bluuebunny/crossref_metadata_2025_split huggingface dataset:
Palaeoproterozoic oblique plate convergence in South Greenland: a reappraisal of the Ketilidian Orogen
Authors: Chadwick B. , Garde A. A. 
Published: April 2008

Abstract
New field and petrographic data are presented for a revised four-fold division of the Ketilidian Orogen into a Border Zone in the north, followed to the south by the Julianehåb batholith, the Psammite Zone and the Pelite Zone, as the basis for a new plate tectonic model. The Border Zone within the southern margin of the Archaean foreland contains shallow marine, volcano-sedimentary basins, granites and appinite dykes which are regarded as part of an incipient backarc. The wedge-shaped Julianehåb batholith comprises polyphase calc-alkaline granites, granodiorites, tonalites and hornblende diorites with swarms of appinite dykes. The batholith was emplaced during sinistral transpression as a result of oblique convergence between the Archaean continental plate to the north and an oceanic plate (no longer preserved) to the south. New Rb-Sr isotopic data from the southern part of the batholith confirm previous views that it consists of juvenile Palaeoproterozoic crust. The batholith is interpreted as the root of a volcanic arc that was the provenance of, and in part the basement to, polymict conglomerates, arkosic arenites, semi-pelites and pelites in the Psammite and Pelite Zones, deposited in intra-arc basins and the inner part of a forearc between the batholith and an ocean to the south. The sedimentary rocks and their subordinate intercalations of basalt and andesite were intensely migmatized and deformed in high temperature-low pressure conditions prior to the emplacement of broadly concordant sheets of granites and related rocks of the rapakivi suite. Appinite dykes were emplaced at various stages of the migmatization and deformation. We attribute the thermal effects which characterize the Ketilidian oblique convergent system to voluminous basaltic underplating in accord with recent work on the rapakivi suite and associated metamorphism.
Geochemical aspects of the aetiology of trace element related diseases
Authors: Mills C. F. 
Published: April 2008

Abstract
Deficiencies, excesses or imbalances in the supply of inorganic elements from dietary sources can have an important influence on animal and human health and susceptibility to disease. Many such situations arise from anomalies in the inorganic element composition of food chains. These, in turn, are frequently attributable to the composition of the geochemical environment as modified by the influence of soil composition and botanical or cultural variables upon the inorganic composition of the diet.
Appreciation of the epidemiological importance of such factors in the aetiology of nutritional diseases can contribute, very significantly, to their detection and effective control.
Although the agricultural relevance of geochemical data is firmly established and widely appreciated, investigation of its value in the context of anticipation and control of major human nutritional diseases in the third world has yet to be undertaken adequately.
Records of seasonal flux in Holocene laminated sediments, Gulf of California
Authors: Pike Jennifer , Kemp Alan E. S. 
Published: April 2008

AbstractHolocene laminated sediments from Guaymas Basin (Gulf of California, Mexico) have, in the past, been described as annual couplets of sedimentation. Couplets comprise an alternation of diatom- and terrigenous-rich sediment reflecting winter and summer flux to the sediment respectively. New data from backscattered electron imagery (BSEI) show that a three-component pattern of sedimentation is preserved, comprising (1) a lithogenic lamina consisting of clays, silt and minor diatomaceous material, deposited during the summer and autumn wet season; (2) a mixed flora diatomaceous lamina deposited during the early winter collapse of the thermocline and onset of water column mixing; and (3) a near-monospecific flora lamina ofChaetocerosresting spores or, more rarely,Skeletonema costatum, representing deposition from, or at the end of, the spring coastal upwelling bloom. Recent sediment trap biogenic and terrigenous flux data also show three to four major flux events per year. Direct comparisons are possible between BSEI records and recent sediment trap flux data to facilitate high-resolution palaeoceanaographic and palaeoclimatic reconstructions throughout the Holocene.
A review of the petrology of harzburgites at Hess Deep and Garrett Deep: implications for mantle processes beneath segments of the East Pacific Rise
Authors: Edwards Stephen J. , Falloon Trevor J. , Malpas John , Pedersen Rolf B. 
Published: April 2008

