Evolution of the oceanic calcium cycle during the late Mesozoic: Evidence from δ44/40Ca of marine skeletal carbonates

Farkaš, Juraj; Buhl, Dieter; Blenkinsop, John; Veizer, Ján

doi:10.1016/j.epsl.2006.10.015

Cited by 106 publications

(82 citation statements)

References 45 publications

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“…The δ 88/86 Sr sw reflects the fact that the Sr content in seawater precipitates (aragonite vs. calcite) differ by a factor of 3-10 (Milliman et al, 1974;Steuber and Veizer, 2002) while for calcium isotopes the isotopic fractionation factors are different (Blättler et al, 2012;Farkaš et al, 2007a) for these two carbonate polymorphs. Specifically, the higher Ca isotope fractionation factor of aragonite in contrast to calcite results in higher δ 44/40 Ca sw during "aragonite" seas (Blättler et al, 2012;Farkaš et al, 2007a;Farkaš et al, 2007b). As a result, both probably related to the shift to more sophisticated calcitic biomineralizers with a Δ 44/40 Ca cc-sw that is more similar to that of aragonite (Blättler et al, 2012).…”

Section: Interpretation Of the δ 88/86 Sr Sw Recordmentioning

confidence: 97%

The Phanerozoic δ88/86Sr record of seawater: New constraints on past changes in oceanic carbonate fluxes

Vollstaedt

Eisenhauer

Wallmann

et al. 2014

Geochimica et Cosmochimica Acta

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107

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The isotopic composition of Phanerozoic marine sediments provides important information about changes in seawater chemistry. In particular, the radiogenic strontium isotope ( 87 Sr/ 86 Sr) system is a powerful tool for constraining plate tectonic processes and their influence on atmospheric CO 2 concentrations. However, the 87 Sr/ 86 Sr isotope ratio of seawater is not sensitive to temporal changes in the marine strontium (Sr) output flux, which is primarily controlled by the burial of calcium carbonate (CaCO 3 ) at the ocean floor. The Sr budget of the Phanerozoic ocean, including the associated changes in the amount of CaCO 3 burial, is therefore only poorly constrained. Here, we present the first stable isotope record of Sr for Phanerozoic skeletal carbonates, and by inference for Phanerozoic seawater (δ 88/86 Sr sw ), which we find to be sensitive to imbalances in the Sr input and output fluxes. This δ 88/86 Sr sw record varies from ~0.25‰ to ~0.60‰ (vs. SRM987) with a mean of ~0.37‰. The fractionation factor between modern seawater and skeletal The oceanic net carbonate flux of Sr (F(Sr) carb ) varied between an output of -4.7x10 10 mol/Myr and an input of +2.3x10 10 mol/Myr with a mean of -1.6x10 10 mol/Myr.On time scales in excess of 100Myrs the F(Sr) carb is proposed to have been controlled by the relative importance of calcium carbonate precipitates during the "aragonite" and "calcite" sea episodes. On time scales less than 20Myrs the F(Sr) carb seems to be controlled by variable combinations of carbonate burial rate, shelf carbonate weathering and recrystallization, ocean acidification, and ocean anoxia. In particular, the Permian/Triassic transition is marked by a prominent positive δ 88/86 Sr sw -peak that reflects a significantly enhanced burial flux of Sr and carbonate, likely driven by bacterial sulfate reduction (BSR) and the related alkalinity production in deeper anoxic waters. We also argue that the residence time of Sr in the Phanerozoic ocean ranged from ~1Myrs to ~20Myrs.

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Section: Interpretation Of the δ 88/86 Sr Sw Recordmentioning

confidence: 97%

The Phanerozoic δ88/86Sr record of seawater: New constraints on past changes in oceanic carbonate fluxes

Vollstaedt

Eisenhauer

Wallmann

et al. 2014

Geochimica et Cosmochimica Acta

Self Cite

107

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“…brachiopods from Steuber and Buhl (2006) and Farkaš et al (2007b). The average of G. vitreus (R3) and the additional G. vitreus samples R3S.1 and R4.1, however, have lower Sr contents and higher δ 44/40 Ca values than T. septentrionalis and the modern brachiopods from Steuber and Buhl (2006) and Farkaš et al (2007b). Nevertheless, these G. vitreus samples plot very close to the experimental inorganic calcite slope (Fig.…”

Section: Calcium Isotopesmentioning

confidence: 88%

“…However, Tang et al (2008) pointed out that the experimental fluid solution did not contain Mg and, hence, might not be directly comparable to seawater and its precipitates. The three modern brachiopods measured by Steuber and Buhl (2006) and Farkaš et al (2007b) plot close together near the experimental slope (Fig. 4).…”

Section: Calcium Isotopesmentioning

confidence: 89%

“…a δ 44/40 Ca errors are given as 2SD for n = 1 and as 2SEM for n >1, 2σ external standard reproducibility is better or equal to ±0.25‰, the Sr value for sample R3S.PL is an estimated average from LA-ICP-MS data (Table1), (n) denotes number of repeat measurements. brachiopods from Steuber and Buhl (2006) and Farkaš et al (2007b). The average of G. vitreus (R3) and the additional G. vitreus samples R3S.1 and R4.1, however, have lower Sr contents and higher δ 44/40 Ca values than T. septentrionalis and the modern brachiopods from Steuber and Buhl (2006) and Farkaš et al (2007b).…”

