Regional Geologic Controls, Geochemical Characteristics, and Thermal Infrared Signatures of Geotherm

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Overview of Nevadas Geothermal Resources
Mark Coolbaugh, Lisa Shevenell Great Basin Center
for Geothermal Energy University of Nevada, Reno
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Geothermal system development in the broader
context of the evolution of the Great Basin
Great Basin 585
170
23
785
16
20
547
25
29
135
4
1,909
407
San Andreas 2,338
54
590
437
Installed Capacity (MWe) in Blue (2000 figures
from IGA)
Little recent volcanism in the Great Basin makes
our geothermal systems somewhat unique
Total 8,074
Adapted from Dr. Greg Arehart
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http//geology.er.usgs.gov/eastern/plates.html
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Two types of Geothermal Systems (Koenig and
McNitt, 1983 Wisian, Blackwell, Richards, 1999)
Magmatic Geothermal - associated with
very youthful silicic volcanism
Extensional Geothermal
Systems
- associated with regions of high heat flow
and recent faulting
Hot Creek, Mammoth, CA.
Bradys Hot Springs, NV.
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Modified from Flynn Schocket, 2001
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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Roosevelt/ Cove Fort
Mammoth
Coso
Boundary of Great Basin
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Faults from dePolo, NBMG
Trend Surface of Geothermal System Temperatures
Nevada is well-endowed with geothermal systems
and hot springs
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Map courtesy of Dave Blackwell, Southern
Methodist University http//www.smu.edu/geothermal
/
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Contribution of SHEAR to maximum extensional
crustal strain based on GPS measurements of
relative velocity vectors.
Figure provided courtesy of Blewitt et al., NBMG,
UNR
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Contribution of DILATION to maximum extensional
crustal strain based on GPS measurements of
relative velocity vectors.
Figure provided courtesy of Blewitt et al., NBMG,
UNR
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Rate of Extension Normal to Dominant Azimuth of
Faults Based on geodetic crustal strain
measurements, Blewitt et al., NBMG
Black lines are Quaternary faults compiled by C.
dePolo, NBMG
Quaternary faults occur throughout the state and
are associated with geothermal activity, but the
faults with higher rates of extension are
associated with higher temperature geothermal
systems.
Strain Rate Scale in Units 1 mm per yr / 1000 km
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Quakes (NV Seismo Lab)
Young Faults (NBMG/USGS)
Young Volcanics (USGS)
Heat flux (SMU)



Statistical Methods Weights-of-Evidence Logistic
Regression Fuzzy Logic
Depth to Groundwater (NWIS)
PZ Carbonates (NBMG)
Boron, Groundwater (NWIS)
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Increasing Favorability
7-Layer Density Function Model Weighted by heat
flux, earthquakes faults, volcanics, groundwater
chemistry, groundwater table, and Paleozoic
carbonate host rock.
Logistic Regression Map 5 Evidence Layers
Unaffected By Groundwater Phenomena Strain
rate, Young Faults, Young volcanics, Quakes,
Gravity
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PREDICTED CRUSTAL DENSITY OF UNDISCOVERED
GEOTHERMAL RESOURCES Coolbaugh Shevenell
Total geothermal resources in Nevada capable of
generating electricity may be 4-5 times the known
reserves
Dark areas have high predicted densities,
medium-red areas have moderately high predicted
densities, light red densities are relatively
low. Circles are known economic and sub-economic
geothermal systems.
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Temp Gradient from David Blackwell, SMU
INPUT MAPS
GPS Strain Rate From Geoff Blewitt
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The End