bluuebunny/crossref_metadata_2025_split huggingface dataset:
Terranes
Authors: Bluck B. J. , Gibbons W. , Ingham J. K. 
Published: August 2007

Abstract
The Precambrian and Lower Palaeozoic foundations of the British Isles may be viewed as a series of suspect terranes whose exposed boundaries are prominent fault systems of various kinds, each with an unproven amount of displacement. There are indications that they accreted to their present configuration between late Precambrian and Carboniferous times. From north to south they are as follows.
In northwest Scotland the Hebridean terrane (Laurentian craton in the foreland of the Caledonian Orogen) comprises an Archaean and Lower Proterozoic gneissose basement (Lewisian) overlain by an undeformed cover of Upper Proterozoic red beds and Cambrian to early mid Ordovician shallow marine sediments. The terrane is cut by the Outer Isles Thrust, a rejuvenated Proterozoic structure, and is bounded to the southeast by the Moine Thrust zone, within the hanging wall of which lies a Proterozoic metamorphic complex (Moine Supergroup) which constitutes the Northern Highlands terrane. The Moine Thrust zone represents an essentially orthogonal closure of perhaps 100 km which took place during Ordovician-Silurian times (Elliott & Johnson 1980). The Northern Highlands terrane records both Precambrian and late Ordovician to Silurian tectonometamorphic events (Dewey & Pankhurst 1970) and linkage with the Hebridean terrane is provided by slices of reworked Lewisian basement within the Moine Supergroup (Watson 1983).
To the southwest of the Great Glen-Walls Boundary Fault system lies the Central Highlands (Grampian) terrane, an area dominated by the late Proterozoic Dalradian Supergroup which is underlain by a gneissic complex (Central Highland Granulites) that has been variously interpreted as either older
Triassic
Authors: Warrington G. , Ivimey-Cook H. C. 
Published: August 2007

Abstract
"The Triassic rocks of Great Britain, if one may judge from statements in the textbooks, are among the simplest of our deposits; but a closer inspection reveals a number of very difficult and intensely interesting problems hidden behind this apparent simplicity." L. J. Wills, 1910.
During latest Permian times, northerly-sourced epeiric marine environments, in which the Zechstein sequence formed, were replaced by predominantly clastic sedimentary regimes. The succeeding Triassic deposits, representing about 45 million years, are largely continental; some formed under transient marine influences but few are biogenic. They succeed Permian deposits conformably and overstep these to rest unconformably upon older rocks. Over much of the region the youngest Triassic deposits represent a transgression that re-established marine environments before the end of the Period.

The region lay in Laurasia, the northern part of the Pangaean supercontinent, some 15 to 20° north of the equator and close to the northern margin of the Tethys (Tollmann & Kristan-Tollmann 1985) but separated from that ocean by the Variscan mountain chain, denudation of which continued from Permian into Triassic times. A monsoonal climate is envisaged (Robinson 1973; Parrish & Curtis 1982; Parrish
et al
. 1982).

The principal onshore Triassic occurrences are in England and Northern Ireland; others in the British Isles are relatively minor (Warrington
et al
. 1980, figs 2 & 3). Concealed developments in The Netherlands (Map Tr2) and northeast France (Mégnien & Mégnien 1980; Debrand-Passard 1980; Berners
et al
. 1984; Maps Tr2-3b & 4c) are contiguous with the tripartite German sequence from
Jurassic
Authors: Bradshaw M. J. , Cope J. C. W. , Cripps D. W. , Donovan D. T. , Howarth M. K. , Rawson P. F. , West I. M. , Wimbledon W. A. 
Published: August 2007

