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Paleomagnetic techniques can date speleothems with high concentrations of detrital material.

ABSTRACT: The U-series dating of young and 'dirty' speleothems is challenging due to difficulties in assessing the isotopic composition of detrital contaminants and the low-abundance of ²³⁰Th generated in situ. Here we propose a new dating approach based on the comparison of a speleothem's paleomagnetic directions to reference curves from global paleomagnetic reconstructions. This approach is demonstrated on a stalagmite collected from the Soprador do Carvalho cave in the Central Region of Portugal. A radioisotopic age model, built using four U-series ages and three ¹⁴C, suggests relatively steady carbonate precipitation from ~ 5760 BCE until ~ 1920 CE. Forty-five 6 mm-thick subsamples were analyzed using alternating field and thermal demagnetization protocols, providing well-defined, primary magnetic directions. An age model of the stalagmite was obtained by fitting its paleomagnetic record with the reference paleosecular variation curves obtained by previous paleo-reconstruction models, applying statistical bootstrapping analysis to define their best fit. The resulting age models fit closely with the radioisotopic age model but provide a significantly higher time resolution. We reach the same conclusion when applying this approach to another stalagmite from the Algarve region of Portugal. Our approach thus appears a promising alternative to date young speleothems with high detrital contents.

SUBMITTER: Sanchez-Moreno EM

PROVIDER: S-EPMC9605962 | biostudies-literature | 2022 Oct

REPOSITORIES: biostudies-literature

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Paleomagnetic techniques can date speleothems with high concentrations of detrital material.

Sánchez-Moreno Elisa M EM Font Eric E Pavón-Carrasco F Javier FJ Dimuccio Luca A LA Hillaire-Marcel Claude C Ghaleb Bassam B Cunha Lúcio L

Scientific reports 20221026 1

The U-series dating of young and 'dirty' speleothems is challenging due to difficulties in assessing the isotopic composition of detrital contaminants and the low-abundance of <sup>230</sup>Th generated in situ. Here we propose a new dating approach based on the comparison of a speleothem's paleomagnetic directions to reference curves from global paleomagnetic reconstructions. This approach is demonstrated on a stalagmite collected from the Soprador do Carvalho cave in the Central Region of Port ...[more]

PMID: 36289261

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Paleomagnetic techniques can date speleothems with high concentrations of detrital material.

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Paleomagnetic techniques can date speleothems with high concentrations of detrital material.

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