Carbon Cycle and Ecosystem Response to the Jenkyns Event in the Early Toarcian (Jurassic)
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The Toarcian Oceanic Anoxic Event, also known as the Jenkyns Event, was a hyperthermal episode which occurred during the early Toarcian (c. 183 Ma; Early Jurassic) and resulted in numerous collateral effects including global warming, enhanced weathering, sea-level change, carbonate crisis, marine anoxia–dysoxia, and a second-order mass extinction. This volume presents the last advances for understanding early Toarcian environmental changes through different disciplines: biostratigraphy, micropalaeontology, palaeontology, ichnology, palaeoecology, sedimentology, integrated stratigraphy, inorganic, organic and isotopic geochemistry, and cyclostratigraphy. The study of this abrupt climate change is critical for predicting future global changes, and for understanding the complex biogeochemical interactions through time between geosphere, atmosphere, hydrosphere and biosphere.
Palaeogeographical homogeneity of trace-fossil assemblages in Lower Jurassic spotted marls and limestones: comparison of the Western Carpathians and the Betic Cordillera Available to Purchase
Correspondence: [email protected]
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Published:November 03, 2021
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CiteCitation
Vladimír Šimo, Matías Reolid, 2021. "Palaeogeographical homogeneity of trace-fossil assemblages in Lower Jurassic spotted marls and limestones: comparison of the Western Carpathians and the Betic Cordillera", Carbon Cycle and Ecosystem Response to the Jenkyns Event in the Early Toarcian (Jurassic), M. Reolid, L. V. Duarte, E. Mattioli, W. Ruebsam
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Abstract
Micritic sediments containing dark, discrete, organic-rich burrows, situated in a light grey background carbonate mud, were deposited over a broad geographical area in deep-shelf, bathyal and basinal environments in the western margin of the Tethys Ocean during the Early and Middle Jurassic. These hemipelagic deposits represent a distinct depositional regime marked by low-energy, soft-bottom and only locally dysoxic environments. Still, it is unclear whether the trace-fossil assemblages occurring in these deposits pertain to a network of several community types – the ichnotaxa differing from basin to basin – or to a single community of environmentally broad-ranging, burrow-producing species. Lower Jurassic trace-fossil assemblages are found in the Western Carpathians and in the Subbetic, Betic Cordillera: that is, in basins separated by more than 2000 km in their original palaeogeographical areas. The stereotypical Chondrites and Zoophycos trace-fossil assemblages that occur in the analysed deposits share two ichnogenera of distinctive morphology (Lamellaeichnus and Teichichnus). Agglutinated foraminifera Bathysiphon occurs together with the described trace-fossil assemblage and determines the epibenthic palaeoenvironmental conditions. In the Western Carpathians, a Lamellaeichnus-dominated assemblage alternates with a Zoophycos-dominated assemblage in small, metre-scale cycles in the upper Pliensbachian, and the proportion of the Zoophycos assemblage increases stratigraphically upwards, probably owing to reduced basin ventilation during the early Toarcian. Within the southern Iberian palaeomargin, represented by the Betic Cordillera, Zoophycos is scarce in the facies.
- assemblages
- Betic Cordillera
- burrows
- carbonate rocks
- Carpathians
- Chondrites ichnofossils
- clastic rocks
- depositional environment
- Europe
- Foraminifera
- Iberian Peninsula
- ichnofabric
- ichnofacies
- ichnofossils
- Jurassic
- limestone
- Lower Jurassic
- marl
- Mesozoic
- microfacies
- microfossils
- Middle Jurassic
- morphology
- Nereites
- Palaeophycus
- paleoenvironment
- paleogeography
- Pieniny Klippen Belt
- Planolites
- Pliensbachian
- Rhizocorallium
- sedimentary rocks
- Southern Europe
- Spain
- Subbetic Zone
- substrates
- Teichichnus
- Tethys
- Thalassinoides
- ventilation
- Western Carpathians
- Zoophycos
- Bathysiphon
- Lamellaeichnus