Saenger, Casey; Affek, Hagit P; Felis, Thomas; Thiagarajan, Nivedita; Lough, Janice M; Holcomb, Michael (2012): Geochemical analyses and Delta47 values in shallow water corals. PANGAEA, https://doi.org/10.1594/PANGAEA.802852, Supplement to: Saenger, C et al. (2012): Carbonate clumped isotope variability in shallow water corals: Temperature dependence and growth-related vital effects. Geochimica et Cosmochimica Acta, 99, 224-242, https://doi.org/10.1016/j.gca.2012.09.035
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Geochemical variations in shallow water corals provide a valuable archive of paleoclimatic information. However, biological effects can complicate the interpretation of these proxies, forcing their application to rely on empirical calibrations. Carbonate clumped isotope thermometry (Delta47) is a novel paleotemperature proxy based on the temperature dependent "clumping" of 13C-18O bonds. Similar ?47-temperature relationships in inorganically precipitated calcite and a suite of biogenic carbonates provide evidence that carbonate clumped isotope variability may record absolute temperature without a biological influence. However, large departures from expected values in the winter growth of a hermatypic coral provided early evidence for possible Delta47 vital effects. Here, we present the first systematic survey of Delta47 in shallow water corals. Sub-annual Red Sea Delta47 in two Porites corals shows a temperature dependence similar to inorganic precipitation experiments, but with a systematic offset toward higher Delta47 values that consistently underestimate temperature by ~8 °C. Additional analyses of Porites, Siderastrea, Astrangia and Caryophyllia corals argue against a number of potential mechanisms as the leading cause for this apparent Delta47 vital effect including: salinity, organic matter contamination, alteration during sampling, the presence or absence of symbionts, and interlaboratory differences in analytical protocols. However, intra- and inter-coral comparisons suggest that the deviation from expected Delta47 increases with calcification rate. Theoretical calculations suggest this apparent link with calcification rate is inconsistent with pH-dependent changes in dissolved inorganic carbon speciation and with kinetic effects associated with CO2 diffusion into the calcifying space. However, the link with calcification rate may be related to fractionation during the hydration/hydroxylation of CO2 within the calcifying space. Although the vital effects we describe will complicate the interpretation of Delta47 as a paleothermometer in shallow water corals, it may still be a valuable paleoclimate proxy, particularly when applied as part of a multi-proxy approach.
Median Latitude: 1.909545 * Median Longitude: 55.362341 * South-bound Latitude: -54.500000 * West-bound Longitude: -129.500000 * North-bound Latitude: 41.528300 * East-bound Longitude: 167.400000
Date/Time Start: 1996-04-05T00:00:00 * Date/Time End: 1996-04-05T00:00:00
Datasets listed in this publication series
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Supplementary Table 1) Sub-annual Red Sea Porites Delta47 reported in the absolute reference frame. https://doi.org/10.1594/PANGAEA.802842
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Supplementary Table 2) Bulk-sampled coral Delta47 reported in the absolute reference frame. https://doi.org/10.1594/PANGAEA.802847
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Supplementary Table 3) Variable growth rate 21-141-B11 absolute reference frame Delta47. https://doi.org/10.1594/PANGAEA.802851
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Supplementary Table 4) Data used to calculate offset values in Figure 7 and 8. https://doi.org/10.1594/PANGAEA.803324
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Table 2) Sub-annual Red Sea Porites geochemical data. https://doi.org/10.1594/PANGAEA.802827
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Table 3) Geochemical results from bulk-sampled coral data. https://doi.org/10.1594/PANGAEA.802832
- Saenger, C; Affek, HP; Felis, T et al. (2012): (Table 4) Geochemical results from variable growth rate 21-141-B11 isochron. https://doi.org/10.1594/PANGAEA.802833