Section: Calcium Isotopesmentioning

confidence: 99%

“…Further studies such as, e.g., Popp et al (1986), Grossman et al (1996) and Buening et al (1998) have proposed taxonomic effects on isotopic and elemental composition of brachiopods. The low Sr content and heavy calcium isotopic signature suggest that the tertiary layer of G. vitreus was secreted more slowly, i.e., close to equilibrium with seawater (either due to taxonomic effects or in relation to the specialized shell structure) than the secondary layers of G. vitreus, T. septentrionalis and other species with higher Sr and lighter calcium isotopic values (Steuber and Buhl, 2006;Farkaš et al, 2007b). The hypothesis of equilibrium precipitation of calcium isotopes in the tertiary layer of G. vitreus is further supported (Steuber and Buhl, 2006;Farkaš et al, 2007b), shows that modern brachiopods plot relatively close to the kinetically driven inorganic experimental slope from Tang et al (2008).…”

Section: Calcium Isotopesmentioning

confidence: 99%

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Stable isotope profiles (Ca, O, C) through modern brachiopod shells of T. septentrionalis and G. vitreus: Implications for calcium isotope paleo-ocean chemistry

et al. 2010

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Brachiopod shells are widely used as an archive to reconstruct elemental and isotopic composition of seawater. Studies, focused on oxygen and carbon isotopes over the last decades, are increasingly extending to the emerging calcium isotope system. To date, only little attention has been paid to test the reliability of fossil brachiopods on their modern counterparts. In this context, the present study investigates two modern brachiopods, Terebratulina septentrionalis (eastern Canada, 5-30 m depth, 7.1°C seasonal temperature variation, two-layer shell) and Gryphus vitreus (northern Mediterranean, 200 m depth, constant all-year round temperature, three-layer shell). Both species were sampled along the ontogenetic growth direction and calcium, oxygen, and carbon isotopes as well as elemental concentration were measured. Calcium isotopes were analyzed on TIMS. The elemental composition was analyzed by LA-ICP-MS and ICP-AES. The results indicate an intra-specimen δ 44/40 Ca variation ranging from 0.16 to 0.33‰, pointing to a fairly homogenous distribution of calcium isotopes in brachiopod shells. However, in the light of the suggested 0.7‰ increase in calcium isotopes over the Phanerozoic such intra-specimen variations constrain ocean reconstruction. δ 44/40 Ca values of T. septentrionalis do not seem to be affected by growth rate. Calcium isotopic values of G. vitreus are heavy in the central part of the shell and trend towards lighter values in peripheral areas approaching the maximum isotopic composition of T. septentrionalis. The maximum interspecies δ 44/40 Ca difference of 0.62‰ between T. septentrionalis and G. vitreus indicates that care should be taken when using different taxa, species with different strontium content or brachiopods with specialized shell structure, such as G. vitreus, for ocean water reconstruction in terms of Ca isotopic composition. T. septentrionalis may record Ca isotopic fractionation related to seasonal seawater temperature variations in its shell but this is difficult to resolve at the current analytical precision. Average δ 18 O-derived temperatures of the two investigated species are close to on-site measured temperatures.

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Global carbon cycle perturbation across the Eocene‐Oligocene climate transition

2016

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The Eocene-Oligocene transition (EOT),~34 Ma, marks a tipping point in the long-term Cenozoic greenhouse to icehouse climate transition. Paleorecords reveal stepwise rapid cooling and ice growth across the EOT tightly coupled to a transient benthic δ 13 C excursion and a major and permanent deepening of the carbonate compensation depth (CCD). Based on biogeochemical box modeling, Merico et al. (2008) suggested that a combination of (1) glacioeustatic sea level fall-induced shelf-basin carbonate burial fractionation and (2) shelf carbonate weathering can account for the carbon cycle perturbation, but this finding has been questioned. Alternative proposed mechanisms include increased ocean ventilation, decreased carbonate burial, increased organic carbon burial, increased silicate weathering, and increased ocean calcium concentration. Here we use an improved version of the biogeochemical box model of Merico et al. (2008) to reevaluate these competing hypotheses and an additional mechanism, the expansion of "carbon capacitors" such as permafrost and peatlands. We find that changes in calcium concentration, silicate weathering, and carbonate or organic carbon burial each yield a response that is fundamentally at odds with the form and/or sign of the paleorecords. Shelf-basin carbonate burial fractionation (CCD change), plus shelf carbonate weathering, sequestration of 12 C-enriched carbon into carbon capacitors, and possibly increased ocean ventilation (δ 13 C excursion), offers the best fit to the paleorecords. Further work is needed to understand why the EOT carbon cycle perturbation is so unique when the forcing mechanisms hypothesized to be responsible (cooling and ice growth) are not peculiar to this event.

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Evolution of the oceanic calcium cycle during the late Mesozoic: Evidence from δ44/40Ca of marine skeletal carbonates

Cited by 106 publications

References 45 publications

The Phanerozoic δ88/86Sr record of seawater: New constraints on past changes in oceanic carbonate fluxes

The Phanerozoic δ88/86Sr record of seawater: New constraints on past changes in oceanic carbonate fluxes

Stable isotope profiles (Ca, O, C) through modern brachiopod shells of T. septentrionalis and G. vitreus: Implications for calcium isotope paleo-ocean chemistry

Global carbon cycle perturbation across the Eocene‐Oligocene climate transition

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