Electronic Thesis and Dissertation Repository

Thesis Format

Monograph

Degree

Master of Science

Program

Geology

Collaborative Specialization

Planetary Science and Exploration

Supervisor

Osinski, Gordon

2nd Supervisor

Nigel, Blamey

Co-Supervisor

Abstract

Impact-generated hydrothermal systems result from interactions between a permeable substrate, an impact-generated heat source, and fluids (e.g., H2O). A comprehensive understanding of the evolution of these terrestrial features has significant implications in the search for habitable environments on Mars, a focus in the emerging field of astrobiology. This thesis presents a detailed case study of the impact-generated hydrothermal alteration of impactites at the Clearwater West impact structure, Quebec, focusing on hydrothermally precipitated quartz vugs in crater-fill impact melt rocks. Sample analysis included optical microscopy, electron microprobe analysis, mass spectrometry, and fluid inclusion microthermometry. Results show 3 main quartz mineralization stages: 1) > 384°C, 2) 382 to 246°C, and 3) 243 to 120°C. Gas analysis indicated volatile sources were primarily atmospheric, with some mixing of local magmatic and crustal sources. This research provides insight into water preservation on Mars and the significance of impact-generated hydrothermal systems for extraterrestrial microbial life.

Summary for Lay Audience

Hydrothermal systems that form in large impact craters (impact-generated hydrothermal systems), through a process involving heat and water, can produce conditions suitable for life. The required heat and rock fracture networks that allow for fluid flow are produced during the initial collision and the water is sourced from the surrounding area (e.g., groundwater, permafrost, lakes, oceans). As hot water circulates through the fractured rocks, many minerals begin to materialize, trapping small amounts of local water and volatiles present. These pockets of fluids, known as fluid inclusions, are essentially small time-capsules of the conditions in which they formed. Fluid inclusions can therefore be used to study temperature, salinity, and volatile content of their parent fluid and assess the habitability of this environment for resilient microbes, such as thermophiles and hyperthermophiles. Investigating such environments on water-bearing rocky bodies, such as Mars, poses a significant challenge. Consequently, studying and using impact-generated hydrothermal systems on Earth as analogues for extraterrestrial surfaces is currently the only avenue for scientific investigation. This thesis provides a case study on the impact-generated hydrothermal system located in the 286-million-year-old Clearwater West impact crater, Quebec, Canada. This impact structure stands as one of the most well-preserved large complex impact structures on Earth. Samples of hydrothermal quartz vugs and associated fluid inclusions were analyzed to contribute to the understanding of: 1) the thermal and fluid evolution of impact-generated hydrothermal systems, 2) their implications for past Mars environments, and 3) their potential role in fostering habitable environments for life. This research provides insight into the preservation and characteristics of water on Mars and the significance of impact-generated hydrothermal systems for extraterrestrial microbial life. Quartz minerals from such systems can, and should, be used in our search for extinct, and perhaps extant, extraterrestrial life across the solar system.

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