Abstract
The interplay of regional or global sea-level changes and continuing crustal extension related to rifting in the North Atlantic and Tethyan megarifts dominated the palaeogeographical evolution of the area. The sea-level rise that commenced in the Rhaetian continued into the Jurassic to usher in a new phase of predominantly marine sedimentation across northwest Europe. The climate was warm and humid, the seas generally shallow. Land areas became well vegetated, as attested by the abundance of fossil driftwood in marine as well as non-marine sediments. The region probably lay about 10° south of present latitudes, in an area of overlap of Tethyan and Boreal marine realms. For much of the Jurassic, sea levels continued to rise but two major falls occurred, coinciding with accelerated extensional movements in the area. The first was during the mid-Jurassic ('mid-Cimmerian phase') when there was a major regional upwarp centred on the North Sea, and the second across the Jurassic/Cretaceous boundary ('late Cimmerian phase') when a global fall in sea level coincided with an important phase of rifting and block faulting. Major structural trends generally follow previously established lines. The basic structural framework for the Jurassic maps has been compiled from numerous sources, including Andrews &Brown (1987); Dunning (1985); Evans et al. (1982); Gardiner &Sheridan (1981); Van Hoorn (1987); Thomas et al. (1985); Whittaker (1985); Ziegler (1982, 1987); and papers in Brooks &Glennie (1987). Fault trends are generalized and selected to pick out the main structural features controlling the geography; their occurrence on
Carboniferous
Authors: Cope J. C. W. , Guion P. D. , Sevastopulo G. D. , Swan A. R. H. 
Published: August 2007

Abstract
Carboniferous geology has developed very rapidly over the past two decades since ideas on sedimentology and new radiometric scales, together with new biostratigraphical schemes based on miospores, conodonts and foraminifera have been synthesized with ideas on plate tectonic processes, climatic changes and oscillations of sea level. The application of the McKenzie model of basin development to the Carboniferous, and the relating of eustatic sea-level changes, which had a profound effect on Carboniferous palaeo-geography, to fluctuations in the size of the Gondwanan ice sheets, have been major factors in the understanding of Carboniferous processes. The Carboniferous evolution of Britain took place to the (present) north of a plate suturing occurring along a line extending from Galicia, through Armorica and the Massif Central to the Vosges, during mid Devonian to early Carboniferous times. In front of this collision zone was the Rheno-Hercynian zone which opened probably during mid Devonian times and which was partly floored by oceanic crust; its closure can be traced through to late Carboniferous times as a series of northwardly directed thrust complexes. To the (present) north of this zone was a foreland on which basins developed on either side of a persistent Wales-London-Brabant High. Studies by Dewey (1982) and Leeder (1982, 1987, 1988) have shown that late Devonian to early Carboniferous extension, involving β factors of up to 2, produced a series of grabens and half-grabens in the Caledonian basement. These developing structures were the dominant control on early Carboniferous sedimentation and produced a sea-bed topography which was
Part 1: Compendium of North Sea Oil and gas fields
Authors: Warren E. A. , Smalley P. C. 
Published: August 2007

This section gives an alphabetical field-by-field compilations of water compositions with accompanying geological descriptions and field maps.
The following abbreviations are used:
AA -- atomic absorption (spectroscopy)
API -- American Petroleum Institute
BCF -- billion cubic feet
DST -- drill stem test
KCF -- Kimmeridge Clay Formation
ICP-AES -- inductively coupled plasma - atomic emission spectroscopy
MMbbls -- million barrels
psi -- pounds per square inch
Prod -- production (sample)
RFT -- repeat formation tester
SMOW -- standard mean ocean water
stb/d -- stock tank barrels per day
TDS -- total dissolved solids
TVD -- true vertical depth
TU -- tritium unit
UKCS -- United Kingdom continental shelf
Part 2: SPWLA Water Resistivity (R
w
) Atlas
Authors: Warren E. A. , Smalley P. C. 
Published: August 2007

Abstract

The resistivity (R
w
) of formation waters is directly related to salinity: the higher the salinity the lower the water resistivity. Knowledge of formation water resistivity is essential in formation evaluation. Most importantly, it is used to derive estimates of water saturation in the hydrocarbon column and, hence, of the volumes of petroleum initially in place.

The resistivity of formation waters is determined by direct electrical measurement in a resistivity cell or estimated, either from chemical analysis or from electric logs. An atlas of formation water resistivity for the North Sea was published by the Society of Professional Well Log Analysts (SPWLA) in 1989 (Amiard & Harrison 1989). The data compiled for this volume were used to update the SPWLA atlas. These new data are presented together with the earlier 1989 data in the same format used by the SPWLA.
Tables and maps of formation water resistivity have been produced according to the guidelines of Amiard & Harrison (1989). These are described below.

A salt-saturated brine at 60°F (15.6°C) and at atmospheric pressure has a maximum salinity of approximately 250 000 ppm NaCl equivalent and is represented as a minimum normalized R
w
value of 0.050 Ω m.

