The hafnium and neodymium isotope composition of seawater in the Atlantic sector of the Southern Ocean

Stichel, Torben; Frank, Martin; Rickli, Jörg; Haley, Brian A.

doi:10.1016/j.epsl.2011.11.025

Cited by 165 publications

(201 citation statements)

References 71 publications

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“…This suggests that Nd isotopes may be advected conservatively in volumetrically large portions of the deep open ocean outside of the influence of major reactive detrital inputs; for example between the southern South Atlantic and western Indian Ocean, via the Atlantic sector of the Southern Ocean. Such conservative behaviour in the Antarctic Circumpolar Current has recently been demonstrated in modern seawater studies (Carter et al, 2012;Stichel et al, 2012) and we show that this was apparently true during both the Holocene and Late Glacial periods. The implication is that evidence on the ε Nd evolution of the Southern Ocean end member through time may be obtained from WIND 5K or RC11-83 (Piotrowski et al, 2005), but not from WIND 28K or V19-188 (Pahnke et al, 2008).…”

Section: Geographic Extent and Paleoceanographic Implications Of Bounsupporting

confidence: 86%

“…The deep Indian Ocean is ventilated at depth from the south by CDW; a well-mixed water mass which originates in the Southern Ocean where its ε Nd composition is homogeneous at around -8.6 ± 0.4 (2σ) (Stichel et al, 2012). The total deep inflow to the Indian Basin is estimated at 11 ± 4 Sverdrups (Ganachaud et al, 2000), which comprises northward flowing CDW that is restricted by ridges and plateaus to a western and a central branch (You, 2000;Schott and McCreary, 2001).…”

Section: Regional Setting and Hydrographymentioning

confidence: 99%

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A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean

Wilson

Piotrowski

Galy

et al. 2012

Earth and Planetary Science Letters

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Section: Geographic Extent and Paleoceanographic Implications Of Bounsupporting

confidence: 86%

Section: Regional Setting and Hydrographymentioning

confidence: 99%

A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean

Wilson

Piotrowski

Galy

et al. 2012

Earth and Planetary Science Letters

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“…2). This lower NADW fills most of the northeast Atlantic below 2500 m today (McCartney, 1992 (Jeandel, 1993;Stichel et al, 2012), site 900 should be sensitive to changes in the relative influence of northern versus southern source waters, as has been demonstrated for other sites further south on glacial-interglacial timescales of the latest Quaternary (e.g., Roberts et al, 2010).…”

Section: Study Areamentioning

confidence: 62%

A major change in North Atlantic deep water circulation 1.6 million years ago

Khélifi

2014

Clim. Past

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Abstract. The global ocean-climate system has been highly sensitive to the formation and advection of deep overflow water from the Nordic Seas as integral part of the Atlantic Meridional Overturning Circulation (AMOC) but its evolution over the Pliocene-Pleistocene global cooling is not fully understood. In particular, changes in the sources and mixing of prevailing deep waters that were involved in driving overturning throughout the Pliocene-Pleistocene climate transitions are not well constrained. Here we investigate the evolution of a substantial deep southward return overflow of the AMOC over the last 4 million years. We present new records of the bottom-water radiogenic neodymium isotope (ε Nd ) variability obtained from three sediment cores (DSDP site 610 and ODP sites 980/981 and 900) at water depths between 2170 and 5050 m in the northeast Atlantic. We find that prior to the onset of major Northern Hemisphere glaciation (NHG) ∼ 3 million years ago (Ma), ε Nd values primarily oscillated between −9 and −11 at all sites, consistent with enhanced vertical mixing and weak stratification of the water masses during the warmer-than-today Pliocene period. From 2.7 Ma to ∼ 2.0 Ma, the ε Nd signatures of the water masses gradually became more distinct, which documents a significant advection of Nordic Seas overflow deep water coincident with the intensification of NHG. Most markedly, however, at ∼ 1.6 Ma the interglacial ε Nd signatures at sites 610 (2420 m water depth (w.d.)) and 980/981 (2170 m w.d.) synchronously and permanently shifted by 2 to 3 ε Nd units to less radiogenic values, respectively. Since then the difference between glacial and interglacial ε Nd values has been similar to the Late Quaternary at each site. A decrease of ∼ 2 ε Nd units at 1.6 Ma was also recorded for the deepest water masses by site 900 (∼ 5 050 m w.d.), which thereafter, however, evolved to more radiogenic values again until the present. This major ε Nd change across the 1.6 Ma transition reflects a significant reorganization of the overturning circulation in the northeast Atlantic paving the way for the more stratified water column with distinct water masses prevailing thereafter.

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“…5c), and also strongly correlated with 456 silicon concentrations (Stichel et al, 2012a). Most of the samples in the Pacific 457 sector are shifted to higher concentrations for a given neutral density when 458 compared to data from the Atlantic sector (Fig.…”

Section: Neodymium Isotopes In the Southern Ocean 366mentioning

confidence: 79%

Neodymium and hafnium boundary contributions to seawater along the West Antarctic continental margin

Rickli

Gutjahr

Vance

et al. 2014

Earth and Planetary Science Letters

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30Neodymium and hafnium isotopes and elemental concentrations (Sm, Nd, Hf, Zr) 31 have been measured in three water column profiles south of the Antarctic 32 Circumpolar Current in, and to the east of the Ross Sea, in conjunction with five 33 bottom water samples from the Amundsen Sea Embayment. 34Neodymium and hafnium both appear to be released from sediments in the 35Embayment. In the case of Nd, this is reflected in radiogenic isotope 36 compositions (εNd up to -5.4) and highly elevated concentrations (up to 41 37 pmol/kg). Hafnium isotopes, on the other hand, are only very slightly altered 38relative to the open ocean sites, and boundary release is most prominently 39 indicated by elevated concentrations (> 1 pmol/kg versus ~0.7 pmol/kg). There 40 is also a local input of both Hf and Nd at the Marie Byrd Seamounts, which leads 41 to Nd isotope compositions as radiogenic as -3.1, and hafnium shifted to less 42 radiogenic compositions in local bottom water.

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The hafnium and neodymium isotope composition of seawater in the Atlantic sector of the Southern Ocean

Cited by 165 publications

References 71 publications

A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean

A boundary exchange influence on deglacial neodymium isotope records from the deep western Indian Ocean

A major change in North Atlantic deep water circulation 1.6 million years ago

Neodymium and hafnium boundary contributions to seawater along the West Antarctic continental margin

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