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

Online Access: Get full text
doi: 10.1002/2014PA002666
Author(s): Pfister, Patrik L.; Stocker, Thomas F.; Rempfer, Johannes; Ritz, Stefan P.
Author Affiliation(s): Primary:
University of Bern, Physics Institute, Bern, Switzerland
Volume Title: Paleoceanography
Source: Paleoceanography, 29(12), p.1214-1237. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 76 refs.; illus., incl. 4 tables
Summary: 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 δNd 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. Abstract Copyright (2014), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2014
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Atlantic meridional overturning circulation; Bern3D; Cenozoic; Central America; Central American Seaway; Drake Passage; Fresh water; Isotope ratios; Isotopes; Leg 113; Leg 177; Marine environment; Maud Rise; Metals; Nd-144/Nd-143; Neodymium; Neogene; Numerical models; ODP Site 1090; ODP Site 689; Ocean Drilling Program; Ocean circulation; Paleo-oceanography; Paleoenvironment; Paleogeography; Quaternary; Rare earths; South Atlantic; Southern Ocean; Stable isotopes; Tertiary; Three-dimensional models; Weddell Sea
Coordinates: S163335 S163335 E0104912 E0104912
S643101 S643100 E0030600 E0030559
Record ID: 2015016319
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom