Sedimentological description of 5 gravity cores from the Faroe-Shetland Channel

Five gravity cores were taken from the continental slope north of the Shetland Isles as part of a transect from the shelf (150 m water depth) to the base of slope (100 m). A total of 19 cores were taken, the other 14 of which were sampled using a multicorer. The 5 gravity cores were taken in water depths between 790 and 990 m with the intention of identifying whether contouritic sediments were forming or had formed at sea bed in the study area. Such sediments have been recovered in equivalent depths to the south, and have been identified in backscatter both south and north of the study area. As a result of equipment failure these 5 cores were not split and described on board ship. Details of the cruise including core locations and sampling methods are given in Leslie (2002). The 5 cores have been logged using a binocular microscope. Rough, handwritten logs are appended at the back of the report. The trends described are a qualitative assessment of core character. The discussion is based on a preliminary examination based on subjective observations and is not meant to be taken as a conclusive interpretation of the cores

Sedimentology and geochemistry of the upper Triassic mercia mudstone group and marginal deposits, southwest Britain

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COMPARATIVA DE TECNOLOGÍAS 3D PARA LA INSPECCIÓN DE MUROS DE PIEDRA

[EN] The maintenance of the external fabric of historic buildings constitutes a large portion of overall building life cycle costs.Advanced reality capture and data processing technologies have the potential to transform existing survey practice,providing surveyors with objective data pertaining to building fabric, in a more rapid (frequent), safe and cost-effectivemanner. In this paper, we present a unique evaluation of several Terrestrial Laser Scanning (TLS) and photogrammetric(PG) systems that assess their relative strengths for the survey of stone walls. The assessment is conducted using anhistoric building selected for its representativeness of form, fabric and condition. The work considers performance interms of data accuracy and precision, data completeness, and process efficiency. The results show that, while TLSprovides good geometric data to generate accurate and valuable 3D models, the quality of PG reconstructions can bealso be sufficient in such contexts. And considering the relatively low-cost and portability of modern digital camerascompared to laser scanners, photogrammetry can constitute a realistic alternative to TLS. In addition, mounting a cameraon a UAV could further solve access issues, preventing the need for any additional infrastructure (e.g. scaffolding), whichwould be required when employing TLS. However, a lesson drawn from this work is that effective acquisition ofphotogrammetric data requires careful planning to select the appropriate camera settings and picture density (andlocations) to ensure accurate and reliable photogrammetric reconstruction. This process may be referred to as: Planningfor Photogrammetry (P4P).[ES] Las labores de mantenimiento de la estructura externa de edificios históricos constituyen una gran parte de los costes asociados al ciclo de vida de estos. Las tecnologías empleadas para la adquisición de datos estructurales y su procesamiento tienen el potencial de transformar, en gran medida, las tareas de inspección tradicionales, proporcionando información relativa al edificio de una manera más rápida, segura y económica. En este trabajo, se evalúan escáneres láser y sistemas basados en fotogrametría, demostrando su solidez para la inspección de paredes de piedra. Esta evaluación se ha llevado a cabo en un edificio histórico representativo y en un buen estado de conservación. En el artículo, se compara la actuación de los diferentes dispositivos en términos de precisión, repetibilidad, densidad de datos y eficiencia del proceso. Los resultados muestran que, mientras que los escáneres proporcionan buena información geométrica y permiten la generación de modelos tridimensionales precisos, la calidad de las reconstrucciones a partir de fotogrametría también pueden ser suficientes en determinados contextos. Considerando, además, el relativo bajo coste y la portabilidad de las cámaras digitales modernas en comparación con los escáneres láser, la fotogrametría puede constituir una alternativa real a estos últimos. Además, la instalación de cámaras en vehículos aéreos no tripulados (drones) puede resolver problemas de accesibilidad y minimizar el uso de infraestructuras adicionales (como andamiajes), las cuales son empleadas en la digitalización mediante escáneres. Sin embargo, una lección que se desprende de estos experimentos es que para conseguir una efectiva adquisición de datos fotogramétricos se requiere una cuidada planificación y una selección apropiada de los ajustes de la cámara, así como su correcto posicionamiento en la escena, con el objetivo de conseguir una adecuada densidad de imágenes y obtener una reconstrucción 3D precisa. Este proceso se denomina Planificación para la Fotogrametría.Valero, E.; Forster, A.; Bosché, F.; Wilson, L.; Leslie, A. (2016). COMPARISON OF 3D REALITY CAPTURE TECHNOLOGIES FOR THE SURVEY OF STONE WALLS. En 8th International congress on archaeology, computer graphics, cultural heritage and innovation. Editorial Universitat Politècnica de València. 14-23. https://doi.org/10.4995/arqueologica8.2015.2582OCS142

