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Title: The Newcastle geothermal system, Iron County, Utah

Geological, geophysical and geochemical studies contributed to conceptual hydrologic model of the blind'' (no surface expression), moderate-temperature (greater than 130{degree}C) Newcastle geothermal system, located in the Basin and Range-Colorado Plateau transition zone of southwestern Utah. Temperature gradient measurements define a thermal anomaly centered near the surface trace of the range-bounding Antelope Range fault with and elongate dissipative plume extending north into the adjacent Escalante Valley. Spontaneous potential and resistivity surveys sharply define the geometry of the dominant upflow zone (not yet explored), indicating that most of the thermal fluid issues form a short segment along the Antelope Range fault and discharges into a gently-dipping aquifer. Production wells show that this aquifer lies at a depth between 85 and 95 meter. Electrical surveys also show that some leakage of thermal fluid occurs over a 1.5 km (minimum) interval along the trace of the Antelope Range fault. Major element, oxygen and hydrogen isotopic analyses of water samples indicate that the thermal fluid is a mixture of meteoric water derived from recharge areas in the Pine Valley Mountains and cold, shallow groundwater. A northwest-southeast trending system of faults, encompassing a zone of increased fracture permeability, collects meteoric water from the recharge area, allowsmore » circulation to a depth of 3 to 5 kilometers, and intersects the northeast-striking Antelope Range fault. We postulate that mineral precipitates form a seal along the Antelope Range fault, preventing the discharge of thermal fluids into basin-fill sediments at depth, and allowing heated fluid to approach the surface. Eventually, continued mineral deposition could result in the development of hot springs at the ground surface.« less
Authors:
; ;  [1] ; ; ;  [2]
  1. (Utah Geological and Mineral Survey, Salt Lake City, UT (USA))
  2. (Utah Univ., Salt Lake City, UT (USA). Dept. of Geology and Geophysics)
Publication Date:
OSTI Identifier:
6931402
Report Number(s):
DOE/ID/12756-1
ON: DE90010574
DOE Contract Number:
FG07-88ID12756
Resource Type:
Technical Report
Research Org:
Utah Geological and Mineral Survey, Salt Lake City, UT (USA)
Sponsoring Org:
DOE/CE
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; GEOTHERMAL FIELDS; HYDROLOGY; ELECTRIC CONDUCTIVITY; FLUID FLOW; GEOLOGIC FAULTS; GEOLOGY; GEOPHYSICAL SURVEYS; GROUND WATER; HEAT TRANSFER; HOT SPRINGS; MATHEMATICAL MODELS; PROGRESS REPORT; TEMPERATURE GRADIENTS; TEMPERATURE MEASUREMENT; DOCUMENT TYPES; ELECTRICAL PROPERTIES; ENERGY TRANSFER; GEOLOGIC FRACTURES; GEOLOGIC STRUCTURES; HYDROGEN COMPOUNDS; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SURVEYS; THERMAL SPRINGS; WATER; WATER SPRINGS Geothermal Legacy 150200* -- Geology & Hydrology of Geothermal Systems