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Clumped isotope composition of cold-water corals: A role for vital effects?

Spooner, Peter T. and Guo, Weifu and Robinson, Laura F. and Thiagarajan, Nivedita and Hendry, Katharine R. and Rosenheim, Brad E. and Leng, Melanie J. (2016) Clumped isotope composition of cold-water corals: A role for vital effects? Geochimica et Cosmochimica Acta, 179 . pp. 123-141. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20160415-083933784

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Abstract

The carbonate clumped isotope thermometer is a promising tool for determining past ocean temperatures. It is based on the temperature dependence of rare isotopes ‘clumping’ into the same carbonate ion group in the carbonate mineral lattice. The extent of this clumping effect is independent of the isotope composition of the water from which carbonate precipitates, providing unique advantages over many other paleotemperature proxies. Existing calibrations of this thermometer in cold-water and warm-water corals suggest clumped isotope ‘vital effects’ are negligible in cold-water corals but may be significant in warm-water corals. Here, we test the calibration of the carbonate clumped isotope thermometer in cold-water corals with a recently collected and well characterised sample set spanning a range of coral genera (Balanophyllia, Caryophyllia, Dasmosmilia, Desmophyllum, Enallopsammia and Javania). The clumped isotope compositions (Δ47) of these corals exhibit systematic dependences on their growth temperatures, confirming the basis of the carbonate clumped isotope thermometer. However, some cold-water coral genera show Δ_(47) values that are higher than the expected equilibrium values by up to 0.05‰ (equivalent to underestimating temperature by ∼9 °C) similar to previous findings for some warm-water corals. This finding suggests that the vital effects affecting corals Δ_(47) are common to both warm- and cold-water corals. By comparison with models of the coral calcification process we suggest that the clumped isotope offsets in these genera are related to the kinetic isotope effects associated with CO_2 hydration/hydroxylation reactions in the corals’ calcifying fluid. Our findings complicate the use of the carbonate clumped isotope thermometer in corals, but suggest that species- or genus-specific calibrations could be useful for the future application of this paleotemperature proxy.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.gca.2016.01.023DOIArticle
http://www.sciencedirect.com/science/article/pii/S0016703716300072PublisherArticle
Additional Information:© 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Received 8 May 2015; accepted in revised form 12 January 2016; available online 2 February 2016. We thank Prof. Benjamin H. Passey for generously providing the 102-GC-AZ01 carbonate standard and help during the construction of the automated clumped isotope analysis system at WHOI and Professors John Eiler and Jess Adkins for providing the facilities at Caltech for the inter-laboratory comparison study and for helpful discussion. This work was supported by a British National Environment Research Council studentship to P. Spooner (NE/K500823/1), National Science Foundation Grant NSF-ANT-1246387 and The Penzance Endowed Fund in Support of Assistant Scientists (WHOI) to W. Guo, and by funds from the European Research Council, the Leverhulme Trust and a Marie Curie Reintegration grant. Oxygen isotope analyses of seawater samples at BGS were funded by the NERC Isotope Geosciences Facilities Steering Committee.
Funders:
Funding AgencyGrant Number
National Environment Research Council (NERC)NE/K500823/1
NSFANT-1246387
Woods Hole Oceanographic InstitutionUNSPECIFIED
European Research Council (ERC)UNSPECIFIED
Leverhulme TrustUNSPECIFIED
Marie Curie FellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20160415-083933784
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160415-083933784
Official Citation:Peter T. Spooner, Weifu Guo, Laura F. Robinson, Nivedita Thiagarajan, Katharine R. Hendry, Brad E. Rosenheim, Melanie J. Leng, Clumped isotope composition of cold-water corals: A role for vital effects?, Geochimica et Cosmochimica Acta, Volume 179, 15 April 2016, Pages 123-141, ISSN 0016-7037, http://dx.doi.org/10.1016/j.gca.2016.01.023. (http://www.sciencedirect.com/science/article/pii/S0016703716300072)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66209
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:16 Apr 2016 16:23
Last Modified:03 Oct 2019 09:54

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