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Exploring Magnetic Minerals for Paleomagnetism Studies

Learn about magnetic minerals like Ferromagnetism and their role in paleomagnetism studies with in-depth details on Natural Rock Magnetizations (NRM, DRM, TRM). Explore key methods, tools, and findings in the field of paleomagnetic measurements. Follow a insightful Grand Canyon paleomag trip experience.

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Exploring Magnetic Minerals for Paleomagnetism Studies

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  1. Magnetic field including all terms Hulot et al., 2002

  2. Magnetic minerals: Ferromagnetism Ternary diagram of the iron-titanium oxide solid solution magnetic minerals

  3. Two most useful natural rock magnetizations • (NRM, Jr) for paleomagnetism • Detrital Remanent Magnetization (DRM) • formed during or soon after deposition of sediments • locked in by compaction and lithification to sedimentary rock • relatively weak • Thermo-remanent Magnetization (TRM) • formed in basic igneous rocks (e.g., basalt) upon cooling through Curie temperature • locked in upon further cooling • very strong

  4. thermo-remanent magnetization, TRM

  5. Detrital remanent magnetization DRM

  6. Paleomagnetic measurements • Collect many suitable samples (e.g. basalt) with in situ orientation determined

  7. 2001 Paleomag trip to Grand Canyon We drilled the Tapeats sandstone from the Cambrian; involved lots of water to cool the drill (me at top, Dave Evans, Yale below) In August, 2001 I was one of about 12 student slaves on a 2 week rafting trip down the Grand canyon to collect paleomag samples. Led by Joe Kirschvink, Caltech Because we were in a national park, we had to patch the drill holes once the samples were removed. Here I am mixing some concete with local rocks

  8. Good result Bad result thermal demag (°C) AC demag (mT)

  9. Isolation from environmental and geomagnetic fields cage Mu metal encased room

  10. corrections for structure

  11. corrections for structure

  12. Blocks rotated during Neogene Mojave extension (Miocene)

  13. Paleomagnetic declinations

  14. Declination vrs age for the western Transverse Block Samples from this area

  15. Closing the North Atlantic Ordovician to Jurassic (500-200 Ma) “Apparent polar wander” (APW) paths for North America and Europe Europe rotated by 38 degrees about rotation pole at 88.5N, 27.7E

  16. Errors (a95cones of confidence)

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