Evidence for a regional warm bias in the Early Cretaceous TEX86 record.

Steinig, Sebastian , Dummann, Wolf, Park, Wonsun , Latif, Mojib , Kusch, Stephanie, Hofmann, Peter and Flögel, Sascha (2020) Evidence for a regional warm bias in the Early Cretaceous TEX86 record. Earth and Planetary Science Letters, 539 . Art.Nr. 116184. DOI 10.1016/j.epsl.2020.116184.

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Supplementary data:

Abstract

Highlights

• New Early Cretaceous South Atlantic TEX86 samples and climate modelling.
• Systematic differences in Cretaceous isoGDGT abundances.
• Regional similarities to modern Mediterranean and Red Sea sediments.

Regional TEX86-temperature calibration enables model-data congruence for OAE 1a.

Abstract

The Cretaceous Period (145-66 Ma) provides an opportunity to obtain insights into the adaptation of the climate system to increased atmospheric greenhouse gas concentrations. The organic paleothermometer TEX86 is one of the few proxies available for reconstructing quantitative estimates of upper ocean temperatures of this time period. Here we show that the sedimentary TEX86 signal in the Early Cretaceous North and South Atlantic shows systematic differences to other Cretaceous samples. In particular, the relative increase in the fractional abundances of the crenarchaeol isomer compared to crenarchaeol exhibits similarities with surface sediments from the modern Mediterranean and Red Sea. Dedicated climate model simulations suggest that the formation of warm and saline deep waters in the restricted North and South Atlantic may have influenced TEX86 export dynamics leading to a warm bias in reconstructed upper ocean temperatures. Applying a regional calibration from the modern Mediterranean and Red Sea to corresponding TEX86 data significantly improves the model-data fit for the Aptian Oceanic Anoxic Event 1a and the overall comparison with other temperature proxies for the Early Cretaceous. Our results demonstrate the need to consider regional and temporal changes of the TEX86-temperature relation for the reconstruction of deep-time ocean temperatures.

Document Type: Article
Keywords: climate modelling, Cretaceous, GDGTs, OAE 1a, paleotemperature, TEX86
Research affiliation: OceanRep > SFB 754 > A7
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.epsl.2020.116184
ISSN: 0012-821X
Projects: DSDP, SFB754, PalMod, Future Ocean
Date Deposited: 06 Apr 2020 07:11
Last Modified: 07 May 2020 07:22
URI: http://oceanrep.geomar.de/id/eprint/49361

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