DOI: 10.25666/dataubfc-2018-07-18-02
title: Clay mineralogical and geochemical expressions of the "Late Campanian Event" in the Aquitaine and Paris basins (France): Palaeoenvironmental implications
title: Expression minéralogique et géochimique du "Late Campanian Event" dans les bassins aquitain et parisien (France) : implications paléoenvironnementales

description: Campanian sediments from two French sedimentary basins were studied, using clay mineralogy and stable isotope (δ13C and δ18O) geochemistry, in order to investigate the Late Campanian Event. The clay fraction of the Campanian sediments from the Tercis-les-Bains section (Aquitaine Basin) and from the Poigny borehole (Paris Basin) is mainly composed of smectite. This background sedimentation was, however, interrupted during the Upper Campanian in the two basins by a substantial increase in detrital inputs, including illite, kaolinite, and chlorite at Tercis-les-Bains, and illite at Poigny. This detrital event, resulting from the enhanced erosion of nearby continental areas triggered by increasing runoff, has also been recognized in the Tethys and South Atlantic oceans. It coincided with a global negative carbon isotope excursion, the Late Campanian Event (LCE). Carbon isotope stratigraphy was used to correlate the two basins with previously studied sections from distant areas. Spectral analysis of the bulk δ13C from Tercis-les-Bains suggests a duration of ca. 400 kyr for a pre-LCE negative excursion and ca. 800–900 kyr for the LCE sensu stricto. The detrital event, as characterized by clay mineralogy, spans the interval that comprises the pre-LCE and the LCE, with a duration of 1.3 Myr. Intensification of continental erosion during the LCE may have resulted either from the Late Campanian polyplocum regression and/or from a regional tectonic pulse that triggered the emersion of previous submerged shelf areas and the increase of silicate erosion. As the LCE seems to be recorded at a large geographic scale, it is proposed here that enhanced chemical weathering and an associated decrease in atmospheric pCO2 levels could have contributed to the long-term Late Cretaceous cooling trend.
description: Les sédiments de deux bassins sédimentaires français ont été étudié à travers la minéralogie des argiles ainsi qu'à travers l'isotopie du carbone et de l'oxygène, dans le but d'étudier "l'événement du Campanien supérieur", soit le "Late Campanian Event". La fraction argileuse des sédiments d'âge Campanien de la coupe de Tercis-les-Bains (bassin d'Aquitaine) et du forage de Poigny (bassin de Paris) est principalement composée de smectites. Cette sédimentation de fond est interrompue, dans ces deux bassins, pendant le Campanien supérieur, par un apport des minéraux argileux détritiques, incluant de l'illite à Poigny et de l'illite, de la kaolinite et de la chlorite à Tercis-les-Bains. Ces événements détritiques résultent d'une intensification de l'altération continentale, engendrée par l'érosion des massifs continentaux adjacents. Ce phénomène a déjà été reconnu dans d'autres grands domaines sédimentaires (Atlantique et Téthys). De plus, ceci coïncide avec une excursion négative globale du carbone, appelée le "Late Campanian Event".
description: Audience: University: master, Research, University: licence
description: UpdatePeriodicity: no update
description: Experimental data: Minéralogie des argiles (DRX) - Isotopie du carbone (Spétrométrie de masse)