bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Mesoproterozoic cratonization of Baltica — new age constraints from SW Sweden
Authors: Connelly J. N. , Åhäll K-I. 
Published: April 2008

Abstract
Comparable early Mesoproterozoic tectonic histories resulted in the formation of 1.71–1.62 Ga Labradorian and 1.75–1.55 Ga Gothian crust in Laurentia and Baltica respectively, along a postulated contiguous margin. New U-Pb geochronology in southwest Sweden has constrained the timing of three consecutive stages of the Gothian Orogeny. Calc-alkaline magmatism, presumably related to subduction, occurred as late as 1587 ± 3 Ma, indicating convergence and consumption of oceanic crust until this time. These magmas intruded terranes of previously accreted arcs, thus providing a minimum age for their juxtaposition and accretion. The age of the latest stage of Gothian migmatization is constrained between 1555 ± 2 and 1553 ± 2 Ma, synchronous with the transition from ductile to brittle conditions at the presently exposed erosional level. This transition permitted the emplacement of a suite of mafic-felsic 1555–53 Ma intrusions during an extensional regime that may have coincided with the post-deformational collapse of the Gothian Orogen. These age refinements in southwest Sweden indicate that the final stage of the Gothian Orogeny in Baltica occurred considerably later than that of the Labradorian Orogeny in Laurentia. The preservation of Gothian-aged titanite from southwest Sweden indicates that post-Gothian metamorphism, including that of Sveconorwegian-Grenvillian age, was not penetrative in this region.
Iodine in the environment and endemic goitre in Sri Lanka
Authors: Dissanayake C. B. , Chandrajith R. L. R. 
Published: April 2008

Abstract
The prevalence of endemic goitre is extremely high in certain parts of Sri Lanka where rates as high as 44% have been observed. With nearly 10 million people at risk the aetiology of endemic goitre in Sri Lanka needs to be clearly ascertained. The endemic goitre belt of Sri Lanka coincides with the wet climatic zone, indicating an apparent relationship of iodine geochemistry with climatic factors. However, the fact that there is a correlation of only −0.64 between the iodine content and the prevalence of goitre suggests the existence of other factors such as humic substances in the soil, clay minerals and soil pH that exert an influence on the bioavailability of iodine.
Iodization of salt used in food is the most convenient method of goitre prevention.
The protective role of trace elements in preventing aflatoxin induced damage: a review
Authors: Nair M. G. , Maxwell S. M. , Brabin B. J. 
Published: April 2008

Abstract

Recent evidence has shown that there are important interactions in experimental models and human beings between trace element status and aflatoxin B
1
(AFB
1
) exposure. The hypothesis is presented that these interactions operate through altered host antioxidant status leading to excess free radical production resulting in cell damage and clinical disease. Geographical differences in the geochemical environment could have a major influence on the pattern of disease. Appropriate nutritional intervention studies are required to determine potential benefits of trace element supplementation in aflatoxin exposed populations.
A Kimmeridgian time-slice through the Humber Group of the central North Sea: a test of sequence stratigraphic methods
Authors: Veldkamp J. J. , Gaillard M. G. , Jonkers H. A. , Levell B. K. , Gaillard M. G. , Jonkers H. A. 
Published: April 2008

Abstract
Reservoir quality of the Fulmar Formation in the UK Central Graben depends on the original distribution of facies as well as subsequent modification by partly facies-dependant diagenesis. Numerous sequence stratigraphical analyses of the Humber Group have been published recently, each of which has elements which are convincing geologically. Nevertheless, it is our experience that facies and reservoir prediction within the Humber Group remain difficult.
Sequence stratigraphical interpretations in the Group are clearly non-unique due to major uncertainties in the data.

(1)
Biostratigraphical uncertainties include species concepts, recognition of agediagnostic taxa in thermally altered floras, validity of repeated micropaleontological events and equivocal paleoenvironmental information.

(2)
Sedimentological uncertainties are due to the gross facies similarity of the Fulmar Formation over a large geographic area and throughout the Upper Jurassic, which make the detection of potential maximum flooding surfaces and especially sequence boundaries difficult even in many cored wells. Furthermore strong syndepositional subsidence variations due to both salt movement and tectonics, lead to aliased sampling of the subsurface in wells, which are mostly situated on highs.

(3)
Seismic correlation difficulties are due to persistent seismic imaging problems below the Late Cimmerian (‘X’) Unconformity.

(4)
The depositional and sequence stratigraphical models for Humber Group deposition need to be set in the context of a transgressively skewed, back-stepping system with strong local subsidence control. The overall transgression is thought to be due to the combination of sea-level rise, widening and deepening of the basin due to tectonics, and reduced sediment supply through time. In this situation existing models have to be applied with even more care than normal if they are not to be misleading (e.g. concepts of forced regressions).

