The Sherwood Sandstone Group of the northeast UK (East Midlands Shelf) has hitherto never been studied in detail to ascertain it's palaeoenvironment of deposition, largely because it is poorly exposed. As such, this paper aims to provide the first modern sedimentological interpretation of the Sherwood Sandstone in the east of England based on a field outcrop at the disused quarry at Styrrup. This is in stark contrast to the western parts of England where the Sherwood Sandstone is well exposed and offshore in the North Sea Basin where it is represented by a substantial library of core material where it is also relatively well understood.The outcrop at Styrrup Quarry allows contrasts to be made with the style and expression of the Sherwood Sandstone between eastern and western England. Specifically, this highlights differences around the variation in fluvial discharge (between lowstand and highstand) and the absence of aeolian facies types. It is interpreted that these differences relate to discharge variations between ephemeral and perennial systems with a perennial model proposed for Styrrup Quarry. This model draws upon inferences of additional water input from more local areas, likely topographic uplands of the London-Brabant and Pennine Highs which supplement the primary source of the Variscan Mountains in France with additional water and sediment.

Demand for groundwater in urban centres across Asia continues to rise with ever deeper wells being drilled to avoid shallow contamination. The vulnerability of deep alluvial aquifers to contaminant migration is assessed in the ancient city of Varanasi, India, using a novel combination of emerging organic contaminants (EOCs) and groundwater residence time tracers (CFC and SF). Both shallow and intermediate depth private sources (<100 m) and deep (>100 m) municipal groundwater supplies were found to be contaminated with a range of EOCs including pharmaceuticals (e.g. sulfamethoxazole, 77% detection frequency, range <0.0001-0.034 μg L), perfluoroalkyl substances (e.g. PFOS, range <0.0001-0.033 μg L) as well as a number of pesticides (e.g. phenoxyacetic acid, range <0.02-0.21 μg L). The profile of EOCs found in groundwater mirror those found in surface waters, albeit at lower concentrations, and reflect common waste water sources with attenuation in the subsurface. Mean groundwater residence times were found to be comparable between some deep groundwater and shallow groundwater sources with residence times ranging from >70 to 30 years. Local variations in aquifer geology influence the extent of modern recharge at depth. Both tracers provide compelling evidence of significant inputs of younger groundwater to depth >100 m within the aquifer system.

Subglacial drainage systems exert a major control on basal-sliding rates and glacier dynamics. However, comparatively few studies have examined the sedimentary record of subglacial drainage. This is due to the paucity of modern analogues, the limited recognition and preservation of upper flow regime deposits within the geological record, and the difficulty of distinguishing subglacial meltwater deposits from other meltwater sediments (e.g. glacier outburst flood deposits). Within this study, the sedimentological and structural evolution of a subglacial to subaerial (ice-marginal / proglacial) drainage system is examined. Particular emphasis is placed upon the genetic development and preservation of upper flow regime bedforms and specifically recognising them within a subglacial meltwater context. Facies attributed to subglacial meltwater activity record sedimentation within a confined, but progressively enlargening, subglacial channel system produced under dune to upper flow regime conditions. Bedforms include rare large-scale sinusoidal bedding with syn-depositional deformation produced by current-induced traction and shearing within the channel margins. Subglacial sedimentation culminated with the abrupt change to a more ephemeral drainage regime indicating channel-abandonment or a seasonal drainage regime. Retreat of the ice margin, led to the establishment of subaerial drainage with phases of sheet-flow punctuated by channel incision and anastomosing channel development under diurnal, ablation-related, seasonal discharge. The presence of extensive hydrofracture networks demonstrate that proglacial groundwater-levels fluctuated markedly and this may have influenced later overriding of the site by an ice stream.

