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Title: Geology and geothermal resources of the Rexburg Area, eastern Idaho

Abstract

A brief description of major Cenozoic geologic features of the Rexburg area and a discussion of their geothermal significance are presented. The study area, identified as having geothermal potential, is approximately circular, about 55 km across, and centered on the town of Rexburg. It is roughly coextensive with a complex of about eight calderas of Pliocene age, here named the Rexburg caldera complex. These calderas were the source of several major rhyolitic volcanic deposits present along the southeast margin of the eastern Snake River Plain. The geology of this area was previously mapped in reconnaissance (Prostka and Hackman, 1974) and much of it as remapped in detail in 1977 because of its recognized geothermal potential.

Authors:
;
Publication Date:
Research Org.:
Geological Survey, Denver, CO (USA)
OSTI Identifier:
6369347
Report Number(s):
USGS-OFR-78-1009
ON: DE83902374
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; IDAHO; GEOLOGY; GEOTHERMAL RESOURCES; CALDERAS; MAPPING; VOLCANIC REGIONS; FEDERAL REGION X; NORTH AMERICA; RESOURCES; USA; Geothermal Legacy; 150201* - Geology & Hydrology of Geothermal Systems- USA- (-1989); 150101 - Geothermal Energy- Resources & Availability- USA- (-1989)

Citation Formats

Prostka, H.J., and Embree, G.F. Geology and geothermal resources of the Rexburg Area, eastern Idaho. United States: N. p., 1978. Web. doi:10.2172/6369347.
Prostka, H.J., & Embree, G.F. Geology and geothermal resources of the Rexburg Area, eastern Idaho. United States. doi:10.2172/6369347.
Prostka, H.J., and Embree, G.F. Sun . "Geology and geothermal resources of the Rexburg Area, eastern Idaho". United States. doi:10.2172/6369347. https://www.osti.gov/servlets/purl/6369347.
@article{osti_6369347,
title = {Geology and geothermal resources of the Rexburg Area, eastern Idaho},
author = {Prostka, H.J. and Embree, G.F.},
abstractNote = {A brief description of major Cenozoic geologic features of the Rexburg area and a discussion of their geothermal significance are presented. The study area, identified as having geothermal potential, is approximately circular, about 55 km across, and centered on the town of Rexburg. It is roughly coextensive with a complex of about eight calderas of Pliocene age, here named the Rexburg caldera complex. These calderas were the source of several major rhyolitic volcanic deposits present along the southeast margin of the eastern Snake River Plain. The geology of this area was previously mapped in reconnaissance (Prostka and Hackman, 1974) and much of it as remapped in detail in 1977 because of its recognized geothermal potential.},
doi = {10.2172/6369347},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 1978},
month = {Sun Jan 01 00:00:00 EST 1978}
}

Technical Report:

