Shared Flashcard Set. Title Anthropology chapter 8. Total Cards Subject Anthropology.
Definition: Paleomagnetic Measurements
Paleomagnetism | Definition of Paleomagnetism by Merriam-Webster
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Every rock contains grains of ferromagnetic or ferrimagnetic minerals, such as magnetite, titanomagnetites, hematite, ilmenites, maghemite, and pyrrhotite. In some rocks the content of magnetic grains is only a fraction of a percent; nevertheless, it is precisely these grains that account for the remanent magnetization of the rocks. It arises primarily during the cooling of melts, or lavas and intrusions; that is, it is characteristic of igneous rocks. TRM can be tens or hundreds of times greater than the magnetization that arises in the same field at room temperature. In order to remove TRM, magnetic fields tens or hundreds of times stronger than the field that created the TRM are required.
This record is preserved by many rocks from the time of their formation. The paleomagnetic data have played an instrumental role in deciphering the history of our planet including a decisive evidence for continental drift and global plate tectonics. The data have also been crucial for better understanding the problems of regional and local tectonics, geodynamics, and thermal history of our planet.