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TitleWhat do aqueous geothermometers really tell us?
AuthorFergusson, G; Grasby, S E; Hindle, S R
Sourcegeofluids vol. 9, 2009 p. 39-48, (Open Access)
Alt SeriesEarth Sciences Sector, Contribution Series 20080515
Mediapaper; on-line; digital
File formatpdf
Subjectshydrogeology; geothermal resources; geothermometry; geothermal temperatures; geothermal surveys; geothermal research; heat flow; thermal springs; springs; groundwater; groundwater temperatures; models; modelling
Illustrationsgraphs; diagrams; tables; plots
ProgramSecure Canadian Energy Supply
AbstractThe application of chemical geothermometry to shallow groundwaters or spring discharge requires that that there is minimal mixing or re-equilibration of water as it travels from depth to the surface. In this study we examine the potential for mixing and re-equilibration by examining heat and fluid flow along crustal-scale faults in tectonic geothermal systems. Numerical modeling results indicate that in situ temperatures could be underpredicted by up to 35% due to mixing of fluids that enter the fault at different depths. This coupled with depression of isotherms by downward groundwater flow in the hanging wall could cause underestimates of maximum circulation depth of greater than 80% in extreme cases. Kinetics do not favour re-equilibration in the shallower portions of faults due to low temperatures and higher fluid velocities. However, in areas of deeper circulation or higher heat flow such reactions are possible.