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Environmental changes and carbon cycle perturbations at the Triassic–Jurassic boundary in northern Switzerland


Looser, Nathan; Schneebeli-Hermann, Elke; Furrer, Heinz; Blattmann, Thomas M; Bernasconi, Stefano M (2018). Environmental changes and carbon cycle perturbations at the Triassic–Jurassic boundary in northern Switzerland. Swiss Journal of Geosciences, 111(3):445-460.

Abstract

The Triassic–Jurassic boundary is characterized by strong perturbations of the global carbon cycle, triggered by massive volcanic eruptions related to the onset of the Central Atlantic Magmatic Province. These perturbations are recorded by negative carbon isotope excursions (CIEs) which have been reported worldwide. In this study, Triassic–Jurassic boundary sections from the southern margin of the Central European Basin (CEB) located in northern Switzerland are analyzed for organic carbon and nitrogen isotopes in combination with particulate organic matter (POM) analyses. We reconstruct the evolution of the depositional environment from Late Triassic to Early Jurassic in northern Switzerland and show that observed negative shifts in d13C of the total organic carbon (d13CTOC) in the sediment are only subordinately influenced by varying organic matter (OM) composition and primarily reflect global changes in the carbon cycle. Based on palynology and the stratigraphic positions of isotopic shifts, the d13CTOC record of the studied sections is correlated with the GSSP section at Kuhjoch (Tethyan realm) in Austria and with the St. Audrie’s Bay section (CEB realm) in southwest England. We also show that in contrast to POM analyses the applicability of organic carbon/total nitrogen (OC/TN) atomic ratios and stable isotopes of total nitrogen (d15NTN) for detecting changes in source of OM is limited in marginal depositional environments with frequent changes in lithology and OM contents.
Keywords Triassic–Jurassic boundary Northern Switzerland Stable carbon and nitrogen isotope geochemistry Sedimentology Palynology Chemostratigraphy

Abstract

The Triassic–Jurassic boundary is characterized by strong perturbations of the global carbon cycle, triggered by massive volcanic eruptions related to the onset of the Central Atlantic Magmatic Province. These perturbations are recorded by negative carbon isotope excursions (CIEs) which have been reported worldwide. In this study, Triassic–Jurassic boundary sections from the southern margin of the Central European Basin (CEB) located in northern Switzerland are analyzed for organic carbon and nitrogen isotopes in combination with particulate organic matter (POM) analyses. We reconstruct the evolution of the depositional environment from Late Triassic to Early Jurassic in northern Switzerland and show that observed negative shifts in d13C of the total organic carbon (d13CTOC) in the sediment are only subordinately influenced by varying organic matter (OM) composition and primarily reflect global changes in the carbon cycle. Based on palynology and the stratigraphic positions of isotopic shifts, the d13CTOC record of the studied sections is correlated with the GSSP section at Kuhjoch (Tethyan realm) in Austria and with the St. Audrie’s Bay section (CEB realm) in southwest England. We also show that in contrast to POM analyses the applicability of organic carbon/total nitrogen (OC/TN) atomic ratios and stable isotopes of total nitrogen (d15NTN) for detecting changes in source of OM is limited in marginal depositional environments with frequent changes in lithology and OM contents.
Keywords Triassic–Jurassic boundary Northern Switzerland Stable carbon and nitrogen isotope geochemistry Sedimentology Palynology Chemostratigraphy

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Paleontological Institute and Museum
Dewey Decimal Classification:560 Fossils & prehistoric life
Uncontrolled Keywords:Geology
Language:English
Date:1 October 2018
Deposited On:19 Dec 2018 13:57
Last Modified:17 Sep 2019 19:47
Publisher:Springer
ISSN:1661-8726
OA Status:Closed
Publisher DOI:https://doi.org/10.1007/s00015-018-0315-6

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