Short reversals of the earth’s magnetic field and its relative paleointensity variations as chronostratigraphic tools - perspectives and limitations

Geomagnetic variations in direction as well as in intensity throughout the geologic history as documented in the remanent magnetization of sediment successions generally offer a potential (the investigations are performed in correlation) for dating of these sediments. Therefore, magnetostratigraphic investigations are performed in order to monitor geomagnetic fluctuations and to correlate them to established reference datasets such as the geomagnetic polarity time scale. The last major reversal of the earth’s magnetic field occured at about 780 ka. Since then, a quite large number of so-called reversal excursions with a duration of a few thousand years interrupted the normal polarity phase of the geomagnetic field, known as the ’Brunhes Chron’, about each 50 to 100 kyr. According to absolute as well as relative paleointensity determinations the field intensity throughout the Brunhes Chron was not constant but variable at least within the range of one order of magnitude. Especially reversal excursions, as expressed by magnetization directions differing largely from the expected dipole direction for a certain site, are associated with pronounced lows in the field intensity. So, in principle, determination of the sediment’s magnetization in terms of direction and intensity of time-calibrated curves can provide a detailed age model of (late) Quaternary sediments.

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Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2019).