Geophysical exploration techniques for metals
- Created by: Brad_ers_B
- Created on: 26-04-15 17:53
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- Geophysical exploration techniques for metals
- Gravity surveys
- Gravimeters mounted on planes, helicopters or land vehicles for regional surveys
- Positive gravity anomaly
- High density mafic / ultramafic intrusion maybe containing ore deposits
- Presence of dense, metallic ore minerals
- Negative gravity anomaly
- Low density silicic intrusion, maybe with hydrothermal mineral veins around it
- Magnetic surveys
- Can be done airbourne for regional surveys and land-based for detailed surveys
- Two types of survey
- Transect survey, measures along a straight line
- Map survey, values plotted on a map, lines plotted by equal magnetic field strength
- Minerals rich in iron produce positive anomalies
- Maybe due to a mafic / ultramafic intrusion, possibly containing ore deposits from gravity settling
- Presence of magnetite
- Electrical resistivity survey
- Two electrodes placed in the ground and an electric current is passed between them
- If the rock is a good conductor it will have a low resistance
- This method is used for gold exploration
- Gravity surveys
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