Improvements in Geothermometry. Final Technical Report. Rev

摘要

Alkali and alkaline earth geothermometers are useful for estimating geothermal reservoir temperatures, though a general theoretical basis has yet to be established and experimental calibration needs improvement. Equilibrium cation exchange between feldspars provided the original basis for the Na-K and Na-K-Ca geothermometers (Fournier and Truesdell, 1973), but theoretical, field and experimental evidence prove that neither equilibrium nor feldspars are necessary. Here, evidence is summarized in support of these observations, concluding that these geothermometers can be expected to have a surprisingly wide range of applicability, but that the reasons behind such broad applicability are not yet understood. Early experimental work proved that water-rock interactions are slow at low temperatures, so experimental calibration at temperatures below 150 exp 0 is impractical. Theoretical methods and field data were used instead for all work at low temperatures. Experimental methods were emphasized for temperatures above 150 exp 0 C, and the simplest possible solid and solution compositions were used to permit investigation of one process or question at a time. Unexpected results in experimental work prevented complete integration of the various portions of the investigation. (ERA citation 08:053841)