GRC 2003: Great Basin Geothermal GIS

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The Important Role of Grass-Roots Exploration in
Expanding the Use of Geothermal Energy in the
Great Basin, USA
Mark Coolbaugh Great Basin Center for Geothermal
Energy University of Nevada, Reno
Funding DOE Financial Assistance Award
DE-FG36-02ID14311 and University of Nevada, Reno
Applied Research Initiative Grant
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METHODS OF INCREASING GEOTHERMAL ENERGY
PRODUCTION
1) Improved Economics (energy prices,
transmission grid) 2) Improved Technology -
plant efficiencies - Engineered Geothermal
Systems (EGS) 3) Political/Regulatory Changes
- tax benefits - acceleration of lease
auctions 4) Increased/Improved Exploration -
known geothermal areas - grass-roots or green
fields exploration
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Two Types of Exploration
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• When resources are challenging to find, but
  rewarding when they are found, grass-roots
  exploration can be a major player
• - oil and gas
• - gold, copper, and other metals
• - geothermal systems
• This is especially true in Great Basin. Why
• - many resources are hidden or blind
• - they can occur over a very large area
• - their precise location is difficult to predict

Tungsten Mountain concealed geothermal system
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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
Many geothermal systems remain to be
discovered. Geothermal activity occurs over a
large part of the G.B. Quaternary faults occur in
all valleys
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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Regional predictive tools can help narrow the
search, but much prospective ground remains to be
explored
www.unr.edu/geothermal
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Many High-Temperature geothermal systems in Great
Basin are blind at the surface
Deep water tables, near-surface impermeable cap
rocks, and laterally flowing groundwater in
aquifers can prevent hot springs from forming at
the surface
Desert Queen area, NV. A near boiling aquifer
lies 70 m below ground with no surface expression
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Blind geothermal system at Teels Marsh, Mineral
County, Nevada
Quaternary strike-slip fault
Displaced landslide toe
Temperatures are as high at 65C (150F) at 9.5
meters below surface, with no surface expression
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Playa fed by geothermal groundwaters -
temperature up to 67C (153C) at 12 in. below
surface - no thermal springs or vents are
present
Salt Wells, NV.
85C (185F) at 1 meter depth
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The mining industry is full of examples where
grass roots (green fields) exploration has
transformed and dramatically increased the known
resource base

• 1) Diamond pipes, Canada and Russia
• 2) Roll-front uranium deposits, Wyoming
• 3) IOCG deposits (Olympic Dam, Australia)
• 4) Closest to Home Gold Mines in Nevada
• - 40 M oz in 100 years (1860-1960)
• - 120 M oz in next 36 yrs (1960-2006)
• - worlds 3rd largest Au producer in 2003
• - HOW?
• - grass-roots exploration
• - new deposit model (Carlin-type gold
  deposits)
• - also old deposit models (Sleeper, Midas,
  Round Mountain)

Round Mountain
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The geothermal industry in the Great Basin is
particularly ripe for such a grass-roots
transformation

• 1) Rising Energy Prices
• 2) Rising Environmental Concerns
• 3) Accelerated Lease Auction Process
• 4) Higher plant efficiencies since last
  exploration boom
• 5) Critical Mass with additional discoveries,
  justification
• for improving the transmission network
  increases
• 6) Improved Exploration Tools

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New or Improved Exploration Tools

• 1) Digital Mapping Techniques
• 2) Remote Sensing
• - InSAR, LIDAR
• 3) Shallow Temperature Measurements
• 4) Geodesy and GPS Measurements
• 5) Digital Databases, GIS-based spatial analysis
• see Monastero and Coolbaugh, GRC2007

GPS station
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New ideas and concepts

• 1) Structural Reservoir Models
• - relationship to plate tectonics
• 2) Lower Temperature Threshholds
• 3) Geothermal Occurrence Models
• - Such as those of Sabin, Monastero
• 4) New types of reservoirs
• - EGS stimulated?