AbstractIn recent years a unique set of samples of uppermost mantle at the mantle-crust transition zone have been collected from two different environments along the fast-spreading East Pacific Rise (EPR): a ‘normal’ spreading segment (represented by samples from Hess Deep) and the end of a spreading segment where the EPR meets the Garrett transform fault (represented by samples from Garrett Deep). A review of the petrology of harzburgites from the two sites demonstrates that these rocks were produced by partial melting of adiabatically upwelling mantle and, subsequently, at the top of the mantle, they were impregnated by reactive and crystallizing mid-ocean ridge basaltic (MORB) melts. Despite this similar history, non-impregnated harzburgites at Garrett Deep have a more fertile spinel chemistry than those at Hess Deep, which is consistent with reduced partial melting of shallow mantle as a transform fault is approached — the ‘transform fault effect’.The extent of reaction between melt and harzburgite during the impregnation event suggests that melt arrived in the uppermost mantle in a highly reactive state because along the adiabatic path it had been highly channelled in spatially restricted conduits. This implies that mantle upwelling below the EPR was, and presumably still is, dominantly two dimensional (sheet-like). Within this framework, the chemical evolution of MORB melt below fast-spreading ridges will be significantly affected by melt-periodotite reaction only when melt reaches the uppermost mantle and mantle-crust transition zone, where along-axis transport of melt may also be important.Although the harzburgites from Hess Deep and Garrett Deep formed and evolved beneath different parts of different first-order segments of the EPR, the petrology of these rocks presents the best analogue available for defining real variations in mantle processes along a single first-order ridge segment in a fast-spreading environment.
Barrovian regional metamorphism: where’s the heat?
Authors: Jamieson R. A. , Beaumont C. , Fullsack P. , Lee B. 
Published: April 2008

Abstract

Coupled thermal-mechanical models of convergent orogens offer a novel way to investigate the interactions between heat and tectonics that lead to regional metamorphism. In this study, the effects of different distributions of heat-producing material in the crust and upper mantle on crustal thermal histories and deformation fields are investigated. The models involve subduction-driven collision with moderate convergence and erosion rates. For models involving standard continental crust, where heat production is initially concentrated in the upper crust,
P-T-t
paths do not intersect the field of typical Barrovian
P-T
conditions. However, heat-producing material can be tectonically redistributed, for example, by subduction of crustal rocks to upper mantle depths, or by formation of thick accretionary wedges or continental margin sequences during convergence. Models that include a wedge of heat-producing material in the upper mantle generate high temperatures in the lower crust and upper mantle that lead to a change in orogenic style; radioactive heating of partially subducted crustal material on time scales of 10–30 Ma yields temperatures high enough for partial melting. However, crustal
P-T-t
paths are unlikely to intersect the Barrovian field unless erosion or convergence rates change. Models that include a crustal-scale region with moderate, uniform heat production, simulating a large accretionary wedge or tectonically thickened continental margin sequence, generate
P-T-t
paths that intersect the Barrovian field. However, as convergence proceeds, the heat-producing region is deformed, eroded, and reduced in volume, so that the model orogen begins to cool down after about 20 Ma. The model results provide an explanation for many first-order tectonic and metamorphic features of small orogens, including metamorphic styles ranging from blueschists to the Barrovian series to granulites, late-orogenic granitoid magmatism, and the crustal-scale tectonic features associated with regional metamorphic belts. We conclude that the thermal state of an orogen is controlled by the evolving competition between cooling by subduction and radioactive heating within the deforming orogen.
Modelling of sandbody connectivity in the Schooner Field
Authors: Mijnssen F. C. J. 
Published: April 2008

