bluuebunny/crossref_metadata_2025_split huggingface dataset:
The metallotectonics in Eastern Shandong gold metallogenetic province, China
Authors: Enhuai Liu 
Published: July 2007

ABSTRACTBased on research into the macro‐ and micro‐structures within the Eastern Shandong gold metallogenetic province, fractures are the main ore‐controlling and ore‐bearing structures, revealing a process of ductile deformation in the early period and brittle deformation in the later period, when gold mineralization mainly occurred.The ore‐bearing structures can be classified into five types: (a) fracture structures; (b) fissure structures; (c) fracture and fissure structures; (d) fracture, fissure and concealed explosion breccia pipe structures; and (e) fracture and explosive breccia structures. NE‐trending fractures are the most favourable to the formation of gold orebodies, next in importance are the NNE‐trending fractures. NW‐trending fractures controlled the distribution and the maximum depth of gold ore shoots during mineralization and intercept the veins with dextral offsets subsequent to mineralization. The different types of orebodies each have their own specific structural controls. Furthermore, the vertical zonation between the auriferous silicified rock and sericite–quartz rock is interpreted as resulting, from convective circulation. The author analyses the areal structural history, sets up a structural model and suggests that the difference between the orebodies in the Zhaoyuan–Yexian and Mupin‐Rushan metallogenetic areas results from the distinct structural controls on the ore‐bearing fractures in the two areas.
Sedimentological investigations of metamorphic clastics: the basal clastic rocks of the Brenner Mesozoic (Stubai Alps, Austria/Italy)
Authors: Stingl Volkmar , Krois Peter 
Published: July 2007

ABSTRACTSedimentological investigations were carried out in the basal clastic rocks of the Brenner Mesozoic in the Stubai Alps. These are Scythian in age and metamorphosed to a greenschist grade. The increase of temperature and pressure from north to south allows the metamorphic effects on Sedimentological features to be gradually traced into higher grade metamorphic areas. The use of various laboratory methods as well as profiling with lithofacies types shows the limitation of using only single methods in sediments suffering thermal and deformational overprint. Only a combined application of different methods allows the extraction of useful sedimentological information.Based on the results of these investigations, a fan delta to shelf succession is proposed for the basal clastic rocks. Petrographic analyses show the relation of the sediments to an underlying weathering horizon.
Late Cretaceous oceanic crust and Early Tertiary foreland basin development, Euboea, Eastern Greece
Authors: Robertson A.H.F. 
Published: July 2007

ABSTRACTIn northern Euboea (Eastern Greece), Late Cretaceous platform carbonates of the Pelagonian Zone pass depositionally upwards into Maastrichtian hemipelagic limestones, possibly reflecting a rifting event in the adjacent Neotethys. This is followed by a c. 1 km‐thick unit of siliciclastic turbidites, debris flows and detached limestone blocks. Thrust intercalations of ophiolitic rocks comprise altered pillow basalts and ultramafic rocks with ophicalcite. Calcite veins in sheared serpentinite contain planktonic foraminifera and the ophicalcite is directly overlain, with a depositional contact, by Globotruncana‐bearing pelagic limestones and calciturbidites of Maastrichtian age. The ophiolitic rocks are interpreted as Late Cretaceous oceanic crust and mantle, that formed at a fracture zone, or rifted spreading axis within a Neotethyan, Vardar basin to the east. During the Early Tertiary (Palaeocene–Eocene), the Neotethyan basin began to close, with development of a subduction‐accretion complex, mainly comprising sheared, trench‐type sandstones, associated with ophiolitic slices. In response to trench/margin collision, the Pelagonian carbonate platform foundered and limestone debris flows and olistoliths were shed into a siliciclastic foreland basin. Suturing of the Neotethyan ocean basin then resulted in westwards thrusting of oceanic units over the foreland basin, thrusting of slices of inferred Late Cretaceous Pelagonian carbonate platform slope and large‐scale recumbent folding.
The Bishop's Castle (UK) Earthquake of 2 April 1990
Authors: Ritchie M.E.A. , Musson R.M.W. , Woodcock N.H. 
Published: July 2007