All R
w
data are reported for a standard temperature of 60°F (15.6°C). Corrections to the resistivity value from the actual measurement temperature to this standard temperature were made using the formulae:

In keeping with Amiard & Harrison (1989), a validity index was assigned to the data. This index attempts subjectively to rank the data
Setting, chronology and consequences of the eruption of Soufrière Hills Volcano, Montserrat (1995-1999)
Authors: Kokelaar B. P. 
Published: August 2007

Abstract
The eruption on Montserrat during 1995-1999 was the most destructive in the Caribbean volcanic arc since that of Mont Pelee (Martinique) in 1902. It began on 18 July 1995 at the site of the most recent previous activity, on the flank of a c. 350-year-old lava dome within a sector-collapse scar. Phreatic explosivity occurred for 18 weeks before the onset of extrusion of an andesitic lava dome. Dome collapses produced pyroclastic flows that initially were confined by the sector-collapse scar. After 60 weeks of unsteadily accelerating dome growth and one episode of sub-Plinian explosivity, the dome eventually overtopped the confining scar. During 1997 almost two-thirds of the island was devastated following major dome collapses, two episodes of Vulcanian explosivity with fountain-collapse pyroclastic flows, and a flank failure with associated debris avalanche and explosive disruption of the lava dome. Nineteen people were killed directly by the volcanic activity and several were injured. From March 1998 until November 1999 there was a pause in magma ascent accompanied by reduced seismic activity, substantial degradation of the dome, and considerable degassing with venting of ash.
The slow progress and long duration of the volcanic escalation, coupled with the small size of the island and the vulnerability of homes, key installations and infrastructure, resulted in a style of emergency management that was dominantly reactive. In order to minimize the disruption to life for those remaining on the island, following large-scale evacuations, scientists at the Montserrat Volcano Observatory had to anticipate hazards and their potential extents of impact with considerable precision. Based on frequent hazards assessments, a series of risk management zone maps was issued by administrative authorities to control access as the eruption escalated. These were used in conjunction with an alert-level system. The unpreparedness of the Montserrat authorities and the responsible UK government departments resulted in hardship, ill feeling and at times acrimony as the situation deteriorated and needs for aid mounted. Losses and stress could have been less if an existing hazards assessment had registered with appropriate authorities before the eruption.
The volcanic evolution of Montserrat using
40
Ar/
39
Ar geochronology
Authors: Harford C. L. , Pringle M. S. , Sparks R. S. J. , Young S. R. 
Published: August 2007

Abstract

40
Ar/
39
Ar dating has facilitated a substantial reinterpretation of the volcanic evolution of Montserrat. Three volcanic centres with non-overlapping volcanic activity are identified: Silver Hills (c. 2600 to c. 1200 ka); Centre Hills (at least c. 950 to c. 550 ka); South Soufrière Hills-Soufrière Hills (at least c. 170 ka to present). The geochronological data show that old xenocrysts are common in the porphyritic andesite, implying that reliable ages are best obtained by dating the groundmass. Soufrière Hills evolved from early eruptions dominated by two-pyroxene andesite to eruptions of hypersthene-hornblende andesite at c. llOka. Between the two varieties of andesite there was an interlude of mafic volcanism at c. 130ka to form South Soufrière Hills. There is evidence of tectonic uplift of early products of the complex along with older submarine volcanic rocks. Consideration of stratigraphy and age data indicates that only a proportion of the dome-forming eruptions are recorded as domes in the geological record. Older products are removed from the subaerial edifice by sector-collapse events. The time-averaged eruption rate of the South Soufrière Hills-Soufrière Hills centre is estimated at 0.005 m
3
s
-1
(c. 0.15 km
3
ka
-1
) (dense rock equivalent). The ongoing eruption is very similar in style to previous activity at Soufrière Hills, and future activity is likely to pose similar hazards. Soufrière Hills have been characterized by alternations of periods of enhanced activity and periods of dormancy, both lasting of the order of 10
4
years. During periods of elevated activity several major dome-forming eruptions are separated by quiescent interludes lasting less than c. 10
3
years. The ongoing eruption may mark the onset of a fourth period of enhanced volcanic activity at Soufrière Hills.
The 26 December (Boxing Day) 1997 sector collapse and debris avalanche at Soufrière Hills Volcano, Montserrat
Authors: Voight B. , Komorowski J-C. , Norton G. E. , Belousov A. B. , Belousova M. , Boudon G. , Francis P. W. , Franz W. , Heinrich P. , Sparks R. S. J. , Young S. R. 
Published: August 2007