Onset of North Atlantic Deep Water production coincident with inception of the Cenozoic global cooling trend : comment

Hohbein et al. (2012) propose an early Mid-Eocene onset of North Atlantic Deep Water (NADW) production by interpreting a mounded deposit at the south-west end of the Faroe-Shetland Basin (FSB) as a contourite drift, which they term the ‘Judd Falls Drift (JFD)’. We argue that this deposit is not a contourite drift; we also question how their model of early NADW production fits with current understanding of the development of the Faroe-Shetland Basin and the wider Arctic–NE Atlantic region, neither of which was convincingly discussed by these authors

Progress in marine geoconservation in Scotland’s seas : assessment of key interests and their contribution to Marine Protected Area network planning

This study was part-funded by Marine Scotland and was undertaken as part of the Scottish Marine Protected Areas (MPA) Programme, a joint initiative between Marine Scotland, Historic Scotland, Scottish Natural Heritage (SNH) and the Joint Nature Conservation Committee (JNCC).Geoconservation in the marine environment has been largely overlooked, despite a wealth of accumulated information on marine geology and geomorphology and clear links between many terrestrial and marine features. As part of the wider characterisation of Scotland’s seas, this study developed criteria and a methodology that follow the established principles of the terrestrial, Great Britain-wide geoconservation audit, the Geological Conservation Review, to assess geodiversity key areas on the seabed. Using an expert judgement approach, eight geodiversity feature categories were identified to represent the geological and geomorphological processes that have influenced the evolution and present-day morphology of the Scottish seabed: Quaternary of Scotland; Submarine Mass Movement; Marine Geomorphology of the Scottish Deep-Ocean Seabed; Seabed Fluid and Gas Seep; Cenozoic Structures of the Atlantic Margin; Marine Geomorphology of the Scottish Shelf Seabed; Coastal Geomorphology of Scotland; and Biogenic Structures of the Scottish Seabed. Within these categories, 35 key areas were prioritised for their scientific value. Specific interests range from large-scale landforms (e.g. submarine landslides, sea-mounts and trenches) to fine-scale dynamic features (e.g. sand waves). Although these geodiversity interests provided supporting evidence for the identification and selection of a suite of Nature Conservation Marine Protected Areas (MPAs) containing important marine natural features, they are only partially represented in these MPAs and existing protected areas. Nevertheless, a pragmatic approach is emerging to integrate as far as possible the conservation management of marine geodiversity with that of biodiversity and based on evidence of the sensitivity and vulnerability geological and geomorphological features on the seabed.PostprintPeer reviewe

