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, 12 (6). pp. 456-461. 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.
Keywords: Cretaceous, Modelling, orbital cycles, biogeochemical feedbacks, seasaw
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
OceanRep > SFB 754
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1038/s41561-019-0359-x
ISSN: 1752-0894
Projects: ICONOX, SFB754
Date Deposited: 22 May 2019 07:37
Last Modified: 13 Jun 2019 07:43
URI: http://oceanrep.geomar.de/id/eprint/46769

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