dc.contributor.author | Bougeault, C | |
dc.contributor.author | Pellenard, P | |
dc.contributor.author | Deconinck, J-F | |
dc.contributor.author | Hesselbo, SP | |
dc.contributor.author | Dommergues, J-L | |
dc.contributor.author | Bruneau, L | |
dc.contributor.author | Cocquerez, T | |
dc.contributor.author | Laffont, R | |
dc.contributor.author | Huret, E | |
dc.contributor.author | Thibault, N | |
dc.date.accessioned | 2017-01-23T10:23:02Z | |
dc.date.issued | 2017-01-17 | |
dc.description.abstract | 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
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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 SinemurianPliensbachian
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 (Subdonosus 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). | en_GB |
dc.description.sponsorship | The study was supported by the “Agence Nationale pour la Gestion des Déchets Radioactifs” (Andra––French National Radioactive Waste Management Agency). | en_GB |
dc.identifier.citation | doi: 10.1016/j.gloplacha.2017.01.005 | en_GB |
dc.identifier.uri | http://hdl.handle.net/10871/25335 | |
dc.language.iso | en | en_GB |
dc.publisher | Elsevier | en_GB |
dc.rights.embargoreason | Publisher policy | en_GB |
dc.subject | Early Jurassic | en_GB |
dc.subject | Pliensbachian | en_GB |
dc.subject | runoff | en_GB |
dc.subject | clay minerals | en_GB |
dc.subject | stable isotope | en_GB |
dc.subject | glacio-eustasy | en_GB |
dc.title | Climatic and palaeoceanographic changes during the Pliensbachian (Early Jurassic) 2 inferred from clay mineralogy and stable isotope (C-O) geochemistry (NW Europe) | en_GB |
dc.type | Article | en_GB |
dc.identifier.issn | 0921-8181 | |
dc.description | This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record. | en_GB |
dc.description | Available online 17 January 2017 | en_GB |
dc.identifier.journal | Global and Planetary Change | en_GB |