bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Antrim–Galway Line: a resolution of the Highland Border Fault enigma of the Caledonides of Britain and Ireland
Authors: Ryan P. D. , Soper N. J. , Snyder D. B. , England R. W. , Hutton D. H. W. 
Published: May 2009

AbstractThe westward continuation of the Highland Border fault of Scotland (HBFZ) into Ireland is problematic. It is widely thought to follow a pronounced magnetic and gravity lineament, the Fair Head-Clew Bay Line (FCL). The advantage of this interpretation is that it places all the Ordovician ophiolitic complexes and associated sedimentary basins to the south of the FCL, which would represent the contact between Laurentia and the outboard terranes. Its main shortcomings are that both the deep structure and timing of strike-slip are different on the HBFZ and FCL. In Ireland the FCL is a north-dipping feature that can be traced to the Moho on BIRPS profiles, while the HBFZ has no such signature. Terrane amalgamation in western Ireland was completed by the late Ordovician, while in Scotland the Midland Valley terrane did not finally dock until the early Devonian. These considerations suggest that in western Ireland a branch of the HBFZ exists, which was active in post-Ordovician time and must lie south of Connemara. An examination of Irish geological, geophysical and image-processed magnetic data shows that a profound lineament can be traced from Antrim to Galway Bay (the Antrim–Galway Line). Stitching plutons date movement on it as pre-405 Ma. We propose that the Antrim–Galway Line represents the continuation of the Scottish HBFZ, while the FCL is a preserved Ordovician splay of the HBFZ system whose northdipping geometry is a product of Ordovician collapse of the orogen in western Ireland.
The stratigraphy, correlation, provenance and palaeogeography of the Skiddaw Group (Ordovician) in the English Lake District
Authors: Cooper A. H. , Rushton A. W. A. , Molyneux S. G. , Hughes R. A. , Moore R. M. , Webb B. C. 
Published: May 2009

AbstractA new lithostratigraphy is presented for the Skiddaw Group (lower Ordovician) of the English Lake District. Two stratigraphical belts are described. Five formations are defined in the Northern Fells Belt, ranging in age from Tremadoc to early Llanvirn. They are all mudstone or sandstone dominated, of turbidite origin; in ascending order they are named the Bitter Beck, Watch Hill, Hope Beck, Loweswater and Kirk Stile formations. Two formations are defined in the Central Fells Belt, ranging in age from late Arenig to Llanvirn. These are the Buttermere Formation – a major olistostrome deposit – overlain by the Tarn Moor Formation, consisting of turbidite mudstones with volcaniclastic turbidite sandstone beds. A revised graptolite and new acritarch biostratigraphy for the Skiddaw Group is presented with eight graptolite biozones and thirteen acritarch assemblages and sub-assemblages. The provenance of the group is assessed from detailed petrographical and geochemical work. This suggests derivation, in the early Ordovician, largely from an old inactive continental arc terrane lying to the southeast, with the appearance of juvenile volcanic material in the Llanvirn. Comparisons and correlations of the Skiddaw Group are made with the Isle of Man and eastern Ireland.
Biostratigraphy of the supra-ophiolite sediments of the Troodos Massif, Cyprus: the Cretaceous Perapedhi, Kannaviou, Moni and Kathikas formations
Authors: Urquhart E. , Banner F. T. 
Published: May 2009

AbstractThe Troodos Massif of Cyprus exposes a classic and much-studied ophiolite sequence representing oceanic crust of Late Cretaceous age. K-Ar dating of the sheeted dykes and of the overlying pillow lavas gives a range of 83±3 Ma (earliest Campanian) and 75±5 Ma (late Campanian) respectively for the formation of the upper levels of the ophiolite. An autochthonous sequence of Late Cretaceous to Recent age sediments is exposed resting on the ophiolite, the oldest part of which reflects sedimentation in an apparently deep marine, oceanic setting. Little biostratigraphical information is available to constrain the chronostratigraphy of these sediments in relation to the complex geological history of the island, including the uplift and unroofing of the ophiolite, despite their richness in microfauna and flora. This paper provides an integrated biostratigraphical study based on radiolaria, planktonic foraminifera and calcareous nannofossils of the oldest part of the supra-ophiolite succession, of the Cretaceous Perapedhi, Kannaviou, Moni and Kathikas formations. For the first time, well-defined micropalaeontological evidence establishes the relative ages of these formations. The umbers of the Perapedhi formation are no younger than Campanian in age while the volcaniclastic sediments of the Kannaviou formation were also deposited during Campanian times. The matrix of the Moni formation contains a microfauna consistent with the hypothesis that it is derived from the Kannaviou. In contrast, the Kathikas formation is composed of sediment derived mainly from the allochthonous Mamonia complex, but autochthonous pelagic interbed horizons demonstrate that it was deposited probably within a very short time interval during the late Maastrichtian. Key index species are figured, including the first published micrographs of Cretaceous planktonic foraminifera from Cyprus.
The geometry and structural evolution of a crustal-scale Caledonian fold complex: the Ballybofey Nappe, northwest Ireland
Authors: Alsop G. I. 
Published: May 2009

