The Paleoinformation Value of Natural Remanent Magnetization of Several Traps in Yakutiaстатья
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Аннотация:Research was carried out to estimate the possibility of determining the direction and strength of the
ancient geomagnetic field (Han) by natural remanent magnetization (In) of nine oriented samples from traps of
the Minor Botuoba Region (Yakutia) aged 260 Ma. Five samples (Pi-10, K-4, K-6, 315-13, and Ki-2) are charac-
terized by negative polarity of In, while four samples (nos. 334-5, 331-2, 315-11, 299-2) have positive polarity
as does the recent geomagnetic field in this region. The ferrimagnetic constituent of the samples with reverse
In polarity appears to be quite variable: samples K-4 and K-5 are characterized by low Curie points (Tc 200C)
of the ferrimagnetic phase, sample Ki-2 contains single-phase oxidized titanomagnetite with Tc 310C, and
the Tc of the Pi-10 ferrimagnetic phase is 540C. Hence, it may be concluded that the primary remanent mag-
netization of the first two samples was formed in a reverse polarity field. These samples also may be used to
determine the paleostrength of the geomagnetic field. The properties of traps containing single-phase oxidized
(sample Ki-2) and disintegrated (sample Pi-10) titanomagnetite require additional investigation. Samples with
positive In polarities are characterized by the self-reversal phenomenon upon thermal demagnetization of the
natural remanent magnetization, which was most likely caused by the occurrence of titanomagnetite exsolution
textures in ferrimagnetic grains. The paleoinformation value of the In of these samples is doubtful.