bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Cenozoic evolution of the Lundy Pull-Apart Basin into the Lundy Rhomb Horst
Authors: Arthur M. J. 
Published: May 2009

AbstractThe NW–SE Cornubian fault zones (FZs) continue to southwest Wales, where they caused dextral offsets during the late Stephanian. A fault bounded area of Devonian–Carboniferous strata, intruded by the Tertiary Lundy Igneous Complex, forms the Lundy Rhomboid. It originated as the Lundy Rhomb Graben, created by 28–40 km of Tertiary sinistral strike–slip faulting along the left-stepping NW–SE Sticklepath–Lustleigh FZ (SLFZ). Tertiary sedimentation in the graben was accompanied by intrusion of the 2.5–4.0 km thick igneous complex into its basement. Sedimentation later spread beyond the graben to form a ‘steer's horns’ basin, of which the Stanley Bank and West Lundy basins are remnants. The strata of the rhomb graben and the ‘steer's horns’ basin constituted the perhaps 4 km deep Lundy Pull-Apart Basin. Subsequent relatively minor dextral faulting on the left-stepping SLFZ inverted the graben into the Lundy Rhomb Horst; the basement of the graben was uplifted ≮ 1–2 km (net) and exposed by erosion of the Tertiary strata. The pull-apart basin developed at the intersection of reactivated Hercynian NW–SE transform FZs, and E–W subduction zone thrusts. Cenozoic N–S tensional and compressional reactivations of the thrusts were respectively associated with transtensional development of the pull-apart basin, transpressional of the rhomb horst.
Sedimentation of a Lower Cretaceous (Aptian) coral mound complex, Zaraya Mountains, northern Spain
Authors: Fernandez-Mendiola P. A. , Garcia-Mondejar J. 
Published: May 2009

AbstractA Lower Cretaceous mixed carbonate-siliciclastic sequence is well exposed in the Zaraya Mountains in Guipuzcoa Province, northern Spain. The sequence begins with interfingering deltaic platform facies and marine patch-reef carbonates. This unit is dominated by mudstones and sandstone with minor interbeds of shallow-water carbonates (calcareous mudstones and sandstones and grainstone-packstones). A thick mixed carbonate-terrigenous unit overlies the siliciclastics and is composed principally of limestones and marls. Periodic influx of terrigenous sediments over a dominantly carbonate sea-floor gave rise to repeated cycles typical of a mixed shallow-water platform. Demise of the southerly derived deltaic input allowed the development of a mainly carbonate third unit. Large (several metres across) bioherms resulted from high in situ organic productivity (mechanical breakage of bioclasts, algal-induced precipitation, trapping and baffling of lime mudstone). The mounds grew making up a coral carbonate mound complex. This prograded to the south, towards a small backreef basin, and slightly retreated in its forereef margin. A period of tectonic instability is thought to have been responsible for the drowning of the shallow-water complex, which was unable to keep pace with relative sea-level rise.
Accuracy of historical earthquake locations in Britain
Authors: Musson R. M. W. 
Published: May 2009

AbstractIf historical earthquake data are to be used in studies of regional seismotectonics, it is essential to include information on likely locational uncertainty. Contributory factors include both geophysical parameters and the social environment of the event. A reconstruction of how a recent earthquake might have appeared had it occurred 300 years ago is used to demonstrate the effects of documentary survival. Limits of uncertainty are estimated for two historical earthquakes (7 October 1690 and 28 November 1880) and shown to be large. It is recommended that such events should be shown on epicentral maps as areas rather than points.
The Mathry Dyke, a quartz-dolerite intrusion of probable Carboniferous age in southwest Wales
Authors: Cave R. , Cornwell J. D. , Evans A. D. 
Published: May 2009

AbstractA previously unrecorded quartz-dolerite dyke some 40 km long and up to 15 m wide intrudes Lower Palaeozoic rocks in southwest Wales between Mathry and Llanboidy. It is of discontinuous subcrop but has an overall WNW trend. This crosscuts the Caledonian strike of the country rocks but is parallel with the line of the Hercynian front to the south. The dyke is probably related to the suite of Dinantian basalts and dolerites near the Bristol Channel, to the east of the South Wales Coalfield.
Sm—Nd isotopic age of Precambrian—Cambrian boundary in China
Authors: Jie-Dong Yang , Wei-Guo Sun , Zong-Zhe Wang , Yin-Xi Wang 
Published: May 2009

