Palaeoenvironmental reconstruction of Lower Toarcian epicontinental black shales (Posidonia Shale, SW Germany): global versus regional control

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

doi:10.1016/s0016-6995(02)00005-0

Cited by 115 publications

(82 citation statements)

References 14 publications

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“…[48] Many previous models for the formation of the organic-rich sediments in the Lower Toarcian of NW Europe have postulated that they accumulated as a response to restriction imposed by isolation of a subpycnoclinal water mass beneath a lower-salinity surface layer, a model often termed the Küspert model [Küspert,1982;Saelen et al, 1996Saelen et al, , 1998Saelen et al, , 2000Röhl et al, 2001;Schmid-Röhl et al, 2002;Bailey et al, 2003;Schwark and Frimmel, 2004;van de Schootbrugge et al, 2005]. This model works, for several reasons.…”

Section: Case For a Pycnoclinementioning

confidence: 99%

“…[62] Previous workers have proposed that the Early Toarcian seas of northwestern Europe had a low-salinity surface layer [Saelen et al, 1996[Saelen et al, , 1998[Saelen et al, , 2000Röhl et al, 2001;Schmid-Röhl et al, 2002;Schwark and Frimmel, 2004, and references therein]. Younger analogs of the restricted Early Toarcian sea might be the eastern Mediterranean, where sapropels formed in response to surface freshening and nutrient supply [Rohling, 1994], or the Arctic, high-latitude, Azolla Ocean of middle Eocene time.…”

Section: Impact Of Restriction On Re-os Datingmentioning

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: Case For a Pycnoclinementioning

confidence: 99%

Section: Impact Of Restriction On Re-os Datingmentioning

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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“…3b, F (Hallam, 198 1;Riegraf, 1984;Riegraf et al, 1984;Reigraf, 1985;Jenkyns, 1985;Hallam, 1987;Espitalié et al, 1987;Fleet et al, 1987;Jenkys,explained in tenns of restricted circulation, salinity stratification, slow sedimentation rates, anoxic bottom waters and low productivity; or even the reverse, high sedimentation rates and high productivity, possible upwelling (parrish and Curtís, 1982;Wignall and Meyers, 1990;Tyson and Pearson, 1991 ;Wignall and Hallam, 1991 ;Jenkyns and Clayton, 1997;Schmid-R6hl et al, 2002). The deposition of the Toarcian black shales is also reflected in another fossil group, the brachiopods, with an important crisis (Choffat, 1947;Goy, 1974;GarciaJoral and Goy, 1984;Goy et al, 1984;Alméras and Elmi, 1993;Ahnéras and Faure, 2000) marked by the a disappearance of spiriferids and the development of very particular faunas (ubiquitous forros belonging to the "Spanish facies" described from the French Provence lo the Atlas Basin).…”

Section: Another Proposed Route For the Entrance Of Thementioning

confidence: 99%

“…Firstly, by the recycling of remineralized carbon from the deeper parts of an intennittently stratified water column up into the photic zone, where it would have been incorporated by photosynthetic phytoplankton (Srelen et al, 2000;Schouten et al, 2000;R6hl et al, 2001;Schmid-R6hl et al, 2002). Secondly, anumber of authors have suggested that the negative ül3e isotope exclusion resulted from the rapid release of carbon dioxide to the ocean-atmosphere system from dissociation of methane hydrate (Hesselbo et al, 2000;Jenkyns, 2(03).…”

Section: G Tethys Oceanmentioning

confidence: 99%

Pliensbachian–Toarcian ostracod biogeography in NW Europe: Evidence for water mass structure evolution

Arias

2007

Palaeogeography, Palaeoclimatology, Palaeoecology

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AbsfractThis paper examines fue role played by palaeoceanographic and c1imatic conditions on the palaeobiogeography of the Pliensbachian Toarcian ostracods (Early Jurassic) in the European Epicontinental Sea (BES). The infIuence of the palaeogeography, ocean currents and sea level, temperature and salinity variations on ostracod abundance, diversity and migration pattems is reconstructed. Ostracod migration follows an antic10cbvise circulation in the eastem side of the EES, with a leading northeast southwest movement, and fue frequent arrival ofTethyan falUlas into fue central and westem parts ofthe EES during the Pliensbachian. A three-fold c1assification ofwater masses based on salinity, temperature, lithological and fossil data is proposed. The repeated inflow ofTethyan ostracods into the EES ended by the earliest Toarcian. This ostracod event is related to the opening ofthe Hispanic Corridor and to the reorganization ofthe surface and deep circulations that may have generated a cold episode at the beginning of the Toarcian.

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Molybdenum‐isotope chemostratigraphy and paleoceanography of the Toarcian Oceanic Anoxic Event (Early Jurassic)

et al. 2017

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Molybdenum (Mo)‐isotope chemostratigraphy of organic‐rich mudrocks has been a valuable tool for testing the hypothesis that the Toarcian Oceanic Anoxic Event (T‐OAE, Early Jurassic, ~183 Ma) was characterized by the spread of marine euxinia (and organic matter burial) at a global scale. However, the interpretation of existing Mo‐isotope data for the T‐OAE (from Yorkshire, Cleveland Basin, U.K.) is equivocal. In this study, three new Mo‐isotope profiles are presented: from Dotternhausen Quarry (South German Basin, Germany), the Rijswijk core (West Netherlands Basin, Netherlands), and the Dogna core (Belluno Basin, northern Italy). Precise biostratigraphic and chemostratigraphic correlation between the three sites allows a direct comparison of the data, enabling some key conclusions to be reached: (i) The Mo‐isotope composition of seawater during the peak of the T‐OAE was probably close to ~1.45‰, implicating a greater removal flux of sulphides from seawater, and a larger extent of global seafloor euxinia compared to the present day; (ii) Mo‐isotope cycles previously identified in the Yorkshire sedimentary succession are attributed to changes in the degree of local Mo drawdown from overlying Cleveland Basin seawater; (iii) The consistency of the new multisite Mo‐isotope data set indicates a secular reduction in the burial of Mo globally in the late stages of the T‐OAE, implying a contraction in the extent of global marine euxinia; (iv) Subtle differences in the Mo‐isotope composition of deposits formed in different euxinic subbasins of the European epicontinental shelf were probably governed by local variations in basin hydrography and rates of water renewal.

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Palaeoenvironmental reconstruction of Lower Toarcian epicontinental black shales (Posidonia Shale, SW Germany): global versus regional control

Cited by 115 publications

References 14 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

Pliensbachian–Toarcian ostracod biogeography in NW Europe: Evidence for water mass structure evolution

Molybdenum‐isotope chemostratigraphy and paleoceanography of the Toarcian Oceanic Anoxic Event (Early Jurassic)

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