Abstract

The southern sector of Soufrière Hills Volcano failed on 26 December 1997 (Boxing Day), after a year of disturbance culminating in a devastating eruptive episode. Sector collapse produced a
c.
50 x 10
6
m
3
volcanic debris avalanche, and depressurized the interior of the lava dome, which exploded to generate a violent pyroclastic density current. The south-directed growth of a lava lobe and build-up of lava-block talus, since early November 1997, brought the hydrothermally weakened sector to a condition of marginal stability. Limit-equilibrium stability analyses and finite-difference stress-deformation analyses, constrained by geomechanical testing of edifice and debris avalanche materials, suggest that the sector collapse was triggered by a pulse of co-seismic exogenous lava shear-lobe emplacement. Slip-surface localization was influenced by strain-weakening.

The source region fragmented into avalanche megablocks, and further disruption generated a chaotic avalanche mixture that included variably indurated and coloured hydrothermally altered material, and much talus. The avalanche consisted of several flow pulses that reflected complexities of source disruption and channel topography. In the proximal zone, within 1.5 km from source, many megablocks preserve pre-collapse stratigraphy. At major bends the avalanche separated into channelled and overspill flows. In the distal region, <2.5km from source, stacked sets of the main lithologies occur with a hummocky surface and abrupt flowage snouts, beyond which sparse hummocks occur in a thinly spread deposit. Textures suggest emplacement by laminar mass transport of partly saturated debris riding on a frictionally sheared base. Three-dimensional numerical simulations of emplacement governed by a Coulomb-type (Pouliquen) basal friction law imply low values of friction (> 15°), consistent with geotechnical test data and the localized presence of pore-water pressures. The best-fit model suggests an emplacement time >3 minutes and a typical maximum velocity of about 40ms
_1
, which are consistent with field estimates.
The explosive decompression of a pressurized volcanic dome: the 26 December 1997 collapse and explosion of Soufrière Hills Volcano, Montserrat
Authors: Woods A. W. , Sparks R. S. J. , Ritchie L. J. , Batey J. , Gladstone C. , Bursik M. I. 
Published: August 2007

Abstract

Abstract: We calculate the gas flux through a pressurized and permeable lava dome as magma slowly ascends to the surface and degasses. This provides an estimate of the mass of gas and the associated energy that may be released following the explosive collapse of such a dome. We estimate that during the 26 December 1997 dome failure of Soufrière Hills Volcano, up to 10
16
J of energy was released. We then develop a model of the dome break-up driven by the pressure jump across a fragmentation wave. We predict that the fragmentation front advances into the dome at a speed of order 10 ms
-1
, while the gas and solid fragments issue from the dome at speeds of order 50-60 ms
-1
. This fragmented material forms a dense fountain of gas and solid fragments. This may rise 100-200 m above the dome and then spread out to form a dense pyroclastic density current, with initial density of order a few hundred kilograms per cubic metre. We anticipate that such flows will become stratified in density and mean grain size. Some new experiments on stratified gravity currents illustrate that the flow propagation speed is similar to a well mixed current of the same total buoyancy, although the flow tends to become laterally stratified, with the dense lower region out-running the fluid higher in the current.
Pyroclastic flow and explosive activity at Soufrière Hills Volcano, Montserrat, during a period of virtually no magma extrusion (March 1998 to November 1999)
Authors: Norton G. E. , Watts R. B. , Voight B. , Mattioli G. S. , Herd R. A. , Young S. R. , Devine J. D. , Aspinnall W. P. , Bonadonna C. , Baptie B. J. , Edmonds M. , Harford C. L. , Jolly A. D. , Loughlin S. C. , Luckett R. , Sparks R. S. J. 
Published: August 2007

Abstract
Dome growth at Soufrière Hills Volcano halted in early March 1998. After dome growth ceased, seismicity reduced significantly, but activity related to dome disintegration and degassing of magma at depth continued. A sustained episode of pyroclastic flows on 3 July 1998 marked the single largest collapse from March 1998 to November 1999. This led to a remarkable episode of dome collapses, low-energy explosions and ash-venting that resulted in the regular production of ash plumes, commonly reaching 1.5-6 km above sea level (a.s.l), but sometimes up to 11 km a.s.l., and the development of a small block-and-ash cone around the explosion crater. During the period of this residual activity, higher levels of activity occurred approximately every five to six weeks. This periodicity was similar to the cycles observed during active dome growth during 1995 to 1998, and probably had a similar cause. The relatively high level of observed activity caused continued concern regarding volcanic hazards and their potential to impact upon the resident population. Vigorous magma extrusion resumed in November 1999. The activity of the intervening period is attributed to the continued cooling and degassing of the dome, conduit and deep magma body, the impact of rising volcanic gases in the volcanic edifice, and limited magma flow in the conduit.
Dynamics of volcanic and meteorological clouds produced on 26 December (Boxing Day) 1997 at Soufrière Hills Volcano, Montserrat
Authors: Mayberry G. C. , Rose W. I. , Bluth G. J. S. 
Published: August 2007

