Andrew Kingdon

A long in situ section of the lower ocean crust: results of ODP Leg 176 drilling at the Southwest Indian Ridge

Ocean Drilling Program Leg 176 deepened Hole 735B in gabbroic lower ocean crust by 1 km to 1.5 km. The section has the physical properties of seismic layer 3, and a total magnetization sufficient by itself to account for the overlying lineated sea-surface magnetic anomaly. The rocks from Hole 735B are principally olivine gabbro, with evidence for two principal and many secondary intrusive events. There are innumerable late small ferrogabbro intrusions, often associated with shear zones that cross-cut the olivine gabbros. The ferrogabbros dramatically increase upward in the section. Whereas there are many small patches of ferrogabbro representing late iron- and titanium-rich melt trapped intragranularly in olivine gabbro, most late melt was redistributed prior to complete solidification by compaction and deformation. This, rather than in situ upward differentiation of a large magma body, produced the principal igneous stratigraphy. The computed bulk composition of the hole is too evolved to mass balance mid-ocean ridge basalt back to a primary magma, and there must be a significant mass of missing primitive cumulates. These could lie either below the hole or out of the section. Possibly the gabbros were emplaced by along-axis intrusion of moderately differentiated melts into the near-transform environment. Alteration occurred in three stages. High-temperature granulite- to amphibolite-facies alteration is most important, coinciding with brittle^ductile deformation beneath the ridge. Minor greenschist-facies alteration occurred under largely static conditions, likely during block uplift at the ridge transform intersection. Late post-uplift low-temperature alteration produced locally abundant smectite, often in previously unaltered areas. The most important features of the high- and low-temperature alteration are their respective

The measured shallow temperature field in Britain

Abstract The move towards a lower carbon society is likely to lead to a greater utilization of geothermal heat as the UK meets the challenge of its EU renewable obligation to source 15% of its energy from renewables by 2020. The shallow temperature field can be estimated, but measured temperatures are the most accurate approach for defining the shallow heat resource. Available measured temperature data have been used to compile maps of temperatures at depths below ground level of 100, 200, 500 and 1000 m. From these data regional trends and anomalies have been defined. From a consideration of all of the data a geothermal gradient of 28 °C km−1 has been calculated for the upper 1 km of the sedimentary crust, which is slightly above the previously quoted value of 26 °C km−1. Elevated temperatures have been mainly observed in eastern and southern England and have been attributed to convection within some of the thicker Permo-Triassic sandstones and the thermal blanketing effect of Triassic and Jurassic argillaceous rocks. Some of the depressed temperatures are associated with thick sequences of Carboniferous arenaceous rocks.

Lower oceanic crust formed at an ultra-slow-spreading ridge: Ocean Drilling Program Hole 735B, Southwest Indian Ridge

Ocean Drilling Program ODP Hole 735B, drilled on Legs 118 and 176, 1508 m of oceanic layer 3 on a transverse ridge adjacent to the Atlantis II Fracture Zone, Southwest Indian Ridge. The cored sequence consists predominantly or olivine gabbro and troctolite and lesser amounts of gabbro, and gabbronorite rich in oxides. The section contains live major blocks of relatively primitive olivine gabbro and troctolite, composed of many smaller igneous bodies. Each Of these composite blocks shows a small upward decrease in Mg# [defined as 100 x Mg/(Mg + Fe 2+)] and contains more fractionated Fe- and Ti-rich gabbros near the top.Small, crosscutting bodies of olivine gabbro and troctolite with diffuse boundaries may represent conduits through crystal mushes for melts migrating upward and feeding individual intrusions. Oxide gabbros and gabbronorites are commonly associated with shear zones of intense deformation, which crosscut the section at all levels, However, oxide-rich rocks decrease in abundance downward and are nearly absent in the lower 500 m of the section. The gabbros and gabbronorites appear to have formed from late-stage, Fe- and Ti-rich, intercumulus melts that were expelled out of fractionating olivine gabbros into the shear zones. The fabrics of the recovered gabbros are consistent with synkinematic cooling and extension of the crustal section in a mid-ocean ridge environment. However, thick intervals of the core have only a weak magmatic foliation. The magmatic foliation is commonly overprinted by a weak, parallel, deformational fabric probably reflecting the transition from a largely magmatic to a largely crystalline state. Deformation in this crustal section decreases markedly downward. Metamorphism and alteration also decrease downward, and much of the core has less than 5% background alteration. Major zones of crystal-plastic (ductile by dislocated creep) deformation in the upper part of the core probably formed under conditions equivalent to granulite-facies conditions when there was little or no melt present. Late-magmatic and hydrothermal fluids produced a variety of plagioclase, amphibole, and diopside veins. Late-stage, low-temperature veins of calcite, smectite, zeolite, prehnite are present in a few intervals. The fact that the cored is unlike ophiolite as defined by the Penrose Conference Participants suggests that no ophiolite representing an ultra-slow-spreading-ridge environment like the Southwest Indian Ridge may be preserved.

