Hulot et al., 2002

Magnetic field including all terms

Ternary diagram of the iron-titanium oxide solid solution magnetic minerals

Magnetic minerals:Ferromagnetism

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

thermo-remanent magnetization, TRM

Detrital remanent magnetization DRM

Paleomagnetic measurements

Collect many suitable samples (e.g. basalt) with in situ orientation determined

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

Good result

Bad result

thermal demag (°C)

AC demag (mT)

Isolation from environmental and geomagnetic fields

cage Mu metal encased room

corrections for structure

corrections for structure

Blocks rotated during Neogene

Mojave extension (Miocene)

Paleomagnetic declinations

Declination vrs age for the western Transverse Block

Samples from this area

Europe rotated by 38 degrees about rotation pole at 88.5N, 27.7E

Closing the North AtlanticOrdovician to Jurassic (500-200 Ma) “Apparent polar wander” (APW) paths for North America and Europe

Errors (95 cones of confidence)