Tectonic synthesis and contextual setting for the Palaeozoic of the Moray Firth region, Orcadian Basin

This report is designed simply to provide a summary tectonic outline and contextual setting against which offshore seismic and well data relating to the Devono-Carboniferous evolution of the Inner Moray Firth region, adjacent areas of the Orcadian Basin, and UK offshore regions can be considered. This summary is intended to help better frame the questions that will arise during interrogation of that data; the findings that result from that analysis are presented elsewhere in the report series (Arsenikos et al., 2016; Kimbell & Williamson, 2016; Monaghan et al., 2016). The pattern of Devonian and Carboniferous tectonics in the Moray Firth region will be strongly influenced by the underlying pattern of (N)NE-(S)SW tending Caledonian basement discontinuities transecting the region, in particular the expression of regional stress patterns along and across the trace of the Great Glen – Walls Boundary Fault Zone (GGFZ). Sinistral motion, on that very large-scale intra-Laurussian structure, is seen throughout most of the Upper Palaeozoic (Dewey and Strachan, 2003) but by the late Carboniferous, interaction of Baltica-Siberia across the Ural Sea foredeep had come into play, promoting dextral shear on the GGFZ (Coward, 1993; cf. Domeier and Torsvik, 2014). In the Devono-Carboniferous, and under the influence of overall sinistral transcurrent motion on the GGFZ, E(SE)-W(NW) directed stretching should be anticipated in the Moray Firth region with N(NE)-S(SW) oriented extensional faults likely. Such structures would be similar in style to the patterns of faulting associated with the Devonian outliers observed onshore in Moray- Buchan, and also as described in the Helmsdale region (Underhill & Brodie, 1993). In addition to a strong ‘basement’ control from inherited Caledonian (N)NE to (S)SW features, there is likely also to be underlying control from any Caledonian plutonic complexes present (Kimbell & Williamson, 2016). The present day pattern of Moray Firth faulting, established depocentres and intra-basinal highs, comprises a strong Mesozoic pattern of tectonic features (e.g. Andrews et al., 1990; Underhill 1991; Thomson and Underhill 1993) superimposed on older (‘post-Caledonian’) tectonic patterns established in the Late Carboniferous, most likely in response to the south-westwards movement of Baltica relative to Laurussia at this time (cf. Coward, 1993). Those regional stresses generated dextral shear in the GGFZ, coincident with strongly partitioned strain in the North Sea basin interior (Leslie et al. 2015). From Late Carboniferous times, N(NW) – S(SE) directed extension in the Inner Moray Firth region generated W(SW)-E(NE) trending extensional faults (e.g. the Banff and Wick faults). This stress régime sets in place the framework of highs and lows preceding any Permian uplift and younger tectonics as the switch to the earliest Atlantic-opening stresses occurred. WNW-ESE directed extension, observed and dated in the Pentland Firth area (267+/-3 Ma, Dichiarante et al. 2015), will likely generate increasingly oblique (sinistral?) wrench on the Wick/Banff Faults from this time. Dip-slip components of movement are likely on the older (N)NE- (S)SW-trending structures inherited from the Caledonian, e.g. the Helmsdale/Strathconnon Faults, and perhaps the GGFZ; the latter may be too steep and fundamental a structure to actively respond in pure extension at this time

An exploration of the progress of open crime data: how do ongoing limitations with the Police.uk website restrict a comprehensive understanding of recorded crime?

Open-source crime data provided by the Police.uk website was introduced in 2008. This provision challenged what had been termed a ‘top down’ political culture and was introduced to help increase government transparency and accountability. We examine these concepts here and outline some of the significant developments over the last decade related to the information contained within the Police.uk resource. Our focus then moves towards limitations of the data set provided, some of which are as pervasive today as they were when this online data source was first introduced. We explore whether these drawbacks are irresolvable and consider the practical implications they will have when this open data set is utilised by members of the public and researchers. Ultimately, we give an assessment of the efficacy of this source of information for the user within the context of the government rhetoric which accompanied it

Seismic interpretation and generation of key depth structure surfaces within the Carboniferous and Devonian of the Orcadian Study Area, Quadrants 7-9, 11-15 and 19-21

