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Unformatted text preview: contains remanent magnetization Three types: 1. Thermoremanence (basalt, granite) At high tempertature, ferromagnetic minerals are paramagnetic Material cools, minerals become ferromagnetic Acquire a magnetization PARALLEL to Earth’s field Currie Temp: temp at which paramagnetic becomes ferromagnetic 580 c for magnetite 680 c for hematite 2. Chemical remanence 3. Detrital remanence Properties of modern geomagnetic field 90% of field can be modeled with a DIPOLE (bar magnet) 10% of field is non-dipole Field Intensity changes over time Intensity is correlated with polarity reversals Expect field to get weaker just before polarity change And, expect to see more field that CAN’T be modeled by dipole Exactly what we see today…...
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- Spring '07
- Magnetism, Magnetic Field, 10%, 90%, Detrital remanence Properties, type Remanent Magnetization