AbstractThe gross geometries exhibited by crustal-scale fold nappes are considered a consequence of both original stratigraphic relationships associated with sub-basin configuration, coupled with the nature of the structural regime and tectonic processes involved in the generation of the nappe pile. The Neo-Proterozoic Dalradian metasediments of northwestern Ireland provide a well-constrained and correlatable stratigraphy which defines a sequence of sub-reclined, tight-isoclinal Caledonian (c. 460 Ma) fold nappes. Within this fold complex, the dominant structure is the crustal-scale Ballybofey Nappe, which may be traced for 40 km along strike and is responsible for a regional (500 km2) stratigraphie inversion. The gentle, NE-plunging attitude of this fold results in a complete spectrum of tectonic levels and deformation gradients being exposed. Relatively low strains in the upper fold limb gradually increase down through the nappe, resulting in the generation of composite foliations and lineations and the development of a 10 km thick shear zone which culminates in a high strain basal detachment with underlying pre-Caledonian basement. The Ballybofey Nappe nucleated and propagated along a major zone of lateral sedimentary facies variation, coincident with the margin of a major Dalradian sub-basin. The large amplitude of the nappe is strongly influenced by the lateral heterogeneity within the metasedimentary sequence, and is associated with a minimum of 25–30 km ESE-directed translation concentrated within the overturned limb. Additional significant displacement is also focused along the basal décollement. Generation of the nappe complex resulted in significant crustal thickening and amphibolite facies metamorphism consistent with 15–18 km of burial, induced by a sequence of nappes propagating in the direction of overshear. The ESE-directed translation of the major fold nappes is away from the Caledonian foreland and a gravity-driven mechanism of nappe emplacement is suggested. Rigorous structural analysis within the cohesive stratigraphie framework enables relationships between the tectonic evolution and stratigraphic patterns to be distinguished, thus allowing models of fold nappe generation and mid-crustal deformation to be evaluated.
Structural data from drill core
Authors: Lopez-Diaz Fernando , Bastida Fernando 
Published: May 2009

AbstractA graphical method for the analysis of the orientation of planar and linear structural elements in drill core is presented. Simple computation and projection operations applied to data taken from elements traced on the cylindrical surface of the core are required. To know a structural element(s) of reference, the method requires detailed structural analysis of the surface geology around the drill hole.
Late Cenozoic basin development in west Turkey: Gördes basin tectonics and sedimentation
Authors: Seyítoğlu Gürol , Scott Barry C. 
Published: May 2009

AbstractThe early Miocene sedimentary succession in the northeast-southwest trending Gördes basin is 1000 m thick and divided into the Daĝdere, Tepeköy and Kuşlukköy formations. The age of this fill can be constrained as between 24.2 Ma and 16.3 Ma, at its widest interval. Paleocurrent directions from south to north demonstrate that the basin had a north dipping basin floor. These observations are inconsistent with a previous model of the Gordes basin as a cross graben with a south dipping basin floor, towards the Alaşehir graben, and an anomalously thick (up to 3000 m) basin filling.
Stratigraphy, structure and geochronology of the Las Cañadas caldera (Tenerife, Canary Islands)
Authors: Martí J. , Mitjavila J. , Araña V. 
Published: May 2009