This report details the rationale, methodology and results of a regional seismic interpretation of the 21CXRM Palaeozoic ‘Orcadian study area’, specifically the Inner Moray Firth and western Outer Moray Firth basins (Quadrants 11–15), the East Orkney Basin (Quadrant 13) and the Grampian High area (Quadrants 19–21). The aim of the interpretation was to create Two-Way Travel Time (TWTT) and depth maps that show the distribution of Palaeozoic basins and highs, and where possible interpret key Devono-Carboniferous surfaces and main structural elements in order to contribute a tectono-stratigraphic model of the Palaeozoic succession. Some 35,000 line kilometres of predominantly 2D seismic data have been interpreted and tied to key released wells in the study area. In total, 8 depth structure maps of key horizons have been produced for the pre-Permian succession. The maps do not cover the entire study area as it was not possible to interpret a specific seismic reflector everywhere due both to seismic resolution and also current day extents (as a result of non-deposition and/or erosion). These maps provide a key element to aid assessment of the petroleum systems of the Palaeozoic sequence within the study area. Where present, the surfaces with a grid spacing of 5000 m, give a regional view of the topography of the horizons, and comprise: Inner and Outer Moray Firth and East Orkney Basin area Base Zechstein; Top Firth Coal Formation; Top Eday Marl Formation; Top Orcadia Formation; Base Orcadia Formation; Top Struie Formation; Top Basement. The geological succession over the Grampian High area was such that only the following surfaces were generated: Base Zechstein; Base Carboniferous/ Top Devonian; Top Basement. The regional structure map of the area constructed for this report, and observations made from the seismic data, have been integrated with peer reviewed published information to describe a tectonic synthesis for the region (Leslie et. al., 2016). A new pre-Permian subcrop map is presented here that builds on existing publications (Smith, 1985; Marshall and Hewett 2003) and incorporates relevant new well penetrations since the previous maps were published. The well dataset has been either validated or re-interpreted before being integrated with the new seismic interpretation. The map extends the interpretation of the pre-Permian subcrop northwards from the published Central North Sea map (Arsenikos et al., 2015)

Seismic interpretation and generation of key depth structure surfaces within the Devonian and Carboniferous of the Central North Sea, Quadrants 25 – 44 area

This report details the rationale, methodology and results of a regional seismic interpretation of the western margin of the Central North Sea (CNS) area, specifically over the Mid North Sea High area, the offshore extension of the Northumberland Trough and the Forth Approaches area. The aim of the interpretation was to create maps that show the distribution of Palaeozoic basins and highs, and where possible interpret key Devono-Carboniferous surfaces and main structural elements in order to build a tectono-stratigraphic model of the Palaeozoic geology. Some 50,000 line kilometres of predominantly 2D seismic data have been interpreted and tied to key released wells in the study area. The seismic and well data were augmented by donated reports from sponsor companies. A set of 5 depth structure maps of selected Palaeozoic horizons has been produced for the pre-Permian succession. These maps provide a key element to aid assessment of the petroleum prospectivity of the Palaeozoic within the study area. The surfaces, with a grid spacing of 5000 m, give a regional view of the topography of the horizons, and comprise: Upper Permian Base Zechstein Group; Lower Carboniferous near Top Scremerston Formation; Lower Carboniferous near Top Fell Sandstone Formation; Lower Carboniferous near Top Cementstone Formation; and Middle Devonian near Top Kyle Limestone Group. The regional structure map of the area constructed for this report and observations made from the seismic data, have been integrated with peer reviewed published information to describe a tectonostratigraphic model for the region (Leslie et. al., 2015). A new pre-Permian subcrop map is presented here that builds on existing publications (Smith,1985a, b; Kombrink et al., 2010) and incorporates all relevant new well penetrations since the previous map was published. The well dataset has been either validated or re-interpreted before being integrated with the new seismic interpretation (Kearsey et al., 2015). Figure 10 in Section 3.3.1 below summarises the regional structures referred to in the general observations listed below. General observations on the structures defined across Quadrants 29, 30, 31, 37, 38 and 39: The Middle-Upper Devonian basins and highs follow a NW-SE trend across Quadrants 29-30 and 37-38; Lower Carboniferous sequences (Tournaisian and Visean) are interpreted to be present in depocentres across much of the area covered by Quadrants 29 to 38; wells, mainly drilled on the structural highs, constrain the edge of the Lower Carboniferous basins; There is a structurally complicated area in the southernmost part of Quadrant 38 which comprises a folded Visean and probably Namurian succession. The structure can be interpreted either as an anticlinal rollover on a low-angle fault, or as a compressional anticlinal fold (see Figure 17 below). The structure trends broadly NNE-SSW, plunging northwards into Quadrant 38

