Evolution of Tethyan phosphogenesis along the northern edges of the Arabian–African shield during the Cretaceous–Eocene as deduced from temporal variations of Ca and Nd isotopes and rates of P accumulation

Soudry, David; Glenn, Craig R.; Nathan, Y.; Segal, Irina; VonderHaar, Denys L.

doi:10.1016/j.earscirev.2006.03.005

Cited by 129 publications

(73 citation statements)

References 136 publications

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“…Thus, stratigraphic records of e^j values in fish debris provide a means to track bottom-water masses through time, but Cretaceous data are sparse. Lowresolution Late Cretaceous ENJ data are available for Tethyan shelf deposits (Puceat et al, 2005;Soudry et al, 2006), and data for intermediate and deep waters are currently only available for the Maastrichtian in the Pacific (Thomas, 2004;Frank et al, 2005). No studies have examined £|,jj changes relative to any OAF in detail.…”

Section: Introductionmentioning

confidence: 99%

Nd isotopic excursion across Cretaceous ocean anoxic event 2 (Cenomanian-Turonian) in the tropical North Atlantic

MacLeod

Martin

Blair

2008

Geol

103

105

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Late Cretaceous fish debris from Demerara Rise exhibits a dramatic positive excursion of 8 Ej^j units during ocean anoxic event 2 (OAE2) that is superimposed on extremely low Ej^jj,) values (-14 to -16.5) observed throughout the rest of the studied interval. The OAE2 E[,j excursion is the largest yet documented in marine sediments, and the majority of the shift is estimated to have occurred over <20 k.y. Low background E^j values on Demerara Rise are explained as the Nd isotopic signature of the South American craton, whereas eruptions of the Caribbean large igneous province or enhanced mixing of intermediate waters in the North Atlantic could have caused the excursion.

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Section: Introductionmentioning

confidence: 99%

Nd isotopic excursion across Cretaceous ocean anoxic event 2 (Cenomanian-Turonian) in the tropical North Atlantic

MacLeod

Martin

Blair

2008

Geol

103

105

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“…Though marine carbonate sediments are the phase most commonly used for the reconstruction of calcium isotopic composition of seawater through time (Skulan et al, 1997;De La Rocha and DePaolo, 2000), the possibility of using other proxies such as foraminifera and phosphorites (Soudry et al, 2004) has been explored. Soudry et al (2006) investigated the use of carbonated fluorapatite formed in marine sediments as a potential candidate for long term reconstructions of isotopic composition of seawater Ca 2+ . Farkas et al (2007) compiled records from various biogenic carbonates and authigenic phosphates to discuss the calcium isotope budget over Phanerozoic times.…”

Section: Introductionmentioning

confidence: 99%

Site-specific equilibrium isotopic fractionation of oxygen, carbon and calcium in apatite

Aufort

Ségalen

Gervais

et al. 2017

Geochimica et Cosmochimica Acta

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The stable isotope composition of biogenic apatite is an important geochemical marker that can record environmental parameters and is widely used to infer past climates, biomineralization processes, dietary preferences and habitat of vertebrates. In this study, theoretical equilibrium isotopic fractionation of oxygen, carbon and calcium in hydroxyapatite and carbonate-bearing hydroxyapatite is investigated using first-principles methods based on density-functional theory and compared to the theoretical isotopic fractionation properties of calcite, CO 2 and H 2 O. Considering the variability of apatite crystal-chemistry, special attention is given to specific contributions of crystal sites to isotopic fractionation. Significant internal fractionation is calculated for oxygen and carbon isotopes in CO 3 between the different structural sites occupied by carbonate groups in apatite (typically 7‰ for both 18 O/ 16 O and 13 C/ 12 C fractionation at 37°C). Compared with calcite-water oxygen isotope fractionation, occurrence of A-type substitution in apatite structure, in addition to the main B-type substitution, could explain the larger temperature dependence of oxygen isotope fractionation measured at low temperature between carbonate in apatite and water. Theoretical internal fractionation of oxygen isotopes between carbonate and phosphate in B-type carbonated apatite ($8‰ at 37°C) is consistent with experimental values obtained from modern and well-preserved fossil bio-apatites. Concerning calcium, theoretical results suggest a small fractionation between apatite and calcite (À0.17‰ at 37°C). Internal fractionation reaching 0.8‰ at 37°C occurs between the two Ca sites in hydroxyapatite. Furthermore, the Ca isotopic fractionation properties of apatite are affected by the occurrence of carbonate groups, which could contribute to the variability observed on natural samples. Owing to the complexity of apatite crystal-chemistry and in light of the theoretical results, measurements of site-specific isotopic fractionation properties could improve our understanding and the interpretation of isotopic records in apatites.

