bluuebunny/crossref_metadata_2025_split huggingface dataset:
A model of sea-levels in the Irish and Celtic seas during the end-Pleistocene to Holocene transition
Authors: Wingfield Robin T. R. 
Published: April 2008

Abstract

A macroscale model is attempted to accommodate offshore observations indicative of former sea-levels in the Irish and Celtic seas. The indications considered here are those that appear to post-date 12 ka
bp
. Raised beaches at about present sea-level, and formed in the Last Interglacial, are found about these seas. This shows that controls to produce the later sea-level changes have acted to return to about their conditions in the Last Interglacial, and that later permanent tectonic displacements have not been significant. A simple, geometrically based model is developed of the interaction of: glacio-eustasy, from graphs based on coral-reef studies; glacio-isostatic depression with an annular forebulge of equal volume, both contracting through the interval considered; and hydro-isostasy, as an enhancement of the other effects by up to 20%. The best fit of the empirical submarine data suggests that from 12 to 9 ka
bp
relative sea-levels varied from 80 m above, and 160 m below present mean sea-level in the two seas. The resultant sea-level graphs for points from Scotland to Ushant compare with published graphs from eastern North America and northern Europe. Derived maps of palaeocoasts show land-bridges from Britain to Ireland and later to the Isle of Man after 11.35 ka
bp
.
The floristic record of Ireland’s Pleistocene temperate stages
Authors: Coxon P. , Waldren S. 
Published: April 2008

Abstract

The unique flora of Ireland, that includes plants with Atlantic, amphi-Atlantic and Mediterranean affinities, has attracted the attention of many biogeographers. Using a database, this paper compiles the Irish Pleistocene plant fossil record and examines the disappearances of some taxa and the continuity of others. A retreat of some plants to the east since the Tertiary, movement of arctic-alpine species to the north and to the mountains, and the long continuity of Atlantic and amphi-Atlantic taxa, including some not present in Britain, can be identified. The flora of the Irish Middle Pleistocene Gortian temperate stage is examined and its uniqueness, and the long continuity of certain taxa, are discussed. The long record of Atlantic and amphi-Atlantic species, as well as wetland and aquatic taxa, suggests the possibility of proximal refugia for some plants. The implications for
in situ
survival and for migration during and after cold stages are discussed in the light of the compiled fossil record.
Database design in geochemistry: BGS experience
Authors: Coats J. S. , Harris J. R. 
Published: April 2008

Abstract
The Minerals Group of the British Geological Survey (BGS) has been successfully using a relational database for over seven years to hold geochemical and related locational and geological data collected by the DTI-sponsored Mineral Reconnaissance Programme (MRP) since 1972. Operational experience has shown that several problems and deficiencies of the database are the result of the lack of normalization of the original data model. A new data model, derived from analysis of the data collected by the MRP and other geochemical programmes, is presented and solves many of these problems. It is designed to hold all BGS geochemical data for the UK landmass and is currently being implemented. It is presented as a contribution to a wider debate on generalized data models for geochemistry.
The nature of data on a geological map
Authors: Giles J. R. A. , Bain K. A. 
Published: April 2008

Abstract

The primary purpose of the traditional geological map is to convey the map maker’s understanding of the geology of an area to the user of the map. A second, and less well understood role is as the
de facto
repository for much of the recorded geological data of an area. With the advent of digital geological map production, geographic information systems and digital geological databases, these traditional roles are changing. The data from which a map is constructed can reside in geological databases and the maps produced from these databases can concentrate on conveying information to the map user.

The design and construction of the digital geological databases used to store the information collected by geologists requires a detailed understanding of the elements of a geological map. This paper attempts to describe those elements and discusses some of the problems caused by the conventions used on geological maps.
Database design and data management on the Swansea-Llanelli Earth Science Mapping Project
Authors: Power S. , Scott M. , Robinson G. , Statham I. 
Published: April 2008

Abstract

Earth science, environmental and planning information was collected for a 200 km
2
area centred around Swansea and Llanelli, South Wales. The aim was to use this data to produce development advice maps for use in the planning process. To ensure efficiency of data storage and retrieval, a relational database was used, combined with a geographic information system (GIS), the GIS helping with data collection and data entry. This required the design of a logical model for data storage and manipulation, together with customized database forms for input and reporting. Information was captured in a variety of forms, ranging from reports and maps to text and existing databases, and often required different input techniques. The resulting comprehensive database was therefore stored in a structured way which has enabled effective interrogation and querying of the data to produce the information around which the final maps can be drawn. These, and the data, have already proved to be of importance and interest within the study area.
Hydrocarbon seepage dating through chemical remagnetization
Authors: Perroud Hervé , Chauvin Annick , Rebelle Michel 
Published: April 2008

