44Ca/42Ca and 143Nd/144Nd isotope variations in Cretaceous–Eocene Tethyan francolites and their bearing on phosphogenesis in the southern Tethys

Soudry, David; Segal, Irina; Nathan, Y.; Glenn, Craig R.; Halicz, Ludwik; Lewy, Zeev; VonderHaar, Denys L.

doi:10.1130/g20438.1

Cited by 43 publications

(24 citation statements)

References 23 publications

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“…Up to now 44 Ca/ 42 Ca, 44 Ca/ 40 Ca and 48 Ca/ 42 Ca are reported and in the future the use of additional ratios is possible (Halicz et al, 1999;Boulyga and Becker, 2001;Fietzke et al, 2004;Marriott et al, 2004;Soudry et al, 2004;Wieser et al, 2004). These different approaches, using isotope ratios with mass differences of 2, 4 and 6 amu, hinder the direct comparison of Ca-isotope data.…”

Section: Calcium Isotope Analysis and Conversion Between Different Camentioning

confidence: 93%

Calcium isotope fractionation in calcite and aragonite

Gussone

Böhm

Eisenhauer

et al. 2005

Geochimica et Cosmochimica Acta

256

148

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Section: Calcium Isotope Analysis and Conversion Between Different Camentioning

confidence: 93%

Calcium isotope fractionation in calcite and aragonite

Gussone

Böhm

Eisenhauer

et al. 2005

Geochimica et Cosmochimica Acta

256

148

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“…As a consequence, they are an important link between global calcium (Ca) and carbon (C) cycling. Because they act as a major Ca sink, coccoliths play an important role in determining the isotopic Ca budget of the marine realm, and consequently their isotopic composition is an important parameter for reconstructing the Ca budget of the global ocean (De La Rocha and DePaolo, 2000;Schmitt et al, 2003;Soudry et al, 2004;Heuser et al, 2005;Fantle and DePaolo, 2005). However, previous studies on coccolith oozes have reported a disparate range of seemingly conflicting Ca isotope values.…”

Section: A U T H O R ' S P E R S O N a L C O P Ymentioning

confidence: 99%

“…These factors become more important for oceanic Ca budget reconstruction when extended further back in earth history cf. (Farkaš et al, 2007;Soudry et al, 2004) to eras in which the chemical composition of the ocean and assemblages of calcifying biota significantly differed from today's conditions.…”

Section: A U T H O R ' S P E R S O N a L C O P Ymentioning

confidence: 99%

Calcium isotope fractionation in coccoliths of cultured Calcidiscus leptoporus, Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera foliosa

Gussone

Langer

Geisen

et al. 2007

Earth and Planetary Science Letters

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Four species of marine calcifying algae, the coccolithophores Calcidiscus leptoporus, Helicosphaera carteri, Syracosphaera pulchra and Umbilicosphaera foliosa were grown in laboratory cultures under temperatures varying between 14 and 23°C, and one species, C. leptoporus, under varying [CO 32− ], ranging from 105 to 219 μmol/kg. Calcium isotope compositions of the coccoliths resemble in both absolute fractionation and temperature sensitivity previous calibrations of marine calcifying species e.g. Emiliania huxleyi (coccolithophores) and Orbulina universa (planktonic foraminifera) as well as inorganically precipitated CaCO 3 , but also reveal small species specific differences. In contrast to inorganically precipitated calcite, but similar to E. huxleyi and O. universa, the carbonate ion concentration of the medium has no statistically significant influence on the Ca isotope fractionation of C. leptoporus coccoliths; however, combined data of E. huxleyi and C. leptoporus indicate that the observed trends might be related to changes of the calcite saturation state of the medium. Since coccoliths constitute a significant portion of the global oceanic CaCO 3 export production, the Ca isotope fractionation in these biogenic structures is important for defining the isotopic composition of the Ca sink of the ocean, one of the key parameters for modelling changes to the marine Ca budget over time. For the present ocean our results are in general agreement with the previously postulated and applied mean value of the oceanic Ca sink (Δ sed ) of about − 1.3‰, but the observed inter-and intra-species differences point to possible changes in Δ sed through earth history, due to changing physico-chemical conditions of the ocean and shifts in floral and faunal assemblages.

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“…Temperature-dependent Ca 2+ aq -CaCO 3 -isotope fractionation has been reported (Nägler et al, 2000;Gussone et al, 2003) and was tested in modern and fossil skeletal carbonates (Chang et al, 2004;Immenhauser et al, 2004;Sime et al, 2005;Hippler et al, 2006). The Ca-isotopic compositions of bulk limestone, foraminifers, and sedimentary carbonate fluorapatite were used to delineate secular changes in the global biogeochemical Ca cycle (De La Rocha and DePaolo, 2000;Soudry et al, 2004;Kasemann et al, 2005) and the marine Ca budget (Skulan et al, 1997;Zhu and McDougall, 1998;Schmitt et al, 2003a). However, the isotope effects that control the Ca-isotope composition of marine carbonates are not well understood and subject to debate (DePaolo, 2004;Lemarchand et al, 2004;Gussone et al, 2005;Sime et al, 2005).…”

Section: Introductionmentioning

confidence: 99%