An Early Jurassic (Sinemurian–Toarcian) stratigraphic framework for the occurrence of Organic Matter Preservation Intervals (OMPIs)

Shallow-water carbonates of the Coimbra Formation, Lusitanian Basin (Portugal): contributions to the integrated stratigraphic analysis of the Sinemurian sedimentary successions in the western Iberian Margin

“…The organic-rich sediments of UD-UG were suggested to be contemporaneous with the regional late Sinemurian (Obtusum, Obtusum-Stellare) Organic Matter Preservation Interval [OMPI S5; Silva et al, 2021]. By extension, the younger negative carbon isotopic excursion and organic-rich sediments associated with the regional (superregional?)…”

“…Much of the research interest arises from the preferred palaeogeographic location of these deposits between the Tethyan and pre-Atlantic realms [Thierry and Barrier, 2000], thus relevant for regional and global biostratigraphic correlations and palaeogeographic and palaeobiogeographic reconstructions [e.g. Ferreira et al, 2019, Rocha et al, 2016, Silva et al, 2021. Except for its base, dated from the Sinemurian, the majority of the Lower Jurassic is composed of hemipelagic marly limestones with abundant benthic and nektonic macrofauna, formally organised in several lithostratigraphic units [e.g.…”

Biomarker and compound-specific isotope records across the Toarcian CIE at the Dormettingen section in SW Germany

“…The Toarcian CIE reflects a perturbation of the global carbon cycle and is potentially associated with the coeval Karoo–Ferrar Large Igneous Province (LIP) (~ 183–182 Ma) (Pálfy et al 2002 ; Burgess et al 2015 ; Ivanov et al 2017 ), but the ultimate trigger for the CIE, which affected the global oceanic and atmospheric carbon reservoirs (e.g., Hesselbo et al 2000a , b ), is still disputed (Silva et al 2021 ). Carbon degassing from the Karoo–Ferrar LIP (Pálfy and Smith 2000 ), generation and release of thermogenic methane during emplacement of the Karoo–Ferrar LIP (e.g., Wignall 2001 ; Svensen et al 2007 ), recycling of isotopically light dissolved inorganic carbon from deeper levels of a stratified water body (e.g., Küspert 1982 ; Jenkyns 1985 ; van de Schootbrugge et al 2005 ), dissociation of methane hydrate in marine sediments (e.g., Hesselbo et al 2000a , b ; Kemp et al 2005 ), increased methane emission from expanding swamps and wetlands (Them et al 2017 ), melting of permafrost (Ruebsam et al 2019 ; Ruebsam and Schwark 2021 ), or increased CO 2 release from the decomposition and oxidation of terrigenous organic matter associated with increased fungal activity (Pienkowski et al 2016 ) have been discussed recently.…”

“…Black shales with total organic carbon (TOC) contents exceeding 10 wt.% have been deposited during and after the Toarcian CIE in many European basins, characterizing the interval, which is known today as early Toarcian oceanic anoxic event (T-OAE; Jenkyns 1985 , 1988 , 2010 ; Neumeister et al 2015 ; Silva et al 2021 ). Lower Toarcian rocks with very high organic matter contents occur in the Central European Epicontinental Basin System (CEBS; Fig.…”

“…These rocks are known as Posidonia Shale in Germany, Whitby Mudstone in England, or Schistes Carton in France (Jenkyns 1985 ; Baudin 1995 ; Röhl and Schmid-Röhl 2005 ). However, coeval sediment successions from southern Europe (Italy, Portugal, and Spain) and from northern Africa lack organic matter-rich deposits (e.g., de Oliveira et al 2006 ; Hesselbo et al 2007 ; Rodrigues et al 2020 ; Silva et al 2021 ).

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