Mid- to late Holocene sea-level rise recorded in Hells Bells 234 U/ 238 U ratio and geochemical composition.

Autor: Schorndorf N; Institute of Earth Sciences, Heidelberg, Germany. nils.schorndorf@geow.uni-heidelberg.de.; Institute of Environmental Physics, Heidelberg, Germany. nils.schorndorf@geow.uni-heidelberg.de., Frank N; Institute of Earth Sciences, Heidelberg, Germany.; Institute of Environmental Physics, Heidelberg, Germany.; Heidelberg Center for the Environment (HCE), Heidelberg, Germany., Ritter SM; Institute of Earth Sciences, Heidelberg, Germany., Warken SF; Institute of Earth Sciences, Heidelberg, Germany.; Institute of Environmental Physics, Heidelberg, Germany., Scholz C; Institute of Earth Sciences, Heidelberg, Germany., Keppler F; Institute of Earth Sciences, Heidelberg, Germany.; Heidelberg Center for the Environment (HCE), Heidelberg, Germany., Scholz D; Institute for Geosciences, Mainz, Germany., Weber M; Institute for Geosciences, Mainz, Germany., Aviles Olguin J; Museo del Desierto, Saltillo, COAH, Mexico.; Grupo Espeleologico Ajau, Mérida, YUC, Mexico., Stinnesbeck W; Institute of Earth Sciences, Heidelberg, Germany.; Heidelberg Center for the Environment (HCE), Heidelberg, Germany.
Jazyk: angličtina
Zdroj: Scientific reports [Sci Rep] 2023 Jun 20; Vol. 13 (1), pp. 10011. Date of Electronic Publication: 2023 Jun 20.
DOI: 10.1038/s41598-023-36777-y
Abstrakt: Hells Bells are underwater secondary carbonates discovered in sinkholes (cenotes) southeast of Cancun on the north-eastern Yucatán peninsula, Mexico. These authigenic calcite precipitates, reaching a length of up to 4 m, most likely grow in the pelagic redoxcline. Here we report on detailed 230 Th/U-dating and in-depth geochemical and stable isotope analyses of specimens from cenotes El Zapote, Maravilla and Tortugas. Hells Bells developed since at least ~ 8000 years ago, with active growth until present day. Initial ( 234 U/ 238 U) activity ratios (δ 234 U 0 ) in Hells Bells calcite decreas from 55 to 15‰ as sea level converges toward its present state. The temporal evolution of the geochemistry and isotope composition of Hells Bells calcites thus appears to be closely linked to sea-level rise and reflects changing hydrological conditions (desalinization) of the aquifer. We suggest that decelerated leaching of excess 234 U from the previously unsaturated bedrock traces Holocene relative sea-level rise. Considering this proxy, the resulting mean sea-level reconstruction contains half as much scatter, i.e. improves by a factor of two, when compared to previously published work for the period between 8 and 4 ky BP.
(© 2023. The Author(s).)
Databáze: MEDLINE
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