Contemporary stress orientations in the Faroe-Shetland region

The Faroe-Shetland Region (FSR) of the NE Atlantic continental margin contains a number of complexly structured Mesozoic-Palaeogene-age rift basins, but in comparison to the contiguous British Isles and North Sea Basin, the state of crustal stress in the FSR is poorly understood. The orientation of maximum horizontal compressional stress (σHmax) across most of NW Europe is ~NW-SE, which is considered to be controlled by forces acting at the plate boundaries. We have determined 16 B-D quality σHmax orientations based on borehole breakouts interpreted in petroleum wells, and define three distinct stress provinces within the FSR. Stress orientations in the NE are ~NW-SE, consistent with the regional pattern of stresses in NW Europe and local neotectonic structural trends. However, contemporary stress orientations in the central and SW of the FSR exhibit short-wavelength (distances <10-50 km) variation, with NE-SW, N-S and E-W orientations that are parallel or sub-parallel to underlying structural trends. This variation is interpreted in terms of stress deflections towards weak faults that downthrow the Mesozoic-Cenozoic sedimentary successions against basement highs. These local-scale sources are superposed on a background ~WNW-ESE σHmax orientation that is controlled by both plate boundary forces and regional-scale sources of stresses

Emplacement of the Little Minch Sill Complex, Sea of Hebrides Basin, NW Scotland

Acknowledgements The work contained in this paper contains work conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil & Gas [grant number RG12649-12] and is fully funded by NERC whose support is gratefully acknowledged. We are also grateful to IHS Markit for provision of, and permission to publish an example from their 2D seismic data volumes and gravity and magnetics database, and to Schlumberger for the donation of Petrel seismic interpretation software licences to Aberdeen University. We acknowledge the UKOilandGasData.com website owned by UK National Data Repository administered by Schlumberger, for access to the seismic data volumes and released UK well database. Stephen Jones and Thomas Phillips are thanked for considered and constructive reviews which helped improved and broaden the appeal of the paper. Stephen Daly is thanked for giving helpful editorial steer and comments on how to improve paper. Funding This work was funded by the Natural Environment Research Council (RG12649-12). Dougal Jerram is partly supported by the Research Council of Norway through its Center of Excellence funding scheme, project 223272 (CEED)Peer reviewedPostprin

Failure of interpolation in the intuitionistic logic of constant domains

This paper shows that the interpolation theorem fails in the intuitionistic logic of constant domains. This result refutes two previously published claims that the interpolation property holds.Comment: 13 pages, 0 figures. Overlaps with arXiv 1202.1195 removed, the text thouroughly reworked in terms of notation and style, historical notes as well as some other minor details adde

Geology and Petroleum Prospectivity of the Sea of Hebrides Basin and Minch Basin, Offshore Northwest Scotland

Funding: This work was funded by the Natural Environment Research Council (RG12649-12). Acknowledgements: The work contained in this paper contains work conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil and Gas. We are also grateful to IHS Markit for provision of, and permission to publish examples from, their 2D seismic data volumes and gravity and magnetics database, and to Schlumberger for their donation of Petrel seismic interpretation software licences to Aberdeen University. We also thank Geognostics for the kind permission to use the Frogtech Geoscience, 2016 depth to basement map (SEEBASE) of offshore northwest Scotland. We acknowledge the UKOilandGasData.com website, owned by UK National Data Repository administered by Schlumberger, for access to the seismic data volumes and released UK well database. We are also grateful to the UK National Onshore Data Library who kindly provided seismic data (UKOGL request 100891 and 100890) to the University of Aberdeen. Dr. Iain Scotchman and Dr. Clayton Grove are thanked for constructive and helpful reviews, which have improved this paper. Laura-Jane would also like to personally thank the late Professor Bernard Owens, who passed away in July 2019, for his informative discussion on Carboniferous outliers along the west coast early on in her PhD. The views held within this paper do not necessarily represent the views of IHS Markit.Peer reviewedPostprin

Inside the volcano : Three-dimensional magmatic architecture of a buried shield volcano

Acknowledgements: Funding from NERC (Oil and Gas CDT) and BGS is gratefully acknowledged. DAJ and SP are part-funded by the Research Council of Norway Centre of Excellence funding scheme (project No. 223272). TGS is thanked for providing seismic data to the University of Aberdeen. Seismic interpretation was undertaken using Schlumberger Petrel software and gravity modelling using ARK CLS XField software. Thanks go to Steffi Burchardt, Eric Horsman and Christian Eide for constructive reviews which greatly improved the manuscript.Peer reviewedPublisher PD

The Effect of Authigenic Clays on Fault Zone Permeability

Leverhulme Trust (GrantNumber(s): ECF-2020-560) Natural Environment Research Council (GrantNumber(s): NE/N003063/1) Open access via Wiley agreementPeer reviewedPublisher PD

New Insights into the Structure, Geology and Hydrocarbon Prospectivity along the Central-Northern Corona Ridge, Faroe-Shetland Basin

