Early Cretaceous sea surface temperature evolution in subtropical shallow seas

Abstract Late Cretaceous sea surface temperatures (SST) are, amongst others, traditionally reconstructed by compiling oxygen isotope records of planktonic foraminifera obtained from globally distributed pelagic IODP drill cores. In contrast, the evolution of Early Cretaceous SSTs is essentially base...

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Autores principales:	Stefan Huck, Ulrich Heimhofer
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/b8011f6bd425472491fc677f841d9c3f
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spelling	oai:doaj.org-article:b8011f6bd425472491fc677f841d9c3f2021-12-02T16:56:48ZEarly Cretaceous sea surface temperature evolution in subtropical shallow seas10.1038/s41598-021-99094-22045-2322https://doaj.org/article/b8011f6bd425472491fc677f841d9c3f2021-10-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-99094-2https://doaj.org/toc/2045-2322Abstract Late Cretaceous sea surface temperatures (SST) are, amongst others, traditionally reconstructed by compiling oxygen isotope records of planktonic foraminifera obtained from globally distributed pelagic IODP drill cores. In contrast, the evolution of Early Cretaceous SSTs is essentially based on the organic TEX86 palaeothermometer, as oxygen-isotope data derived from well-preserved ‘glassy’ foraminifer calcite are currently lacking. In order to evaluate the extraordinary warm TEX86-derived SSTs of the Barremian to Aptian (130–123 Ma) subtropics, we present highly resolved sclerochemical profiles of pristine rudist bivalve shells from Tethyan and proto-North Atlantic shallow water carbonate platforms. An inverse correlation of seasonal ontogenetic variations in δ18Orudist and Mg/Ca ratios demonstrates the fidelity of oxygen isotopes as palaeotemperature proxy. The new data shows moderate mean annual SSTs (22–26 °C) for large parts of the Barremian and Aptian and transient warm pulses for the so-called Mid-Barremian Event and Oceanic Anoxic Event 1a (reaching mean annual SSTs of 28 to 30 °C). A positive shift in mean annual oxygen-isotope values (δ18O: ≤ − 0.3‰) coupled with invariant Mg/Ca ratios at the Barremian–Aptian boundary points to a significant net loss of 16O in Tethyan shallow-marine settings. As the positive oxygen-isotope rudist shell values are recorded immediately beneath a major superregional hiatal surface, they are interpreted to be related to a major cooling phase and potential glacio-eustatic sea-level lowering. Our new sclerochemical findings are in clear contrast to open ocean SST records based on TEX86, which indicate exceptionally warm Barremian to earliest Aptian subtropical oceans and weak meridional SST gradients.Stefan HuckUlrich HeimhoferNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Stefan Huck Ulrich Heimhofer Early Cretaceous sea surface temperature evolution in subtropical shallow seas
description	Abstract Late Cretaceous sea surface temperatures (SST) are, amongst others, traditionally reconstructed by compiling oxygen isotope records of planktonic foraminifera obtained from globally distributed pelagic IODP drill cores. In contrast, the evolution of Early Cretaceous SSTs is essentially based on the organic TEX86 palaeothermometer, as oxygen-isotope data derived from well-preserved ‘glassy’ foraminifer calcite are currently lacking. In order to evaluate the extraordinary warm TEX86-derived SSTs of the Barremian to Aptian (130–123 Ma) subtropics, we present highly resolved sclerochemical profiles of pristine rudist bivalve shells from Tethyan and proto-North Atlantic shallow water carbonate platforms. An inverse correlation of seasonal ontogenetic variations in δ18Orudist and Mg/Ca ratios demonstrates the fidelity of oxygen isotopes as palaeotemperature proxy. The new data shows moderate mean annual SSTs (22–26 °C) for large parts of the Barremian and Aptian and transient warm pulses for the so-called Mid-Barremian Event and Oceanic Anoxic Event 1a (reaching mean annual SSTs of 28 to 30 °C). A positive shift in mean annual oxygen-isotope values (δ18O: ≤ − 0.3‰) coupled with invariant Mg/Ca ratios at the Barremian–Aptian boundary points to a significant net loss of 16O in Tethyan shallow-marine settings. As the positive oxygen-isotope rudist shell values are recorded immediately beneath a major superregional hiatal surface, they are interpreted to be related to a major cooling phase and potential glacio-eustatic sea-level lowering. Our new sclerochemical findings are in clear contrast to open ocean SST records based on TEX86, which indicate exceptionally warm Barremian to earliest Aptian subtropical oceans and weak meridional SST gradients.
format	article
author	Stefan Huck Ulrich Heimhofer
author_facet	Stefan Huck Ulrich Heimhofer
author_sort	Stefan Huck
title	Early Cretaceous sea surface temperature evolution in subtropical shallow seas
title_short	Early Cretaceous sea surface temperature evolution in subtropical shallow seas
title_full	Early Cretaceous sea surface temperature evolution in subtropical shallow seas
title_fullStr	Early Cretaceous sea surface temperature evolution in subtropical shallow seas
title_full_unstemmed	Early Cretaceous sea surface temperature evolution in subtropical shallow seas
title_sort	early cretaceous sea surface temperature evolution in subtropical shallow seas
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/b8011f6bd425472491fc677f841d9c3f
work_keys_str_mv	AT stefanhuck earlycretaceousseasurfacetemperatureevolutioninsubtropicalshallowseas AT ulrichheimhofer earlycretaceousseasurfacetemperatureevolutioninsubtropicalshallowseas
_version_	1718382701453508608

Early Cretaceous sea surface temperature evolution in subtropical shallow seas

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