Tectonic synthesis and contextual setting for the Central North Sea and adjacent onshore areas, 21CXRM Palaeozoic Project

This report is designed simply to provide a summary tectonic outline and contextual setting against which offshore seismic and well data relating to the Devono-Carboniferous evolution of the Central North Sea, Forth Approaches, and adjacent UK onshore region can be considered. This summary is intended to help better frame the questions that will arise during interrogation of that data; the findings that result from that analysis are presented elsewhere in the report series (Arsenikos et al., 2015; Kimbell & Williamson, 2015; Monaghan et al., 2015). Apparently contradictory, wrench- or extension-dominated patterns of Lower Carboniferous basin development are recorded in the Forth Approaches, Quadrant 29, North Dogger and Silverpit basins of the Central North Sea, as well as the Midland Valley of Scotland (MVS) and Northumberland and Solway basins onshore. Partitioning Carboniferous deformation across inherited pre-existing Caledonian or Tornquist structures is likely to be an important control on the tectonic architecture developed in these regions during intervals of the geological record in the Carboniferous. Onshore, spatially separate but contemporaneous domains of extension-dominated tectonics versus wrench-dominated tectonics explain the contrasting tectonic framework of the MVS/Forth Approaches region (wrench-dominated) compared with Northumberland Basin (classic ‘stags head’ structure). NE-SW trending Caledonian inheritance strongly controls the domain boundaries and the patterns of deformation created in each of these domains. Offshore, in the Devono-Carboniferous basins of the Central North Sea, the likelihood that strain is partitioned in a similar way across features inherited from the NW-SE Tornquist trend is proposed and examined. The data currently under consideration suggests that a NW-SE trending wrench-dominated domain is spatially associated with the region underlain by the Dogger Granite pluton; domains affected by extension-dominated tectonics appear to be arranged on either side of that feature, namely the Quadrant 29 and North Dogger basins to the NE, and the Silverpit Basin to the SW. Extension is expressed as a NE-SW directed stretch in both of these domains. Patterns of broadly N-S trending fold axes need to be carefully assessed in terms of their structural setting, as folding cannot implicitly be linked with inversion/compression when partitioned strains are developed. Superficially similar features can develop in the MVS in dextral transpression, in north Northumberland buttressed around the Cheviot Granite in overall dextral wrench, and as superimposed late compressional folds in end-Variscan convergence, for example in the Boldon syncline of County Durham. Offshore, similar inversion effects can be seen in the patterns of transpressive faulting associated with features such as the Murdoch Ridge, and with examples of superimposed NE-SW trending extensional faults active in the latest Carboniferous to early Permian

Palaeozoic petroleum systems of the Irish Sea

This report synthesises the results of the 21CXRM Palaeozoic project in the Irish Sea to describe the Palaeozoic petroleum systems of that area. One hydrocarbon play system dominates the basin system: Namurian organic-rich marine shales (Bowland Shale Formation) generated oil and gas with a peak during maximum burial of the system in late Jurassic/early Cretaceous time. These hydrocarbons passed to reservoirs in the Triassic Ormskirk Sandstone (Sherwood Sandstone Group) by way of structures generated during the Variscan Orogeny and Cenozoic inversion, resulting in the Morecambe, Hamilton and other gas and oil fields The Palaeozoic study of the wider Irish Sea area has assessed the potential for more widespread petroleum systems situated outside the well-known play, particularly within the Carboniferous. Within the Main Graben system of the East Irish Sea Basin, Coal Measures strata were partially removed following Variscan inversion and early Permian uplift. They are not rich in coals, and not inferred to be a significant source rock. There is some potential in the Millstone Grit and Yoredale sequences, as some shales (particularly those associated with marine bands) are known to have high Total Organic Contents. The source rock potential of shales within the Carboniferous Limestone sequence is poorly constrained by data. A Devonian source rock is unproven and considered unlikely. Potential Namurian source rocks, such as the Yoredale Group, have been largely eroded in the Peel and North Channel basins, considerably reducing their prospectivity, although terrestrial sequences of equivalent age in the Solway Basin may offer better potential. The variable seismic data quality at Carboniferous levels and sparsity of deep well control have led to challenges in interpretation, particularly of the deeper picks. The interpretation of the surfaces contains a strong model-driven element, evidenced by the onshore relationships and areas where seismic picks can be made with the greatest confidence. Based upon the integration of regional seismic mapping with a limited well, source rock and reservoir property dataset, the most prospective parts of the region, outside the Ormskirk conventional gas play, are considered to be: The thick Westphalian sequences preserved in the Eubonia Tilt-Block in Quadrant 109, outside the main Permian-Mesozoic graben system and unaffected by Cenozoic inversion. The presence and quality of seals form a major risk as the Cumbrian Coast Group seal is thin or absent and Carboniferous intraformational seals are required but untested. Based on the limited dataset available in adjacent basins, reservoir quality is also a significant risk. A belt of Variscan inversion structures correlated with structures on the Formby Platform, and Ribbledale Foldbelt onshore, from which hydrocarbons have leaked into the overlying, Ormskirk-hosted Hamilton fields. The biggest risk here is whether reservoirs remain unbreached at the Pre-Permian level, and retain good poroperm characteristics at depths of about 2500 m. A more speculative play lies in the extensive carbonate platform in Quadrant 109 and surrounding the Isle of Man, in reefal facies with enhanced secondary porosity. Here, source rock presence and migration pathways, reservoir properties and seal quality are major risks