Abstract

The 26 December 1997 explosive activity of Soufrière Hills Volcano, Montserrat, provided an opportunity to study the evolution of a volcanic cloud by merging data from various satellites with wind-trajectory data. The activity involved a debris avalanche that descended SSW from the lava dome, to the coast, and a pyroclastic density current that traversed the coast and entered the sea. The slope failure and subsequent dome collapse occurred at
c
. 07:01 universal time (UT; 03:01 local time), lasted 15.2 minutes, and produced an upwardly convecting volcanic ash cloud that cloud temperatures suggest rose to
c
. 15 km. The volcanic ash cloud was unusual because the pyroclastic density current transported hot fine ash to the sea, where it rapidly transferred its heat to the sea water. The evaporation of large volumes of water produced a volcanogenic meteorological (VM) cloud that convected along with the volcanic ash cloud.

The evolution of the volcanic and VM clouds was studied using an isentropic wind trajectory model and data from three satellite sensors: Geostationary Observational Environmental Satellite 8 (GOES 8), Advanced Very High Resolution Radiometer (AVHRR), and Total Ozone Mapping Spectrometer (TOMS). The high temporal resolution of the GOES 8 images filled many of the time gaps the other satellites left, and allowed quantitative retrievals to be performed using a two-band infrared retrieval method. The three-dimensional morphology of the volcanic cloud was reconstructed using GOES 8 data and by determining the heights of air parcels from wind-trajectory data. The volcanic cloud was estimated to contain up to 4.5 x 10
7
kg of silicate ash. Between
c
. 07:39 UT and 13:39 UT the ash signal of the volcanic cloud was masked by the VM cloud, which had a mass of up to 1.5 x 10
8
kg of ice. Ice forms when moist air is convected upwards to temperatures of less than -40°C and becomes saturated.

Ice formation in volcanic clouds is especially likely when hot volcanic material is cooled by seawater rather than the atmosphere. The efficiency of evaporation of the seawater was calculated to be
c
. 5%, based on physical and GOES 8 data. TOMS data showed the SO
2
in the volcanic cloud rose higher than the ash in the volcanic cloud, as has occurred in several other eruptions.

A comparison between GOES 8 and AVHRR data showed that AVHRR data retrieved higher fine-ash silicate masses and higher cloud areas than GOES 8 due to the finer spatial resolution of AVHRR images. The effect on retrieval data of the high water vapour content in the lower troposphere of the tropical atmosphere was quantified; the high humidity in the Montserrat region caused the characteristic ash signal to the infrared sensors to be depressed by up to 80%. This signal depression caused a corresponding underestimation of the mass and area of the volcanic cloud when the infrared brightness temperature difference retrieval technique was used.
The relationship between degassing and rockfall signals at Soufrière Hills Volcano, Montserrat
Authors: Luckett R. , Baptie B. , Neuberg J. 
Published: August 2007

Abstract
One of the most common types of seismic event recorded during the eruption of Soufrière Hills Volcano from 1995 to 1999 is known as a rockfall signal because signals recorded when rockfalls were observed on the dome are of this type. Evidence is presented that two seismic sources contributed to these events. The action of falling debris on the dome generated seismicity between 2 Hz and 8 Hz, while many rockfall signals also have a marked spectral peak between 1 Hz and 2 Hz. Deployment of a pressure sensor near the volcano has shown that the 1-2 Hz energy was associated with degassing at the surface of the dome; however, the relative timing of gas escape and seismic signal showed that the first was not the direct source of the second. Resonance of the magma conduit linked to degassing at the surface is invoked as a probable source for the 1-2 Hz seismicity. The relative importance of the two seismic sources that contributed to rockfall signals is examined in the context of the behaviour of the volcano.