ABSTRACTA large earthquake, by British standards, occurred near Bishop's Castle in the Welsh Borders on 2 April 1990 at 13:46 GMT. This magnitude 5.1 ML event was felt over a wide area of Britain, from Ayrshire in the north to Cornwall in the south, Kent in the east and Dublin in the west. The epicentre was near the village of Clun, 7 km SSW of Bishop's Castle. Damage was minor and limited to the epicentral area, north to Wrexham and in particular Shrewsbury, which suffered most. Results from a macroseismic survey by BGS revealed that the maximum intensity in the epicentral area was 6 MSK.The mainshock had a focal depth of 14.3±4.7 km; however, better located aftershocks further constrained the mid‐crustal seismicity to 15±0.2 km in the best cases. The marked lack of aftershocks contrasts with some previous similar magnitude events for intraplate earthquakes in Britain and throughout the world and may represent a large stress drop due to almost total relief of strain energy by the mainshock. The aftershock epicentral distribution shows a preference for an approximately N‐S orientation which is consistent with one of the focal planes of the mainshock focal mechanism and suggests that this is the fault plane. Movement on this plane was predominantly strike‐slip with a component of thrust and was consistent with a maximum compressive stress axis orientated NW‐SE. The NE striking Welsh Borderland Fault System dominates the epicentral area; however, there is no surface fault which can clearly be related to the seismicity.
Ophiolitic melange and flyschoidal sediments of the Tithonian–Lower Cretaceous in Albania
Authors: Shallo Minella 
Published: July 2007

ABSTRACTOphiolitic melange and flyschoidal sediments of the Tithonian‐Lower Cretaceous age are widespread in the Eastern Albanides. They lie transgressively or normally on top of the ophiolitic sequence through radiolarian cherts of the Kimmeridgian‐Tithonian age, or on top of the carbonate sequence of the periphery of the ophiolites through Middle Liassic‐Dogger‐Malm pelagic limestones with manganese nodules and radiolarian cherts. They are overlain by conglomerates or neritic limestones of the Lower Cretaceous age.Ophiolitic melange consists of ophiolitic conglobreccias, often of homogenous composition: serpentinite melange with a ‘sedimentary’serpentinite matrix, or basaltic ‘sedimentary’tuffagglomerate. Less commonly they have a heterogeneous composition with small amounts of fine‐grained matrix and marls with calpionellids. In other examples, the ophiolitic melange contains heterogeneous exotic blocks including all the members of the ophiolite suite: serpentinite, ophicalcite, gabbro, plagiogranite, diabase, basalts, dacites, amphibolite, sulphide and chromite ores as well as blocks of radiolarites, limestones etc. in the argillic matrix. They are overlain by conglomerate‐sandstone‐marly flyschoidal deposits with abundant ophiolitic detritus and calpionellids.These deposits are linked with Tithonian‐Lower Cretaceous tectogenesis, which led to the fragmentary uplift of ophiolites and partly of their sedimentary periphery, and to the formation of the faulted topography.The presence of the ophiolitic melange and flyschoidal sediments both over the ophiolites and the associated sedimentary rocks of their periphery indicate that the latter were not the basement of an ophiolite nappe during the Late Jurassic time.
Fractal models in rock fracture analysis
Authors: Silberschmidt V.V. , Silberschmidt V.G. 
Published: July 2007

ABSTRACTOn the basis of a statistical‐thermodynamic description, we have derived constitutive equations of a medium with microstructural defects. Using a fractal approach, we account for the stochastic nature of mechanical properties and their effect on the process of fracture development. As an example, we have performed a numerical simulation of quasi‐brittle fracture of a beam having a rectangular cross‐section. We have studied the effect of non‐uniform strength on the fracture process. We propose an effective computational procedure to study the fracture development in time and space compatible with the conventional discretization schemes (finite elements or others).Prospects of application of this approach to the fracture of a real rock mass are discussed.
Continental drift and a theory of convection
Authors: Wilson J. Tuzo 
Published: July 2007

