bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geochemical interactions between landfill leachate and sodium bentonite
Authors: Spooner A. J. , Giusti L. 
Published: April 2008

Abstract
The disposal of municipal, commercial and industrial waste by landfill has been, and is, widely used around the world. Within the landfill, leachate is generated with the input of atmospheric water, and by mixing with the moisture already present from the decomposition of waste materials. The potentially hazardous components of leachate have the ability to pollute surface and groundwaters unless stringent criteria are met for the location of landfills, suitable materials are used to build basal barriers and capping systems, and modern leachate collection and disposal techniques are employed. Different types of barriers have been used, including naturally occurring soil/clay liners, compacted clay liners, geosynthetic materials, and composite sealing systems composed of a mineral layer and a synthetic membrane. One of the substances most commonly used in the sealing of landfill sites, either on its own or in combination with synthetic materials, is sodium bentonite. Despite its widespread use, there is some evidence that this material may not be capable of attenuating some of the substances contained in landfill leachate, and that the clay mineral structure itself may be damaged as a result of long-term exposure with the various organic/inorganic components of municipal landfill leachate. In particular, bentonites tend to collapse and shrink once exposed to certain toxic effluents. The stability, chemical resistance and permeability of a bentonite clay liner appear to be significantly affected by landfill leachates and other inorganic/organic solutions used in experimental work. The main aims of this paper are: (i) to describe the properties of bentonite and municipal solid waste leachates, and (ii) to summarize the available information on the interactions between bentonite and leachate.
Metal retention from landfill leachate by glacial clays: laboratory experiments
Authors: Hurst E. L. , Holmes S. P. 
Published: April 2008

Abstract
Two sets of laboratory experiments were carried out to investigate the role of clay liners on the retention of metals present in landfill leachate. In the first experiment leachate was passed through clay filled columns and comparisons made of the metal content in treatment columns (leachate) with that in the control columns (de-ionized water). The metals Na, K, Mg, Ca, Al and Fe show elevated concentrations when compared with the control columns. In addition, a black sludge was observed on the upper surface of the treatment columns. On analysis this sludge was found to be Fe-rich when compared with the surrounding leachate/clay matrix. In the second experiment a simple tank system was used to investigate sludge formation at the leachate: clay liner interface. The observed sludge was found to have elevated metal concentrations, with a corresponding decrease in metal levels in leachate samples, compared with analysis before the experiment. From these observations it was concluded that the sludge may be acting as a sink for key metal contaminants from leachate.
Evaluation of the containment properties of geological and engineered barriers by pore-water extraction and characterization
Authors: Reeder Shaun , Cave Mark R. 
Published: April 2008

Abstract
In the construction of underground repositories for the disposal of potentially toxic wastes, it is critical to the development of a safety case that the chemical composition of waters flowing through the proposed containment barrier is fully understood. Because the barrier material is usually chosen to have low permeability, to minimize the risk of long-term transport of toxic material into the biosphere, it is often not possible to obtain sufficient flowing groundwater samples to allow complete hydrogeochemical characterization. In order to study the chemical composition of the water in these formations it is necessary, therefore, to use specialized pore-water extraction techniques.
In this study, the practicalities of three methods for extracting and characterizing porewaters from potential containment materials are discussed. These are: (i) mechanical squeezing using a hydraulic press; (ii) centrifugation using a heavy liquid displacent; and (iii) aqueous leaching of residual salts from crushed core material.
Three case studies are presented which demonstrate how each of the different pore-water characterization methods may be applied practically, and how the data obtained can prove invaluable in understanding the hydrogeochemistry of sites.
Microresistivity and ultrasonic imagers: tool operations and processing principles with reference to commonly encountered image artefacts
Authors: Cheung Philip S. 
Published: April 2008

