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

Abstract Mudstones from the Argiles de Châtillon Formation exposed in Boulonnais region of Northern France represent a proximal lateral equivalent organic-rich Kimmeridge Clay Formation. The is composed two subunits that straddle Kimmeridgian–Tithonian boundary. Each subunit contains an interval. conspicuous intervals have been linked to either periods high sea level or greenhouse warming. Here, we use palynology further understand climate and environmental mechanisms drove organic matter enrichment. We bulk carbon isotope records (δ 13 C org ) correlate sections with those palynological results suggest stratigraphically lower interval (Kimmeridgian) was deposited under suboxic anoxic stratified conditions. A large-scale shift cooler/humid warmer/arid conditions marked boundary, influencing enrichment higher (Tithonian). In contrast interval, there are no indications for Within this thicker cyclic variations amorphous distribution, total δ trends on 2 m scale observed. They co-occur fluctuations assemblages, indicative more humid versus arid conditions, likely alternating ∼100 kyr eccentricity timescale. Our show most phases these overall sulfurization carbohydrates dominant control preservation. This climate-controlled process drives Tithonian can be recognized basin-wide scale.