The comparison of core and geophysical log measurements obtained in the Nirex investigation of the Sellafield region

Abstract The Sellafield region, west Cumbria, is the focus of one of the most thorough geological investigations in the United Kingdom. The Sellafield Site is defined as an area immediately around the potential repository, extending 6.5 km north-south by 8 km eastwest. Twenty six deep boreholes were drilled within the area up to the end of 1995, with a total depth of approximately 28 km. Most of these boreholes have been continuously cored, a total of over 17 kilometres of core, with average core recovery well in excess of 90%. All boreholes were logged with a comprehensive suite of geophysical logs, including many state of the art tools. Laboratory physical property analysis of hundreds of sample cores has been carried out. Pilot studies were carried out to compare and contrast datasets and to investigate the relationships between the different data scales. Various techniques, including fractal analysis and Artificial Neural Networks, were tried in order to explore the relationships of these data at a variety of measurement scales. The pilot study was conducted in two stages: (1) evaluation of the primary controlling factors of the physical properties; (2) testing the validity of ‘Up-scaling’. The rocks of the Borrowdale Volcanic Group provided the most challenging problems due to the physical properties being dominated by fracturing and associated alteration zones. Relationships between data types at different scales were established suggesting that the extrapolation of properties derived from core and wireline logs across three-dimensional seismic grids would allow an understanding of the properties throughout a three-dimensional volume.

Future of technology in NERC data models and informatics: outputs from InformaTEC

Abstract The ‘Big Data’ paradigm will revolutionize understanding of the natural environment. New technologies are revolutionizing our ability to measure, model, understand and make robust, evidence-based predictions at increasingly spatial and temporal resolutions. Realising this potential will require reengineering of environmental sciences in the observation infrastructure, in data management and processing, and in the culture of environmental sciences. Collectively these will deliver vibrant, integrated research communities. Manipulating such enormous data streams requires a new data infrastructure underpinned by four technologies. Pervasive environmental sensor networks will continuously measure suites of environmental parameters and transmit these wirelessly to scientists, regulators and modellers in real time. Integrated environmental modelling will process data, streamed from sensor networks, using components synthesizing natural systems developed by domain experts, each of which will be linked at runtime to other expert developed components. Semantic interoperability will facilitate cross-disciplinary working, as has already happened within the biosciences so that data items can be exchanged with unambiguous, shared meaning. Cloud computing will revolutionize data processing allowing scalable computing close to observations on an as-needed basis. Leveraging the full potential of these technologies requires a major culture change in the environmental sciences where national and continental scale observatories of sensors networks become basic scientific tools.

The potential for the use of model fusion techniques in building and developing catastrophe models

Abstract Global economic losses related to natural hazards are large and increasing, peaking at US

The Development of Linked Databases and Environmental Modelling Systems for Decision-Making in London

380 billion in 2011 driven by earthquakes in Japan and New Zealand and flooding in Thailand. Catastrophe models are stochastic event-set based computer models, first created 25 years ago, that are now vital to risk assessment within the insurance and reinsurance industry. They estimate likely losses from extreme events, whether natural or man-made. Most catastrophe models limit the level of user interaction, stereotyped as ‘black boxes’. In this paper we investigate how model fusion techniques could be used to develop ‘plug and play’ catastrophe models and discuss the impact of open access modelling on the insurance industry and other stakeholders (e.g. local government).

First account of resistivity borehole micro-imaging (FMI) to assess the sedimentology and structure of the Preesall Halite, NW England: implications for gas storage and wider applications in CCS caprock assessment

A basic requirement for a city’s growth is the availability of land, raw material and water. For continued and sustainable development of today’s cities we must be able to meet these basic requirements whilst being mindful of the environment and its relationship with anthropogenic activity. The heterogeneous and complex nature of urban systems where there are obvious environmental and anthropogenic inter-dependencies necessitates a more holistic approach to decision-making. New developments such as linked databases of environmental data and integrated environmental modelling systems provide new ways of organising cross-disciplinary information and a means to apply this to explain, explore and predict the urban systems response to environmental change. In this paper we show how, accessibility to linked databases, detailed understanding of the geology and integrated environmental modelling solutions has the potential to provide decision-makers and policy developers with the science based information needed to understand and address these challenges.

Borehole Imaging and its Impact on Unconventional Reservoir Characterisation in the United Kingdom

UK future energy infrastructure will include solution-mined salt caverns in bedded halite deposits providing short to medium term, fast-cycle underground gas storage volumes. Assessing the stratigraphy, sedimentology and structure of halite beds is essential for understanding and developing gas storage caverns. This paper highlights perhaps the first application of Schlumberger’s FMITM resistivity borehole imaging tool to characterize and provide a detailed understanding of bedded halites. Widely used in the hydrocarbons industry for over 20 years the potential value of such tools has yet to be fully recognized in the solution mining industry and is applied to the Triassic Preesall Halite in NW England with promising results. There may be wider applications in, for example, CCS caprock assessment.

Orientation of drill core by use of borehole geophysical imaging

New exploration of unconventional reservoirs in the United Kingdom is seeking to establish the scale of potential hydrocarbon reserves. This presents both new opportunities for development of economic resources but also new challenges over whether such such resources can be developed in densely populated regions with societal license. The British Geological Survey is undertaking a review of the national in-situ stress regime to identify its potential implications on both the safety and efficacy of any future hydraulic fracturing operations. This is a unique application of imaging technology to undertake national scale investigation with potentially highly controversial impacts.