Aeromagnetic Survey

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Exploration Technique: Aeromagnetic Survey

Exploration Technique Information
Exploration Group: Geophysical Techniques
Exploration Sub Group: Magnetic Techniques
Parent Exploration Technique: Magnetic Techniques
Information Provided by Technique
Lithology:
Stratigraphic/Structural: map structure, basin fill thickness, and magnetic mineral concentrations in ore bodies
Hydrological:
Thermal:
Cost Information
Low-End Estimate (USD): 22.532,253 centUSD
0.0225 kUSD
2.253e-5 MUSD
2.253e-8 TUSD
/ mile
Median Estimate (USD): 167.3416,734 centUSD
0.167 kUSD
1.6734e-4 MUSD
1.6734e-7 TUSD
/ mile
High-End Estimate (USD): 1,126.30112,630 centUSD
1.126 kUSD
0.00113 MUSD
1.1263e-6 TUSD
/ mile
Time Required
Low-End Estimate: 0.26 days7.118412e-4 years
6.24 hours
0.0371 weeks
0.00854 months
/ 100 mile
Median Estimate: 0.86 days0.00235 years
20.64 hours
0.123 weeks
0.0283 months
/ 100 mile
High-End Estimate: 2.33 days0.00638 years
55.92 hours
0.333 weeks
0.0766 months
/ 100 mile
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Aeromagnetic Survey:
Aeromagnetic surveys measure variations in Earth’s magnetic field using high-precision magnetometers (0.1 nanoTesla sensitivity) and are flown using a helicopter, fixed wing, or ultra light aircraft, depending on location and topographic relief.
Other definitions:Wikipedia Reegle



 
Use in Geothermal Exploration
 

Mapping Structure
  • In geothermal exploration, magnetic surveys are used to determine basement depth and to locate concealed intrusive, faults, and areas of hydrothermal alteration.
  • Intrusive rocks are associated with magnetic highs (alternatively sedimentary rocks are associated with lows); while the location of faults and zones of hydrothermally altered rocks are associated with magnetic lows.[1]
  • In general, the use of magnetic methods provide useful first-order datasets that can be used to define prospects in a broad context.




 
Data Access and Acquisition
 

  • On a regional scale, aeromag data has flown at 2-5 km line spacings over much of the western U.S.[1]
  • Higher resolution, prospect-scale data is typically collected at constant, low elevation (80-150 m above ground surface) on 0.25-0.50 km line spacings using an ultra-light aircraft.

 
Best Practices
 

  • As with gravity data, magnetic results are rarely unique and other data are needed to fully interpret and understand them.
  • As a standalone method, magnetic surveys tend to be less informative than other methods due to low depth of penetration and resolution, complexity of interpretation, and insensitivity to the presence of water.[2]
  • Joint inversion of magnetic data with gravity or other geophysical data types, however, makes it more useful.

 
Potential Pitfalls
 

  • In the past, magnetic surveys were used to determine Curie isotherm depths (i.e., the depth at which temperatures are high enough to cause rock demagnetization), which could be used to indicate depth to thermal anomalies, but subsequent work has proven otherwise.





 
References
 
  1. 1.0 1.1 (Goldstein 1988) Subregional and Detailed Exploration for Geothermal-Hydrothermal Resources in Geothermal Science and Technology
  2. (Bruhn et al 2010) "Geothermal Energy Systems: Exploration, Development, and Utilization"


Page Area Activity Start Date Activity End Date Reference Material
Aeromagnetic Survey (Nannini, 1986) 1986 1986


Aeromagnetic Survey At Baltazor Hot Springs Area (Isherwood & Mabey, 1978) Baltazor Hot Springs Area


Aeromagnetic Survey At Blue Mountain Geothermal Area (Fairbank Engineering Ltd, 2003) Blue Mountain Geothermal Area 1988 1988


Aeromagnetic Survey At Blue Mountain Geothermal Area (U.S. Geological Survey, 2012) Blue Mountain Geothermal Area 2008 2009


Aeromagnetic Survey At Chena Area (Erkan, Et. Al., 2008) Chena Geothermal Area 2008


Aeromagnetic Survey At Chena Geothermal Area (Kolker, 2008) Chena Geothermal Area 2005 2007


Aeromagnetic Survey At Clear Lake Area (Skokan, 1993) Clear Lake Area


Aeromagnetic Survey At Coso Geothermal Area (1977) Coso Geothermal Area 1977 1977


Aeromagnetic Survey At Coso Geothermal Area (1980) Coso Geothermal Area 1980 1980


Aeromagnetic Survey At Dixie Valley Geothermal Area (Grauch, 2002) Dixie Valley Geothermal Area 2002 2002


Aeromagnetic Survey At Glass Buttes Area (DOE GTP) Glass Buttes Area


Aeromagnetic Survey At Hualalai Northwest Rift Area (Thomas, 1986) Hualalai Northwest Rift Area


Aeromagnetic Survey At Kawaihae Area (Thomas, 1986) Kawaihae Area


Aeromagnetic Survey At Kilauea East Rift Geothermal Area (Gardner, Et Al., 1995) Kilauea East Rift Geothermal Area 1986 1986


Aeromagnetic Survey At Kilauea East Rift Geothermal Area (Thomas, 1986) Kilauea East Rift Geothermal Area 1978 1987


Aeromagnetic Survey At Kilauea Southwest Rift And South Flank Area (Thomas, 1986) Kilauea Southwest Rift And South Flank Area


Aeromagnetic Survey At Kilauea Summit Area (Zablocki, 1978) Kilauea Summit Area


Aeromagnetic Survey At Lightning Dock Area (Cunniff & Bowers, 2005) Lightning Dock Area


Aeromagnetic Survey At Lightning Dock Area (Warpinski, Et Al., 2002) Lightning Dock Area


Aeromagnetic Survey At Maui Area (DOE GTP) Maui Area


Aeromagnetic Survey At Mauna Loa Northeast Rift Area (Thomas, 1986) Mauna Loa Northeast Rift Area


Aeromagnetic Survey At Mokapu Penninsula Area (Thomas, 1986) Mokapu Penninsula Area


Aeromagnetic Survey At Mt Princeton Hot Springs Geothermal Area (Case, Et Al., 1984) Mt Princeton Hot Springs Geothermal Area 1984 1984


Aeromagnetic Survey At Mt St Helens Area (Towle, 1983) Mt St Helens Area


Aeromagnetic Survey At Raft River Geothermal Area (1978) Raft River Geothermal Area 1978 1978


Aeromagnetic Survey At Raft River Geothermal Area (1981) Raft River Geothermal Area 1981 1981


Aeromagnetic Survey At Roosevelt Hot Springs Geothermal Area (Faulder, 1991) Roosevelt Hot Springs Geothermal Area 1991 1991


Aeromagnetic Survey At Roosevelt Hot Springs Geothermal Area (Ward, Et Al., 1978) Roosevelt Hot Springs Geothermal Area 1978 1978


Aeromagnetic Survey At Waunita Hot Springs Geothermal Area (Lange, 1981) Waunita Hot Springs Geothermal Area 1972 1972


Aeromagnetic Survey At Yellowstone Region (Finn & Morgan, 2002) Yellowstone Caldera Geothermal Region


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