Abstract
A magnetostratigraphic study of Permian red sandstones from the Van Dyck well, offshore the Netherlands, revealed an anomalous magnetization, with normal polarity and a high inclination (+47°), interpreted as a Jurassic chemical remagnetization. An extensive investigation of the magnetic mineralogy indicated that, in addition to the main carrier (hematite), minor magnetic phases were present (magnetite, maghemite or pyrrhotite). This last phase is unstable with temperature and has a Curie point of 350°C. As an interpretation, late hematite precipitation (200–150 Ma ago) is proposed, following an initial dissolution of the original hematite and precipitation of magnetite and/or other low coercivity minerals, possibly in association with seepage of reducing fluids such as hydrocarbons. This model allows the proposition of a Jurassic age for the end of the hydrocarbon migration, giving new constraints to the origin of the fossil products in this basin.
Palaeomagnetic implications for the timing of hematite precipitation and remagnetization in the Carboniferous Barren Red Measures, UK southern North Sea
Authors: Johnson S. A. , Turner P. , Hartley A. , Rey D. 
Published: April 2008

Abstract
Although rocks of the Carboniferous Barren Red Measures in the UK southern North Sea are often primarily reddened, they also show secondary reddening by fine-grained hematite precipitated as a result of deep weathering below the Permian unconformity. However, palaeomagnetic and petrographic analyses of samples from wells 49/1–3 and 49/2–3 have shown that a third phase of hematite was precipitated in the Triassic. The specularite grains associated with this magnetization are larger than those precipitated in the Permian and also contain a more dominant magnetic signature. Although Permian hematite precipitation was largely produced as a result of oxidation through vertical percolation, the occurrence of Triassic hematite grains appears to be related to distinct fluvial channels. It is suggested that lateral fluid flow is responsible for the precipitation of hematite in the Triassic and that this is associated with fluvial channel sandstones which have the best permeabilities and interconnectivities. The palaeomagnetic technique is therefore useful for assessing the degree of lateral communication in reservoir sandstones.
Magnetostratigraphic correlations in two cores from the late Triassic Lunde Formation, Beryl Field, northern North Sea, UK
Authors: Hounslow Mark W. , Maher Barbara A. , Thistlewood Laurence , Dean Kevin 
Published: April 2008

Abstract

The magnetostratigraphy of two cores from the late Triassic Lunde Formation of the northern North Sea are compatible with the calibrated magnetostratigraphy for the Norian stage determined by Gallet
et al.
(1993) from Tethyan carbonates. The polarities of the cores indicate a lower to upper Norian age for core 9/13A–36 and lower to middle Norian age for core 9/13A–A45. The isolated characteristic magnetizations are due to a Triassic detrital remanent magnetization, which is partially overprinted with a drilling-induced remanence of two origins. The drilling-induced remanences are associated with (1) the main coring procedure, producing an overprint which is oriented downcore and (2) the subsample coring procedure, which produces an overprint parallel to the subsample core axis and directed outwards from the main core axis. The elimination of those specimens with a significant drilling-induced remanence is important for the determination of the magnetostratigraphy in these cores.
Phenotypic experiments into new pelagic niches in early Danian planktonic foraminifera: aftermath of the K/T boundary event
Authors: Koutsoukos Eduardo A. M. 
Published: April 2008

Abstract

In the aftermath of the Cretaceous-Tertiary (K/T) boundary event it appears that unusual phytoplankton blooms were boosted by the abundant nutrient levels left over from a short-lived ‘Strangelove Ocean’ period, which possibly gave rise to the negative-to-positive δ
13
C surface-to-bottom gradient in the Danian.

The highly plastic morphology of the planktonic foraminifera at the base of the Palaeocene appeared, most likely, as an adaptive response of functional morphology to the pelagic habitat of the species and its mode of life. The diversification episodes of Danian planktonic foraminifera appear to correspond to times of reduced oceanic mixing, stratified water masses, recovery of the surface water productivity and a progressive expansion of the trophic-resource continuum, with periods of maximum diversity corresponding to widespread oceanic surface-water oligotrophic conditions. These suggest a parallel adaptive trend of feeding strategies caused by the changing availability of nutrients in the water column, with probable increasing reliance in symbiosis under low nutrient conditions later in the Danian.

Guembelitria cretacea
, one of the few Cretaceous survivors, has been recorded in northeastern Brazil up to the lower part of the P2 Zone. A triserially coiled planktonic morphotype, this species started to diversify immediately after the K/T transition. After only a few thousand years, in the earliest Danian, the first Tertiary taxa (the
Guembelitria- Woodringina
lineage) appeared; these are microperforate nonspinose forms that were probably restricted to shallow epipelagic waters. There is a trend towards uncoiling of the triserial pattern by progressively changing the positioning of the aperture, without any detectable ecophenotypic preference at first.