These difficulties are clarified in the context of a Kimmeridgian time slice through the Humber Group. Multiple options exist in well log correlations. As a result palaeogeographic reconstructions of the time-slice have an error margin of ±15 km, which has serious implications on the validity of reservoir quality predictions.
The application of sequence stratigraphy to the understanding of Late Jurassic turbidite plays in the Central North Sea, UKCS
Authors: Carruthers Alan , Mckie Tom , Price John , Dyer Robin , Williams Gwydion , Watson Paul 
Published: April 2008

Abstract
The identification and correlation of genetic sequences has significantly enhanced our understanding of the Late Jurassic stratigraphy in the Central North Sea. The integration of genetic sequences with an appreciation of the basinal mudrock stratigraphy, and the identification of depositional sequence boundaries provides a powerful tool to understand and potentially predict the distribution of subtle stratigraphic turbidite plays.

The largely syn-rift Late Oxfordian-Kimmeridgian was deposited during a low frequency, second-order sea-level rise, culminating in the
eudoxus
condensed section. Deposition was dominated by shallow marine shelfal sandstones and offshore mudrocks. Sandy turbidites are rare. Whilst the requisite depositional slopes and deep water areas are likely to have existed, the effects of high frequency relative sea-level falls are likely to have been suppressed. As the second-order sea-level rise accelerated towards the
eudoxus
condensed section, the supply of sand into the basin was reduced such that the potential for turbidite deposits was minimal.

The largely post-rift Kimmeridgian-Volgian section is dominated by basinal mudrocks. However, regionally correlatable ‘hot’ and ‘cool’ units provide information on sediment flux into the basin which may be linked to relative sea-level changes on the basin margin, with cool units interpreted to be the product of enhanced depositional rates during lowstand. Turbidites commonly occur within the ‘cool’ mudrock units. A Middle Volgian ‘cool’ unit is likely to represent a second-order sea-level fall, within which are composite turbidite packages which are considered to be the product of higher frequency lowstands (lowstand sequence set).
Image analysis and microscopic investigation of annually laminated lake sediments from Fayetteville Green Lake (NY, USA) Lake C2 (NWT, Canada) and Holzmaar (Germany): a comparison
Authors: Zolitschka Bernd 
Published: April 2008

Abstract
Counts and measurements of annually laminated sediments are often time consuming and subjective. An automated and computerized method to accelerate the generation of varve data and to make these data more comprehensible is required. The approach taken here is to digitize thin sections of varved lacustrine sediments of different composition and mean lamination thickness. Density variations within an area scan of the digitized image are then measured. The data obtained provide peaks and troughs of light transmission corresponding to the pale and dark alternating laminae. After comparing these results with microscopic varve measurements it is clear that light transmission data alone do not allow the counting of varves. The composite nature of laminations causes high-frequency noise which is hard to distinguish from thin varves without additional microscopic information.
Composition and origins of laminae in late Quaternary and Holocene sediments from the Santa Barbara Basin
Authors: Bull David , Kemp Alan E. S. 
Published: April 2008

Abstract
Late Quaternary and Holocene sediments from the Santa Barbara Basin have been analyzed using backscattered electron imaging (BSEI) techniques to identify the origins of laminae and document intra- and inter-annual ocean/climate variability over the last glacial cycle. Laminae observed in X-ray radiography and BSEI are entirely defined by variations in the relative abundance and grain size of biogenic and terrigenous components. There is no evidence to suggest that bacterial mat mediation may have played a role in lamina formation. The simplest lamination type comprises silt-rich, silt-poor couplets which originate from seasonal variation in the supply of silt to the basin. The second lamination type contains an additional lamina of diatom ooze to form terrigenous sediment-diatomaceous triplets. The thicker diatom ooze laminae commonly exhibit a vertical succession of diatom floras which represents intra-annual variation in productivity. The variation in thickness and assemblage of diatom ooze laminae is probably a function of the amount of diatom flux, which is controlled by upwelling-driven primary productivity in the basin. Laminated sediments deposited during cooler periods generally contain thicker diatom ooze laminae, consistent with more vigorous regional circulation and increased upwelling.
The Southeast Indian Ridge between 127° and 132°40′E: contrasts in segmentation characteristics and implications for crustal accretion
Authors: Sempéré Jean-Christophe , West Brian P. , Géli Louis 
Published: April 2008

Abstract
The Australian-Antarctic Discordance is an anomalously deep section of the Southeast Indian Ridge which overlies a colder than normal region of the upper mantle. The Southeast Indian Ridge exhibits large contrasts in its geophysical and geochemical characteristics across the eastern boundary of the Discordance. We present new geophysical data collected along the Southeast Indian Ridge between 127°00′E and 132°40′E which define the segmentation characteristics of this portion of the Indo-Australian-Antarctic plate boundary. The Southeast Indian Ridge within our survey area can be broken into three first-order segments bounded by one transform fault and two propagating rifts. The transform fault, located at the west end of the study area, forms the eastern boundary of the Australian-Antarctic Discordance.