Abstract
Borehole images obtained from microresistivity and ultrasonic imager tools form an important source of geological information. The interpretation of these images is often hampered by the presence of artefacts, arising from peculiarities of the logging tools, and/or unexpected borehole conditions. In this paper, the operations of microresistivity and ultrasonic imager tools are reviewed, with a special emphasis on the tool features and borehole conditions that may give rise to artefacts in the resultant borehole images. The origin and characteristics of some commonly encountered artefacts are discussed, pointing out how they can be identified. Processing methods that may help to remove or reduce the effects of the artefacts are described. This information should help an interpreter to initially better understand the origin and significance of commonly encountered artefacts in terms of tool response, and secondly ensure that undesirable effects of such artefacts are minimised by using available data processing methods.
Application of borehole image logs in constructing 3D static models of productive fracture networks in the Apulian Platform, Southern Apennines
Authors: Trice Robert 
Published: April 2008

Abstract
Fractured reservoirs of the Apulian Platform carbonates present significant challenges from the perspective of formation evaluation. Evaluation problems manifest themselves at all stages of reservoir development from exploration and production drilling through to reserves calculation and reservoir simulation. A significant aspect of these problems arises from the difficulty in locating and testing productive fractures during drilling operations. Once productive fractures have been identified the problem then becomes how to model them away from the borehole and to assign field scale fracture parameters. A key data set in such evaluations is provided by borehole image logs. This paper discusses how borehole image logs have been used to describe the Apulian Platform carbonates with respect to: (a) identify producing fractures, (b) to understand and model the relationship of fractures to the stress field, (c) to provide input to 3D models of producing fracture systems, and (d) how the 3D models were used to quantify the fracture system. The combination of these elements has led to a practical methodology by which a significantly improved understanding of the Apulian Platform fracture system has been achieved.
A sedimentological application of ultrasonic borehole images in complex lithologies: the Lower Kimmeridge Clay Formation, Magnus Field, UKCS
Authors: Goodall Ian , Lofts Jeremy , Mulcahy Matthew , Ashton Michael , Johnson Sam 
Published: April 2008

Abstract
Ultrasonic borehole image tools are generally considered to be of limited value as an interpretative sedimentological tool because thick packages of a single lithology have similar acoustic properties resulting in resolution of very little diagnostic detail. In addition, build-up of mudcake in porous sandstones typically masks geological information by impeding the acoustic signal. In contrast, in heterolithic sediments, differences in acoustic impedance between intercalated lithologies enable clear distinction of sandstones and mudrocks from ultrasonic amplitude images. Whilst resolution of internal detail is still limited, valuable diagnostic data may be obtained for the sandstones by careful examination of the geometries and orientations of their lower and upper contacts with enclosing mudrocks. This is the case in the Lower Kimmeridge Clay Formation reservoir in the Magnus Field, UKCS, using the Schlumberger Ultrasonic Borehole Imager tool (UBI). Here, the bulk of the reserves are held in relatively thin, depositionally flat-lying, high-density turbidite sandbodies which are donors to variably inclined and complexly bifurcating sandstone injections. Recognition of sandstone injections and an understanding of their orientations is crucial to future development of this reservoir because they may be the principal means of communication between sandbodies and also have pay potential. Whilst this is not possible using conventional openhole logs it is easily achieved using UBI amplitude images.
FMS Images from carbonates of the Bahama Bank Slope, ODP Leg 166: Lithological identification and cyclo-stratigraphy
Authors: Williams Trevor , Pirmez Carlos 
Published: April 2008

Abstract
Ocean Drilling Program (ODP) Leg 166 cored a transect of holes through the prograding carbonate sequences that form the western slope of the Great Bahama Bank, with the aim of detailing the relationship between the sequences and changes in sea-level over the last 25 Ma. A total of 1200m of FMS resistivity images from Site 1003 (lower slope) and Site 1005 (mid-slope) were divided into three image facies types, with the aid of calibration against the recovered core. Type 1 was conductive (poorly cemented) sediment dominated by pelagic components, Type 2 was resistive (well cemented) sediment dominated by platform (neritic) components, and Type 3 was highly resistive (very well cemented) sediment, usually calciturbidites but occasionally hardgrounds. Much of the section is composed of metre-scale alternations between Type 1 and Type 2 sediment. We have used the cycle thicknesses in the Middle Miocene to obtain a sedimentation rate curve and to refine the biostratigraphy. The cyclicity is modulated by the precessional astronomical cycle. The FMS images were used to evaluate the lithostratigraphic position and significance of prominent isolated uranium peaks. The peaks tend to occur just below the tops of calci-turbidite-rich units, sometimes coincident with sequence boundaries and maximum flooding surfaces.
Contributions of acoustic imaging to the development of the Bruce Field, Northern North Sea
Authors: Parkinson D. N. , Dixon R. J. , Jolley E. J. 
Published: April 2008

