Periodic changes in the Cretaceous ocean and climate caused by marine redox see-saw

Wallmann, Klaus, Flögel, Sascha, Scholz, Florian, Dale, Andrew W., Kemena, Tronje Peer, Steinig, Sebastian and Kuhnt, Wolfgang (2019) Periodic changes in the Cretaceous ocean and climate caused by marine redox see-saw Nature Geoscience . DOI 10.1038/s41561-019-0359-x.

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Abstract

Periodic changes in sediment composition are usually ascribed to insolation forcing controlled by Earth’s orbital parameters. During the Cretaceous Thermal Maximum at 97–91 Myr ago (Ma), a 37–50-kyr-long cycle that is generally believed to reflect obliquity forcing dominates the sediment record. Here, we use a numerical ocean model to show that a cycle of this length can be generated by marine biogeochemical processes without applying orbital forcing. According to our model, the restricted proto-North Atlantic and Tethys basins were poorly ventilated and oscillated between iron-rich and sulfidic (euxinic) states. The Panthalassa Basin was fertilized by dissolved iron originating from the proto-North Atlantic. Hence, it was less oxygenated while the proto-North Atlantic was in an iron-rich state and better oxygenated during euxinic periods in the proto-North Atlantic. This redox see-saw was strong enough to create significant changes in atmospheric pCO2. We conclude that most of the variability in the mid-Cretaceous ocean–atmosphere system can be ascribed to the internal redox see-saw and its response to external orbital forcing.

Document Type: Article
Additional Information: The UVic model and the REDBIO box model (written in MATHEMATICA) are available from S.F. (sfloegel@geomar.de) and K.W., respectively.
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University
Refereed: Yes
DOI etc.: 10.1038/s41561-019-0359-x
ISSN: 1752-0894
Date Deposited: 22 May 2019 07:37
Last Modified: 22 May 2019 07:38
URI: http://eprints.uni-kiel.de/id/eprint/46769

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