Influence of the Central American Seaway and Drake Passage on ocean circulation and neodymium isotopes: A model study

Pfister, Patrik L.; Stocker, Thomas F.; Rempfer, Johannes; Ritz, Stefan P. (2014). Influence of the Central American Seaway and Drake Passage on ocean circulation and neodymium isotopes: A model study. Paleoceanography, 29(12), pp. 1214-1237. American Geophysical Union 10.1002/2014PA002666

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The sensitivity of the neodymium isotopic composition (ϵNd) to tectonic rearrangements of seaways is investigated using an Earth System Model of Intermediate Complexity. The shoaling and closure of the Central American Seaway (CAS) is simulated, as well as the opening and deepening of Drake Passage (DP). Multiple series of equilibrium simulations with various intermediate depths are performed for both seaways, providing insight into ϵNd and circulation responses to progressive throughflow evolutions. Furthermore, the sensitivity of these responses to the Atlantic Meridional Overturning Circulation (AMOC) and the neodymium boundary source is examined. Modeled ϵNd changes are compared to sediment core and ferromanganese (Fe-Mn) crust data. The model results indicate that the North Atlantic ϵNd response to the CAS shoaling is highly dependent on the AMOC state, i.e., on the AMOC strength before the shoaling to shallow depths (preclosure). Three scenarios based on different AMOC forcings are discussed, of which the model-data agreement favors a shallow preclosure (Miocene) AMOC (∼6 Sv). The DP opening causes a rather complex circulation response, resulting in an initial South Atlantic ϵNd decrease preceding a larger increase. This feature may be specific to our model setup, which induces a vigorous CAS throughflow that is strongly anticorrelated to the DP throughflow. In freshwater experiments following the DP deepening, ODP Site 1090 is mainly influenced by AMOC and DP throughflow changes, while ODP Site 689 is more strongly influenced by Southern Ocean Meridional Overturning Circulation and CAS throughflow changes. The boundary source uncertainty is largest for shallow seaways and at shallow sites.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics

UniBE Contributor:

Pfister, Patrik; Stocker, Thomas; Rempfer, Johannes and Ritz, Stefan

Subjects:

500 Science > 530 Physics

ISSN:

0883-8305

Publisher:

American Geophysical Union

Language:

English

Submitter:

Doris Rätz

Date Deposited:

29 Jan 2015 11:07

Last Modified:

18 Jun 2015 02:30

Publisher DOI:

10.1002/2014PA002666

BORIS DOI:

10.7892/boris.62576

URI:

https://boris.unibe.ch/id/eprint/62576

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