Abstract
An interpretation of four acoustic images from the Bruce Field is presented. It provides an example of what can be achieved using moderate-quality data from a North Sea siliciclastic reservoir. Faults have been detected and oriented using evidence from large-scale block rotations, small-scale drag, direct imaging of fault planes, identification of fault damage zones and breakout rotation. Fracture frequency is highly variable and is dominantly controlled by fault-related damage, though rock properties may also be important. Damage zones are some 25–50 m thick and appear to be concentrated on the hanging walls of their controlling faults. These damage zones are important barriers to flow. Fractures are orientated NNE-SSW. A stress-field map has been produced combining image and dip-log data. The dominant orientation of the minimum horizontal principal stress is parallel to the fractures, though it is influenced locally by structure. The combination of stress field and fracture studies predict the dominance of east-west fluid flow in the reservoir, ‘baffled’ by north-south fracture barriers. Palaeocurrent information has been used to help construct a suite of time-slice palaeogeographies which describe the sedimentary heterogeneity.
Previous ideas and models of the stratigraphy, structure and mineral deposits of the Manx Group, Isle of Man
Authors: Ford T. D. , Wilson Eva , Burnett D. J. 
Published: April 2008

Abstract

Since Bishop Wilson’s [Wilson, Bishop T. (1772)
The Works of Bishop T. Wilson
, Cruttwell, Bath] account of the geology of the Isle of Man there has been a succession of increasingly sophisticated accounts of the Manx slates. Outlines were provided by Woods [Woods, G. (1811)
An account of the Past and Present State of the Isle of Man, Including … a Sketch of its Geology
, Baldwin, London], Berger [Berger, J. F. (1814)
Transactions of the Geological Society of London
,
2
; (1824)
Annals of Philosophys, Series 2
,
viii
] and MacCulloch [MacCulloch, J. (1819)
A Description of the Western Isles of Scotland, Including the Isle of Man
, Constable, London] in the early nineteenth century but the first attempt at a stratigraphic subdivision was by Cumming in 1846 [Cumming, J. G. (1846)
Quarterly Journal of the Geological Society
,
31
]. Lamplugh’s map and memoir at the turn of the century provided the first full account [Lamplugh, G. W. (1903)
The Geology of the Isle of Man
, HMSO]. Later, Gillott [e.g. Gillott, J. E. (1955)
Geological Magazine
,
92
] examined the Manx slate in more detail but it was not until the 1960s that Simpson [Simpson, A. (1963)
Quarterly Journal of the Geological Society
,
119
] defined an 11 unit stratigraphic succession and delineated a refolded synclinal structure. Subsequently, discoveries of graptolites and acritarchs have necessitated revisions to both Simpson’s succession and structure. Correlation with some parts of the Skiddaw Group is now well established.
Magnetic survey of the Poortown Dolerite, Isle of Man
Authors: Piper J. D. A. , Biggin A. J. , Crowley S. F. 
Published: April 2008

