Palaeointensity
Ancient magnetic
intensity of the geomagnetic field, based on measurements of remanent
magnetisation of rock and sediments. Samples that acquired their
natural remanent magnetisation as thermoremanent magnetisation (e.g.
lavas), can be used to determine absolute ancient field intensities
(absolute palaeointensity) by reheating experiments in a known
laboratory field. In this case on speak about absolute palaeointensity
determinations.
The ChRM
intensity of certain sediments as normalised by an artificial remanence
(e.g. ARM) is used as indicator for relative changes of the geomagnetic
field. Here one speak about relative palaeointensity determination.
Palaeomagnetism
Study of the behaviour of the geomagnetic field
during geological times based on remanent magnetisation of
rocks.
Paramagnetism
In materials with unpaired electrons and when the atoms or ions,
carrying a magnetic moment, are diluted (gas or ions
carrying a magnetic moment in silicate
matrix). The susceptibility is weak
and positive. Examples: materials with
rare Earth or transitional elements:
clays, pyroxene, amphibole.
Partial
thermo-remanent magnetisation (pTRM)
Remanent magnetisation of a sample at room
temperature, acquired in a temperature interval
[T1;T2] (with T2 ≤ Curie- / Néel-Temperature and T1
> than room temperature) in the presence of a magnetic field (see
also total
thermo-remanent magnetisation, tTRM).
Post-depositional
remanent magnetisation (pDRM)
Magnetic remanence acquired by a sediment after its
deposition, when all magnetic particles are
fixed in the sedimentary matrix.
This remanent magnetisation is preserved over geological
timescales (see also depositional
remanent magnetisation).