Adkins, J. F. and Boyle, E. A. and Curry, W. B. and Lutringer, A. (2003) Stable isotopes in deep-sea corals and a new mechanism for “vital effects”. Geochimica et Cosmochimica Acta, 67 (6). pp. 1129-1143. ISSN 0016-7037 http://resolver.caltech.edu/CaltechAUTHORS:20120830-132156981
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Offsets from isotopic equilibrium in biogenic carbonates have complicated paleoclimate reconstructions for decades. A new archive of climate, deep-sea corals, is used to evaluate the calcification processes, independent of photosynthesis, that contribute to these offsets. Carbon and oxygen stable isotope data from six modern deep-sea corals show strong linear trends between δ^(13)C and δ^(18)O. Slopes of these trends between samples are similar and range between 1.9 to 2.6 for Δδ^(13)C/Δδ^(18)O. Linear trends intersect isotopic equilibrium for δ^(18)O and are slightly depleted for δ^(13)C. Variations in the isotopic ratios are strongly correlated with the density banding structure. Isotopically depleted aragonite is associated with light, quickly precipitating bands, whereas isotopically enriched points correspond to slowly accumulating, less dense aragonite. The densest white band at the trabecular center is furthest from isotopic equilibrium for both carbon and oxygen. Data from this region fall off the linear trend between δ^(18)O and δ^(13)C. This deviation, where δ^(13)C remains constant while the δ^(18)O continues to decrease, does not support “vital effect” mechanisms that call upon kinetic fractionation to explain offsets from isotopic equilibrium. We propose a new mechanism for vital effects in these deep-sea corals that is based on a thermodynamic response to a biologically induced pH gradient in the calcifying region.
|Additional Information:||© 2003 Elsevier Science Ltd. Received January 24, 2002; accepted in revised form September 13, 2002. This research was supported by NSF grant number OCE-0096373 and an NCAR Global Climate Change Postdoctoral Fellowship to J.F.A. We thank David Lea, Howie Spero, Richard Zeebe, and an anonymous reviewer for constructive comments that improved the article. In addition to the above people, conversations with Jonathan Erez, Francios Morel, Michael Bender, and Jele Bjima have helped to shape our thinking about vital effects. Associate editor: D. Lea|
|Official Citation:||J.F. Adkins, E.A. Boyle, W.B. Curry, A. Lutringer, Stable isotopes in deep-sea corals and a new mechanism for “vital effects”, Geochimica et Cosmochimica Acta, Volume 67, Issue 6, 15 March 2003, Pages 1129-1143, ISSN 0016-7037, 10.1016/S0016-7037(02)01203-6.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||30 Aug 2012 23:09|
|Last Modified:||30 Aug 2012 23:10|
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