Abstract

A ground magnetic survey of a 1.5 × 1 km
2
area surrounding the Poortown Dolerite emplaced into Early Ordovician Manx Group metasediments has identified two regions of high-amplitude and short-wavelength anomalies; the first region extends for 300 m north of the quarry outcrop and the second lies between 100 and 500 m to the east. Linear anomalies have trends ranging from east-west to east-northwest-west-southwest. Palaeomagnetic and rock magnetic studies of the exposed intrusion show that the magnetization resides in Ti-poor titanomagnetite, which is predominantly multidomained. The natural remanent magnetization is dominated by a viscous remanence in the present geomagnetic field and the magnetic anomalies can therefore be modelled using the ambient field direction. A smaller high-blocking temperature component has a westerly direction of negative inclination and is compatible with a normal magnetization acquired during Late Ordovician times. 2D Geometrical models are developed to fit the observed magnetic anomalies. They show that the igneous complex comprises one or two north dipping sheets at its eastern and western peripheries, which expand into a set of multiple sheets separated by screens of Manx Group country rock in the area immediately north of the present quarry outcrop. The sheets may be components of a smaller number of sill-like intrusions repeated by faulting. This general model is supported by results from six boreholes.
Geological structure and tectonic evolution of the Lower Palaeozoic rocks of the Isle of Man
Authors: Fitches W.R. , Barnes R. P. , Morris J. H. 
Published: April 2008

Abstract
The Lower Palaeozoic sedimentary rocks of the Isle of Man, deposited near the margin of the Avalonian plate, were folded and cleaved during continental closure and collision. Although folds on a scale of several kilometres can be inferred, the large-scale structure of the Isle of Man remains uncertain in the absence of detailed and widespread biostratigraphical controls on the stratigraphy and other difficulties. A working model suggests that the island is composed of several northeast trending, strike-parallel ‘tracts’ separated by vertical or steeply northwest dipping faults. Stratigraphic sequences may be apparent within tracts but cannot easily be correlated between tracts. The within-tract structure is the result of two main stages of deformation (D1 and D2) and one or more localized later events (D3). F1 folds have axial surfaces which dip steeply northwest or southeast, near-horizontal hinges, and wavelengths ranging up to several kilometres. The F2 folds, seen mostly on a small scale, are reclined to recumbent and coaxial with F1 folds. The D1 and D2 structures were imposed on the Wenlock rocks of the Niarbyl Formation but are absent from the Peel Sandstone (late Silurian-early Devonian), constraining the main deformation to the Caledonian (Acadian) orogeny.
The D1 structures are the products of collisional tectonics but the origin of the flat-lying D2 structures is unclear, although vertical flattening is more likely than thrusting. Most of the inferred tract-bounding structures cannot be characterized in the absence of exposure or precise stratigraphical controls. Two of them, however, are inferred to be northwest dipping faults. One of these faults cuts D1 structures whilst the other appears to be pinned by a syn-D1 intrusion, suggesting broadly syn-D1 age. Localized, steep northeast striking zones of late to post-D1 high strain, which are exposed on the west coast of the island, in part reflect partitioning of coaxial or transpressive deformation into the boundaries between rocks of contrasted ductility. The Niarbyl Fault Zone (‘shear zone’) is shown to be a belt of ductile and brittle deformation whose tectonic history and regional significance have yet to be fully resolved. Brittle thrust faults are exposed in several parts of the Isle of Man and include the Niarbyl Thrust, which, in one interpretation, is taken to separate the Niarbyl high-strain phyllonite belt from the overlying Niarbyl Formation. Most thrusts are north to northwest dipping and displacements are typically on a metre scale. Many of them may be attributed to the latest stages of the Caledonian collision processes on the basis that similar structures also deform the late Silurian-early Devonian Peel Sandstone of the Isle of Man and rocks of similar age elsewhere in the region.
The Auckland volcanic field, New Zealand: geophysical evidence for its eruption history
Authors: Cassidy John , Locke Corinne A. , Miller Craig A. , Rout David J. 
Published: April 2008