Acknowledgements This paper forms part of the lead author’s Ph.D. research conducted as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil and Gas at the University of Aberdeen. It is funded by the University of Aberdeen and sponsored by Total E&P UK Limited, whose support is gratefully acknowledged. PGS are thanked for the generous provision of the FSB MegaSurveyPlus seismic dataset to the Ph.D. project and also for permission to publish part of the dataset (Fig. 3). This paper contains information provided by the North Sea Transition Authority and/or other third parties. Seismic data used throughout this paper were purchased from the UK North Sea Transition Authority (NSTA) National Data Repository (NDR) portal. Well data used throughout this paper are freely available and can be downloaded from the UK NSTA NDR portal. Core photographs were obtained from the BGS Offshore well database. Seismic interpretation was undertaken using Schlumberger Petrel software and well log interpretation was performed using Schlumberger Techlog software, of which academic licenses were kindly provided by Schlumberger and are gratefully acknowledged. Thanks to Conrado Climent, Ole-Petter Hansen, Michael Hertle, Anders Madsen, and Stuart Archer for invaluable discussions during the lead author’s time spent working with TotalEnergies in Copenhagen. Thanks also to Christopher Bugg and Matthew Rowlands at TotalEnergies in Aberdeen. Reviewers Tony Doré, Peter Dromgoole and Clayton Grove are thanked for their detailed constructive reviews which improved this manuscript. The views held within this paper do not necessarily represent the views of Schlumberger, TotalEnergies and Ørsted. Funding: The University of Aberdeen (grant number: RT10121-14), Natural Environment Research Council Centre for Doctoral Training (CDT) in Oil and Gas (grant number: NE/M00578X/1) and Total E&P UK Limited. Principal award-recipient: Lucinda Kate Layfield.Peer reviewedPublisher PD

3D Seismic reflection evidence for lower crustal intrusions beneath the Faroe–Shetland Basin, NE Atlantic Margin

Lower crustal intrusion is considered to be a common process along volcanic or magma-rich passive margins, including the NE Atlantic Margin, where it is thought to have occurred during phases of Paleogene magmatism, both prior to and during continental break-up between NW Europe and Greenland. Evidence of Paleogene magmatism is prevalent throughout the sub-basins of the Faroe–Shetland Basin as extensive lava flows and pervasive suites of igneous intrusions. However, in contrast with other areas located along the NE Atlantic Margin, no lower crustal reflectivity indicative of lower crustal intrusion has been documented beneath the Faroe–Shetland Basin. The nearest documentation of lower crustal reflectivity and interpretation of lower crustal intrusion to the Faroe–Shetland Basin is NW of the Fugloy Ridge, beneath the Norwegian Basin of the Faroese sector. Despite this, the addition of magma within the lower crust and/or at the Mohorovičić discontinuity is thought to have played a part in Paleogene uplift and the subsequent deposition of Paleocene–Eocene sequences. Advances in sub-basalt seismic acquisition and processing have made significant improvements in facilitating the imaging of deep crustal structures along the NE Atlantic Margin. This study used broadband 3D seismic reflection data to map a series of deep (c. 14–20 km depth) high-amplitude reflections that may represent igneous intrusions within the lower crust beneath the central-northern Corona Ridge. We estimate that the cumulative thicknesses of the reflections may be >5 km in places, which is consistent with published values of magmatic underplating within the region based on geochemical and petrological data. We also estimate that the total volume of lower crustal high-amplitude reflections within the 3D dataset may be >2000 km3. 2D gravity modelling of a seismic line located along the central-northern Corona Ridge supports the interpretation of lower crustal intrusions beneath this area. This study provides evidence of a potential mechanism for Paleogene uplift within the region. If uplift occurred as a result of lower crustal intrusions emplaced within the crust during the Paleogene, then we estimate that c. 300 m of uplift may have been generated within the Corona Ridge area

Palaeogeographical evolution of the Rattray Volcanic Province, Central North Sea

Funded by Carnegie Trust for the Universities of Scotland PHD060365Peer reviewedPostprin

Structural signatures of igneous sheet intrusion propagation

The geometry and distribution of planar igneous bodies (i.e. sheet intrusions), such as dykes, sills, and inclined sheets, has long been used to determine emplacement mechanics, define melt source locations, and reconstruct palaeostress conditions to shed light on various tectonic and magmatic processes. Since the 1970’s we have recognised that sheet intrusions do not necessarily display a continuous, planar geometry, but commonly consist of segments. The morphology of these segments and their connectors is controlled by, and provide insights into, the behaviour of the host rock during emplacement. For example, tensile brittle fracturing leads to the formation of intrusive steps or bridge structures between adjacent segments. In contrast, brittle shear faulting, cataclastic and ductile flow processes, as well as heat-induced viscous flow or fluidization, promotes magma finger development. Textural indicators of magma flow (e.g., rock fabrics) reveal that segments are aligned parallel to the initial sheet propagation direction. Recognising and mapping segment long axes thus allows melt source location hypotheses, derived from sheet distribution and orientation, to be robustly tested. Despite the information that can be obtained from these structural signatures of sheet intrusion propagation, they are largely overlooked by the structural and volcanological communities. To highlight their utility, we briefly review the formation of sheet intrusion segments, discuss how they inform interpretations of magma emplacement, and outline future research directions.Facultad de Ciencias Naturales y Muse