 |
| Titel |
Low-temperature magnetic transition temperatures of synthetic titanomagnetite-ilmenitess assemblages |
| VerfasserIn |
A. Kontny, R. Engelmann, D. Lattard |
| Konferenz |
EGU General Assembly 2009
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026144
|
|
|
|
|
|
| Zusammenfassung |
| An increasing amount of data on low-temperature magnetic properties of Fe-Ti oxides is
meanwhile available. They show that low-temperature magnetometry has a high potential in
characterising the magnetic mineral assemblage, especially for basaltic rocks. We present
low-temperature magnetic transition temperatures of synthetic Fe-Ti oxide assemblages in
which the ilmenite solid solutions (0.7 < Xilm < 1) have compositions near to the ilmenite
endmember (FeTiO3) and titanomagnetites have intermediate to Fe-rich compositions
(0 < Xusp < 0.8). These compositions are ubiquitous in natural basic magmatic
rocks. The magnetic transition temperatures of ilmenitess and titanomagnetite were
identified using a combination of frequency-dependent AC in-phase and out-of phase
susceptibility and saturation magnetization in the temperature range of 5 and 300 K,
combined with hysteresis measurements at defined temperatures. We shall focus
on the determination of critical transition temperatures such as the isotropic point
(Ti) of titanomagnetite (between 50 and 100 K in the investigated compositional
range), as well as the spin glass temperature and the transition to superparamagnetic
behaviour for ilmenitess. All these transition temperatures are characterised by
frequency dependent out-of phase susceptibility signals and we shall discuss their
significance for the interpretation of low-temperature magnetometry data in natural
rocks. We shall also present data concerning the Curie and Neel temperatures for the
investigated Fe-Ti oxides and discuss how the different transition temperatures can be
discriminated. |
|
|
|
|
|
|