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Facies heterogeneity in the Triassic Sherwood Sandstone Group of the UK: comparing and contrasting coeval depositional basins

Thompson, Joanna; Wakefield, Oliver; Hough, Ed; Cripps, Cath. 2014 Facies heterogeneity in the Triassic Sherwood Sandstone Group of the UK: comparing and contrasting coeval depositional basins. [Speech] In: British Sedimentological Research Group AGM 2014, Nottingham, UK, 20-22 Dec 2014. British Geological Survey. (Unpublished)

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Abstract/Summary

The primarily fluvial Triassic Sherwood Sandstone Group is found at outcrop fringing the northern part of the Needwood Basin (between Stoke-on-Trent and Nottingham) then northwards along the western margin of the East Midlands Shelf (Figure 1). The offshore lateral equivalents of the group in the East Irish Sea and North Sea (Ormskirk and Bunter sandstones) are reservoirs for oil and gas. Additionally, the Sherwood Sandstone Group is of regional importance in eastern England as the principle groundwater aquifer that supplies water for potable and industrial use. In some areas the aquifer has become contaminated by a variety of pollutants including Non-Aqueous Phase Liquids (NAPLs) and nitrates. Some pathways through the aquifer are via intergranular flow and this is partly influenced by variations in porosity and permeability, of which lithofacies is a major control. As such, further understanding of the spatial relationships between different lithofacies and associated properties at outcrop can be used to augment predictive models applicable to both the water and hydrocarbons industries. Data collection for this study focussed on 6 field localities covering the East Midlands Shelf and Needwood Basin. From these field localities numerous lithofacies have been identified and these include: i) clean homogeneous massive sandstones, ii) sandy conglomerates, iii) poorly- to moderately- sorted cross-bedded sandstones, iv) fine to very-fine cross-laminated sandstones, and v) thin horizontally laminated siltstones. Data from these field localities comprises a series of pseudo-three dimensional architectural panels which illustrate the relationship and three-dimensional configuration of observed lithofacies types. Cores from eight boreholes were also logged and provide information on the spatial distribution and relative abundance of the identified lithofacies where outcrop is sparse. This study allows a comparison of the Sherwood Sandstone Group between depocentres separated by the Charnwood palaeo-high. The dataset is being used to create qualitative and quantitative models that depict the variations in lithofacies types and configurations in the Sherwood Sandstone Group spatially; contrasting lithofacies from linked contemporaneously depositing basins. Preliminary results suggest more lateral and vertical variation in lithofacies types than has been previously described, which implies that a greater complexity of lithofacies architecture needs to be captured to improve models of fluid flow in the Sherwood Sandstone Group.

Item Type: Publication - Conference Item (Speech)
Additional Keywords: Facies, Triassic, Sherwood Sandstone, Chester Formation, Nottingham Castle Formation, Lenton Sandstone, Basin, Coeval, Sedimentology, Fluvial
NORA Subject Terms: Earth Sciences
Date made live: 10 May 2017 13:57 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/517003

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