Erratum to “The Posidonia Shale (Lower Toarcian) of SW-Germany: an oxygen-depleted ecosystem controlled by sea level and palaeoclimate”

Röhl, Hans–Joachim; Schmid‐Röhl, Annette; Oschmann, Wolfgang; Frimmel, Andreas; Schwark, Lorenz

doi:10.1016/s0031-0182(01)00201-2

Cited by 54 publications

(61 citation statements)

References 36 publications

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“…At Wickensen, TOC remains above 10% over most of the Toarcian; at Dotternhausen [Schouten et al, 2000;Röhl et al, 2001] it is above 6% through most of the Toarcian. At Mögglingen and Weiach, TOC frequently dips below 5%.…”

Section: Stratigraphic Profiles Of Environmental Proxiesmentioning

confidence: 94%

“…[31] In Germany, Röhl et al [2001] showed that euxinia was prevalent throughout deposition of the Posidonia shale from the mid-semicelatum Subzone into the upper bifrons Zone. Photic zone euxinia was also documented by Schouten et al [2000] to be present at each of the seven levels that were examined through the same stratigraphic interval, but was shown to be absent at three lower stratigraphic levels.…”

Section: Euxinia and Aliasingmentioning

confidence: 99%

“…[32] Despite the prevalence of long-term euxinia over a substantial part of the time represented by the section in the Cleveland Basin, the presence of fossil ''event communities'' at uncommon, discrete, horizons within the sections in Yorkshire and the Posidonia shale of Germany [Howarth, 1962;Röhl et al, 2001] show that conditions were occasionally oxygenic, if only for periods of a few weeks to a few years at a time. The geochemical signal of oxygenation is aliased because sampling has not been undertaken (even by Pearce et al [2008] or Röhl et al [2001]) at a resolution high enough to capture the short periods when euxinia was interrupted and life flourished, briefly, in the Toarcian seas of NW Europe.…”

Section: Euxinia and Aliasingmentioning

confidence: 99%

“…The geochemical signal of oxygenation is aliased because sampling has not been undertaken (even by Pearce et al [2008] or Röhl et al [2001]) at a resolution high enough to capture the short periods when euxinia was interrupted and life flourished, briefly, in the Toarcian seas of NW Europe. We discuss this below.…”

Section: Euxinia and Aliasingmentioning

confidence: 99%

“…[4] Other palaeoenvironmental interpretations of European black shales hold that they formed in response to water mass restriction in, for example, silled basins, in which anoxic or euxinic bottom water was separated by a pycnocline from a surface water mass of low salinity that isolated the underlying water from atmospheric oxygen [Küspert, 1982;Saelen et al, 1996Saelen et al, , 1998Saelen et al, , 2000Röhl et al, 2001;Schmid-Röhl et al, 2002;Schmid-Röhl and Röhl, 2003;Schwark and Frimmel, 2004;van de Schootbrugge et al, 2005]. These models invoke local processes, such as basin restriction via salinity stratification, as the driving force for deposition of these shales: their formation is thus detached from global events.…”

Section: Introductionmentioning

confidence: 99%

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Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

et al. 2008

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[1] Profiles of Mo/total organic carbon (TOC) through the Lower Toarcian black shales of the Cleveland Basin, Yorkshire, United Kingdom, and the Posidonia shale of Germany and Switzerland reveal water mass restriction during the interval from late tenuicostatum Zone times to early bifrons Zone times, times which include that of the putative Early Toarcian oceanic anoxic event. The degree of restriction is revealed by crossplots of Mo and TOC concentrations for the Cleveland Basin, which define two linear arrays with regression slopes (ppm/%) of 0.5 and 17. The slope of 0.5 applies to sediment from the upper semicelatum and exaratum Subzones. This value, which is one tenth of that for modern sediments from the Black Sea (Mo/TOC regression slope 4.5), reveals that water mass restriction during this interval was around 10 times more severe than in the modern Black Sea; the renewal frequency of the water mass was between 4 and 40 ka. The Mo/TOC regression slope of 17 applies to the overlying falciferum and commune subzones: the value shows that restriction in this interval was less severe and that the renewal frequency of the water mass was between 10 and 130 years. The more restricted of the two intervals has been termed the Early Toarcian oceanic anoxic event but is shown to be an event caused by basin restriction local to NW Europe. Crossplots of Re, Os, and Mo against TOC show similar trends of increasing element concentration with increase in TOC but with differing slopes. Together with modeling of 187 Os/ 188 Os and d 98 Mo, the element/TOC trends show that drawdown of Re, Os, and Mo was essentially complete during upper semicelatum and exaratum Subzone times (Mo/TOC regression slope of 0.5). Drawdown sensitized the restricted water mass to isotopic change forced by freshwater mixing so that continental inputs of Re, Os, and Mo, via a low-salinity surface layer, created isotopic excursions of up to 1.3% in d 98 Mo and up to 0.6% for 187 Os/ 188 Os. Restriction thereby compromises attempts to date Toarcian black shales, and possibly all black shales, using Re-Os chronology and introduces a confounding influence in the attempts to use d 98 Mo and initial 187 Os/ 188 Os for palaeo-oceanographic interpretation.

