Calcareous nannofossils and Mesozoic oceanic anoxic events

Erba, Elisabetta

doi:10.1016/j.marmicro.2004.04.007

Cited by 449 publications

(343 citation statements)

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“…Mesozoic glacial intervals are from (Price, 1999). Mesozoic anoxic intervals are from (Erba, 2004). Timing of the P/T anoxia are from (Isozaki, 1997).…”

Section: Figure Captionsmentioning

confidence: 99%

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

102

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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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“…Mesozoic glacial intervals are from (Price, 1999). Mesozoic anoxic intervals are from (Erba, 2004). Timing of the P/T anoxia are from (Isozaki, 1997).…”

Section: Figure Captionsmentioning

confidence: 99%

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

102

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“…These palaeoenvironmental changes culminated in widespread oxygen depletion and globally distributed deposition of black shales, which are characteristic features of OAEs (Jenkyns, 2003;Schlanger & Jenkyns, 1976). Since a large part of the CO 2 injected into the atmosphere would have been ultimately absorbed by seawater to cause a fall in pH, ocean acidification is commonly envisaged as a twin evil of global warming and seawater anoxia, all initially triggered by a large increase in atmospheric pCO 2 (Erba, 2004;Erba et al, 2010;Hönisch et al, 2012;Jenkyns, 2010;Kump et al, 2009;Wissler et al, 2003;Zeebe, 2012).…”

Section: Introductionmentioning

confidence: 99%

Lithium-isotope evidence for enhanced silicate weathering during OAE 1a (Early Aptian Selli event)

Lechler

Strandmann

Jenkyns

et al. 2015

Earth and Planetary Science Letters

100

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An abrupt rise in temperature, forced by a massive input of CO 2 into the atmosphere, is commonly invoked as the main trigger for Oceanic Anoxic Events (OAEs). Global warming initiated a cascade of palaeoenvironmental perturbations starting with increased continental weathering and an accelerated hydrological cycle that delivered higher loads of nutrients to coastal areas, stimulating biological productivity.The end-result was widespread anoxia and deposition of black shales: the hallmarks of OAEs. In order to assess the role of weathering as both an OAE initiator and terminator (via CO 2 sequestration) during the Early Aptian OAE 1a (Selli Event, ~120 Ma) the isotopic ratio of lithium isotopes was analysed in three sections of shallowmarine carbonates from the Pacific and Tethyan realm and one basinal pelagic section from the Tethyan domain. Because the isotopic composition of lithium in seawater is largely controlled by continental silicate weathering and high-and lowtemperature alteration of basaltic material, a shift to lighter  7 Li values is expected to characterize OAEs. The studied sections illustrate this phenomenon:  7 Li values decrease to a minimum coincident with the negative carbon-isotope excursion that effectively records the onset of OAE 1a. A second negative  7 Li excursion occurs coeval with the minimum in strontium isotopes after the event. The striking similarity to the strontium-isotope record argues for a common driver. The formation and destruction (weathering) of an oceanic LIP could account for the parallel trend in both isotope systems. The double-spike in lithium isotopes is probably related to a change in weathering congruencies. Such a chemostratigraphy is consistent with the hypothesis that an increase in silicate weathering, in conjunction with organic-carbon burial, led to drawdown of atmospheric CO 2 during the early Aptian OAE 1a.

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“…The onset of OAE 2 is characterized by an important positive excursion in the d 13 C carbonate bulk-rock record of approximately 2.5& (Schlanger and Jenkyns, 1976;Jenkyns, 1980;Schlanger et al, 1987;Gale et al, 1993;Erbacher et al, 1996;Jarvis et al, 2006;Voigt et al, 2006). OAE 2 is also marked by an extinction event and turnover in planktonic foraminifera, radiolaria and nannofossil assemblages (Eicher and Worstell, 1970;Hart and Bigg, 1981;Caron and Homewood, 1992;Leckie, 1985;Hart and Ball, 1986;Lamolda et al, 1997;Grosheny and Malartre, 1997;Keller et al, 2001;Leckie et al, 2002;Erba, 2004;Caron et al, 2006;Grosheny et al, 2006), a sealevel rise (Haq et al, 1987) Sr ratio (Jones and Jenkyns, 2001). Recently, Mort et al (2007) showed that the onset of OAE 2 correlates with a general increase in P-accumulation rates, which may have triggered an overall increase in sea surface-water productivity.…”

Section: Introductionmentioning

confidence: 99%

Evidence for oxic conditions during oceanic anoxic event 2 in the northern Tethyan pelagic realm

Westermann

Caron

Fiet

et al. 2010

Cretaceous Research

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Upper Cenomanian pelagic sediments from the northern Alpine Helvetic fold-and-thrust belt (northern Tethyan margin) coeval with Oceanic Anoxic Event (OAE) 2 are characterized by the temporal persistence of micrite sedimentation and lack of organic carbon-rich layers. We studied an expanded section in the Chrummflueschlucht (east of Euthal, Switzerland), which encompasses the OAE 2 time interval. In order to identify the paleoceanographic and paleoenvironmental conditions during OAE 2 in this part of the northern Tethyan margin, and more specifically to trace eventual changes in nutrient levels and oxic conditions, we investigated the biostratigraphy (planktonic foraminifera), the bulk-rock mineralogy, and measured stable carbon-and oxygen-isotopes, total phosphorus (P) and redox-sensitive trace-element (RSTE) contents.We were able to determine e with some remaining uncertainties e the different planktonic foraminiferal biozones characteristic of the CenomanianeTuronian boundary interval (Rotalipora cushmani, Whiteinella archaeocretacea and Helvetoglobotruncana helvetica zones). In the lower part of the section (R.cushmani total range zone), the bulk-rock d 13 C record shows a long-term increase. Within sediments attributed to the W. archaeocretacea partial range zone, d13 C values reach a maximum of 3.3& (peak "a").In the following the values decrease and increase again to arrive at a plateau with high d13 C values of around 3.1&, which ends with a peak of 3.3& (peak "c"). At the top of the section, in sediments belonging to the H. helvetica total range zone, d13 C values decrease to post-OAE values of around 2.2&.The last occurrence of R. cushmani is observed just above the positive d 13 C shift characterizing OAE 2. P contents display small variations along the section with a long-term decreasing trend towards the top. Before the OAE 2 interval, P values show higher values and relatively good covariation with detrital input, indicating higher nutrient input before OAE 2. In sediments corresponding to the onset of the d 13 C positive excursion, P content is marked by a sharp peak probably linked to a slowdown in sedimentation rates and/or the presence of a small hiatus, as is shown by the presence of glauconite and phosphatic grains. In the interval corresponding to OAE 2, P values remain low and increase slightly at the end of the positive shift in the d 13 C record (in the H. helvetica total range zone). The average contents of RSTE (U, V, As, Co, Mo and Mn) remain low throughout the section and appreciable RSTE enrichments have not been observed for the sedimentary interval corresponding to OAE 2. No correlation is observed with stratigraphic trends in RSTE contents in organic-rich deeper-water sections. The presence of double-keeled planktonic foraminifera species during most of the Cenomanian/Turonian boundary event is another evidence of relatively well-oxygenated conditions in this part of the northern Tethyan outer shelf.Our results show that the Chrummflueschlucht section corresponds to one of the most...

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Calcareous nannofossils and Mesozoic oceanic anoxic events

Cited by 449 publications

References 84 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

Lithium-isotope evidence for enhanced silicate weathering during OAE 1a (Early Aptian Selli event)

Evidence for oxic conditions during oceanic anoxic event 2 in the northern Tethyan pelagic realm

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