The paleoinformation value of natural remanent magnetization of several traps in Yakutia |
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Authors: | J R Mbele V I Maksimochkin V I Trukhin |
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Institution: | 1.Faculty of Physics,Moscow State University,Moscow,Russia |
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Abstract: | Research was carried out to estimate the possibility of determining the direction and strength of the ancient geomagnetic
field (H
an
) by natural remanent magnetization (I
n
) 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 characterized 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 I
n
polarity appears to be quite variable: samples K-4 and K-5 are characterized by low Curie points (T
c
≈ 200°C) of the ferrimagnetic phase, sample Ki-2 contains single-phase oxidized titanomagnetite with T
c
≈ 310°C, and the T
c
of the Pi-10 ferrimagnetic phase is 540°C. Hence, it may be concluded that the primary remanent magnetization 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 I
n
of these samples is doubtful. |
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Keywords: | |
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