Seismic interpretation and generation of depth surfaces for Late Palaeozoic strata in the Irish Sea Region

This report describes the methodology and results of a regional seismic interpretation of the basins of the Irish Sea. It does not review the basins of the Celtic Sea. The aim of the interpretation was to map the distribution of Palaeozoic basins and highs, interpreting the key Devonian-Carboniferous surfaces and main structural elements of the area. About 40,000 km of 2D seismic reflection data have been interpreted and tied to key released wells in the project area. The seismic and well data were augmented by donated reports from sponsor companies. A set of 8 depth structure maps of key horizons have been produced for the pre-Permian succession. These maps provide a key dataset to aid assessment of the petroleum systems of the Palaeozoic strata within the study area. The surfaces, supplied digitally at a grid spacing of 5000 m, give a regional view of the topography of the horizons, and comprise: ‘UVAR’ (Variscan Unconformity) beneath Permian and Triassic strata Base Warwickshire Group (late Westphalian - ?Stephanian) Top Namurian (Base Pennine Coal Measures Group) Top Intra-Namurian (Top Bowland Shale in south, Base Millstone Grit elsewhere) Top Visean (Lower Carboniferous) Intra-Visean (amalgamated with Top Middle Border Group in north) Base Carboniferous (amalgamated with Base Clyde Plateau lavas in the North Channel to South-West Arran Sub-Basin) ‘UCAL’ Acadian (Caledonian) Unconformity) It is important to note that the variable data quality and sparsity of deep wells leads to a seismic interpretation which is strongly driven by regional geological models, themselves heavily dependent on inference from the onshore area. This is particularly the case with the deeper Carboniferous horizons which are not penetrated by any well and which may be only weakly reflective. In such cases, picks from better quality data may be interpolated through areas with poor quality data, as a modelled surface, to ensure a continuous surface for gridding. The well dataset has been re-interpreted (Wakefield et al., 2016) before integration with the seismic interpretation. The following general observations are made: The present study has confirmed the Permian-Mesozoic structural framework for the region established by Jackson and Mulholland (1993) and Jackson et al. (1995, 1996, 1997). The basin recognised in Quadrant 109 by Jackson and co-workers (op. cit.) is reinterpreted as a major Carboniferous half-graben structure controlled by a syndepositional fault on its NW side. It continues beneath thin Permo-Triassic cover into the Eubonia Basin and Ogham Platform, preserving a thick Westphalian succession, including inferred Warwickshire Group strata. It is inferred to have continued eastward into the Lagman Basin prior to its tectonic dissection by a combination of Variscan inversion and Permo-Mesozoic graben development along the Keys Fault. A belt of Variscan fold/thrust inversion structures on the Godred Croven Platform is correlated with structures on the Formby Platform and Ribblesdale Foldbelt onshore. CR/16/041 Last modified: 2016/05/30 09:37 10 The area of Carboniferous (undivided) subcrop depicted on mapping by BGS (1994) to north and west of the Isle of Man has been reclassified into Visean and Namurian elements. The presence of significant thicknesses of Carboniferous strata in the southern part of the North Channel is regarded as doubtful, but farther north, in the Larne, Rathlin and South-West Arran Sub-basins, greater thicknesses may be present. A detailed description of tectono-stratigraphic development based on the seismic interpretation is given in Pharaoh et al. (2016b), integrated with the petroleum system analysis

