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

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Presentation on theme: "Hulot et al., 2002 Magnetic field including all terms."— Presentation transcript:

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

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

3 Two most useful natural rock magnetizations (NRM, J r ) 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 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 We drilled the Tapeats sandstone from the Cambrian; involved lots of water to cool the drill (me at top, Dave Evans, Yale below) 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

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12 Blocks rotated during Neogene Mojave extension (Miocene)

13 Paleomagnetic declinations

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

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

24 Errors (  95 cones of confidence)


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