Exploration geophysics
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Exploration geophysics is the applied branch of geophysics which uses surface methods to measure the physical properties of the subsurface Earth, in order to detect or infer the presence and position of concentrations of ore minerals and hydrocarbons.
Exploration geophysics is the practical application of physical methods (such as seismic, gravitational, magnetic, electrical and electromagnetic) to measure the physical properties of rocks, and in particular, to detect the measurable physical differences between rocks that contain ore deposits or hydrocarbons and those without.
Exploration geophysics can be used to directly detect the target style of mineralisation, via measuring its physical properties directly. For example one may measure the density contrasts between iron ore and silicate wall rocks, or may measure the conductivity contrast between conductive sulfide minerals and barren silicate minerals.
Exploration geophysics is also used to map the subsurface structure of a region, to elucidate the underlying structures, spatial distribution of rock units, and to detect structures such as faults, folds and intrusive rocks. This is an indirect method for assessing the likelihood of ore deposits or hydrocarbon accumulations.
Methods devised for finding mineral or hydrocarbon deposits can also be used in other areas such as monitoring environmental impact, imaging subsurface archaeological sites, ground water investigations, subsurface salinity mapping, civil engineering site investigations and interplanetary imaging.
In addition to universities and technical institutes such as the Colorado School of Mines, University of British Columbia, Curtin University, professional societies such as the Society of Exploration Geophysicists (SEG) (seg.org) and the CSEG and ASEG have the most recent updates of the sciences and technologies of exploration geophysics.
Exploration Geophysics careers are in such widely varying industries as oil & gas exploration, mining, environmental studies, planetary physics and even archaeology.
The following techniques are used:
- Seismic methods, such as reflection seismology, seismic refraction and seismic tomography.
- Magnetotellurics
- Scientific drilling
- Transient electromagnetic (EM) (see, e.g. Geonics instruments)
- Radio frequency electromagnetic propagation (e.g., ground penetrating radar)
- Electrical techniques, including Electrical resistivity tomography and induced polarization
- Magnetic techniques, including aeromagnetic surveys and magnetometers.
- Gravity and Gravity Gradiometry
- Geodesy
- Remote sensing
[edit] See also
- Archaeological geophysics
- Petroleum geology
- Hydrocarbon exploration
- Kola Superdeep Borehole
- Mineral exploration
- Ore genesis
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