Neodymium isotopes and concentrations in aragonitic scleractinian cold-water coral skeletons - Modern calibration and evaluation of palaeo-applications

• Published in: Chemical Geology
• Main Authors: Struve, Torben, van de Flierdt, Tina, Burke, Andrea, Robinson, Laura F., Hammond, Samantha J., Crocket, Kirsty C., Bradtmiller, Louisa I., Auro, Maureen E., Mohamed, Kais J., White, Nicholas J.
• Other Authors: University of St Andrews. Earth and Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Neodymium isotopes; Rare earth elements; Cold-water corals; Seawater; Sediments; Drake Passage; GE Environmental Sciences; NDAS; GE; North Atlantic
• Online Access: http://hdl.handle.net/10023/10384; https://doi.org/10.1016/j.chemgeo.2017.01.022

TvdF and TS acknowledge financial support for a bursary by the Grantham Institute of Climate Change and the Environment and a Marie Curie Reintegration grant (IRG 230828), as well as funding from the Leverhulme Trust (RPG-398) and the NERC (NE/N001141/1). Additional financial support was provided to LFR by the USGS-WHOI Co-operative agreement, NSF-ANT grants 0636787 and 80295700, The European Research Council, the Leverhulme Trust and a Marie Curie Reintegration grant. LB was supported by a NOAA/UCAR Climate and Global Change Postdoctoral Fellowship and KJM acknowledges funding from a Marie Curie International Outgoing fellowship (IOF 236962). Cold-water corals (CWCs) are unique archives of mid-depth ocean chemistry and have been used successfully to reconstruct the neodymium (Nd) isotopic composition of seawater from a number of species. High and variable Nd concentrations in fossil corals however pose the question as to how Nd is incorporated into their skeletons. We here present new results on modern specimens of Desmophyllum dianthus, Balanophyllia malouinensis, and Flabellum curvatum, collected from the Drake Passage, and Madrepora oculata, collected from the North Atlantic. All modern individuals were either collected alive or uranium-series dated to be < 500 years old for comparison with local surface sediments and seawater profiles. Modern coral Nd isotopic compositions generally agree with ambient seawater values, which in turn are consistent with previously published seawater analyses, supporting small vertical and lateral Nd isotope gradients in modern Drake Passage waters. Two Balanophyllia malouinensis specimens collected live however deviate by up to 0.6 epsilon units from ambient seawater. We therefore recommend that this species should be treated with caution for the reconstruction of past seawater Nd isotopic compositions. Seventy fossil Drake Passage CWCs were furthermore analysed for their Nd concentrations, revealing a large range from 7.3 to 964.5 ng/g. Samples of the species D. ...