The morphology of the spreading axis is that of an axial high akin to that found along the East Pacific Rise. The non-transform discontinuities found along the axis of accretion are also similar to those encountered at fast-spreading centres. These characteristics are in marked contrast with those of the spreading axis within the Australian-Antarctic Discordance, which resembles a slow-spreading centre despite its intermediate spreading rate (
c.
74 mm a
−1
). We suggest that the geophysical and geochemical transitions that occur along the Southeast Indian Ridge near the eastern boundary of the Australian-Antarctic Discordance may be ascribed to varying mantle temperature and melt production rate along the spreading centre at constant spreading rate.

The two propagating rifts, located near 127°45′E and 131°E, are actively migrating toward the Discordance down the regional, along-axis gradient in bathymetry at the rates of 43 and 46 mm a
−1
, respectively. Propagating rifts play a dominant role in the reorganization of the spreading centre east of the Australian-Antarctic Discordance. Satellite gravity data reveal a number of V-shaped, west-pointing structures on the flanks of the Southeast Indian Ridge. These structures appear to have been spawned near the George V ridge-transform intersection at 139°E. Four of these features display a clear association with active propagating rifts. Some of the remaining features may be due to the migration of melting anomalies entrained by asthenospheric flow along the axis of the Southeast Indian Ridge.
Segmentation of the Mid-Atlantic Ridge south of the Azores, based on acoustic classification of TOBI data
Authors: Blondel Philippe 
Published: April 2008

Abstract
The European MARFLUX/ATJ project has investigated volcanic, tectonic and hydrothermal processes along 500 km of the Mid-Atlantic Ridge near the Azores. During cruises CD89-CD90, multibeam bathymetry and high-resolution TOBI sidescan sonar data were acquired and added to the existing Geographical Information System. From the Azores Triple Junction, between 35° and 38°N, the ridge runs 227°, oblique to the 100° spreading direction. It is partitioned into several short ridge segments dominated by tectonism rather than volcanism, and is characterised by abundant hydrothermal activity. Textural analysis quantifies the second-order statistics of TOBI imagery, enabling the detection of details invisible to the human eye. The results of this analysis are used to quantify the relationship between tectonism and volcanism along-axis, and suggest declining neovolcanic activity away from the Triple Junction. They show that the discontinuities are heavily sedimented, whereas the segments are mostly volcanic and the segment ends are more densely faulted. Textural analysis quantifies the differences in style and activity of the different spreading segments, and the evolution of the discontinuities.
Initiation and evolution of boundary-wall faults along the Mid-Atlantic Ridge, 25–29°N
Authors: McAllister Eddie , Cann Johnson R. 
Published: April 2008

Abstract
The major faults that bound the median valley on slow spreading ridges form a staircase that migrates upwards and outwards from the valley floor like a slow escalator. Each boundary wall fault is generated at the margin of the median valley floor at about 2 km from the spreading axis. Boundary wall faults that appear to be single scarps on the relatively low resolution Seabeam multibeam echosounder maps are shown by high resolution TOBI sidescan sonar images in some cases to be single faults, but in others to be complex anastomosing fault zones. The major faults in such zones are often scalloped in plan view. There is no systematic relation between fault zone geometry and segment type.
We conclude that during the growth of boundary wall faults the strain is first accommodated over a wide area, in which an array of small faults dissects the volcanic surface. However, with time, and with continued extension, the strain becomes organized into increasingly narrower zones of deformation until a major boundary wall fault develops. Faults grow by propagation and linkage with other nearby faults. The early stages of linkage include tilted ramps, but at later stages brittle faults cut across the ramps, and eventually become part of a scalloped fault trace. In some places, linkage is through zones of small-scale diffuse faulting, rather than through a single fault. Fault capture and linkage can occur over lateral distances (perpendicular to the mean azimuth of the faults) of up to 1.5 km.
This deformation takes place within a fault growth window fixed relative to the spreading axis, through which the lithosphere passes as seafloor spreading continues. Most of the growth of each boundary fault takes place before the next fault is initiated. We conclude that the location and size of the narrow fault growth window is controlled by the changing mechanical properties of the ocean lithosphere as it spreads away from the axis. Its inner boundary represents the position at which a normal fault reaches the sea floor after originating at the base of the lithosphere at the spreading axis. Its outer boundary is interpreted as the point at which the strength of the boundary wall fault, increasing as the lithosphere ages and thickens, becomes greater than the strength of the lithosphere at the spreading axis, when a new fault is generated. The process of fault generation at mid-ocean ridges has relevance to fault generation in other extensional environments.
Hydrothermal activity and ridge segmentation on the Mid-Atlantic Ridge: a tale of two hot-spots?
Authors: German C. R. , Parson L. M. , Murton B. J. , Needham H. D. 
Published: April 2008

