Rare earth element association with foraminifera

Roberts, Natalie L; Piotrowski, Alexander M; Elderfield, Henry; Eglinton, T. I.; Lomas, Michael W.

doi:10.1016/j.gca.2012.07.009

Cited by 90 publications

(98 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our interpretation that leaching of nondecarbonated sediments recovers a bottom water e Nd signal is based on the validation of uncleaned foraminiferal e Nd as a bottom water e Nd carrier at sites elsewhere (Palmer and Elderfield, 1985;Elmore et al, 2011;Piotrowski et al, 2012) and the evidence that any surface-derived Nd present within the foraminiferal carbonate lattice makes up only a minor part of its Nd budget (Palmer, 1985;Roberts et al, 2012;Tachikawa et al, 2013). Any possible benefit gained from the removal of surface-derived Nd using decarbonation in acetic acid would appear to be outweighed by the loss of the Mn-associated authigenic phase (Section 4.1.1; Fig.…”

Section: Recommended Leaching Proceduresmentioning

confidence: 93%

“…5b). REEs in sedimentary foraminifera have been shown to be carried by authigenic nano-phases (Palmer, 1985;Palmer and Elderfield, 1986;Roberts et al, 2012;Tachikawa et al, 2013), and in the case of WIND 24B this probably represents a Mn oxide phase. Subtracting the REE concentrations of the shortest duration leach (30 min) from those of the longest duration leach (480 min) allows us to characterise the REE pattern of the slow-reacting Fe-and Al-rich phase (Fig.…”

Section: Dissolution Of Multiple Phases Under a Kinetic Controlmentioning

confidence: 99%

“…6c) indicates that the two phases from which Nd is extracted (inferred to be Mn oxides and Fe oxides) have the same or similar e Nd compositions (À11.0 to À11.5) and the agreement with e Nd from uncleaned foraminifera implies an authigenic origin. The REE budget of uncleaned sedimentary planktonic foraminifera is dominated by authigenic coatings derived from bottom water (Palmer, 1985;Palmer and Elderfield, 1986;Roberts et al, 2012) that likely comprise iron (oxyhydr)oxides, manganese oxides and/or manganese carbonates (e.g. Boyle, 1983;Haley et al, 2005;Pena et al, 2008;Tachikawa et al, 2013).…”

Section: Nd Isotopic Evidence On the Phases Involvedmentioning

confidence: 99%

“…4b and 6c). Uncleaned foraminifera are considered to represent the authigenic e Nd composition (Palmer and Elderfield, 1985;Roberts et al, 2012), which indicates an authigenic origin for these extracted components. Boundary exchange involving such components derived from local bottom water is expected to have a minimal isotopic effect.…”

Section: Extraction Of An Authigenic Componentmentioning

confidence: 99%

“…We have previously demonstrated that boundary exchange may be important in modifying bottom water e Nd in this region (Wilson et al, 2012) such that comparison to the open ocean water profiles of Bertram and Elderfield (1993) must be made with caution. However, recent studies indicate that uncleaned sedimentary planktonic foraminifera reliably record bottom water e Nd compositions in most settings (Elmore et al, 2011;Piotrowski et al, 2012;Roberts et al, 2012;Tachikawa et al, 2013). We therefore use uncleaned foraminifera as a proxy for the local bottom water e Nd compositions at our sites (Fig.…”

Section: Implications For Recovering the Past Seawater E Nd By Leachingmentioning

confidence: 99%

See 4 more Smart Citations

Reactivity of neodymium carriers in deep sea sediments: Implications for boundary exchange and paleoceanography

Wilson

Piotrowski

Galy

et al. 2013

Geochimica et Cosmochimica Acta

Self Cite

117

141

View full text Add to dashboard Cite

The dissolved neodymium (Nd) isotopic distribution in the deep oceans is determined by continental weathering inputs, water mass advection, and boundary exchange between particulate and dissolved fractions. Reconstructions of past Nd isotopic variability may therefore provide evidence on temporal changes in continental weathering inputs and/or ocean circulation patterns over a range of timescales. However, such an approach is limited by uncertainty in the mechanisms and importance of the boundary exchange process, and the challenge in reliably recovering past seawater Nd isotopic composition (e Nd ) from deep sea sediments. This study addresses these questions by investigating the processes involved in particulatesolution interactions and their impact on Nd isotopes. A better understanding of boundary exchange also has wider implications for the oceanic cycling and budgets of other particle-reactive elements.Sequential acid-reductive leaching experiments at pH $2-5 on deep sea sediments from the western Indian Ocean enable us to investigate natural boundary exchange processes over a timescale appropriate to laboratory experiments. We provide evidence that both the dissolution of solid phases and exchange processes influence the e Nd of leachates, which suggests that both processes may contribute to boundary exchange. We use major element and rare earth element (REE) data to investigate the pools of Nd that are accessed and demonstrate that sediment leachate e Nd values cannot always be explained by admixture between an authigenic component and the bulk detrital component. For example, in core WIND 24B, acid-reductive leaching generates e Nd values between À11 and À6 as a function of solution/solid ratios and leaching times, whereas the authigenic components have e Nd % À11 and the bulk detrital component has e Nd % À15. We infer that leaching in the Mascarene Basin accesses authigenic components and a minor radiogenic volcanic component that is more reactive than Madagascan-derived clays. The preferential mobilisation of such a minor component demonstrates that the Nd released by boundary exchange could often have a significantly different e Nd composition than the bulk detrital sediment.These experiments further demonstrate certain limitations on the use of acid-reductive leaching to extract the e Nd composition of the authigenic fraction of bulk deep sea sediments. For example, the detrital component may contain a reactive fraction which is also acid-extractible, while the incongruent nature of this dissolution suggests that it is often inappropriate to use the bulk detrital sediment elemental chemistry and/or e Nd composition when assessing possible detrital contamination of leachates. Based on the highly systematic controls observed, and evidence from REE patterns on the phases extracted, we suggest two approaches that lead to the most reliable extraction of the authigenic e Nd component and good agreement with foraminiferal-based approaches; either (i) leaching of sediments without a prior decarbona...

show abstract