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“…Prior to isotopic analysis, possible weathering of the CFA phase was checked from their structural CO 2 and from their Sr/P, Ca/P, and (La/Sm) N ratios. The results of CO 2 concentration as well as the Sr/P, Ca/P and (La/Sm) N ratios (Soudry et al 2006 Appendix A; see also Tables 5 and 6, this study) indicate that the analyzed CFAs suffered little weathering.…”

Section: Nd and Ca Isotope Analysismentioning

confidence: 67%

“…These two ratios on the contrary are rather high (2.14 and 2.26, respectively) in the Turkish samples (Table 4). Moreover, nor do the high CO 2 contents (*5 wt %) and F/P 2 O 5 ratios (*0.14) in these samples or the Ca/P and Sr/P ratios in a few separated CFA phases (Soudry et al 2006; Appendix A) support post-depositional alteration as a cause of strong REE depletion.…”

Section: Discussionmentioning

confidence: 94%

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Geochemical, mineralogical and isotopic signatures of the Semikan, West Kasrık “Turkish” phosphorites from the Derik–Mazıdağı–Mardin area, SE Anatolia

Imamoglu

Nathan

Çoban

et al. 2008

Int J Earth Sci (Geol Rundsch)

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The geochemistry and mineralogy of a condensed section, *6 m thick of the West Kasrik member (Coniacian-Santonian) near the uplifted northern flank of the Mardin-Derik anticline (south-eastern Turkey) was studied. The only deposit exploited in Turkey is found in this area. The sediment textures as well as the mineralogical and the geochemical results collectively suggest that these recycled phosphorites accumulated in areas of intensive very early diagenesis of the sediments in highly oxic bottom waters, and almost no detrital apport. The total concentration of redox-sensitive trace metals is very low (\600 lg/g); in addition the structural CO 2 and F/P 2 O 5 are unusually high (*5 wt % and 0.14, respectively). REE distribution shows a clear ''seawater'' pattern with a strongly negative Ce-anomaly (0.20 ± 0.02) and heavy REE enrichment (Lu N /La N = 1.50 ± 0.12), however their total concentration is very low. The low REE contents, quite unexpected in recycled phosphorites, are explained by the scarcity of terrigenous components which leads to minimal incorporation of REEs from detrital clastic phases in the CFA fraction. Weathering previously suggested as responsible for the high P enrichment of the Mazidagi phosphorites is rather improbable in the samples we studied, in view of their high structural CO 2 , high F/P 2 O 5 , high (La/Nd) N and (La/Sm) N ratios, and high Sr/P and Ca/P of separated CFA fractions that all negate post-depositional weathering. More likely, the high P enrichment of some rocks (P 2 O 5 content reaches 34%) was produced by sedimentary and early diagenetic processes acting in oxygenated areas of starved sedimentation on and around tectonic highs.

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Evolution of Tethyan phosphogenesis along the northern edges of the Arabian–African shield during the Cretaceous–Eocene as deduced from temporal variations of Ca and Nd isotopes and rates of P accumulation

Cited by 129 publications

References 136 publications

Nd isotopic excursion across Cretaceous ocean anoxic event 2 (Cenomanian-Turonian) in the tropical North Atlantic

Nd isotopic excursion across Cretaceous ocean anoxic event 2 (Cenomanian-Turonian) in the tropical North Atlantic

Site-specific equilibrium isotopic fractionation of oxygen, carbon and calcium in apatite

Geochemical, mineralogical and isotopic signatures of the Semikan, West Kasrık “Turkish” phosphorites from the Derik–Mazıdağı–Mardin area, SE Anatolia

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