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TitleThe persistence of brines in sedimentary basins
AuthorFerguson, G; McIntosh, J C; Grasby, S E; Hendry, M J; Jasechko, S; Lindsay, M B J; Luijendijk, E
SourceGeophysical Research Letters vol. 45, issue 10, 2018 p. 4851-4858,
Alt SeriesNatural Resources Canada, Contribution Series 20170385
PublisherAmerican Geophysical Union
Mediapaper; on-line; digital
File formatpdf; html
Subjectssedimentology; geochemistry; hydrogeology; sedimentary basins; brine; geological history; burial history; depositional history; fluid dynamics; bedrock geology; lithology; sedimentary rocks; evaporites; traps; groundwater; groundwater movement; groundwater regimes; groundwater geochemistry; sea water geochemistry; salinity; driving force ratio; flushing rates; Phanerozoic
Illustrationsmodels; geoscientific sketch maps; profiles; bar graphs; graphs
ProgramGeothermal Energy, Geoscience for New Energy Supply (GNES)
Released2018 05 08
AbstractBrines are commonly found at depth in sedimentary basins. Many of these brines are known to be connate waters that have persisted since the early Paleozoic Era. Yet questions remain about their distribution and mechanisms for retention at depth in the Earth's crust. Here we demonstrate that there is insufficient topography to drive these dense fluids from the bottom of deep sedimentary basins. Our assessment based on driving force ratio indicates that sedimentary basins with driving force ratio > 1 contain connate waters and frequently host large evaporite deposits. These stagnant conditions appear to be relatively stable over geological time and insensitive to factors such as glaciations, erosion, compaction, and hydrocarbon generation.
Summary(Plain Language Summary, not published)
Sedimentary basins in Canada can have a strategic value for isolating fluids and wastes from the atmosphere and more active parts of the hydrosphere. These basins have received large volumes of produced waste water from the oil and gas industry, and have more recently become targets for carbon sequestration and nuclear waste storage. Demonstration that fluids in deep sedimentary basins are stable over geologic time scales thus becomes critical to assessing waste storage proposals (e.g. ~1 million years is a requirement for nuclear waste based on radioactive half lives of critical nuclides). We developed a novel methods to assess long-term stability of deep basin fluids. The findings demonstrate the potential for long-term sequestration of wastewater and anthropogenic CO2 in deep basins and provide insight into the maximum depth of low TDS groundwater in sedimentary basins.