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

Wilson, David J.; Piotrowski, Alexander M; Galy, Αlbert; McCave, I Nick

doi:10.1016/j.epsl.2012.06.009

Cited by 69 publications

(41 citation statements)

References 70 publications

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“…Therefore, preferential contribution from a single mineral phase within the lithogenic component is possible. Preferential contribution is consistent with laboratory leaching experiments in which the ε Nd obtained was dependent on the fraction of the particles reacting with the leach solution (Wilson et al, 2012(Wilson et al, , 2013.…”

Section: Constraints On Pore Fluid ε Ndsupporting

confidence: 77%

“…Currently, the proposal of a trace mineral preferentially dominating the particulate-fluid interaction is consistent with observations in the modern ocean and in the laboratory (e.g. Jeandel and Oelkers, 2015;Pearce et al, 2013;Rousseau et al, 2015;Wilson et al, 2012Wilson et al, , 2013. Evidence for this radiogenic trace mineral exists in bottom water from HH200.…”

Section: Cryptic Trace Mineralmentioning

confidence: 62%

“…This idea builds upon studies that have highlighted the importance of sediments as a source of Nd to the ocean (e.g. Abbott et al, 2015aAbbott et al, , 2015bArsouze et al, 2009;Bayon et al, 2011;Carter et al, 2012;Elderfield and Sholkovitz, 1987;Freslon et al, 2014;Grousset et al, 1988;Haley and Klinkhammer, 2003;Jeandel et al, 2007;Jeandel, 2001, 2005;Sholkovitz and Elderfield, 1988;Sholkovitz et al, 1989;Tachikawa et al, 2003;van de Flierdt et al, 2004;Wilson et al, 2013), and that this benthic source likely determines the ε Nd distribution of the deep ocean (Abbott et al, 2015b).…”

Section: Introductionmentioning

confidence: 96%

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The impact of sedimentary coatings on the diagenetic Nd flux

Abbott

Haley

McManus

2016

Earth and Planetary Science Letters

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Because ocean circulation impacts global heat transport, understanding the relationship between deep ocean circulation and climate is important for predicting the ocean's role in climate change. A common approach to reconstruct ocean circulation patterns employs the neodymium isotope compositions of authigenic phases recovered from marine sediments. In this approach, mild chemical extractions of these phases is thought to yield information regarding the ε Nd of the bottom waters that are in contact with the underlying sediment package. However, recent pore fluid studies present evidence for neodymium cycling within the upper portions of the marine sediment package that drives a significant benthic flux of neodymium to the ocean. This internal sedimentary cycling has the potential to obfuscate any relationship between the neodymium signature recovered from the authigenic coating and the overlying neodymium signature of the seawater. For this manuscript, we present sedimentary leach results from three sites on the Oregon margin in the northeast Pacific Ocean. Our goal is to examine the potential mechanisms controlling the exchange of Nd between the sedimentary package and the overlying water column, as well as the relationship between the ε Nd composition of authigenic sedimentary coatings and that of the pore fluid. In our comparison of the neodymium concentrations and isotope compositions from the total sediment, sediment leachates, and pore fluid we find that the leachable components account for about half of the total solid-phase Nd, therefore representing a significant reservoir of reactive Nd within the sediment package. Based on these and other data, we propose that sediment diagenesis determines the ε Nd of the pore fluid, which in turn controls the ε Nd of the bottom water. Consistent with this notion, despite having 1 to 2 orders of magnitude greater Nd concentration than the bottom water, the pore fluid is still <0.001% of the total Nd reservoir in the upper sediment column. Therefore, the pore fluid reservoir is too small to maintain a unique signature, and instead must be controlled by the larger reservoir of Nd in the reactive coatings. In addition, to achieve mass balance, we find it necessary to invoke a cryptic radiogenic (ε Nd of +10) trace mineral source of neodymium within the upper sediment column at our sites. When present, this cryptic trace metal results in more radiogenic pore fluid.

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Section: Constraints On Pore Fluid ε Ndsupporting

confidence: 77%

Section: Cryptic Trace Mineralmentioning

confidence: 62%

Section: Introductionmentioning

confidence: 96%

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The impact of sedimentary coatings on the diagenetic Nd flux

Abbott

Haley

McManus

2016

Earth and Planetary Science Letters

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“…Batch experiments or sequential leaching slightly illuminated the processes by confirming that a fraction of the lithogenic material can be dissolved, releasing some of the elements it contains and contributing to balance their isotopic composition [29][30][31][32]51]. These experiments also showed that secondary phases are rapidly formed, scavenging a large part of most of the released species.…”

Section: (D) What Do the Models Tell Us?mentioning

confidence: 70%

Overview of the mechanisms that could explain the ‘Boundary Exchange’ at the land–ocean contact

Jeandel¹

2016

Phil. Trans. R. Soc. A.

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“…[5] For the interpretation of variations in Nd as changes in overturning circulation it is important to be able to disentangle variations resulting from changes in Nd sources from variations that are due to changes in overturning circulation [e.g., Wilson et al, 2012]. This in turn requires a good overall knowledge of the nature and magnitude of these sources.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Nd isotopic composition in seawater to changes in Nd sources and paleoceanographic implications

Rempfer¹,

Stocker²,

Joos³

et al. 2012

J. Geophys. Res.

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.[1] It has been argued that past changes in the sources of Nd could hamper the use of the Nd isotopic composition ( Nd ) as a proxy for past changes in the overturning of deep water masses. Here we reconsider uncertainties associated with Nd in seawater due to potential regional to global scale changes in the sources of Nd by applying a modeling approach. For illustrative purposes we describe rather extreme changes in the magnitude of source fluxes, their isotopic composition or both. We find that the largest effects on Nd result from changes in the boundary source. Considerable changes also result from variations in the magnitude or Nd of dust and rivers but are largely constrained to depths shallower than 1 km, except if they occur in or upstream of regions where deep water masses are formed. From these results we conclude that changes in Nd sources have the potential to affect Nd . However, substantial changes are required to generate large-scale changes in Nd in deep water that are similar in magnitude to those that have been reconstructed from sediment cores or result from changes in meridional overturning circulation in model experiments. Hence, it appears that a shift in Nd comparable to glacial-interglacial variations is difficult to obtain by changes in Nd sources alone, but that more subtle variations can be caused by such changes and must be interpreted with caution.

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

Abstract: The use of neodymium (Nd) isotopes to reconstruct past water mass mixing relies upon the quasi-conservative behaviour of this tracer,

Cited by 69 publications

References 70 publications

The impact of sedimentary coatings on the diagenetic Nd flux

The impact of sedimentary coatings on the diagenetic Nd flux

Overview of the mechanisms that could explain the ‘Boundary Exchange’ at the land–ocean contact

Sensitivity of Nd isotopic composition in seawater to changes in Nd sources and paleoceanographic implications

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