From Faulds et al., 2006
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The best evidence that hidden geothermal
resources remain to be discovered in the Great
Basin many significant discoveries are being
made now, even though grass-roots geothermal
exploration is still in its infancy
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McGinness Hills (information generously provided
by NewCrest Resources and Tom Kilbey)
- exploration gold drilling to 1200 ft in 2004
steam encountered - 600 meter diameter
sinter terrace chalcedony and opal -
quartz-adularia veins beneath sinter dated at
3.2-2.2 Ma
There are additional occurrences of young
surficial opal and chalcedony in Nevada that have
not been drilled.
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Bedded sinter, McGinness Hills
Water samples yield geothermometers Drill-hole
25 214C (417F) Na-K-Ca-Mg 151C (304F)
quartz Drill-hole 26 209C (408F)
Na-K-Ca-Mg 193C (379F) quartz analyzed in 2006
at NBMG
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Tungsten Mountain discovered during Au
exploration drilling in 2005,
2006 (information provided courtesy NewCrest
Resources, Tom Kilbey) - northwest side of
Edwards Creek Valley, Nevada - geothermal
system occupies possible step-over in range
bounding fault

• All 23 exploration holes hit hot water, with
• temperatures ranging from 50-95C, often with
  steam, at
• depths of 300-900 ft
• Hot water encountered over 2 km strike length,
  open in
• all directions

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Tungsten Mountain thermal area, looking
northeast across drilled area
Drill pad, hole 23
Deep water from last hole drilled yielded
geothermometer temperature estimates Drill-hole
23 85C (185F) water at TD of 605 ft (180 m)
174C (345F) Na-K-Ca-Mg 177C (351F)
quartz analyzed in 2006 at DRI
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Tufa tower near Astor Pass, Pyramid Lake Paiute
Reservation - near-boiling water (94C) at 200
ft depth beneath tower - other than the tufa,
there are no other surface geothermal
indicators - a strong shallow temperature
anomaly is present
Needle Rocks 6 km away
Discovered during reconnaissance geothermal
exploration - young northwest-striking
faults extending from Needle Rocks -
argillic alteration in adjacent Terraced Hills
- tufa tower
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Smoke Creek Desert, Pyramid Lake Paiute
Reservation - discovered during
reconnaissance geothermal exploration
large sulfate anomaly detected with
hyperspectral imagery
systematic spring and well sampling program
Estimates of geothermal reservoir temperature
148-165C (298-329F)
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Pyramid Lake Paiute Reservation
Pyramid Rock - boiling spring - 153C
(307F) geothermom ( 15 miles from Needle Rocks)
There are other poorly documented occurrences of
hot water in the Great Basin that have not been
evaluated
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Spring geotherm. Na-K-Ca-Mg 192C
(378F) Quartz 118C (244F)
65C (150F) at 9.5 m
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Teels Marsh
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Teels Marsh, looking southwest
Thermal anomalies
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Rhodes Marsh, Mineral County, NV. Red
strike slip fault Black normal fault
opalized sands
springs/wells
Warm well with borates 155C / 162C cation/qtz
geotherm. (311F/324F)
361 ppm Cl, 414 ppm SO4 sampled 2005
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Rhodes Marsh, Nevada
Opalized sands are exposed in small windows in
the piedmont colluvium over a distance of gt 2,000
ft
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Rhodes Marsh
Opalized sands
21.6C (70.9F) artesian well, borates 155/162C
NaKCaMg qtz geotherm (311/324F)
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The range front east of Rhodes Marsh is a site of
active faulting with apparently complex fault
geometries.
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Fernley
Hot well, 60C at depth, 32C in storage
tank 149C qtz 149C Na-K-Ca-Mg (300F)
geothermometers
Warm well, 29C in storage tank 145C qtz 132C
Na-K-Ca-Mg (293F qtz 270F Na-K-Ca-Mg) geothermo
meters
Intersection of Carson Lineament and Pyramid Lake
fault zone
34.0C (93F) warm spring
Lahontan Reservoir
Silver Springs
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CONCLUSIONS
1) Many undiscovered geothermal systems remain to
be found in the Great Basin - it is not likely
that limited research exploration by the
University of Nevada, Reno has found the only
ones 2) Grass roots exploration can play a
fundamental role in expanding the production of
geothermal energy
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The End