In: Contributions to Geophysics and Geodesy, vol. 35, no. 2
Oto Orlický
Details:
Year, pages: 2005, 95 - 112
Keywords:
basalts, Fe-Ti inversion low-temperature phase the source of intensive NRM (thermo-viscous or chemico-viscous origin) of rocks
About article:
The Late Miocene to Quaternary basalts from central and southern
Slovakia, the Eocene to Miocene basalts from České Středohoří Mts., the
Cretaceous and the Neogene basalts from Syrian Arab Republic, the Cretaceous,
Jurassic nepheline basanites and the Quaternary basalts from Nigeria, the
basalts from recent Etna and Kilauea volcanoes were studied. The high
intensities of natural remanent magnetization (NRM) of volcanic rocks are
mostly linked with the presence of the time-variable secondary inversion
low-temperature magnetic phase in the rocks. The high NRM is of the
chemico-viscous or the thermoviscous origin. An origin of this phase in
volcanics is due to low-temperature oxidation (in the range 25 to above around
of 350°C) of original Ti-rich titanomagnetites (Ti-Mt-es), which were
in the superparamagnetic (SP) state. The successive creation of more oxidized
Ti-Mt phase with the nucleation of the thermodynamically stable domains takes
place. A magnetostatic interactions among a portion of the original SP state
magnetic particles of Ti-Mt-es and those gradually originated oxidized
(Ti-Mt-es - titanomaghemites - Ti-Mgh-es) is actual in this system. Due to
these interactions a highly viscous and very easily excitable phase has arisen
in this system. This phase is able to acquire a thermoviscous or
chemico-viscous remanent magnetization having been exposed to the external
magnetic field. This is quite new phenomenon. The importance of this knowledge
has resulted in its application to the interpretation of geomagnetic
anomalies. The high intensities of NRM contribute to the total magnetization
of volcanic body and so, they can generate intensive geomagnetic anomalies
with respect to the volume of the volcanic body. These anomalies do reflect
the presence of only high intensities of NRM, but not the sources of the high
Fe concentration of deposits.
How to cite:
ISO 690:
Orlický, O. 2005. An origin and the source of extreme high intensity of natural remanent magnetization (NRM) of oxidized titano-magnetite bearing basaltic and andesitic rocks. In Contributions to Geophysics and Geodesy, vol. 35, no.2, pp. 95-112. 1338-0540.
APA:
Orlický, O. (2005). An origin and the source of extreme high intensity of natural remanent magnetization (NRM) of oxidized titano-magnetite bearing basaltic and andesitic rocks. Contributions to Geophysics and Geodesy, 35(2), 95-112. 1338-0540.