An oscillating trend in Phanerozoic non-skeletal carbonate mineralogy

Sandberg, Philip A.

doi:10.1038/305019a0

Cited by 724 publications

(492 citation statements)

References 21 publications

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“…Our model results support the proposition that secular changes in the dominant mineralogy of non-skeletal carbonate precipitates (Sandberg, 1983;Stanley and Hardie, 1998) have a large influence on F(Sr) carb , D(F) Sr , and (Sr/Ca) sw . The dominant carbonate mineralogy is expected to be controlled by (Mg/Ca) sw , because calcite forms only below a critical (Mg/Ca) sw ratio, which is ~5/1 at 6°C (Morse et al, 1997).…”

Section: Calcite and Aragonite Seassupporting

confidence: 78%

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

108

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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: Calcite and Aragonite Seassupporting

confidence: 78%

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

108

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“…La calcita alta en Mg, así como la aragonita, coinciden con la composición química propuesta para los océanos Triásicos (Sandberg, 1983;Lowenstein et al, 2001;Hühne, 2005). El contenido alto de Mg en alomicritas puede deberse a la presencia de pequeñas cantidades de cementos dolomíticos contenidos en ellas, mismos que fueron observados por medio de examinación petrográfica (Sánchez-Beristain et al, 2011).…”

Section: Discussionunclassified

Análisis geoquímico (elementos mayores, menores, traza, δ13C, δ18O y tierras raras) de microbialitas selectas provenientes de la Formación San Casiano (Triásico Medio - Superior, NE de Italia)

Sánchez‐Beristain¹,

Kranksith²

2011

BSGM

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Análisis geoquímico de microbialitas de la Formación San Casiano 399 ResumenSe presentan los resultados del análisis geoquímico de 28 elementos (mayores, menores, traza y tierras raras), así como de isótopos de carbono y oxígeno aplicado a 17 muestras microbialíticas provenientes de la Formación San Casiano (NE de Italia). Dicho análisis ha permitido caracterizar la composición de las microbialitas como calcitas magnesianas (> 4.00 % mol Mg), determinar su buen estado de preservación y detectar la presencia de sedimentación siliciclástica fina durante su crecimiento. Asimismo, ha permitido inferir las condiciones rédox del paleoambiente y comparar sus señales geoquímicas con los componentes esqueléticos, alomicritas y cementos en busca de relictos metabólicos y/o de actividad biológica a partir de ciertos elementos traza.Para efectuar este análisis se utilizaron dos métodos: la Espectrometría de Plasma-Masa Inductivamente Acoplada por Ablación Láser (LA-ICP-MS), y espectrometría de masas para la medición de isótopos estables de carbono y oxígeno. Las muestras presentan un contenido medianamente alto de silicio y aluminio. Dichos elementos reflejan la sedimentación de arcillas durante el crecimiento de las microbialitas. No existe una correlación entre los valores de Mn/Sr y δ 18 O o entre δ 13 C y δ 18 O, indicando así una ausencia de efectos de diagénesis meteórica. Las concentraciones de hierro y manganeso exhiben correlaciones medias con el azufre, lo que permite ligar el origen de estos elementos con fenómenos diagenéticos tempranos, mismos que se pueden constatar por medio del alto contenido de estroncio y de los valores de δ 18 O. Las microbialitas están enriquecidas con una amplia gama de elementos menores y traza. Se corrobora la ausencia de implicación biológica conocida para algunos elementos (Rb, Ti, Zr, Nb y Th), que se encuentran asociados con algunos elementos mayores, reiterando su origen terrigénico (r 2 con Si >0.5). Otros (Zn, Sb, Cr, V, Sn, Ni, Co) no presentan asociación alguna con silicio o aluminio, pero tampoco pueden ser considerados como relictos metabolismo microbiano debido a su enriquecimiento en fases abióticas. En cambio, algunos de estos elementos (Cr, V, Ni, Co) son útiles para determinar las condiciones rédox del paleoambiente de la Formación San Casiano como ligeramente disóxico. Solamente el cobre y el molibdeno están relacionados a un origen microbiano. El molibdeno sirve adicionalmente para reiterar las condiciones rédox inferidas. Los resultados del análisis de Tierras Raras no son conclusivos, toda vez que las concentraciones de fósforo, silicio y aluminio alteran significativamente la precipitación de las mismas. Debido a la excelente preservación del material estudiado, es posible interpretar las señales geoquímicas obtenidas como primarias.

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“…During the period dominated by calcite seas, aragonite was soluble and capable of dissolving and so there were likely selective pressures to precipitate a less soluble calcite shell during these periods (Sandberg 1983;Palmer et al 1988;Harper et al 1997). Dissolution of aragonitic mollusks during these periods was likely extensive and significantly altered the nature of benthic assemblages recorded in the fossil record (Cherns and Wright 2000).…”

Section: Discussionmentioning

confidence: 99%

Dissolution mortality of juvenile bivalves in coastal marine deposits

Green

Jones

Boudreau

et al. 2004

Limnology & Oceanography

162

102

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We evaluate experimentally the effect of carbonate saturation state at the sediment-water interface (SWI) on survivorship of various size classes of the juvenile bivalve Mercenaria mercenaria. Populations of 0.2-mm, 0.3-mm, 1-mm, and 2-mm M. mercenaria were introduced to sediments realistically undersaturated (experimental, saturation state with respect to aragonite ϭ ⍀ aragonite ϭ IMP/K ϭ ϳ0.3) and saturated (control, ⍀ aragonite ϭ ϳ1.5) Ј sp with respect to aragonite in order to evaluate the impact of saturation state and dissolution on survivorship. Linear regression analysis was used to examine mortality within each treatment over time and show significant mortality for each size class in experimental-undersaturated treatments only (P Ͻ 0.05). Mortality rates in experimentalundersaturated sediments were Ϫ11.8, Ϫ4.8, Ϫ1.9, and Ϫ1.1% d Ϫ1 for the 0.2-, 0.3-, 1.0-, and 2.0-mm bivalves, respectively. Analysis of covariance (ANCOVA) was used to examine differences in mortality between treatments over time and show significantly different mortality rates for the 0.2-, 0.3-, and 1-mm individuals (P Ͻ 0.05).

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An oscillating trend in Phanerozoic non-skeletal carbonate mineralogy

Cited by 724 publications

References 21 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

Análisis geoquímico (elementos mayores, menores, traza, δ13C, δ18O y tierras raras) de microbialitas selectas provenientes de la Formación San Casiano (Triásico Medio - Superior, NE de Italia)

Dissolution mortality of juvenile bivalves in coastal marine deposits

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