SNSF | P3 Research Database

Fluid inclusions; hydrothermal; experimental; synthesis; fluid; thermodynamic properties

English title	Physicochemical properties of crustal fluids in fluid inclusions
Applicant	Diamond Larryn W.
Number	111834
Funding scheme	Project funding (Div. I-III)
Research institution	Institut für Geologie Universität Bern
Institution of higher education	University of Berne - BE
Main discipline	Geochemistry
Start/End	01.07.2006 - 30.06.2008
Approved amount	310'171.00

Lead

Lay summary
SNSF Project "Physicochemical properties of crustal fluids in fluid inclusions" Evidence from minerals and their enclosed fluid inclusions has shown that huge quantities of hot water have circulated though the rocks of the Earth's Crust for more than 3 billion years. In order to understand the resulting rock-water interaction, we must know the basic physical and chemical properties of groundwaters at high temperatures and under high pressures. Pure water is well characterised but water in the Crust is never pure; it most commonly contains some dissolved mineral salts (e.g.sodium-chloride, NaCl) and some gases, usually carbon-dioxide (CO2). The presence of these dissolved constituents radically changes the properties of water, especially its chemical reactivity. Despite numerous scientific studies in the past, our knowledge of such "impure" water is still far from complete. This lack of information motivates our research into two aspects of CO2- and NaCl-bearing water in this project. First, we conduct experiments in which we reproduce the extreme pressures and temperatures that prevail deep within the Earth' Crust. We subject fluid mixtures to these conditions and measure some of their properties (volumes and stability limits). We would have to conduct many thousands of such experiments if we wanted to cover all the interesting situations in nature and in potential environmental applications, but our lifetimes would be too short for this task. Therefore, we are also following a second approach in which we develop mathematical equations (known as "equations of state") that correlate, interpolate and predict the fundamental properties of the deep groundwaters, based on what we learn from our experiments. This combination of methods, we hope, will provide us with the missing information we need. Our results will be useful to several kinds of scientists: to geologists investigating how metallic ore-deposits form and how more deposits can be discovered, to environmental geochemists looking for solutions to CO2-sequestration, geothermal energy exploitation and toxic- and radioactive-waste disposal, and to chemists working on a variety of high-pressure industrial processes.