Paleomagnetic analyses on Badenian–Sarmatian drill cores from the North Carpathian foredeep (Middle Miocene, Poland)

K. Sant, Arjan de Leeuw, L. Chang, Grzegorsz Czapowski, Andrzej Gasiewicz, W. Krijgsman

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Accurate dating of the Badenian–Sarmatian transition, a boundary between two regional Middle Miocene stages of the
semi-isolated Paratethys Sea, is crucial to understand what event caused the corresponding major turnover in faunal assemblage at that
point in time. The general opinion is that this event resulted from a sudden isolation of the Eastern Paratethys from ocean water, due to
the closure of the Eastern Anatolian seaway to the Indian Ocean, but it remains debated if the final isolation had a tectonic or climatic
cause. This pilot study presents paleomagnetic analyses of two drill cores from the North Carpathian Foredeep in Poland that straddle the
Badenian–Sarmatian transition. Rock magnetic experiments, including thermomagnetic runs in air on a Curie balance, and hysteresis measurements
on a MicroMag, indicate that the dominant magnetic carrier is the iron sulphide greigite. This is in agreement with the observed
gyroremanence obtained during alternating field demagnetization above 40 mT. Alternating field and thermal demagnetization results are
in good agreement and show a weak, mixed-polarity, signal for most of the Badenian, rapidly shifting to a much stronger and dominantly
normal polarity signal in the Sarmatian part of the cores. First order reversal curves diagrams indicate that the greigite in the Sarmatian
part is clearly of diagenetic origin, it thus most likely concerns a secondary overprint by the present-day field that cannot be used for magnetostratigraphic
correlations. We conclude that the Paratethys-wide paleoenvironmental change that occurred at the Badenian–Sarmatian
transition had probably also created different conditions for the formation and/or preservation of magnetic minerals
Original languageEnglish
Pages (from-to)179-192
JournalBiuletyn Państwowego Instytutu Geologicznego
Volume461
DOIs
Publication statusPublished - 2015

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