Abstract The Bowland sub-basin is a target for hydrocarbon exploration, but to a large extent it remains unexplored. To determine the economic potential of the Bowland sub-basin, it is important to identify the oceanographic processes involved in the deposition of the Bowland Shale Formation in the Late Mississippian (c. 330 Ma). Palaeoceanographic processes are known to be a major control on the development of hydrocarbon source rocks. This study investigates core (Preese Hall-1 and Becconsall-1Z) materials from the Upper Bowland Shale, and makes a comparison with previously published data (outcrop Hind Clough), all from the Bowland sub-basin, Lancashire, UK. The sedimentology and geochemistry of this formation were determined via a multi-technique approach including X-ray fluorescence, sedimentology, gamma-ray spectra, X-ray diffraction and Rock-Eval pyrolysis. Key trace metal abundances and enrichment factors were used to assess sediment provenance and to determine the bottom-water redox conditions during the deposition of the Upper Bowland Shale. Our results support interpretations of contemporaneous anoxia developing in bottom waters in at least three sites in the Bowland sub-basin. In a comparison with the Fort Worth Basin (Barnett Shale, USA), the Bowland sub-basin was apparently less restricted and deposited under a much higher mean sediment accumulation rate. Knowledge from this study will improve future resource estimates of the Bowland Shale Formation, and challenge the early assumptions that the Barnett Shale is an analogue of the Bowland Shale.

Abstract Surface currents constitute an efficient transport agent for (larvae of) marine faunas, while the circulation of water masses in the ocean interior drives nutrient redistribution, ventilates the ocean and contributes to shaping surface biological productivity and the benthic redox landscape. Therefore, a robust understanding of ocean circulation, both shallow and deep, and of its response to climate change, is required to interpret palaeobiogeographic signals, biological productivity patterns and biodiversity trends. This is especially critical during periods of dynamic biological change, such as the Ordovician. Yet, oceanic circulation patterns leave no direct evidence in the geological record and can therefore be reconstructed solely based on indirect indicators, such as the distribution of faunas and geochemical proxies. General circulation models offer independent, physically robust insights onto the coupling between climate change and ocean circulation. Integrated approaches based on the assimilation of geological data in numerical models thus constitute a promising way forward. We here provide a literature review and updated synthesis of the current understanding of the Ordovician ocean circulation, based on data and models.