The first specimens of the
Eoglobigerina-Pseudosubbotina, Eoglobigerina-Subbotina
and
Praemurica
lineages, cancellate spinose and non-spinose forms, also evolved in the Danian in a nearly coeval and parallel evolutionary trend from a probably ancestral Hedbergella stock.

A revised phylogeny is suggested for the early Palaeocene planktonic foraminifera based on recorded stratigraphic ranges and morphological affinities (chamber arrangement and surface texture ornamentation).
Recovery of North Caucasus foraminiferal assemblages after the pre-Danian extinctions
Authors: Bugrova E. M. 
Published: April 2008

Abstract

The planktonic changes associated with the Maastrichtian-Danian boundary are described from successions in the North Caucasus, Russia. The extinctions recorded in the benthonic fauna are less sudden than those recorded in the plankton, with many pre-dating the end of the Maastrichtian. The Danian benthonic fauna contains a number of survivor taxa with few new species. The recovery interval for the benthonic fauna was much shorter and the increase in diversity occurred earlier than that of the planktonic fauna. Within the
Globorotalia angulata
Zone the recovery of the foraminiferal assemblage was almost complete.
A critique of techniques for modelling normal-fault and rollover geometries
Authors: Hauge T. A. , Gray G. G. 
Published: April 2008

Abstract
A review of the published literature indicates that antithetic oblique shear, at an angle of 30 ± 10° measured from the vertical, is the most appropriate algorithm for quantitative modelling of geometric relationships between downward-flattening normal faults and the strata in their hanging walls. This conclusion is based on 2D analysis of 11 natural examples (listric normal faults without apparent salt involvement, shale mobility, or footwall deformation) and selected laboratory physical models. It may not apply where mobile salt, mobile shale, or significant footwall tilting or deformation is present. Antithetic oblique shear, like all modelling algorithms, does not accurately simulate natural deformation processes, which are significantly more complex.
Analysis of fault geometry and displacement patterns
Authors: Needham D. T. , Yielding G. , Freeman B. 
Published: April 2008

Abstract
Interpretation of the subsurface is still often performed on suites of vertical seismic sections with structures being correlated from line to line to build up a map view at a particular horizon. The advent of 3D seismic surveys and routine use of interpretation software has made it common to produce ‘horizon-based’ interpretations, using auto-tracking techniques. Neither of these approaches guarantees a three-dimensionally consistent interpretation because of ambiguities in lateral and vertical correlation of structures. More reliable descriptions of a faulted surface can be obtained if the three-dimensional properties of a fault network are observed directly. Fault traces picked on vertical sections can be used to model the fault surfaces, which are then viewed in perspective to give an immediate assessment of the plausibility of the interpreted fault geometry. By associating horizon terminations with their respective fault segments this cut-off information can be shown on the perspective view of the fault surface, allowing the interpreter to examine in detail how reservoir layers are disrupted and juxtaposed by the fault network. The horizon cut-off information can also be used to calculate displacement-related values (throw, heave, separation) which may be gridded over the entire picked surface in order to produce displacement maps, also in the perspective view. Isolated single faults have simple displacement patterns with a maximum near the fault centre. Fault arrays show partitioning of displacement between the various splays, with relatively abrupt changes in the displacement at branchlines. Long ‘single faults’ are frequently shown to be segmented into en-echelon arrays rather than being simple continuous structures. Antithetic faults exhibit a downward decrease in displacement towards a tip line near their master fault. In areas of cross-cutting fault trends, displacement patterns can discriminate between different possible kinematic histories. Fault displacement can also be used to calculate other attributes such as fault seal potential, which can also be posted onto the perspective view of the fault surface. These analyses of fault geometry and displacement allow a more objective assessment of subsurface interpretation. They do not rely on particular assumptions about deformation mechanisms, only on the observation that displacement variation on individual fault surfaces is systematic.
Crustal fault reactivation facilitating lithospheric folding/buckling in the central Indian Ocean
Authors: Beekman F. , Bull J. M. , Cloetingh S. , Scrutton R. A. 
Published: April 2008

Abstract

High-quality, normal-incidence seismic reflection data confirm that tectonic deformation in the central Indian Ocean occurs at two spatial scales: whole lithosphere folding with wavelengths varying between 100 and 300 km, and compressional reactivation of crustal faults with a characteristic spacing of
c.
5 km. Faults penetrate through the crust and probably into the upper mantle. Both types of deformation are driven by regional large intraplate stresses originating from the Indo-Eurasian collision. Numerical modelling of the spatial and temporal relationships between these two modes of deformations shows that, in agreement with geophysical observations, crustal faults are reactivated first with stick-slip behaviour. Subsequent lithospheric folding does not start until horizontal loading has significantly reduced the mechanical strength of the lithosphere, as predicted by elasto-plastic buckling theory. Modelling suggests that lithospheric folding does not develop in the absence of fault reactivation. Crustal fault reactivation, therefore, appears to be a key facilitating mechanism for oceanic lithospheric buckling in the central Indian Ocean.
Internal structure of a detachment horizon in the most external part of the Pyrenean fold and thrust belt (northern Spain)
Authors: Sans M. , Sánchez A. L. , Santanach P. 
Published: April 2008