AbstractBy the new method of Sm—Nd isotopic dating on phosphatic small skeletal fossils and collo-phanite minerals, the Zhongyicun Member of the earliest Cambrian Meishucun Stage at Meishucun in Yunnan, southern China, has been dated at 562.8 ± 7.9 Ma and 562.1 ± 5.7 Ma. Another Sm—Nd age, 570.3 ± 17.1 Ma, has been obtained with samples from the Zhongyicun Member in Yunnan and its stratigraphic equivalents in Sichuan and Xinjiang. These data tend to suggest that the best age estimate of the Precambrian—Cambrian boundary is very likely within the range of 560–570 Ma. As biophosphates and sedimentary phosphates are widely distributed in sequences of the Precambrian—Cambrian transition, the Sm-Nd isotopic method is recommended as an effective approach for precise dating of the initial Cambrian boundary.
Biotite porphyroblast nucleation and growth: control by microfracture of pre-existing foliations in schists in the Robertson River Metamorphics, Australia
Authors: Davis B. K. 
Published: May 2009

AbstractA macroscopic fold formed during the fourth deformation, D4, in the Robertson River Metamorphics, north Queensland, Australia. Growth of biotite, garnet, staurolite and andalusite porphyroblasts also occurred synchronous with D4. Only biotite porphyroblasts have formed preferred alignments across the fold, and they define two dominant orientations. The more common is parallel to D4 fold axes, which is also parallel to D1 D2 and D4 intersection lineations. The other varies up to 90° from this within the D4 axial plane. Mineral elongation lineations do not reflect the extension direction of the deformation in which they formed (D4), but are a function of pre-existing anisotropics in the rock parallel to intersection lin-eations. Porphyroblast growth is inferred to be a result of microfracturing along favourably oriented linear anisotropics formed by multiple intersection of foliations, as well as parting of the the S1, and S2 foliations.
Trace fossils and biofabrics at the Precambrian–Cambrian boundary interval in western Mongolia
Authors: Goldring R. , Jensen S. 
Published: May 2009

AbstractA small suite of trace fossils from the Zavkhan Basin (Govi-Altay) includes many of the ichnotaxa typical of the Nemakit-Daldynian, Tommotian and younger Cambrian stages, and other indeterminate forms. The traces are almost entirely from the sandstone intervals of the large-scale alternations of carbonate and siliciclastic sediments, thus emphasizing the facies and taphonomic controls on trace fossil distribution, and hence the inherent difficulties in using trace fossils in detailed global correlation, especially in using first appearances. The assemblage of traces and biofabrics is seen as resulting from the partly non-uniformitarian (non-actualistic) sedimentary environments that pertained over the boundary interval, rather than as evolutionary failures and subsequently vacated environments.
Integrated chemo- and biostratigraphic calibration of early animal evolution: Neoproterozoic–early Cambrian of southwest Mongolia
Authors: Brasier M. D. , Shields G. , Kuleshov V. N. , Zhegallo E. A. 
Published: May 2009

AbstractFive overlapping sections from the thick Neoproterozoic to early Cambrian sediments of western Mongolia were analysed to yield a remarkable carbon-isotope, strontium-isotope and small shellyfossil (SSF) record. Chemostratigraphy suggests that barren limestones of sequences 3 and 4, which lie above the two Maikhan Uul diamictites, are post-Sturtian but pre-Varangerian in age. Limestones and dolomites of sequence 5, withBoxonia grumulosa, have geochemical signatures consistent with a post-Varangerian (Ediacarian) age. A major negative δ13C anomaly (feature ‘W’) in sequence 6 lies a shortdistance above anAnabarites trisulcatusZone SSF asemblage with hexactinellid sponges, of probable late Ediacarian age. Anomaly ‘W’ provides an anchor point for cross-correlation charts of carbon isotopes and small shelly fossils. Trace fossil assemblages with a distinctly Cambrian character first appear in sequence 8(PurellaZone), at the level of carbon isotopic feature ‘B’, provisionally correlated with the upper part of cycle Z in Siberia. A paradox is found from sequence 10 to 12 in Mongolia: Tommotian-type SSFs continue to appear, accompanied by Nemakit-Daldynian/Tommotian-type87Sr/86Sr ratios but by increasingly heavyδ13C values that cannot be matched in the Tommotian of eastern Siberia. The steady rate of generic diversification in Mongolia also contrasts markedly with the Tommotian ‘diversity explosion’ in eastern Siberia, which occurs just above a major karstic emergence surface. One explanation is that sequences 10 to 12 in Mongolia preserve a pre-Tommotian portion of the fossil record that was missing or removed in easternSiberia. The Mongolian sections certainly deserve an important place in tracing the true course and timing of the ‘Cambrian radiation’.
Pb-isotope evidence on the origin of the West Shropsh orefield, England
Authors: Haggerty R. , Rohl B. M. , Budd P. D. , Gale N. H. 
Published: May 2009