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Section: Stratigraphic Profiles Of Environmental Proxiesmentioning

confidence: 94%

Section: Euxinia and Aliasingmentioning

confidence: 99%

Section: Euxinia and Aliasingmentioning

confidence: 99%

Section: Euxinia and Aliasingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

et al. 2008

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Why are the δ¹³C_org values in Phanerozoic black shales more negative than in modern marine organic matter?

Meyers

2014

Geochem Geophys Geosyst

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The d13 C org values of Phanerozoic black shales average 227&, whereas those of modern marine organic matter average 220&. The black shale isotopic values mimic those of continental organic matter, yet their organic geochemical properties mandate that they contain predominantly marine organic matter. Hypotheses that proposed to explain the low d13 C values of black shales include diagenetic losses of isotopically heavier organic matter components, releases of isotopically light carbon from methane clathrates or extensive magmatic events, greater photosynthetic discrimination against 13 C during times of higher atmospheric pCO 2 , and greenhouse climate stratification of the surface ocean that magnified photic zone recycling of isotopically light organic matter. Although the last possibility seems contrary to the vertical mixing that leads to the high productivity of modern oceanic upwelling systems, it is consistent with the strongly stratified conditions that accompanied deposition of the organic carbon-rich Pliocene-Pleistocene sapropels of the Mediterranean Sea. Because most Phanerozoic black shales contain evidence of photic zone anoxia similar to the sapropels, well-developed surface stratification of the oceans was likely involved in their formation. Existence of isotopically light land plant organic matter during several episodes of extensive magmatism that accompanied black shale deposition implies massive release of mantle CO 2 that added to the greenhouse conditions that favored oceanic stratification. The 13 C depletion common to most Phanerozoic black shales apparently resulted from a greenhouse climate associated with elevated atmospheric pCO 2 that led to a strongly stratified ocean and photic zone recycling of organic matter in, augmented by magmatic CO 2 releases.

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Calibrating the magnitude of the Toarcian carbon cycle perturbation

et al. 2015

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Sedimentary rocks recording the Toarcian oceanic anoxic event (T-OAE) are marked by a negative carbon isotope excursion (CIE) reaching up to À7‰ and ranking among the largest known in the Phanerozoic. These records suggest a dramatic perturbation of the carbon cycle that has been linked to the transfer of juvenile carbon from the endogenic to the exogenic reservoirs. Nevertheless, the magnitude of the Toarcian CIE varies significantly from one substrate to another, hence complicating mass balance evaluation of the potential driving mechanisms. Here we show, using high-resolution, paired records of δ 13 C total organic carbon (TOC) and hydrogen index from the Denkingen core and Dotternhausen quarry (Germany), that the amplitude of the negative CIE in marine organic matter is considerably exaggerated by changes in organic matter sourcing. Our corrected 3-4‰ CIE implies a constant carbon isotope fractionation between organic and carbonate carbon across the T-OAE and may point to a prominent role of cyanobacteria as organic matter producers during the Early Jurassic. These results also suggest that the difference between inorganic and organic carbon isotope values in marine strata constitutes a poor proxy of pCO 2 levels across the T-OAE. Moreover, this corrected 3-4‰ CIE, together with evidence for >5°C seawater warming across the T-OAE, point to the input of >25,000 Gt C with much more 13 C-enriched signature than previously modeled. Our results thus allow reconciling inorganic and organic δ 13 C records of the T-OAE and have important implications for the evaluation of their causal mechanisms.

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Erratum to “The Posidonia Shale (Lower Toarcian) of SW-Germany: an oxygen-depleted ecosystem controlled by sea level and palaeoclimate”

Cited by 54 publications

References 36 publications

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

Why are the δ¹³C_org values in Phanerozoic black shales more negative than in modern marine organic matter?

Calibrating the magnitude of the Toarcian carbon cycle perturbation

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Erratum to “The Posidonia Shale (Lower Toarcian) of SW-Germany: an oxygen-depleted ecosystem controlled by sea level and palaeoclimate”

Cited by 54 publications

References 36 publications

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

Basinal restriction, black shales, Re‐Os dating, and the Early Toarcian (Jurassic) oceanic anoxic event

Why are the δ13Corg values in Phanerozoic black shales more negative than in modern marine organic matter?

Calibrating the magnitude of the Toarcian carbon cycle perturbation

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Why are the δ¹³C_org values in Phanerozoic black shales more negative than in modern marine organic matter?