A global reference for black shale geochemistry and the T-OAE revisited: upper Pliensbachian – middle Toarcian (Lower Jurassic) chemostratigraphy in the Cleveland Basin, England

Jarvis, Ian; Atar, Elizabeth; Gröcke, Darren R.; Herringshaw, Liam G.; Trabucho-Alexandre, João P.

Abstract

The Pliensbachian–Toarcian succession of North Yorkshire provides a global reference for the interval incorporating the Toarcian Oceanic Anoxic Event (T-OAE, ∼183 Ma). Major and trace element, carbon stable-isotope (δ13Corg) and total organic carbon (TOC) data for the Dove’s Nest core, drilled close to the classic outcrop sections of the Yorkshire coast, demonstrate geochemical, mineralogical and grain-size trends linked to sea level and climate change in the Cleveland Basin. High-resolution correlation between the core and outcrop enables the integration of data to generate a comprehensive chemostratigraphic record. Palaeoredox proxies (Mo, U, V, TOC/P, DOP and Fe speciation) show a progressive shift from oxic bottom waters in the late Pliensbachian through dysoxic–anoxic conditions in the earliest Toarcian to euxinia during the T-OAE. Anoxia–dysoxia persisted into the middle Toarcian. Elemental and isotope data (Re, Re/Mo, δ34SCAS, δ98Mo and ε205Tl) from the coastal sections evidence global expansion of anoxic and euxinic seafloor area driving drawdown of redox-sensitive metals and sulfate from seawater leading to severe depletion in early Toarcian ocean water. The record of anoxia–euxinia in the Cleveland Basin largely reflects global-scale changes in ocean oxygenation, although metal depletion was temporarily enhanced by periods of local basin restriction. Osmium and Sr isotopes demonstrate a pulse of accelerated weathering accompanying the early Toarcian hyperthermal, coincident with the T-OAE. The combined core and outcrop records evidence local and global environmental change accompanying one of the largest perturbations in the global carbon cycle during the last 200 Ma and a period of major biotic turnover.

Citation

Jarvis, I., Atar, E., Gröcke, D. R., Herringshaw, L. G., & Trabucho-Alexandre, J. P. (2024). A global reference for black shale geochemistry and the T-OAE revisited: upper Pliensbachian – middle Toarcian (Lower Jurassic) chemostratigraphy in the Cleveland Basin, England. Geological Magazine, 161, Article e13. https://doi.org/10.1017/s0016756824000244

• Journal Article Type: Article
• Acceptance Date: Sep 25, 2024
• Online Publication Date: Oct 25, 2024
• Publication Date: 2024
• Deposit Date: Nov 26, 2024
• Publicly Available Date: Nov 26, 2024
• Journal: Geological Magazine
• Print ISSN: 0016-7568
• Electronic ISSN: 1469-5081
• Publisher: Cambridge University Press
• Peer Reviewed: Peer Reviewed
• Volume: 161
• Article Number: e13
• DOI: https://doi.org/10.1017/s0016756824000244
• Public URL: https://durham-repository.worktribe.com/output/3107162