Periodic changes in the Cretaceous ocean and climate caused by marine redox see-saw
Wallmann, K.; Flögel, S.; Scholz, F.; Dale, A. W.; Kemena, T.P.; Steinig, S.; Kuhnt, W. (2019). Periodic changes in the Cretaceous ocean and climate caused by marine redox see-saw. Nature Geoscience 12(6): 456-461. https://dx.doi.org/10.1038/s41561-019-0359-x
In: Nature Geoscience. Nature Publishing Group: London. ISSN 1752-0894; e-ISSN 1752-0908, more
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| Authors | | Top |
- Wallmann, K.
- Flögel, S.
- Scholz, F.
- Dale, A. W.
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- Kemena, T.P.
- Steinig, S.
- Kuhnt, W., more
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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 \(p_{\mathrm {CO}_2}\). 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. |
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