Black shale deposition during the Early Jurassic: Geochemistry of Pliensbachian and Toarcian sedimentary rocks of the Hunzen Well, Hils Syncline, Northwest German Basin

作者：P. Wijesinghe, Ralf Littke, Linda Burnaz, Martin Blumenberg, Jochen Erbacher, Thomas Mann, Florian Amann, Thorsten Bauersachs · 发表于：The Depositional Record · 年份：2025 · DOI：10.1002/dep2.70037 · 被引用次数：1 · 研究领域：Paleontology and Stratigraphy of Fossils、Hydrocarbon exploration and reservoir analysis、Methane Hydrates and Related Phenomena

Abstract The Toarcian stage of the Early Jurassic witnessed warm global temperatures, oceanic anoxia (Toarcian Oceanic Anoxic Events) and extensive deposition of organic‐rich black shales. While black shale deposition in the Southwest German Basin on the Northwest Tethyan shelf has been well‐studied, the palaeodepositional conditions in the Northwest German Basin remain poorly constrained. The present study aims to bridge that gap by examining a completely cored well covering Upper Pliensbachian to Upper Toarcian sediments in the Hils Syncline. Inorganic and organic geochemical, as well as biostratigraphic information, carbon isotope and organic petrological results are interpreted to reconstruct depositional conditions and organic matter accumulation in a shallow Jurassic Sea. The study results demonstrate a Late Pliensbachian regression leading to the deposition of claystone in shallow water under humid conditions with a high terrigenous and freshwater influx, and well‐oxygenated bottom water environments. A transgression in the Early Toarcian initiated the deposition of laminated and organic matter‐rich calcareous black shale, the so‐called Posidonia Shale. This climatic shift caused deepening of the water column, resulting in salinity stratification and bottom water anoxia that favoured organic matter preservation. Black shale deposition was probably triggered by low oxygen solubility in warm waters and intensified monsoonal rainfall. The lowermost part of the Posidonia S...