GRC 2003: Great Basin Geothermal GIS

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McGinness Hills Tungsten Mountain Astor
Pass Smoke Creek Desert Pyramid Rock Rhodes
Marsh Salt Wells north
Geothermal Exploration Short Stories in Progress
in Nevada, USA
Geothermal Exploration Technologies
Workshop Geothermal Resources Council Annual
Meeting San Diego, CA. Sept. 8, 2006
Mark Coolbaugh Great Basin Center for Geothermal
Energy University of Nevada, Reno
Funding U.S. Department of Energy, Assistant
Secretary Energy Efficiency and Renewable Energy
under DOE Golden Field Office Financial
Assistance Award DE-FG36-02ID14311
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• Disadvantage These stories are not complete (no
  production yet)
• Advantage All have been recently discovered
  (last 2 years)
• We can review the exploration methods that led to
  recognition of new geothermal resources today

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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
McGinness Hills
Roosevelt/ Cove Fort
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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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 Na-K-Ca-Mg 151C
quartz Drill-hole 26 209C Na-K-Ca-Mg
193C quartz analyzed in 2006 at NBMG
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Hydrothermal eruption breccia, McGinness Hills
sinter
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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Tungsten Mountain
Roosevelt/ Cove Fort
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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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

• Most of 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
Deep water from last hole drilled yielded
geothermometer temperature estimates Drill-hole
23 85C water at TD of 605 ft (180 m) 174C
Na-K-Ca-Mg 177C quartz analyzed in 2006 at DRI
Drill pad, hole 23
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Why was this area drilled? - small outcrop of
intense siliceous alteration along range
front - hydrothermal brecciation - anomalous
gold
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Other surface features - structurally
controlled tufa with vertical flow channels -
these same structures host chalcedony veins
Tufa
Discovery monument
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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Astor Pass
Roosevelt/ Cove Fort
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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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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Detailed gravity and magnetic surveys were used
for specific drill-hole targeting and played a
key role in the discovery
Temperatures in 2-meter-deep auger holes were
used to minimize the number of temperature
gradient wells drilled
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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Smoke Creek Desert
Roosevelt/ Cove Fort
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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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
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Shallow temperature measurements at 2-meter depth
helped pinpoint possible upwelling zone near
tufas at step-over in range front fault (orange
ellipse)
Smoke Creek Desert
Warmer colored squares indicate warmer
temperatures at a 2-meter depth
Purple remotely sensed gypsum anomaly
Yellow, orange, and red stars are warm and hot
wells and springs
Many tufa mounds in Nevada remain untested
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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Pyramid Rock
Roosevelt/ Cove Fort
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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Pyramid Lake Paiute Reservation
Pyramid Rock - boiling spring - 153C
geothermometers ( 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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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Roosevelt/ Cove Fort
Rhodes Marsh
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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Quaternary borate deposits in Nevada and Oregon
are closely associated with geothermal activity
Star geothermal system ? 150C Square
Quaternary borates Background colors B in
groundwater (warmer colors higher
concentrations)
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Many evaporites minerals, including borates and
sulfates, have distinctive reflectance spectra
mirabalite thenardite
gypsum (sulfate)
halite
mirabalite (sulfate)
tincalconite (borate)
thenardite (sulfate)
tincalconite
halite
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Rhodes Marsh, Mineral County, NV. Red
strike slip fault Black normal fault
Soda Springs, 112 geotherm.
X
Well, 146 / 148 geotherm. 1,830 ppm SO4,
sampled 1959
Active range front faulting
opalized sands
springs/wells
Warm well with borates 155 / 162 geotherm. 361
ppm Cl, 414 ppm SO4 sampled 2005
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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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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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Newberry Crater
Geothermal Systems in Nevada Great Basin, USA
Big Southern Butte
China Hat
Borax Lake
Medicine Lake
Roosevelt/ Cove Fort
Salt Wells
Mammoth
Current GB Geothermal Power Plant Capacity is
600 MWe
Coso
Boundary of Great Basin
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Detailed mapping of surface geothermal features
at Salt Wells has 1) identified faults that
control geothermal fluid flow 2) increased
awareness of a possible second upwelling
zone on the north end 3) identified surface and
near- surface hot waters on the north end
that can be sampled for geochemical
analysis
North End
South End (power plant under construction)
1 km
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Multiple faults with different strikes appear to
intersect at the northern end of the Salt Wells
geothermal system
Hot Springs
N
1 km
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Hot Springs and groundwater, north end, Salt
Wells, NV. geothermometers average 180C
57C
Borax Hot Spring, 81C
66C
85C at 1 meter depth
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CONCLUSIONS
1) Even in well explored areas, many additional
geothermal prospects remain to be discovered 2)
The discovery process is most efficient when all
available tools (geology, geochemistry,
geophysics) are appropriately used together
Successful production well, south end Salt Wells,
April 2005
Photo Brad Platt
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The End