Correlation of the Kimmeridgian-Tithonian (Jurassic) boundary beds exposed in the Boulonnais, France with those at Kimmeridge, Dorset, UK

Gallois, R.W.; Vadet, A.; Etches, Steve

doi:10.1016/j.pgeola.2018.12.002

Cited by 1 publication

(2 citation statements)

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“…Apparently, local factors that could have the influenced the δ 13 C org signal, such a sediment supply from the hinterland, climate and vegetation, were quite comparable through the basin, as well as on a larger regional scale. However, the differences between these formations in terms of lithology, depositional setting and absolute TOC are considerable (Proust et al 1993; Herbin et al 1995; Morgans-Bell et al 2001; Wignall & Newton, 2001; Braaksma et al 2006; Gallois et al 2019). Therefore, a basin-wide controlling mechanism is required to explain the enhanced accumulation of OM in the basin.…”

Section: Discussionmentioning

confidence: 99%

“…The ACF spans the transition from the Kimmeridgian to the Tithonian (Gallois et al 2019), a period that records a climate change in NW Europe, evolving from warm and humid conditions in late Kimmeridgian time ( Eudoxus and Autissiodorensis ammonite zones) to more arid conditions in early Tithonian time ( Elegans ammonite Zone; Abbink et al 2001; Deconinck & Baudin, 2008; Hesselbo et al 2009). Smaller-scale Milankovitch cyclicity-controlled climate variations have been recorded in the ACF as well as in the KCF, with alternations on a decimetre–metre scale (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Climate-controlled organic matter accumulation as recorded in the Upper Jurassic Argiles de Châtillon Formation, a shallow-marine counterpart of the Kimmeridge Clay Formation

Hoeven

Verreussel²,

Riboulleau

et al. 2022

Geol. Mag.

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Mudstones from the Argiles de Châtillon Formation exposed in the Boulonnais region of Northern France represent a proximal lateral equivalent of the organic-rich Kimmeridge Clay Formation. The Argiles de Châtillon Formation is composed of two subunits that straddle the Kimmeridgian–Tithonian boundary. Each subunit contains an organic-rich interval. The two conspicuous organic-rich intervals have been linked to either periods of high sea level or greenhouse warming. Here, we use palynology to further understand climate and environmental mechanisms that drove organic matter enrichment. We use bulk organic carbon isotope records (δ13Corg) to correlate the Boulonnais sections with those of the Kimmeridge Clay Formation. The palynological results suggest that the stratigraphically lower organic-rich interval (Kimmeridgian) was deposited under suboxic to anoxic stratified conditions. A large-scale climate shift from cooler/humid to warmer/arid conditions marked the Kimmeridgian–Tithonian boundary, influencing organic matter enrichment in the stratigraphically higher organic-rich interval (Tithonian). In contrast with the lower organic-rich interval, there are no indications of stratified conditions for the higher organic-rich interval. Within this thicker organic-rich interval, cyclic variations in amorphous organic matter distribution, total organic carbon and δ13Corg trends on a 2 m scale are observed. They co-occur with fluctuations of the palynological assemblages, indicative of more humid versus arid climate conditions, likely alternating on a ∼100 kyr eccentricity timescale. Our results show that under the most humid phases of these overall arid climate conditions, sulfurization of carbohydrates was the dominant control on organic matter preservation. This climate-controlled process that drives organic matter enrichment in the Tithonian can be recognized on a basin-wide scale.

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