in Germany, and also at Environment & Climate Change Canada. He gained a PhD. from the University of Toronto and Bachelor of Science with honours from Griffith University in Australia. Dr. McLagan’s research uses a total systems approach to improving our understanding of contaminant biogeochemical cycling in the environment with a focus on developing novel, accessible technologies that produce direct, tangible impacts on science, society and the environment.

Ryan’s career path has been unusual and sometimes a bit weird. He finished his PhD at Queen’s in 2015, where he worked in carbonates and geochemistry. Since graduating, he has been a sometimes-successful entrepreneur, a postdoctoral researcher, a craft beer brewer, an exploration geologist in the mining industry, an instructional designer for online health science courses, head of a small Ag-tech startup, an adjunct assistant professor, and a geotechnical consultant. Most people have a planned career trajectory, but Ryan’s experience more closely resembles a hike through the bush without a map or a compass or an actual final destination. He does have great company and good snacks, though.

Lindsay completed a BScH in Environmental Geology at Queen’s before pursuing a MSc in Structural Geology with Dr. Laurent Godin. Since graduating in 2015, Lindsay has worked in academia, exploration geology, with the Nuclear Waste Management Organization, and, most recently, in geotechnical consulting. Lindsay works for BGC Engineering based out of the office here in Kingston. She works with the rock mechanics and engineering geology teams and is currently the site investigation lead for the Pueblo Viejo project in the Dominican Republic. Lindsay lives in Kingston with her husband, Ryan, and their wildling ex-street dog, Lentil. Her favourite food is tacos, and her favourite dinosaur is the Archaeopteryx.