Using Geodesy to Explore Correlations between Crustal Deformation Characteristics and Geothermal Res

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Using Geodesy to Explore Correlations between
Crustal Deformation Characteristics and
Geothermal Resources

• Corné Kreemer, Geoffrey Blewitt, William C.
  Hammond

Great Basin Center for Geothermal Energy Nevada
Bureau of Mines and Geology, University of
Nevada, Reno
Acknowledgement This project is funded by the
Department of Energythrough the Great Basin
Center for Geothermal Energy
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PROJECT PURPOSE

• Assess crustal strain rate as an exploration
  toolfor non-magmatic geothermal systems
• Geothermal systems in the Great Basin known to be
  associated with active faulting
• Which faults are good geothermal candidates?
• Role of style of faulting and rates of fault
  slip?
• Use GPS to map crustal strain rate (2-d tensor
  field)
• Understand correlations with known geothermal
  systems
• Understand its relationship with faulting
  directions/styles
• lt 1 mm/yr accuracy, 20 km spacing over 200 km
• Potential discovery of blind geothermal systems

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Geothermal Systems
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MAGNET
MobileArray ofGPS forNEvadaTranstension
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GPS INSTALLATION
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TIME-SERIES
RENO
CLAN
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TIME-SERIES
UPSA
UHOG
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TIME-SERIES
SLID
Transient strain at SLID inferred to be related
to a lower crustal magma intrusion underneath
Lake Tahoe in late 2003 Smith et al., 2004,
Science.
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GPS VELOCITIES
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STRAIN RATE TENSOR FIELD
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CENTRAL NEVADA SEISMIC BELT HISTORIC EARTHQUAKES
Hammond, Kreemer, Blewitt, submitted manuscript
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CORRECTED GPS VELOCITIES
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STRAIN RATE TENSOR FIELD
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STRAIN RATE TENSOR FIELD
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STRAIN RATE TENSOR FIELD
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STRAIN RATE TENSOR FIELD
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STRAIN RATE TENSOR FIELD
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STRAIN RATE TENSOR FIELD Lateral changes in styles
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STRAIN RATE TENSOR FIELD Transtension
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BLOCK MODELLING Transtension
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TECTONIC CONTROL ON GEOTHERMAL POTENTIAL ?

• Transtension is mainly found in transition
  between Walker Lane Shear and Basin and Range
  Extension. This area experiences high
  temperatures.
• In areas of transtension,
• a) shear is associated with strike-slip faulting
  through the entire crust and allows transports
  fluid and heat from great depths
• b) Dilitation is associated with normal
  faulting - sustains fluid flow by pulling
  fractures apart

Maximum Temperatures

• Plants at Dixie and Rye Patch are in extensional
  domain. Relationship between extension direction
  and fault orientation needs to be further
  explored there.

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OUTLOOK

• GPS position estimate repeatability 1-2 mm,
  horizontal 5 mm, vertical, conform
  expectations.
• Velocity field for long running sites is
  consistent with regional continuous sites, but
  2.5 yr of data is required we need more time
• Strain rate maps confirm correlation between
  transtensional strain and current geothermal
  output.
• Exceptions exist, e.g. Dixie Valley
• Relationships between strain and faulting
  orientations needs to be established
• Network needs to be expanded to provide better
  constraints to the south (e.g. Wabuska) and the
  Rye Patch and Pumpernickel Valley areas
• Reliable assessment of new areas with potential
  (blind) geothermal systems is expected for
  mid-2007.

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Thanks !