Abstract
The thick Eocene Cardona salt forms the detachment horizon of the most external part of the Pyrenean fold and thrust belt. This salt horizon forms the cores of anticlines and is intensively mined for potash. The study of the structure of the salt layer at three sites (Cabanasses, Súria-Shaft IV and Balsareny underground mines) reveals that the metric and decametric scale structures are consistent with deformation in a shear zone (detachment horizon) with a shear sense of top-to-the-south and not related to compressional or diapiric folding. A further study shows that these structures are later modified by larger wavelength folds and thrusts which have a surface expression. The total horizontal shortening in the two anticlines studied (Súria and El Guix) is a minimum of 750 m. All the folds developed in the detachment horizon have horizontal axes which are normal to the shear direction. This contrasts with folds developed in detachment horizons with intense shearing, where folds with axes parallel to shear direction are common.
Influence of salt on fault geometry: examples from the UK salt basins
Authors: Stewart S. A. , Harvey M. J. , Otto S. C. , Weston P. J. 
Published: April 2008

Abstract
The influence of salt layers on cover faulting during thick-skinned extensional faulting is examined using seismic examples from the salt basins offshore UK. The ratio of salt layer thickness to basement fault displacement is a key geometric parameter governing spatial offset between cover and basement fault segments. The influence of geological factors such as stratigraphic variation in salt thickness, basement fault zone geometry and basement fault growth through time on this parameter are individually examined. 3D models are constructed to illustrate the spectra of possible fault geometries which result from variations in these factors. Lateral stratigraphic variations within individual ‘salt’ layers are also considered, as are complications introduced by the addition of further salt layers into cover stratigraphy. Since diapiric intrusions occur after cover fault geometries are established and are localized by such faulting, an understanding of basement-cover fault relationships also illuminates salt diapir-basement fault relationships. An example from the Central North Sea diapir province is subject to such a genetic analysis, relating the diapir and its location to an underlying basement fault. The influence of salt on cover fault reactivation during basin inversion is discussed, focusin on the southern North Sea, where inhibition of reverse fault propagation from basement to cover is noted. It is suggested that analysis of local basement-cover relationships should form a first step in any attempt at a genetic classification of salt bodies.
Genesis of large counter-regional normal fault by flow of Cretaceous salt in the South Atlantic Santos Basin, Brazil
Authors: Szatmari P. , Guerra M. C. M. , Pequeno M. A. 
Published: April 2008

Abstract
The outstanding feature of the Santos Basin is a gigantic landward-dipping listric fault, about 300 km long, which trends NE parallel to the coast and is soled in the Aptian salt. This fault forms the seaward limit of a half-graben, up to 50 km wide and restricted to the post-salt sediments. In the present work we show, by physical modelling, that such a fault can result from the flow of salt in response to progradation of sediments over a spreading salt layer.
Global δ
13
C changes across the Paleocene-Eocene boundary: criteria for terrestrial-marine correlations
Authors: Stott Lowell D. , Sinha Ashish , Thiry Medard , Aubry Marie-Pierre , Berggren William A. 
Published: April 2008

Abstract

The early Cenozoic marine carbon isotopic record is marked by a long-term shift from high δ
13
C values in the late Paleocene to values that are 2 to 3 lower in the early Eocene. The shift is recorded in fossil carbonates from each ocean basin and represents a large change in the distribution of
12
C between the ocean and other carbon reservoirs. Superimposed upon this long-term shift are several distinct carbon isotopic negative excursions that are also recorded globally. These carbon isotopic ‘events’ near the Paleocene-Eocene boundary provide stratigraphic information that can facilitate intersite correlations between marine and non-marine sequences.

Here we present a detailed marine carbon isotopic stratigraphy across the Paleocene-Eocene boundary that is constrained by calcareous nannofossil and planktonic foraminifera biostratigraphy and magnetostratigraphy. We show that several distinct carbon isotopic changes are recorded in uppermost Paleocene and lowermost Eocene marine biogenic carbonate sediments. At least one of these isotopic changes in the ocean’s carbon isotopic composition was transmitted to terrestrial carbon reservoirs, including plant biomass via atmospheric CO
2
. As a consequence of this exchange of
12
C between the ocean and terrestrial carbon reservoirs, it is possible to use carbon isotope stratigraphy to correlate the uppermost Paleocene and lowermost Eocene non-fossiliferous terrestrial sediments of the Paris Basin with marine sequences.