Climatic and palaeoceanographic changes during the Pliensbachian (Early Jurassic) inferred from clay mineralogy and stable isotope (C-O) geochemistry (NW Europe)

Autor: Pierre Pellenard, Théophile Cocquerez, Rémi Laffont, Ludovic Bruneau, Stephen P. Hesselbo, Cédric Bougeault, Jean-Louis Dommergues, Nicolas Thibault, Jean-François Deconinck, Emilia Huret
Přispěvatelé: Biogéosciences [Dijon] ( BGS ), Université de Bourgogne ( UB ) -AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique ( CNRS ), Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Agence Nationale pour la Gestion des Déchets Radioactifs ( ANDRA ), Department of GeoSciences and Natural Resource Management ( IGN ), University of Copenhagen ( KU ), Study supported by the 'Agence Nationale pour la Gestion des Déchets Radioactifs' (Andra––French National Radioactive Waste Management Agency)., Biogéosciences [UMR 6282] [Dijon] (BGS), Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Centre National de la Recherche Scientifique (CNRS), Agence Nationale pour la Gestion des Déchets Radioactifs (ANDRA), Department of Geosciences and Natural Resource Management [Copenhagen] (IGN), Faculty of Science [Copenhagen], University of Copenhagen = Københavns Universitet (KU)-University of Copenhagen = Københavns Universitet (KU), Centre National de la Recherche Scientifique (CNRS)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement
Jazyk: angličtina
Rok vydání: 2017
Předmět:
010506 paleontology
Runoff
Geochemistry
Structural basin
engineering.material
010502 geochemistry & geophysics
Oceanography
[ SDU.STU.ST ] Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
01 natural sciences
chemistry.chemical_compound
Paleontology
[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Water cycle
Glacio-eustasy
Chlorite
0105 earth and related environmental sciences
Global and Planetary Change
geography
geography.geographical_feature_category
Stable isotope ratio
Early Jurassic
Pliensbachian
Massif
15. Life on land
[ SDU.STU.GC ] Sciences of the Universe [physics]/Earth Sciences/Geochemistry
Stable isotope
Clay minerals
Boreal
chemistry
13. Climate action
Isotopes of carbon
[SDU.STU.ST]Sciences of the Universe [physics]/Earth Sciences/Stratigraphy
Illite
engineering
Geology
Zdroj: Global and Planetary Change
Global and Planetary Change, Elsevier, 2017, 149, pp.139-152. 〈http://www.sciencedirect.com/science/article/pii/S0921818116304271〉. 〈10.1016/j.gloplacha.2017.01.005〉
Global and Planetary Change, Elsevier, 2017, 149, pp.139-152. ⟨10.1016/j.gloplacha.2017.01.005⟩
ISSN: 0921-8181
DOI: 10.1016/j.gloplacha.2017.01.005〉
Popis: 14 pages; International audience; The Early Jurassic was broadly a greenhouse climate period that was punctuated by short warm and cold climatic events, positive and negative excursions of carbon isotopes, and episodes of enhanced organic matter burial. Clay minerals from Pliensbachian sediments recovered from two boreholes in the Paris Basin, are used here as proxies of detrital supplies, runoff conditions, and palaeoceanographic changes. The combined use of these minerals with stable isotope data (C-O) from bulk carbonates and organic matter allows palaeoclimatic reconstructions to be refined for the Pliensbachian. Kaolinite/illite ratio is discussed as a reliable proxy of the hydrological cycle and runoff from landmasses. Three periods of enhanced runoff are recognised within the Pliensbachian. The first one at the Sinemurian-Pliensbachian transition shows a significant increase of kaolinite concomitant with the negative carbon isotope excursion at the so-called Sinemurian Pliensbachian Boundary Event (SPBE). The Early/Late Pliensbachian transition was also characterised by more humid conditions. This warm interval is associated with a major change in oceanic circulation during the Davoei Zone, likely triggered by sea-level rise; the newly created palaeogeography, notably the flooding of the London-Brabant Massif, allowed boreal detrital supplies, including kaolinite and chlorite, to be exported to the Paris Basin. The last event of enhanced runoff occurred during the late Pliensbachian (Subnodosus Subzone of the Margaritatus Zone), which occurred also during a warm period, favouring organic matter production and preservation. Our study highlights the major role of the London Brabant Massif in influencing oceanic circulation of the NW European area, as a topographic barrier (emerged lands) during periods of lowstand sea-level and its flooding during period of high sea-level. This massif was the unique source of smectite in the Paris Basin. Two episodes of smectite-rich sedimentation (‘smectite events’), coincide with regressive intervals, indicating emersion of the London Brabant Massif and thus suggesting that an amplitude of sea-level change high enough to be linked to glacio-eustasy. This mechanism is consistent with sedimentological and geochemical evidences of continental ice growth notably during the Latest Pliensbachian (Spinatum Zone), and possibly during the Early Pliensbachian (late Jamesoni/early Ibex Zones).
Databáze: OpenAIRE
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