AbstractPb-isotope data on ore galenas from the West Shropshire orefield show a significant spread of20pb/204pb values, with minor variation in 207Pb/204Pb and 208Pb/204Pb ratios. These indicate that lead was derived from multiple sources, some of them uranium-enriched and incompletely mixed prior to ore deposition. Four possible mineralizing agents are considered: circulating sea-water, metamorphic waters, basinal brines and convecting formation waters. Pb-isotope data exclude a circulating sea-water origin for the mineralization, and best support a convecting formation water mineralizing agent. A model involving a single fluid tapping multiple lead sources is proposed to explain the observed Pb-isotope variation.
An interpretation of the gravity anomaly at Warlingham, Surrey
Authors: Kearey P. , Rabae A. M. 
Published: May 2009

AbstractAn interpretation of the negative gravity anomaly at Warlingham, Surrey, controlled by a seismic reflection profile and several boreholes, suggest that it may be caused by a wedge-shaped body of lowdensity Upper Palaeozoic rocks. The seismic reflection data suggest that the upper boundary of the body may be thrust-controlled and originated during Variscan compression. The location of the thrusting appears to be controlled by the southern margin of the stable London Platform. Comparison with similar structures of this type elsewhere suggests that the Variscan Front in this area lies just to the north of Warlingham.
Sedimentary rhythms in the Jurassic and Cretaceous of Svalbard
Authors: Dypvik Henning 
Published: May 2009

AbstractThe Janusfjellet Subgroup on Svalbard consists on a 400 to 500 m thick sequence representing shallow marine depositional environments. Coarsening-upward units, often separated by carbonate beds, are commonly found in rhythmic developments. Rhythmicities (285000(?) and 850000(?) years) in the sedimentary sections show periods which may reflect pulses in nearby sea-floor spreading or strike-slip fault regimes. An astronomical control of the cycles cannot be excluded, although such changes most probably should be expected in superimposed episodes of shorter duration.
The geology and geomorphology of the Beacon Cottage Farm Outlier, St Agnes, Cornwall
Authors: Jowsey N. L. , Parkin D. L. , Slipper I. J. , Smith A. P. C. , Walsh P. T. 
Published: May 2009

AbstractThe mid-Oligocene sediments forming the Beacon Cottage Farm Outlier at St Agnes, Cornwall, have a stratigraphical and geomorphological importance which is out of all proportion to their modest residual bulk (some 300000 m3). During 1986–8 61 holes were sunk into the area surrounding Beacon Cottage Farm; many penetrated the Palaeozoic floor beneath the outlier. Collectively, these show that the outlier mostly covers rotten granite and Killas. The sub-Oligocene unconformity is uneven and varies in altitude by at least 20 m. The local Bovey Formation succession comprises two members: Basal Sand, which is often pebbly, and sandy silts, known commercially as Candle Clay, the whole totalling a maximum of 8.9 m. There is indirect evidence either that slopes on the rotted Palaeozoic floor locally exceed 45° or that several post-mid-Oligocene faults affect the outlier. We conclude that the Beacon Cottage Farm sediments probably represent aeolian, colluvially and fluvially redistributed rotten rock residues, formed locally during a break in the long period of late-Palaeogene subtropical weathering and pediplanation. The outlier is considered in relation to the geomorphological evolution of the Cornubian Massif.
Is Gaia endothermic?
Authors: Hsü K. J. 
Published: May 2009