AbstractAfter a long period of subaerial fissure-fed extrusions of basaltic magmas (∼ 12 to > 3 Ma) volcanic activity was then concentrated in the central part of Tenerife. Phonolitic magma chambers formed and a central volcanic complex was constructed (the Las Canadas edifice). The formation of a large depression (the Las Canadas caldera) truncated the top of the edifice. The active twin strato-cones Teide—Pico Viejo are sited in this depression. The history of the Las Canadas caldera and edifice are established from stratigraphy, geochronology (K—Ar dates) and volcanological studies. Two different groups are recognized, separated by a major unconformity. The Lower Group is dated at 2 to 3 Ma and includes the products of several volcanic centres, which together represent several cycles. The Upper Group ranges from 1.56 to 0.17 Ma and includes three different formations representing three long-term (∼ 100 to 300 Ka) volcanic cycles. The periods of dormancy between each formation were of ∼ 120 to 250 Ka duration. The Las Canadas caldera is a multicyclic caldera which formed over the period 1.18–0.17 Ma. Each cycle of activity represented by a formation culminated in caldera collapse which affected different sectors of the Las Canadas edifice. Geological observation and geochronology support an origin by collapse into a magma chamber. The minimum volume of pyroclastic ejecta is substantially greater than the present caldera depression volume (45 km3), but approaches the inferred volume of the original caldera depression (> 140 km3). After the formation of the caldera, sector collapses could also occur at the northern flank of the volcano causing the disappearance of the northern side of the caldera wall.
The carbonate-flysch transition (late Maastrichtian-late Palaeocene) in the Arachova sequence of the Parnassus-Ghiona Zone, central Greece
Authors: Gregou Sophia , Solakius Nikolaos , Pomoni-Papaioannou Fotini 
Published: May 2009

AbstractThe transition from the carbonate to the flysch facies in the Arachova sequence of the Parnassus-Ghiona Zone is represented by argillaceous limestone beds with flaser structures deposited during latest Maastrichtian-Palaeocene time in a pelagic carbonate environment with a periodic clastic influx. Deposition was continuous except for a short interruption during the K/T boundary interval and the earliest Palaeocene when the area was subaerially exposed. This interruption gave rise to the development of a brecciated carbonate horizon through soil-forming processes. The mineralogical composition of the clastic influx (i.e. quartz, feldspars, clay minerals, amorphous iron oxides, amorphous phosphatic compounds), in particular the clay mineral assemblages (i.e. illite, chlorite, irregularly interstratified illite-vermiculite), shows that the clastic supply represents erosional material that originated from a tectonically active continental setting of both carbonate and clastic rocks, presumably the Pelagonian Zone, as for the flysch of the Beotian and Sub-Pelagonian Zones. The arrival of the first clastic material in the Arachova area as early as latest Maastrichtian time, its Pelagonian origin and the persistence of pelagic conditions of sedimentation throughout the Palaeocene, indicate that the Arachova area was situated along the northeastern margin of the Parnassus platform and that it subsided into the Beotian basin. While the central areas of the platform remained tectonically stable during middle Palaeocene times and there was an extensive development of stromatolites, the northeastern marginal areas transitional to the Beotian basin continued to subside allowing pelagic carbonate sedimentation with periods of clastic influx. The total collapse of the platform in the late Palaeocene gave rise to the deposition of the flysch over the entire zone.
Testing the climatic significance of dropstones: an example from southeast Spain
Authors: Bennett Matthew R. , Doyle Peter , Mather Anne E. , Woodfin Joanne L. 
Published: May 2009

AbstractDropstones are clasts which pose a hydrodynamic paradox or which have an exotic lithology with uncertain provenance. Dropstones are usually associated with glacial processes and have recently been used to substantiate the presence of cool climatic phases in the geological record. The aim of this paper is to demonstrate, using an example from southeast Spain, that dropstones can be unreliable palaeoclimatic indicators, and that greater care is required in their interpretation.
Introduction to papers on the Cambrian–Ordovician Boundary
Authors: Norford B. S. 
Published: May 2009