Seismic mapping of key Palaeozoic surfaces in the East Irish Sea-North Channel region has been incorporated into a review of hydrocarbon prospectivity. The major Carboniferous basinal and inversion elements are identified, allowing an assessment of the principal kitchens for hydrocarbon generation and possible migration paths. A major Carboniferous tilt-block is identified beneath the central part of the (Permian to Mesozoic) East Irish Sea Basin (EISB), bounded by carbonate platforms to south and north. The importance of the Bowland Shale Formation as the key source rock is reaffirmed, the Pennine Coal Measures having been eroded over wide areas as a result of Variscan inversion and erosion prior to Permian deposition. Peak generation from the Bowland source rock coincided with maximum burial of the system in late Jurassic/early Cretaceous time. A multiphase history of Variscan inversion has generated numerous structural traps whose potential remains essentially unexplored. Leakage of hydrocarbons from these into the overlying Triassic Ormskirk Sandstone reservoirs is likely to have occurred on a number of occasions, but currently unknown is how much resource remains in place below the Base-Permian unconformity. Poor permeability in the Pennsylvanian strata beneath the Triassic fields is a significant risk; the same may not be true in the less deeply buried marginal areas of the EISB, where additional potential plays are present in Mississippian carbonate platforms and latest Pennsylvanian clastic sedimentary rocks. Outside the EISB, the North Channel, Solway and Peel basins also contain Devonian and/or Carboniferous rocks. There have however been no discoveries, largely a consequence of the absence of a high quality source rock and a regional seal comparable to the Mercia Mudstone Group and Permian evaporites of the Cumbrian Coast Group in the EISB. The productive oil and gas fields of the EISB evidence a working, Carboniferous-sourced petroleum system. Whilst a great deal may be known of the Triassic reservoir and seal (Meadows et al. 1997), little is known about Carboniferous and Permian petroleum systems at depth and in adjacent basins, that may offer significant additional potential. Following the Wood Review (2014), Palaeozoic plays, including that of the greater Irish Sea area were identified as priority for building regional digital datasets and stimulating exploration. In response, the 21 st Century Exploration Roadmap: Palaeozoic Project running from 2014-2016 and openly released in 2017, undertook regional scale seismic and well interpretation, source and reservoir screening studies and basin modelling. This paper provides a re-interpretation of the structural history of the greater Irish Sea, and its influence on potential Carboniferous and Permian prospectivity including the marginal basins. The Carboniferous structure and stratigraphy of the UK sector of the East Irish Sea-North Channel region has been reviewed using all available well and seismic reflection data. The project interpreted about 40,0...

Wakefield and MountneyStratigraphical architecture of back filled incised valley system

Abstract. Borehole core provides detailed vertical data which is used to interpret subsurface sand body architectures, but assumptions are made on the relationship between the lateral and vertical thickness, and the interconnectivity of units. The sedimentological complexity of the Sherwood Sandstone Group succession in this area, passing between aeolian and fluvial packages creates local- to regional-scale heterogeneities which will impact flow pathways within the rockmass. Measured thickness in boreholes might represent an architectural element's true maximum thickness or more likely, a partial thickness as a result of incision by overlying facies types or as a result of the borehole sitting towards the margins of individual elements (e.g. tapering margin of channel elements). Length and thickness data were measured from a suite of primary core data and secondary published outcrop studies in north-west England. The addition of outcrop studies in combination with the borehole data provides a dataset from which the likely lateral extent of the architectural frameworks within the Triassic sandstones can be extrapolated. The interpreted high resolution sub-seismic architecture contributes to an increased understanding of flow pathways and the effect these may have on groundwater as well as sustainable energy technologies such as low-temperature geothermal aquifers, carbon storage and energy storage.

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Groundwater abstractions from the Carboniferous Fell Sandstone, Northumbria, north-east England, provide water supply to the Berwick-upon-Tweed area. Management of these abstractions, totalling 6.5 Ml/day, by the water company along with the regulator for sustainability issues is required. Groundwater abstraction takes place from different sandstone units, which are separated by mudstones, with monitored groundwater heads showing variable responses to system stresses. To improve understanding of this complex system, various activities have been undertaken. Geological mapping and interpretation have been conducted to characterise the nature, geometry, and interconnection of the sandstone units, along with the superficial deposits. Recharge modelling has used to quantify inputs to the system and to understand the long-term water balance. A time-variant model has been implemented to simulate groundwater flow in the sandstone units and to quantify the groundwater balance. The work confirms that the Fell can be split into seven discrete sandstone units, separated by low permeability mudstones, but they are not necessarily laterally connected. There is a range of timescales of groundwater response to recharge events from slow (six months) to very rapid (∼1 day). These findings confirm the complexity of this groundwater system and offer lessons for similar sandstone systems in the UK and worldwide. Thematic collection: This article is part of the Hydrogeology of Sandstone collection available at: https://www.lyellcollection.org/cc/hydrogeology-of-sandstone