First paleomagnetic record of the Matuyama-Brunhes transition in the loess-paleosol series of Tajikistan

Kulakova, E.; Kurbanov, R.

Авторы: Kulakova E., Kurbanov R.
Сборник: Problems of Geocosmos—2022. ICS 2022. Springer Proceedings in Earth and Environmental Sciences
Серия: Springer Proceedings in Earth and Environmental Sciences
Глава в коллективной монографии
Год издания: 2023
Издательство: Springer
Местоположение издательства: New York
Первая страница: 67
Последняя страница: 84
DOI: 10.1007/978-3-031-40728-4_6
Аннотация: Detailed paleomagnetic records of the Matuyama-Brunhes (M/B) magnetic polarity transition in continuous sedimentary sequences both provide a geochronological constraint on the sequence and expand our knowledge of the reversal process. Although the age of the Matuyama-Brunhes reversal has been studied in detail, some high-resolution geological archives show a discrepancy in the actual and expected position of the M/B boundary, e. g. loess-paleosol sequences of Central Asia and China. We have carried out a detailed paleomagnetic study of the M/B transition in the loess-paleosol sequence at the Kuldara site, Tajikistan, the first such study in the region. Matuyama-Brunhes transition at the Kuldara site encompasses 3 m thick zone, and includes 7 polarity flips and zones with anomalous directions. The transition zone begins in the MIS 20 loess and ends in the lowermost part of the MIS 19 warm stage. Preliminary duration estimate for the transition is ~22 kyr, and its lower and upper limits have older ages than expected (809–787 ka). However, the last reliable zone of reverse polarity is found at the beginning of MIS 19, reported for the first time for this loess-paleosol section. Furthermore, we have found an excursion (852–847 ka) ~38 kyr prior to the reversal which manifests itself as a 22 cm thick zone with anomalous directions and instable paleomagnetic signal. Nevertheless, the magnetic reversal event appears somewhat older compared to other sedimentary and volcanic records of the M/B transition. Delayed acquisition or superimposed younger magnetization in the studied loesses may be the reason for this discrepancy, and requires further study.
Добавил в систему: Кулакова Екатерина Петровна

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First paleomagnetic record of the Matuyama-Brunhes transition in the loess-paleosol series of Tajikistanстатья Глава в книге Исследовательская статья

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