The Role of Fluids in Geological Processes
The role and behavior of fluids in hydrothermal and magmatic environments have been studied. Experimental studies have been carried out to determine fluid properties, in natural environments and in both synthetic and natural fluid and melt inclusions. One of these studies dealt with the effect of composition on the critical P-T-X properties of aqueous salt solutions approximated by the H2O-NaCl-KCl-CaCl2 system. The results indicate a systematic variation in critical properties as a function of composition over the range of P-T-X studied. A technique for analyzing individual H2O-CO2 inclusions using Raman spectroscopy has also been developed. The resulting empirical equation relating Raman intensities and composition is valid for compositions â ¤50mol% CO2. The technique has been applied to H2O-CO2 inclusions from the Butte, MT Porphyry Cu-Mo deposit and the results agree with compositions estimated from microthermometric and petrographic observations. The aim of another study was to study water loss from melt inclusions during laboratory heating. Melt inclusions had lost insignificant amounts of water when held at experimental conditions (800Â°C, 1 kbar) for â ¤24 hours. However, significant water loss was observed for longer duration experiments. Ocelli, which are globular bodies of felsic minerals are interpreted as products of magmatic melt immiscibility. As such, the carbonate aggregates in Cretaceous lamprophyres from Hungary with similar petrographic characteristics have also generally been interpreted to be products of magmatic immiscibility. Petrographic and geochemic studies have shown three three distinct genetic groups for these aggregates, none of which were consistent with a magmatic origin.
- Doctoral Dissertations