hulot et al., 2002 magnetic field including all terms
TRANSCRIPT
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)