AbstractGeological evidence suggests that Gaia is endothermic: her body temperature has varied, but within limits; there has been no runaway greenhouse like Venus, nor deep freeze like Mars. This paper presents a hypothesis that the Earth's climate has been ameliorated by living organisms: they have served either as heaters or air-conditioners, and their ecological tolerance is the sensor of Gaia's thermostat. At the beginning, 3.8 or 3.5 Ga ago, only anaerobic autotrophs capable of tolerating high temperatures thinned out the atmospheric CO2 through carbon fixation. Fossil organic carbon was utilized by anaerobic heterotrophs to reinforce the effectiveness of the late Archean greenhouse, when solar luminosity was weaker than it is now. With the increasing solar luminosity during early Proterozoic time, new life forms such as cyanobacteria evolved, removing CO2 from the atmosphere and storing it in stromatolitic carbonates. Over-eager cyanobacteria may have consumed too much greenhouse CO2 to cause glaciation. Their decline coincided in timing with the rise of the Ediacaran faunas which had no carbonate skeletons. The change in the mode of carbon-cycling may have started the warming trend after the Proterozoic glaciation. The Cambrian explosion was an event when skeletal eukaryotes usurped the function of prokaryotes in removing greenhouse CO2 through CaCO3 precipitation. With the evolution of land plants, coal-makers took over the ‘air-conditioning’ duty. They over-did it, and Permo-Carboniferous glaciation ensued. After a wholesale turnover of the faunas and floras at the end of the Palaeozoic, more CO2 was released than fixed in early Mesozoic time. The warming trend reached its zenith in the early Cretaceous, when flowering trees and calcareous plankton began to flourish. The decline since then, with a temporary restoration during early Palaeogene time, could be a manifestation of the varying efficiency of extracting and burying carbon dioxide, in the form of inorganic and organic carbon. The relation of atmospheric CO2 and climatic variation is documented by study of air bubbles in ice cores. Yet there is also correlation to astronomical cycles. The latter seem to have triggered changes which are amplified by feedback mechanisms of carbon cycling.
Neotectonic development of the Struma (Kraištid) Lineament, southwest Bulgaria and northern Greece
Authors: Zagorčev I. S. 
Published: May 2009

AbstractThe Struma (Kraištid) Lineament is a part of a fault belt of regional importance. It strikes NNW-SSE and cuts through different Alpine tectonic zones along the whole Balkan Peninsula. Normal and strike-slip faults occurred in environments of extension and graben formation during collapse after or between collision epochs in the Palaeogene and Early Neogene, and in a back-arc extensional environment during the neotectonic (end of Middle Miocene-Quaternary) stage. The last Alpine compression phase occurred in the beginning of the Miocene, and Early-Middle Miocene planation formed the initial peneplain. New intense faulting marked the beginning of the neotectonic stage (Late Badenian), and the neotectonic development, including sedimentation, proceeded in four regional macrocycles: Badenian-Sarmatian; Maeotian; Pontian-Dacian; and Eopleistocene-Pleistocene. The neotectonic development was marked by formation of the Serbo-Macedonian Swell as well as by rifting (the Vardar and Struma rifts).
The age of the Büyük Menderes graben (west Turkey) and its tectonic implications
Authors: Seyіtoǧlu Gürol , Scott Barry C. 
Published: May 2009

AbstractThe age of formation of the Büyük Menderes graben (middle Burdigalian-middle Serravallian) is earlier than previously considered (Tortonian). This supports the contention of Seyitogˇlu & Scott that north-south extensional tectonics in west Turkey commenced at the latest during early Miocene time, following a Palaeogene compression.
Chronometric calibration of mid-Ordovician to Tournaisian conodont zones: a compilation from recent graphic-correlation and isotope studies
Authors: Fordham Barry G. 
Published: May 2009

AbstractThree available graphic-correlation analyses are used to calibrate mid-Palaeozoic conodont zonations: Sweet's scheme for the mid- to Upper Ordovician; Kleffner's for the mid- to Upper Silurian; and Murphy & Berry's for the lower and middle Lower Devonian. The scheme of Sweet is scaled by applying the high-precision U-Pb zircon date of Tucker and others for the Rocklandian and linked with that of Kleffner by scaling the graptolite sequence of the Ordovician-Silurian global stratotype section to fit two similarly derived dates from this sequence. The top of Kleffner's scheme, all of Murphy & Berry's, as well as standard zones to the Frasnian are calibrated by using tie-points of the latest Cambridge-BP time-scale (GTS 89). However, the recent microbeam zircon date by Claoué-Long and others for the Hasselbachtal Devonian-Carboniferous auxiliary stratotype is used to calibrate the standard Famennian zones. Also the similarly derived but preliminary determination reported by Roberts and others from the Isismurra Formation of New South Wales is tentatively taken as the top of the Tournaisian and so used to calibrate Tournaisian zones. Despite the considerable extrapolation required to compile these schemes and their inherent errors, the resultant time-scale closely agrees with other dates of Tucker and others from the Llanvirn as well as the GTS 89 Homerian-Gorstian tie-point. This suggests that stratigraphic methods can be usefully applied to geochronometry. The Llandovery appears to have lasted longer (16 m. y.) than usually envisaged and the Ordovician-Silurian boundary may need to be lowered to approximately 443.5 Ma. Certainly, chrons varied widely in duration and further stratigraphic studies to estimate their relative durations as well as high-resolution dating for their calibration will be crucial to more accurate biochronometries.
The lichid trilobiteRadiolichasin the Silurian of Arctic Canada and Gotland, Sweden
Authors: Adrain Jonathan M. , Ramsköld Lars 
Published: May 2009

