PALEOMAGNETIC AND
ROCK MAGNETIC

Technique

 

Paleomagnetic and rock magnetic techniques provide means of understanding the Earth's ancient geomagnetic field by using the magnetic record contained in rocks and archeological materials. Most materials contain a record of the direction of the magnetic field that was present at the time the rock was formed. Variations in field intensity also can be obtained from those rocks and archeological materials that cooled fromhigh temperature in the Earth's field. The knowledge gained is then applied toward the solution of geologic problems. The magnetic polarity record of the past few million years can provide the means of dating young geologic materials where isotopic determinations are unavailable or equivocal. Magnetic directions are used to detect tectonic disruptions ranging from tilt and rotation of small structural blocks to large-scale movements of terranes and continental masses. Magnetic directions also are usedto differentiate between lava flows or archeological artifacts with a resolution that is unattainable with radiometric dating. Knowledge of variations in geomagnetic field strength during Quaternary time is important for determining the production rate of cosmogenic nuclides that are used in dating and correlation of geologic materials.
 


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URL http://geology.cr.usgs.gov/capabilities/paleom/paleorock/tech.html
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