Abstract
The Late Quaternary monogenetic basalt volcanoes of the Auckland volcanic field exhibit styles of eruption ranging from phreatomagmatic to magmatic. New detailed aeromagnetic and other geophysical data from the southern half of the field provide constraints on the style and relative timing of eruptions. Concealed basalt bodies are shown to be common beneath maars indicating deep excavation by phreatomagmatic events and subsequent filling by magma. Depth of excavation is unrelated to the presence of surficial and potentially saturated Plio-Pleistocene sediments but commonly involves magma-water interaction in widespread aquifers within the underlying Miocene sediments. Coincident anomalous bulk magnetization directions show that at least three volcanoes were active contemporaneously and suggest a very short duration of activity which is probably typical of other centres in the field. These results emphasize the spasmodic nature of activity in the field over the last 140 ka culminating in the most recent centre, Rangitoto, which erupted after a long quiescent period and represents a large spasm of activity, confined to a single centre. The locations of contemporaneous centres are tentatively correlated with the regional NNW-SSE structural trend.
Volcanic hazards in Auckland, New Zealand: a preliminary assessment of the threat posed by central North Island silicic volcanism based on the Quaternary tephrostratigraphical record
Authors: Newnham Rewi M. , Lowe David J. , Alloway Brent V. 
Published: April 2008

Abstract

The City of Auckland (population
c.
1 million), built on a basaltic volcanic field active as recently as
c.
ad
1400, faces an additional volcanic threat: that from several large and productive rhyolitic and andesitic eruptive centres of the central North Island, 140–280 km to the south and southeast. Non-basaltic tephra fallout layers originating from these distal eruptive centres are numerous and widespread in the Auckland region and have primary thicknesses ranging from
c.
1 mm to ⩾ = 0.6 m; ignimbrites up to 9 m thick are also documented but are uncommon. The assessment of volcanic hazards in Auckland is made problematical by the different types of volcanic threat posed by these two spatially distinct source areas, and by the lack of recognition hitherto given to the threat from the distal sources. This paper reviews the Quaternary records of distal volcanism affecting Auckland and outlines current investigations into the assessment of environmental impacts of past eruptions. Our preliminary results indicate that the potential threat to Auckland from the distal volcanic sources has been underestimated and that further research into the impacts of Quaternary volcanism on Auckland’s environment and infrastructure is essential. The importance of this threat was underscored in mid-1996 when a small magnitude eruption of Mt Ruapehu necessitated closure of Auckland International Airport for three nights.
Modelling the impact of Icelandic volcanic eruptions upon the prehistoric societies and environment of northern and western Britain
Authors: Grattan John , Gilbertson David , Charman Daniel 
Published: April 2008

Abstract
Many studies now address the impact of Icelandic volcanic eruptions upon the societies and environment of Britain and Ireland. It has become apparent that the assumptions of the magnitude of volcanic impact inherent in these studies are open to question. The scale of climatic change following many eruptions has been observed to be ephemeral or non-existent, whilst the impact of toxic volatile gases and aerosols is dependent, to a large degree, on the vulnerability of the receptor rather than the scale of deposition. The scale and extent of volcanic climatic-forcing mechanisms are examined and the popular perception of the effectiveness of these is challenged. In particular, the concepts of harsh volcanic winters and cool volcanic summers is examined via case studies of the impacts of the three largest eruptions of recent and historical times, i.e. those of the Laki fissure, Tambora and Mount Pinatubo. Alternative volcanic forcing mechanisms for environmental change are considered, principally those concerned with the transport and deposition of toxic volatile material. The need for caution in the adoption of these models is also urged. It is suggested that workers in this field need to adopt a clearer theoretical framework when contemplating the association of palaeoenvironmental data and volcanic events. Such a framework is proposed.
Crustal anisotropy and differential uplift: their role in long-term landform development
Authors: Battiau-Queney Y. 
Published: April 2008

Abstract
The British Isles belong to a passive continental margin where recently acquired geophysical data have confirmed the great heterogeneity of the crust. In such an area, models based on time-related landform evolution leading to planation fail to explain the long-term development, at least since the North Atlantic began to open. The concept of a morphotectonic system taking into account a continuous input of energy (due to plate tectonics) and a state of stress controlled by pre-existing crustal discontinuities is well adapted to the British area and other similar areas. The spatial units of a morphotectonic system are defined by the crustal framework and do not generally coincide with drainage basins. Regional-scale landforms are not time-related but depend on crustal properties, and denudation rates might strongly differ on either side of main crustal hinges, whatever the proximity of the sea.