Geochemistry and related studies of Clyde Estuary sediments

Geochemical and related studies have been made of near-surface sediments from the River Clyde estuary and adjoining areas, extending from Glasgow to the N, and W as far as the Holy Loch on the W coast of Scotland, UK. Multibeam echosounder, sidescan sonar and shallow seismic data, taken with core information, indicate that a shallow layer of modern sediment, often less than a metre thick, rests on earlier glacial and post-glacial sediments. The offshore Quaternary history can be aligned with onshore sequences, with the recognition of buried drumlins, settlement of muds from quieter water, probably behind an ice dam, and later tidal delta deposits. The geochemistry of contaminants within the cores also indicates shallow contaminated sediments, often resting on pristine pre-industrial deposits at depths less than 1 m. The distribution of different contaminants with depth in the sediment, such as Pb (and Pb isotopes), organics and radionuclides, allow chronologies of contamination from different sources to be suggested. Dating was also attempted using microfossils, radiocarbon and 210Pb, but with limited success. Some of the spatial distribution of contaminants in the surface sediments can be related to grain-size variations. Contaminants are highest, both in absolute terms and in enrichment relative to the natural background, in the urban and inner estuary and in the Holy Loch, reflecting the concentration of industrial activity

Pushing the margins : research in the Ocean Margins LINK programme

Continental margins are areas of intense exploration interest at the present day, both in NW Europe and across the world. Investigation of the processes involved in shaping margin geology, from crustal geometry to sub-seismic scale reservoir configuration, have contributed to the greater understanding of geological structure in areas of transition from continental crust to oceanic crust. The Ocean Margin LINK Programme is a research programme co-funded by NERC and industry focusing on the geological evolution of ocean margins. The LINK scheme is the Government’s principal mechanism for promoting partnership in research between industry and the academia. The first small grants were allocated in 2000, since which time 14 full projects along with 9 stand-alone studentships have been funded by the Programme, which will end in late 2006. On 16th November 2004 a Workshop was held at DTI in London, giving proponents of projects a chance to summarise research progress and to discuss future collaborations and themes for research

Moray Firth 3D onshore-offshore modelling

Improved 3D visualisation and interpretation of the geology of the Inner Moray Firth in North East Scotland has been achieved as a result of collaborative investigations by a team of BGS land and marine surveyors feeding combined data sets into GSI3D models. A calculated regional fault network, has been generated, incorporating data from the Great Glen-Moray Firth tectonic model, informed by detailed bedrock survey data from the coastal zone. This network has been amalgamated with cross-sections, based upon those generated for the GB3D model and by numerous additional helper sections, to produce a fully calculated model of the onshore and off shore cover sequence of the Inner Moray Firth between Inverness, Helmsdale and Portsoy (c. 8,500 km2)

Structure of the Culm Basin : rapid mapping of the Tiverton Sheet and the latest Variscan inversion in Devon

The Silesian (Upper Carboniferous) sedimentary rocks of the Culm Basin, to the west of Tiverton, belong to the Crackington and Bude Formations. These comprise turbidite and debrite sandstone, interbedded with mudstone. In the field the formations are differentiated on the basis of thickness and weathering characteristics of the sandstone packages. In the study area although bedrock is commonly obscured by overlying superficial deposits, the character of these deposits can be used as an indicator of bedrock geology. Using both bedrock and superficial analytical techniques, the Crackington / Bude boundary has been mapped in the study area. Tracing of large scale structure has been helped by the use of shaded relief digital terrain models, however in areas of moorland the distinctive featuring is not present and there are no indicators of the underlying bedrock structure. Geophysical data, in particular a recent gravity survey, provide considerable information on the structure of the Culm Basin. It is clear that the east-west trend of the Tiverton Trough, depicted by a negative gravity anomaly over the Permo-Triassic infill, continues westwards in the Silesian sedimentary rocks. Further west of the Tiverton Trough an area of relatively high gravity covers the area of Witheridge and Rackenford moors. North of this is a negative gravity anomaly whose northern boundary lies close to the crop of the basal Crackington Formation and whose southern margin follows the Crackington / Bude boundary. The strong east-west linear nature of the gravity anomalies indicates that the structure controlling the northern boundary of the Tiverton Trough was probably active during Variscan inversion. The gravity high over Witheridge is thought to be related to the presence of dense, earlier Palaeozoic rocks that form a structural high underlying the Silesian; given its linear nature and its alignment with the northern boundaries of both the Tiverton and Crediton troughs