Abstract
The Schooner field will be one of the first stand-alone developments of a gas accumulation in the Carboniferous Barren Red Measures Group of the UK Sector of the Southern North Sea. It illustrates the potential of Barren Red Measures Group as a future play in this area.
The Schooner Field, located some 150 km (94 miles) east of the South Yorkshire coastline, is a NW-SE-oriented faulted dip closure. The reservoir consists predominantly of fluvial channel sandstones of the Barren Red Measures Group, with small amounts of gas located in the underlying Coal Measures Group. The sandstone channels are embedded in flood plain mudstones, which comprise 65–70% of the stratigraphic section. Because of the relatively low proportion of sandstone to mudstone, sandbody connectivity has been identified as the critical factor affecting recovery of gas.
In order to asses the impact of sandbody connectivity on recovery efficiency, reservoir modelling work was performed based on eight different geological models and three well design options. The factors that were varied in order to build the geological models included (1) presence of minor faults, (2) the width of the channels, and (3) channel orientation. Well design options considered included (1) wells with deviations between 10 and 63°, (2) subhorizontal wells drilled along the strike of the structure, and 3) sub horizontal wells drilled along the dip of the structure.
The results of the modelling work showed that sandbody orientation had the largest influence on connectivity, with connectivity being the highest when the channels were oriented along the strike of the structure. The width of the channels and the presence of minor faults had some impact on connectivity, while varying well design made little or no difference. Close inspection of the models did, however, show that the major faults compartmentalize the reservoir, resulting in large quantities of gas being by-passed if wells are not properly positioned. Consequently, more work is needed to evaluate the optimal location of the development wells.
Tectonic evolution of the Larne Basin
Authors: Shelton Rob 
Published: April 2008

Abstract

The Larne Basin lies in the Midland Valley terrane between Northern Ireland and SW Scotland. A proportion of the basin lies onshore Northern Ireland, with an offshore continuation into the North Channel seaway. The basin is orientated NE-SW, and the sedimentary basin fill thickens to the west. Extensional faults in the south of the basin dip generally to the east, those in the north to the northwest. Preserved sediments range in age from Carboniferous to Tertiary, but are predominantly Permo-Triassic. Integration of seismic interpretations, well data and outcrop fault and fracture measurements has revealed a number of Mesozoic and Cenozoic tectonic events. Late Carboniferous N-S compression was followed by a major phase of regional early Permian ENE-WSW/NE-SW extension. ENE-WSW extension followed in the late Triassic and early Jurassic with post-early Jurassic to late Cretaceous minor subsidence and uplift resulting in a major erosional unconformity between the Lower Lias and Upper Cretaceous Greensand and Chalk. Early Tertiary (Palaeocene) uplift and NE-SW extension led to extensive basalt extrusion, and later NW-SE to NNE-SSW extension and faulting resulted in the deposition of the Upper Oligocene Lough Neagh Clays in the neighbouring Lough Neagh Basin. The late Tertiary (Miocene) saw a phase of compression, leading to uplift and erosion. AFTA® analyses of Permian and Triassic samples indicate
c.
450 m of Tertiary uplift and erosion. Sonic velocity analysis of the Mercia Mudstone Group and Sherwood Sandstone Group suggests uplift of 0.5–1.1 km, possibly reflecting maximum burial at an earlier? Jurassic time.
The hydrocarbon potential of the Cheshire Basin
Authors: Mikkelsen P. W. , Floodpage J. B. 
Published: April 2008