The cosmological simulation code GADGET-2

We discuss the cosmological simulation code GADGET-2, a new massively parallel TreeSPH code, capable of following a collisionless fluid with the N-body method, and an ideal gas by means of smoothed particle hydrodynamics (SPH). Our implementation of SPH manifestly conserves energy and entropy in regions free of dissipation, while allowing for fully adaptive smoothing lengths. Gravitational forces are computed with a hierarchical multipole expansion, which can optionally be applied in the form of a TreePM algorithm, where only short-range forces are computed with the `tree'-method while long-range forces are determined with Fourier techniques. Time integration is based on a quasi-symplectic scheme where long-range and short-range forces can be integrated with different timesteps. Individual and adaptive short-range timesteps may also be employed. The domain decomposition used in the parallelisation algorithm is based on a space-filling curve, resulting in high flexibility and tree force errors that do not depend on the way the domains are cut. The code is efficient in terms of memory consumption and required communication bandwidth. It has been used to compute the first cosmological N-body simulation with more than 10^10 dark matter particles, reaching a homogeneous spatial dynamic range of 10^5 per dimension in a 3D box. It has also been used to carry out very large cosmological SPH simulations that account for radiative cooling and star formation, reaching total particle numbers of more than 250 million. We present the algorithms used by the code and discuss their accuracy and performance using a number of test problems. GADGET-2 is publicly released to the research community.Comment: submitted to MNRAS, 31 pages, 20 figures (reduced resolution), code available at http://www.mpa-garching.mpg.de/gadge

Structural development of the Devono-Carboniferous plays of the UK North Sea

Decades of oil and gas exploration across the North Sea have led to a detailed understanding of its Cenozoic–Mesozoic structure. However, the deeper basin architecture of Paleozoic petroleum systems has been less well defined by seismic data. This regional structural overview of the Devono-Carboniferous petroleum systems incorporates interpretations from more than 85 000 line-kilometres of 2D seismic data and 50 3D seismic volumes, plus a gravity, density and magnetic study, from the Central Silverpit Basin to the East Orkney Basin. A complex picture of previously unmapped or poorly known basins emerges on an inherited basement fabric, with numerous granite-cored blocks. These basins are controlled by Devono- Carboniferous normal, strike-slip and reverse faults. The main basins across Quadrants 29–44 trend NW–SE, influenced by the Tornquist trend inherited from the Caledonian basement. North of Quadrants 27 and 28, and the presumed Iapetus suture, the major depocentres are NE–SW (e.g. the Forth Approaches and Inner Moray Firth basins) to east–west (e.g. the Caithness Graben), and WNW–ESE trending (e.g. the East Orkney Basin), reflecting the basement structural inheritance. From seismic interpretation, there are indications of an older north–south fault trend in the Inner Moray Firth that is difficult to image, since it has been dissected by subsequent Permo-Carboniferous and Mesozoic faulting and rifting

UKGEOS: Glasgow Geothermal Energy Research Field Site (GGERFS): initial summary of the geological platform

The preferred second UKGEOS site is at Clyde Gateway, in the east end of Glasgow, Scotland. The focus of this, the Glasgow Geothermal Energy Research Field Site (GGERFS), is on characterising and monitoring the subsurface for minewater and hot sedimentary aquifer geothermal energy, and for cooling and heat storage. This report details BGS data and knowledge at late 2016, to define initial characterisation of the ‘geological platform’ relevant for the planning of a geothermal research facility and associated environmental baseline monitoring. The report covers knowledge of the bedrock and superficial deposits geology, abandoned coal mines, hydrogeology, geothermal datasets, geochemistry, remote sensed data, seismicity, stress fields, engineering geology and rock property datasets. BGS holds a great deal of legacy borehole, mining and geochemistry data and has updated existing bedrock and superficial deposits models of the area. However, deep borehole and seismic data are lacking to define the geology and structure of the area below a few hundred metres. Hydrogeological and temperature data are also lacking for the bedrock strata. Regional datasets and knowledge have (and can be further) used to reduce uncertainty and risk in these aspects of the geological characterisation