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  • Water samples were collected from 31 wells and springs in eastern Idaho and western Wyoming to help evaluate the potential geothermal resources in the Teton River area, Idaho. The water analyses included the common anions and cations, oxygen-18, deuterium, and several minor elements. Actual temperatures of the sampled thermal waters ranged from 23 to 49/sup 0/C. Estimated aquifer temperatures, as derived from geochemical thermometers, ranged from 45 to 145/sup 0/C based on silica concentrations and 45 to 205/sup 0/C based on sodium-potassium-calcium ratios. Using the cation thermometer, two analyses indicated aquifer temperatures that were lower than the actual measured temperatures.more » Estimated temperatures using a mixing-model method ranged from 205 to 320/sup 0/C, the higher temperature being of questionable value. The different methods used to estimate aquifer temperatures showed little correlation. On the basis of isotope data, the warm waters may be of local meteoric origin and have not been heated enough to react significantly with the aquifer rocks, or they originated as precipitation at high altitude and great distance from the area.« less
  • Lawrence Livermore Laboratory (LLL) is studying ways in which the environmental quality of The Geysers-Calistoga known geothermal resources area may be protected from any significant harmful consequences of future geothermal development. The LLL study includes the effects of development on air and water quality, geology, the ecosystem, socioeconomics, and noise. The Geothermal Resource Impact Projection Study (GRIPS) has grants to undertake similar work. On 28 and 29 November 1977, LLL and GRIPS jointly sponsored a workshop at Sonoma State College at which knowledgeable earth scientists presented their views on the potential geological hazards of geothermal development. The workshop produced recommendationsmore » for studies in geological mapping, slope stability, subsidence, seismicity, and groundwater hydrology. These recommendations will be evaluated along with other considerations and in conjunction with the other subjects of the LLL study. The results of the study will be contained in a preplanning report of final recommendations to the Department of Energy.« less
  • This open-file report presents the results of the Santiam Pass drilling program. The first phase of this program was to compile all available geological, geophysical and geothermal data for the Santiam Pass area and select a drill site on the basis of these data (see Priest and others, 1987a), A summary of the drilling operations and costs associated with the project are presented in chapter 1 by Hill and Benoit. An Overview of the geology of the Santiam Pass area is presented by Hill and Priest in chapter 2. Geologic mapping and isotopic age determinations in the Santiam Pass-Mount Jeffersonmore » area completed since 1987 are summarized in chapter 2. One of the more important conclusions reached in chapter 2 is that a minimum of 2 km vertical displacement has occurred in the High Cascade graben in the Santiam Pass area. The petrology of the Santiam Pass drill core is presented by Hill in chapter 3. Most of the major volcanic units in the core have been analyzed for major, minor, and trace element abundances and have been studied petrographically. Three K-Ar ages are interpreted in conjunction with the magnetostratigraphy of the core to show that the oldest rocks in the core are approximately 1.8 Ma. Geothermal and geophysical data collected from the Santiam Pass well are presented by Blackwell in chapter 4. The Santiam Pass well failed to penetrate beneath the zone of lateral groundwater flow associated with highly permeable Quaternary volcanic rocks. Calculated geothermal gradients range from about 50[degree]C/km at depth 700-900 m, to roughly 110[degree]C/km from 900 m to the bottom of the well at 929 m. Heat-flow values for the bottom part of the hole bracket the regional average for the High Cascades. Blackwell concludes that heat flow along the High Cascades axis is equal to or higher than along the western edge of the High Cascades.« less
  • This open-file report presents the results of the Santiam Pass drilling program. The first phase of this program was to compile all available geological, geophysical and geothermal data for the Santiam Pass area and select a drill site on the basis of these data (see Priest and others, 1987a), A summary of the drilling operations and costs associated with the project are presented in chapter 1 by Hill and Benoit. An Overview of the geology of the Santiam Pass area is presented by Hill and Priest in chapter 2. Geologic mapping and isotopic age determinations in the Santiam Pass-Mount Jeffersonmore » area completed since 1987 are summarized in chapter 2. One of the more important conclusions reached in chapter 2 is that a minimum of 2 km vertical displacement has occurred in the High Cascade graben in the Santiam Pass area. The petrology of the Santiam Pass drill core is presented by Hill in chapter 3. Most of the major volcanic units in the core have been analyzed for major, minor, and trace element abundances and have been studied petrographically. Three K-Ar ages are interpreted in conjunction with the magnetostratigraphy of the core to show that the oldest rocks in the core are approximately 1.8 Ma. Geothermal and geophysical data collected from the Santiam Pass well are presented by Blackwell in chapter 4. The Santiam Pass well failed to penetrate beneath the zone of lateral groundwater flow associated with highly permeable Quaternary volcanic rocks. Calculated geothermal gradients range from about 50{degree}C/km at depth 700-900 m, to roughly 110{degree}C/km from 900 m to the bottom of the well at 929 m. Heat-flow values for the bottom part of the hole bracket the regional average for the High Cascades. Blackwell concludes that heat flow along the High Cascades axis is equal to or higher than along the western edge of the High Cascades.« less
  • Demand for ground water in the 600-square-mile Bruneau study area has also increased since 1954 because of the agricultural development. Declining flow at Indian Bathtub spring is adversely affecting a unique species of snail that inhabits the spring. The purpose of the third phase of the study, described in this report is to determine the cause or causes of declining flow at Indian Bathtub Spring. The third phase, completed in 1992, included (1) evaluating all available information about the regional geothermal aquifer system; (2) describing the geohydrology of the Bruneau study area, including ground-water recharge, discharge, movement, and hydraulic head;more » and (4) determining the effects of discharge from wells on hydraulic heads and spring flows in the study area.« less