Abstract
Permo-Triassic basins, both onshore and offshore UK, typically have good reservoir rocks and frequently good seals, but their continental depositional environment requires that source beds of a different age must be invoked if they are to be prospective. In the Dorset-English Channel Basin, the overlying Liassic shales provide an oil prone source, while in the Southern Gas Basin of the North Sea and the East Irish Sea, the underlying Carboniferous has generated large volumes of gas and some oil. Other Permo-Triassic basins, onshore, are generally devoid of hydrocarbons and this can in large part be explained by an absence of an adequate source rock.
The Cheshire Basin lies adjacent to the East Irish Sea Basin and contains a similar, thick Permo-Triassic sequence. The presence of outcropping Coal Measures on three sides of the Basin gives encouragement as to sourcing potential. However, the six exploration wells drilled in the Basin to date (four during the last ten years) have proved dry.
Review of recent seismic data, particularly mid-late 1980s vibroseis surveys, suggests that the Basin developed as a Permo-Triassic half-graben over a Hercynian inversion. Therefore, as one moves from the western edge towards the basin centre progressive erosion of Westphalian strata below the base Permian event may be observed, culminating in a likely Lower Palaeozoic subcrop in the southeastern part of the Basin. A large, faulted high in the centre of the Basin, in many ways similar to the Morecambe Field structure, was proven dry by the Burford-1 well, apparently due to an absence of an underlying source. Nevertheless, seismic data in the northern part of the Basin, supported by the Knutsford-1 penetration, suggest the presence of underlying Coal Measures. However, regional projections suggest that the thick, Dinantian-Namurian bituminous shales which appear to have sourced the East Irish Sea fields, are absent from much of the Basin.
A further difference between the Cheshire and East Irish Sea Basins is the presence, in the former, of the Tarporley ‘Siltstone’ Formation above the main reservoir objective of the Helsby Sandstone Formation. The former may be regarded as a likely non-sealing waste zone over much of the central and eastern parts of the Basin, but in the SW where the coarser Malpas Sandstone facies is developed, and in the north, it becomes a viable reservoir target in its own right, sealed by the Bollin Mudstone Formation and, ultimately, by the Northwich Halite.
It is therefore proposed that the successful exploration for hydrocarbons in the Basin is likely to depend on finding a combination of sub-cropping Coal Measures and reservoir-grade Tarporley Siltstone, sufficiently deeply buried to retain an effective Mercia Mudstone and preferably halite seal. These conditions appear to prevail in the NW part of the Basin, where the search for suitably large, closed structures is currently in progress.
Fluid migration history in the north Irish Sea-North Channel region
Authors: Parnell John 
Published: April 2008

Abstract
Basins in the north Irish Sea region have experienced numerous stages of fluid migration. Carboniferous and Permo-Triassic sandstones both experienced rapid cementation due to high sedimentation/burial rates. Both successions also experienced syn-sedimentary faulting which focused cement precipitation and created permeability barriers. Further fracture-based diagenesis occurred post-lithification, and accompanying hydrothermal activity associated with Tertiary intrusions. The extensional activity which helped to define Permo-Triassic basins in the Southern Uplands terrane also channelled mineralizing fluids in the same terrane. These fluids included hydrocarbons in at least two districts. Along the North Solway Fault Zone, basinal fluids from the Carboniferous Solway Basin interacted with metalliferous groundwaters to precipitate metalliferous bitumens. The Solway Carboniferous outcrop also contains intergranular oil residues.
The Douglas Oil Field
Authors: Yaliz A. M. 
Published: April 2008

Abstract

The Douglas Field, with an estimated STOIIP of 225 MMBBL and on stream in February 1996, is the first oil field to be developed in the offshore East Irish Sea basin. The field structure consists of three tilted fault blocks formed during extensional faulting in Triassic-early Jurassic times, and later readjusted by contractional movements during Tertiary inversion. The oil is trapped in the Triassic Helsby Sandstone Formation, which comprises moderate- to high-permeability aeolian and fluvial sandstones. The reservoir depth is shallow (2200 ft) with a maximum oil column of 330 ft. The sandstones can be divided into several laterally extensive units based on vertical facies variations. Although reservoir quality is principally controlled by primary depositional processes, a complex diagenetic history is recognized, with various phases of silica and carbonate cements. Authigenic clay minerals are not important, but bitumen is extensive in limited areas of the field, causing significant permeability reduction. The hydrocarbon filling history of the field was complex, with the occurrence of at least two phases of oil generation and migration. The Douglas Field contains a relatively ‘dead’ oil with a low GOR, thus 11 production and seven water injection wells are planned. Although the crude is classified as sweet it contains low levels of mercaptans and H
2
S, which will be removed during processing offshore. First oil is planned for December 1995 with peak oil production reaching 40000 BPD.
An overview of the hydrocarbon potential of the Spratly Islands archipelago and its implications for regional development
Authors: Blanche J. B. , Blanche J. D. 
Published: April 2008

