Abstract

The overthrust belt of Central Utah follows the boundary of the Basin and Range and Colorado Plateau geologic provinces-as such it is an area of complex geology, wide ranges of water chemistry, major changes in geophysical patterns, and has a large potential for hydrothermal resources. These hydrothermal systems are predominantly known in the transition zone or in the Basin and Range Province; few occur in geologic environments of the Colorado Plateau.

Hydrothermal systems require a source of heat, water to transfer the heat, and permeability for water movement. In central Utah, the low- and moderate-temperature hydrothermal systems (< 150°C) typically derive their heat from the regional heat flow, while volcanic input may be contributing to the heat of some high-temperature systems. The water is meteoric. Permeability is typically along faults and fractures, or possibly through stratigraphic horizons, at depth. Shallow circulation primarily along faults, with leakage commonly along alluvium-bedrock interfaces.

Measured temperatures of central Utah hydrothermal systems are as high as 269°C; chemical geothermometry indicates, however, that most systems are much cooler. Other chemical characteristics of their waters corroborate these results.

Central Utah is a region of major geophysical changes, reflecting the more igenous environment in its southern portion.

Understanding of the nature of central Utah hydrothermal systems has been greatly enhanced by the large number of geologic, geochemical, and geophysical exploration data sets that have been placed in the public domain, especially from the low-temperature Monroe Hot Springs system, and the high-temperature Roosevelt Hot Springs and Cove Fort-Sulphurdale systems.