AbstractThe Working Group has the responsibility of recommending a specific level within a suitable stratigraphic section to serve as the global stratotype for the Cambrian–Ordovician Boundary. Commencing in 1974, comprehensive studies culminated in a plenary session in Calgary in 1985 resulting in decisions on the ‘golden-spike’ principle of selecting the boundary at a horizon just below the first influx of nematophorous graptolites. Conodonts are to be used as the primary guide for the selection of the specific horizon and the global stratotype section must have potential for studies using paleomagnetism, geochemistry and other non-biological correlation tools. The specific horizon will correspond approximately to the base of the Tremadoc Series of Wales and slightly higher than the base of Canadian Series as used in western North America.The Calgary meeting considered the Broom Point and Green Point sections in Newfoundland, Canada, and the Xiaoyangqiao section at Dayangcha, China, as prime candidates to serve as the global stratotype. A delegation from the Working Group inspected the Dayangcha sections in 1986. For this visit, comprehensive documentation and description of the sequence were prepared and published and are briefly summarized in the present issue.Specific uncertainties remain to be resolved for the Dayangcha and Newfoundland stratigraphic sections before the Working Group will be ready to recommend selection of a global stratotype.
Review of trilobite biofacies distributions at the Cambrian–Ordovician Boundary
Authors: Shergold J. H. 
Published: May 2009

AbstractDetailed analysis of trilobite assemblages at the Cambrian–Tremadoc transition reveals the presence of four, possibly five, biogeographic provinces: Baltic, North China, Southeast China, North American, and possibly Siberian. One or more discrete biofacies characterize the transition in each province. When plotted palaeogeographically these appear to be largely temperature controlled. Interdigitation of provincialized trilobite biofacies is recognized by the representation of dominant types of trilobite, olenaceans, ceratopygaceans, remopleuridaceans, dikelocephalaceans and leio-stegiaceans in particular, on key boundary sections. These sections, at Nochixtlán, Mexico; Batyrbay, southern Kazakhstan; Broken Skull River, District of Mackenzie, Canada; and Jiangshan–Chang-shan, western Zhejiang, China, permit the correlation of biogeographic provinces globally. As a result of the application of trilobite biostratigraphy relatively few problems prevent the maintenance of a Cambrian–Ordovician Boundary stratotype section in its traditional Baltic biogeographic setting.
The Nærsnes section, Oslo Region, Norway: trilobite, graptolite and conodont fossils reviewed
Authors: Bruton D. L. , Koch L. , Repetski J. E. 
Published: May 2009

AbstractNew collections of trilobites, graptolites and conodonts, the latter figured for the first time, have been made from an unbroken, uniform sedimentary succession across the Cambrian–Ordovician Boundary. The zonal conodont Cordylodus proavus first appears in undoubted pre-Tremadoc strata. Additional conodonts show that the base of the Tremadoc lies within beds correlative with the Symphysurina Zone of North America and at a level above the base of the Hirsutodontus simplex subzone of the C. proavus Zone. Cordylodus lindstromi and Iapetognathus preaengensis first appear at the base of the Tremadoc. The olenid trilobite Jujuyaspis occurs in the same lower Tremadoc interval and has great potential for interregional correlation.
The Chitradurga greenstone succession in south India and evolution of the late Archaean basin
Authors: Bhattacharyya P. K. , Bhattacharya H. N. , Mukherjee A. D. 
Published: May 2009

AbstractThe Chitradurga greenstone succession of south India comprises a thick pile (~ 10 km) of late Archaean volcanic flows and terrigenous clastic sediments, metamorphosed from greenschist to low-grade amphilobite facies. An older near-shore sedimentary sequence of cratonic affiliation and an off-shore bimodal volcanic sequence were deposited contemporaneously on a gneissic basement. The volcanics are metasomatically altered, and major, minor and trace element data fail to discriminate the metavolcanics in terms of modern plate settings. A younger turbidite sequence of coarser elastics covered the older deposits without any apparent tectonic or erosional break. All the rocks of the succession display evidence of similar deformation, prior to invasion by younger granites (~ 2.5 Ga)in a late syn-kinematic phase.This suggests that initially a simple flat-lying downwarp in a continental crust served as the passive receptacle of the platform-type sediments, and also witnessed volcanism along extensional faulting. This phase of the basin was not associated with any compressive deformation. Subsidence of the Chitradurga basin by the denser volcanics and uplift in the gneissic borderlands provided the infrastructure for subsequent development of the younger turbidite sequence covering the still virtually undeformed older deposits. A compressive orogeny, accompanied by granitic intrusion (~ 2.5Ga) in a late kinematic phase, ultimately deformed and uplifted the basin-fill during the declining phase of basinal activity.There is no evidence in the belt to suggest that the plate-tectonic (Wilson cycle) processes, pending a terminal orogeny, were operative during evaluation of the Chitradurga basin.
Transgressions and regressions: a model for the influence of tectonic subsidence, deposition and eustasy, with application to Quaternary and Carboniferous examples
Authors: Collier R. E. Ll. , Leeder M. R. , Maynard J. R. 
Published: May 2009

