Cross-Basin Mo and U Analysis of the Upper Mississippian Bowland Shale UK

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 ( ca . 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 compares to previously published data (outcrop Hind Clough), all from the Bowland sub-basin, Lancashire, UK. The sedimentology and geochemistry of this formation was determined via a multi-technique approach including x-ray fluorescence (XRF), sedimentology, gamma ray spectra, x-ray diffraction (XRD) and RockEval(6) TM 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 that contemporaneous anoxia developed 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 compared to the Fort Worth Basin. Knowledge from this study improves future resource estimates of the Bowland Shale Formation, and challenges the early assumptions that the Barnett Shale is an analogue to the Bowland Shale.