Geophysical Journal | 2012 volume 34 3

Use of sedimentary rocks for determining intensity of ancient geomagnetic field

© Kurazhkovskii Yu.A., Kurazhkovskaya N.A., Klain B.I.

The results of investigations of the orientational remanent magnetization of artificial and natural marine sediments depending on the conditions in which their formation took place are synthesized. Requirements to magnetic properties of samples and the procedure of their re-deposition while determining the ancient magnetic field intensity have been formulated. It is shown that the depth and climatic zone in which deposits were formed do not affect the results of determination of geomagnetic field intensity. Results of the method examination of the ancient geomagnetic field intensity determination (using re-sedimentation) on contemporary sediments are presented. The intensity of the magnetic field in which sedimentation occurred can be determined with (16-20) % accuracy. The comparison of the average values of the paleointensity of the Late Cretaceous, Early Cretaceous, Late Jurassic, Triassic, Permian, Late and Early Carboniferous obtained on sedimentary and thermomagnetized rocks has been made. It is shown that the sedimentary and thermomagnetized rocks give equal concept on changes of the paleointensity. Based on the study of modern and ancient marine aleurite grey-colored deposits a new method has been proposed for determining the absolute values of the paleointensity in which re-deposition is not used.

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