Deep groundwater circulation and associated methane leakage in the northern Canadian Rocky Mountains |
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| Institution: | 1. Geological Survey of Canada, Natural Resources Canada, 3303 33rd St. NW, Calgary, AB T2L 2A7, Canada;2. Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada;3. Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada;1. CIEMAT, Department of Environment, Av. Complutense, 40, 28040 Madrid, Spain;2. Amphos21 Consulting S.L., Pg. Garcia-Fària 49, 08019 Barcelona, Spain;3. Andra, R&D Division, 1-7 rue Jean Monnet, 92298 Châtenay-Malabry, France;1. Sri Jayewardenepura University, Faculty of Applied Science, Department of Forestry and Environmental Science, Gangodawila, Nugegoda, Sri Lanka;2. Uva Wellassa University, 90000 Badulla, Sri Lanka;3. Department of Geology, Faculty of Science, University of Peradeniya, Sri Lanka;4. Department of Physical Sciences, Faculty of Applied Sciences, South Eastern University, Sri Lanka;1. Metti Consulting Company, Pittsburgh, PA, USA;2. Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA;3. Department of Psychiatry, University of California San Francisco, San Francisco, CA, USA;4. Department of Neurology, University of California San Francisco, San Francisco, CA, USA;5. Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA;6. Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA;7. Laboratory of Epidemiology, Demography and Biometry, National Institute on Aging, Bethesda, MD, USA;8. Department of Psychology, University of Pittsburgh, Pittsburgh, PA, USA;9. Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA;10. Department of Internal Medicine, Wake Forest University, Medical Center Boulevard, Winston-Salem, NC, USA;11. Division of Pediatric Rheumatology, University of Pittsburgh School of Medicine, UPMC Children''s Hospital of Pittsburgh, Pittsburgh, PA, USA;12. Department of Pediatrics and Immunology, University of Pittsburgh School of Medicine, UPMC Children''s Hospital of Pittsburgh, Pittsburgh, PA, USA;1. Institute of New Energy, Sinopec Star Petroleum LTD., Beijing, 100083, China;2. China National Research and Technology Center of Geothermal Energy, Beijing, 100083, China;3. Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China;4. University of Chinese Academy of Sciences, Beijing 100049, China;5. School of Geosciences, Yangtze University, Wuhan, 430100, China;1. School of Science and Technology, Geology Section, Università di Camerino, via Gentile III da Varano 7, 62032 Camerino MC, Italy;2. School of Science and Technology, Chemistry Section, Università di Camerino, via S. Agostino 1, 62032 Camerino MC, Italy;3. Geothermal Center of Excellence, Enel Green Power SpA, via Andrea Pisano 120, 56126 Pisa, Italy;4. C.N.R. (Italian Council for Research), Istituto Geoscienze e Georisorse, via G. Moruzzi 1, 56124 Pisa, Italy |
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| Abstract: | Concern over potential impact of shale gas development on shallow groundwater systems requires greater understanding of crustal scale fluid movement. We examined natural deeply circulating groundwater systems in northeastern British Columbia adjacent to a region of shale gas development, in order to elucidate origin of waters, depths of circulation, and controls on fluid flow. These systems are expressed as thermal springs that occur in the deformed sedimentary rocks of the Liard Basin. Stable isotope data from these springs show that they originate as meteoric water. Although there are no thermal anomalies in the region, outlet temperatures range from 30 to 56 °C, reflecting depth of circulation. Based on aqueous geothermometry and geothermal gradients, circulation depths up to 3.8 km are estimated, demonstrating connection of deep groundwater systems to the surface. Springs are also characterised by leakage of thermogenic gas from deep strata that is partly attenuated by methanotrophic microbial communities in the spring waters. Springs are restricted to anomalous structural features, cross cutting faults, and crests of fault-cored anticlines. On a regional scale they are aligned with the major tectonic features of the Liard Line and Larsen Fault. This suggests that while connection of surface to deep reservoirs is possible, it is rare and restricted to highly deformed geologic units that produce permeable pathways from depth through otherwise thick intervening shale units. Results allow a better understanding of potential for communication between deep shale gas units and shallow aquifer systems. |
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| Keywords: | Shale gas Thermal spring Methane leakage |
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