Abstract
The hydrocarbon potential of the Spratly Islands archipelago is relatively unknown and can thus only be evaluated via analogues. This area of the South China Sea has been, and remains, a region of many disputes and conflicts which has further confined the availability of hard technical information, in particular seismic and well data, to the confidential vaults of the claimant states. In addition, the authors have been constrained by the area’s political sensitivity and the commercial confidentiality of technical data. The Spratly Islands are claimed, either in whole or in part, by the People’s Republic of China (PRC), the Republic of China (ROC/Taiwan), Vietnam, the Philippines, Brunei and Malaysia.
The archipelago is surrounded by oil-producing areas, i.e. the Nam Con Son (Wan’an Bei) basin of Vietnam, the East and West Natuna basins of Indonesia, the Northwest Palawan (Nansha Trough) basin of the Philippines, the productive Luconia Shelf (Zengmu Shelf) offshore Sarawak and the Brunei/North West Sabah basins which provide regional analogues. This frontier region may yield considerable reserves, the range of which varies from 1–2 billion barrels to 225 billion barrels of oil equivalent. It is anticipated that the Spratly Island archipelago and Dangerous Grounds area of the South China Sea will become the focus of exploration for hydrocarbons over the next decade, once the multi-national boundary disputes are resolved, hopefully by negotiation and peaceful means by the claimant states.
This paper presents an overview of the hydrocarbon potential of this area within the context of regional political relationships.
Investigation and management of pesticide pollution in the Lincolnshire Limestone aquifer in eastern England
Authors: Sweeney J. , Hart P. A. , McConvey P. J. 
Published: April 2008

Abstract
This case study describes pollution of the Lincolnshire Limestone aquifer, predominantly by the herbicide Mecoprop, to the north of Peterborough, Cambridgeshire. Key features of the case study are the occurrence of a series of former landfill sites located on the Lincolnshire Limestone aquifer outcrop, a nearby groundwater abstraction for public supply within the confined aquifer and the presence of a major geological fault and its associated control on groundwater movement. At the time of licensing, the fault was considered to hydraulically isolate the landfill sites from the abstraction.
A multiphase investigation, begun in 1990, was conducted by the National Rivers Authority and involved close liaison with the Cambridgeshire County Council, landowners, site operators and the Anglian Water Company. Investigations have focused on identifying and proving the source of pollution and determining its severity and extent. Remedial strategies and the implications of future change in hydraulic conditions have also been considered.
A medium-term risk management strategy for the area has been devised. This is in line with the UK Government’s principles for contaminated land management.
Sediment delivery to the Gulf of Alaska: source mechanisms along a glaciated transform margin
Authors: Dobson M. R. , O’Leary D. , Veart M. 
Published: April 2008

Abstract
Sediment delivery to the Gulf of Alaska occurs via four areally extensive deepwater fans, sourced from grounded tidewater glaciers. During periods of climatic cooling, glaciers cross a narrow shelf and discharge sediment down the continental slope. Because the coastal terrain is dominated by fjords and a narrow, high-relief Pacific watershed, deposition is dominated by channellized point-source fan accumulations, the volumes of which are primarily a function of climate. The sediment distribution is modified by a long-term tectonic translation of the Pacific plate to the north along the transform margin. As a result, the deep-water fans are gradually moved away from the climatically controlled point sources. Sets of abandoned channels record the effect of translation during the Plio-Pleistocene.
Large-scale debrites and submarine landslides on the Barra Fan, west of Britain
Authors: Holmes R. , Long D. , Dodd L. R. 
Published: April 2008

Abstract
The Barra Fan is a large Neogene to Pleistocene composite fan that has built out into the deep-water basin of the Rockall Trough west of Britain. The bulk of the landward depocentre of the Barra Fan takes the form of a relatively undisturbed shelf-margin wedge, in places more than 600 m thick, that is perched above the deep-water basin and, together with the Donegal Fan, partially engulfs the Hebrides Terrace Seamount. A continuous series of slope-front channels and gullies incise into the shelf-margin wedge of the northernmost Barra Fan and are the likely transport paths for small- to medium-scale debrites found on the middle and lower slope-front. In contrast, at least four large-scale submarine landslide events making up the Peach Slide appear to have translated the bulk of the slope-front of the northern Barra Fan to the northwest, so that debrites and hemipelagic sediments exhibit maximum composite thicknesses of approximately 450 m on the deep-water basin floor of the eastern Rockall Trough. The extent and volume of successive large-scale debrite units decrease with age. From an interpretation of a limited historical dataset it is thought that the ground accelerations from earthquakes have been sufficient to trigger slope-front instability and sediment transfer.