AbstractRadiolichashas been a poorly known and exclusively Devonian genus of very limited diversity.Radiolichas raydaviesisp. nov. andR. davedaviesisp. nov. are the best-known members of the genus, and extend its stratigraphic and geographic range to the Wenlock of the central Canadian Arctic. A further Silurian occurrence is an unnamed species from the Wenlock Slite Beds of Gotland, Sweden.Radiolichasis most similar toDicranogmus. Together, the genera lack any of the robust trochurine apomorphies (linear pygidial postaxial ridge, prominent pygidial border, prominent cranidial fossula) and appear to fall outside the phylogenetic structure of that subfamily. They are similar to members of the Tetralichinae, particularly in pygidial features, but lack the composite cranidial lobe characteristic of that subfamily. Their systematic position is presently unresolved.
Pluton emplacement by wall-rock thrusting, hanging-wall translation and extensional collapse: latest Devonian plutons of the Cobequid fault zone, Nova Scotia, Canada
Authors: Koukouvelas I. , Pe-Piper G. , Piper D. J. W. 
Published: May 2009

AbstractLatest Devonian A-type granite-gabbro plutons, in part ductilely deformed, are spatially associated with the strike-slip Cobequid fault zone. The youngest intrusions are close to the Cobequid fault zone, which was the main conduit for magma. Two phases of deformation accompanying magma emplacement are recognized. Early magmas intruded ductile rocks during left-lateral oblique thrust movements. A second stage of right-lateral oblique slip normal faulting accommodated uplift of the plutons when coarse granite was emplaced in the crestal regions. Cross-cutting late stage porphyries, granitic clasts in marginal basins cut by granitic dykes, and superposition of brittle on ductile structures all indicate rapid uplift of the plutons. The geometry of the Cobequid fault zone shows that pluton emplacement was not the result of extension in releasing bends during transcurrent shear. Rather, flower-structure high-angle faults acted as magma conduits and space was created by two processes: translation of wall rocks along thrust faults at depth, developing space away from the master fault zone and backward collapse of the uplifted magma chamber creating space towards the fault zone.
On the first partial skull of an ankylosaurian dinosaur from the Lower Cretaceous of the Isle of Wight, southern England
Authors: Norman David B. , Faiers Tamsin 
Published: May 2009

AbstractThe specimen is identified as the partial cranium of a nodosaurid ankylosaur (Ornithischia: Thyreophora) on the basis of the presence of bone which is fused to the dorsal surface of the skull and has secondarily closed the upper temporal fenestrae. The only unequivocally nodosaurid material recovered from the Isle of Wight to date comes from Wealden facies, and has been referred to the genusPolacanthus; it is considered highly probable that this new skull is referable to the same genus. Despite having undergone abrasion, through post-emergence water-rolling, the skull and cranial walls have proved to be relatively informative of the general anatomy of the braincase and the neural and vascular anatomy of this part of the head. The anatomy of the braincase of most ankylosaurs (with the notable exception of the juvenile specimens of the ankylosauridPinacosaurus) is surprisingly poorly known, despite the relative abundance of cranial material in North American and Asian collections.The cranial neural and vascular anatomy is well shown in this specimen and enables the first detailed description of nodosaurid endocranial structures. The general form of the brain can be outlined from the structure of the endocast and the principal lobes can be identified; the majority of the cranial nerves have been identified, and a significant component of the associated vascular system is also visible. In most respects the endocast shows a neural anatomy which is common to that known in most dinosaurs. When compared to their nearest relatives, the ankylosaurid ankylosaurs (Euoplocephalus), the nodosaurid endocranial cast shows a more pronounced cerebral flexure, a forebrain which is broader and more expanded dorsally, and a more prominent cerebellum (although there is no evidence for a floccular lobe); there are minor differences in the arrangement of the cranial nerves, and the dorsal portions of the vascular system are better shown.Because of erosion, the olfactory lobes of this specimen of cf.Polacanthusare not preserved, and cannot be compared to those of ankylosaurid ankylosaurs; the latter are unusual in the strong separation of the lobes (reflected in the divergent olfactory stalks); this feature may be associated with the very complex passages within the nasal region of the skull, which are lacking in the nodosaurids described to date.