Abstract
In the past five years we have completed systematic seabed and water column surveys of two key sections of the Reykjanes Ridge and the Mid-Atlantic Ridge, between 36° and 38° North, close to the Iceland and Azores hot-spots, respectively. These surveys have provided a data set which provides a unique opportunity to address the relationship between the incidence and location of hydrothermal venting relative to volcanism/tectonism and ridge segmentation. Along the Reykjanes Ridge, running SW from Iceland, deep-tow (TOBI) sidescan sonar and swath bathymetry data have indicated a pattern dominated by volcanism in the form of axial volcanic ridges with only minor tectonic fracturing. A water column survey along this section of ridge crest, using conventional profiling techniques, indicated no evidence for high-temperature hydrothermal activity except at 63°N where the Reykjanes Ridge intercepts the bathymetric platform (≤500m water depth) which surrounds Iceland. Along the Mid-Atlantic Ridge between 36–38°N, running SW from the Azores archipelago, TOBI and swath bathymetry data have imaged a ridge with spreading rate and obliquity of spreading motion similar to the Reykjanes Ridge. But this ridge-section is dominated by tectonism rather than volcanism, the axis being partitioned into a series of short (20–55 km length) segments of spreading axis, each systematically displaced from its neighbours by right-lateral non-transform offsets of 15–50 km. Hydrothermal activity (as detected by a combination of deep-tow instruments and conventional profiling) is much more common along this latter section of spreading centre: evidence for discrete sources of hydrothermal discharge was obtained on fourteen different occasions, in seven separate segments of ridge crest. Sources of hydrothermal activity, including the major Rainbow hydrothermal field, were observed to coincide consistently with ridge-offset intersections suggesting a strong link between tectonic segmentation and the occurrence of high temperature venting.
Regional metamorphism due to anorogenic intracratonic magmatism
Authors: Gibson Roger L. , Stevens Gary 
Published: April 2008

Abstract

The Vredefort Dome, the central uplifted portion of the
c.
300 km diameter, 2.02 Ga Vredefort Impact Structure, exposes a
c.
20 km deep profile through the crust of the Kaapvaal Craton of southern Africa which displays evidence of greenschist- to granulite-facies low-pressure metamorphism. Reaction textures in the medium- to high-grade metamorphic rocks indicate an anticlockwise isobaric cooling
P-T
evolution, and peak metamorphic temperatures consistent with a mid- to upper-crustal geotherm of 40–50°C km
−1
. The metamorphism is attributed to craton-wide intraplating of mantle-derived magmas into the deep crust during the 2.05–2.06 Ga Bushveld Event. Felsic volcanic rocks and high-level intrusions in the Bushveld Complex represent anatectic derivatives from the deeper, high-grade parts of the metamorphic terrane. The intracratonic setting, the absence of evidence of concomitant orogenic deformation, and the preservation of the pre-existing diamondiferous lithospheric root beneath the craton, suggest that the thermal event was triggered by the transient positioning of the Kaapvaal Craton over a mantle plume.
Disequilibrium during metamorphism: the role of nucleation kinetics
Authors: Rubie David C. 
Published: April 2008

Abstract
The sluggishness of nucleation, one of the most poorly understood and least-discussed processes involved in mineral reactions, is an important cause of disequilibrium during metamorphism. Both field-based and experimental petrological studies show that metastable phases can persist far from equilibrium on long time scales because the stable phases are unable to nucleate. This behaviour applies not only to solid-solid reactions but also to some dehydration and melting reactions. Although the degree of overstepping required for nucleation during polymorphic phase transformations is relatively small (2–4 kbar on an experimental time scale), nucleation can be much more sluggish for reactions involving two or more product phases. When reactions occur at conditions of large overstepping due to delayed nucleation, reaction rates can be very fast because of the effect of the large free energy change on growth kinetics. Under these circumstances, new metastable phases may form instead of the stable mineral assemblage, as predicted by the Ostwald step rule. Such metastable phases can persist during metamorphism, even during high-strain ductile deformation and fluid influx, but without any obvious texture evidence to indicate that they are metastable.