AbstractThe position of a coastline in time and space is determined by (1) the vertical displacement and/or tilting of the depositional surface, (2) the rate of sediment accumulation or erosion across that surface, and (3) variation of sea-level. All three rates of change may vary through time. We present computer simulations of coastline movements that illustrate the interaction of the above variables, with (1) and (2) held at various defined levels whilst (3) is varied according to the late Quaternary glacio-eustatic sea-level curve. The Corinth Canal section in central Greece exposes uplifted late Quaternary coastal transgressive cycles, each of which may be related to a radiometrically dated, c. 100 ka duration, cycle of sea-level change. Observed stratigraphic sequence geometries are predicted by forward modelling based on the known glacio-eustatic history over the last 430 ka. Milankovitch orbital parameters are calculated for the Carboniferous period. The obliquity and precession parameters are found to have been significantly shorter than at present. A simulation is presented of the effects of sea-level changes across low gradient, fluvio-deltaic environments such as existed in northern England and other parts of the Laurentian continental margin during Upper Carboniferous time.
A model for marine shelf storm deposition in the Lower Cambrian Fucoid Beds of northwest Scotland
Authors: McKie Thomas 
Published: May 2009

AbstractThe Lower Cambrian Fucoid Beds of northwest Scotland are a 20 m thick mixed clastic-carbonate sequence of thinly bedded storm beds deposited on the western margin of the Iapetus Ocean. Proximal facies display plane beds, current ripple laminations and wave ripple laminations and were deposited under the influence of combined steady andoscillatory currents. The steady component of flow appears to have expanded in an offshore direction and weakened during the final stages of storm deposition with respect to the oscillatory component, producing less asymmetrical ripples with less evidence of a preferred migration direction. Distal facies are represented by thin ‘graded rhythmites’. The palaeocurrent data suggest a wide spread of sediment transport directions, but with a north to northeasterly mode which may reflect a geostrophic component of flow. Following storms these beds were burrowed and echinoderms colonized the sea floor, although the limited extent of these processes and the presence of abundant collophane suggests that the fairweather Fucoid Beds shelf was generally quiescent and possibly dysaerobic.
Thrust systems of the Southwest Pyrenees and their control over basin subsidence
Authors: Turner J. P. , Hancock P. L. 
Published: May 2009

AbstractThere are two thrust systems in the Southwest Pyrenees: a NW-SE trending, thin-skin system exposed in the post-Triassic cover and a larger, thick-skin system of NE-SW thrusts in the Palaeozoic basement. The ‘cover’ thrust system propagated and migrated both southward and westward in response to the non-orthogonal collision of Iberia with Europe during Palaeogene mountain building. The ‘basement’ thrust system is interpreted to be a longer-lived structure, initiated during the extensional tectonic regime in mid Cretaceous time, and inverted during the main episode of Pyrenean collision. A model in which interaction of the two thrust systems controlled the timing and magnitude of thrust-induced, flexural subsidence is presented. The development of the basement thrust system caused regional subsidence along the South Pyrenean foreland margin that was subsequently halted by local uplift associated with the west-migratingcover thrust system.
Anatomy of a channel-bank collapse structure in Tertiary fluvio-lacustrine sediments of the Lower Rhine Basin, Germany
Authors: Williams H. , Flint S. 
Published: May 2009

AbstractAn exceptionally well-preserved synsedimentary deformation feature is described from uppermost Miocene fluvio-lacustrine coastal plain sediments, exposed in lignite mines of the Lower Rhine Basin, Germany. The feature is interpreted as a complex, multi-stage channel-bank collapse structure. Rotational slumping of bank material into the channel along two failure surfaces extending below the channel toe generated a series ofminor compressional ‘thrust/backthrust’ structures within the muddy channel-fill sediments. A reconstruction of the failure event is proposed which is linked toa lowering of river stage and subsequent channel abandonment. The accurate description of this unusually well-preserved channel-bank collapse structure may have general application in the interpretation of similar, but less-well-exposed-preserved phenomena elsewhere.