ABSTRACTEarly geologists considered that the Earth's surface is rigid and unchanging. They assumed that the whole Earth is static, except for enough sub‐surface contraction to build mountains. After seismology developed, most geophysicists agreed. A few scientists, notably Wegener, favoured a more mobile Earth. About 1965 fresh evidence showed that both theories were too simple. This evidence explained why neither theory had been able to relate the whole Earth's behaviour to laws of physics. Hence different aspects of geology had only been solved separately which had fragmented Earth science.This paper proposes a compromise. It is that the rigid lithosphere fractures according to Navier's law of brittle failure which explains the properties and provides methods for classifying faults, plate boundaries and mountains and that the ductile mantle convects by laws of fluid flow in patterns partly controlled by lithospheric fractures. These dual, interacting influences explain tectonic behaviour. The pattern of currents is hidden. At any one time upwelling beneath continents only affects a few limited areas; today some are in southwestern United States, Central Asia, Botswana, Antarctica and rifts in East Africa, Europe and Siberia. Nevertheless recognition of upwelling currents may revolutionize geology because their cumulative effects have been great and neglected.
Structure and seismicity of the Aegean subduction zone
Authors: Wortel M.J.R. , Goes S.D.B. , Spakman W. 
Published: July 2007

ABSTRACTTomographic results show the presence of a high‐velocity anomaly dipping north beneath the Aegean Sea (Hellenic arc), down to a depth of at least 600 km. This anomaly is interpreted as the image of the subducting lithosphere of the African plate. No deep seismicity, however, is associated with this downgoing slab, although this would be expected on the basis of the age of the downbending lithosphere (approximately 100 Myr) and the inferred duration of the present ongoing episode of subduction.Using a thermo‐mechanical model for the subduction zone we find that the non‐stationary input of the subduction zone‐both in convergence rate and in thermal structure of the downgoing lithosphere ‐ adequately accounts for both the presence of a velocity anomaly associated with a slab and the absence of deep seismicity. The non‐stationarity follows from the large‐scale tectonic setting of the Eastern Mediterranean basin.
Tomographic studies of the upper mantle beneath the Italian region*
Authors: Babuška V. , Plomerová J. 
Published: July 2007

ABSTRACTTeleseismic P arrivals at seismological stations are inverted into a model of velocity perturbations down to a depth of about 470 km. Directionally independent average residuals, computed from steeply inciding waves, are transformed into a model of lithospheric thickness. Both models show a good correspondence with the main tectonic features of the Italian Peninsula. Positive velocity perturbations are observed beneath the Alps and in depths over 200 km also beneath the Po Basin. A high‐velocity anomaly of the Tyrrhenian subduction is less pronounced, probably due to a directional dependence of P velocities in the mantle. Negative velocity perturbations indicate several low‐velocity regions, e.g. beneath the Northern Apennines, the Sicily region and in the upper 100 km beneath the Po Basin. The amplitudes of velocity perturbations beneath the depth of 200 km are smaller on the average than those in the upper two layers. The whole region is characterized by large undulations of the lithosphere base which reaches depths from less than 60 km to more than 150 km. The most prominent lithospheric root beneath the Alps is a product of the collision between the European and the Adriatic plates while the lithospheric thickening beneath the Calabrian coast is likely to be connected with the eastern wing of the Tyrrhenian subduction. The dramatic changes of lithosphere thickness between the northern and the southern Apenninic arcs and northern Calabria as well as the thinnings at the western closure of the Po Basin, indicate important deep‐seated boundaries of lithospheric blocks of autonomous geodynamic development.
Is there a correlation between lithosphere structure and the statistical properties of seismicity?
Authors: Panza Giuliano F. , Prozorov Albert G. , Suhadolc Peter 
Published: July 2007

ABSTRACTThe elastic parameters and the thickness of the lithospheric part of the mantle, the lid, are correlated with the seismicity of Italy and surrounding areas through the estimation of several statistical parameters. In particular, the intensity of the flow of seismic events, deprived of aftershocks, reveals concentrations associated with large gradients in the lithospheric thickness. The average depth of crustal shocks tends to be very shallow in areas of thin and soft (low shear‐wave velocities) lid. The positive influence, probably reflecting the thermal state in the lithosphere, is very large in connection with the thin and soft lid and where strong gradients in lid thickness are observed, and is small in connection with a thick and hard lid (high shear‐wave velocities).
Local source tomography: applications to Italian areas
Authors: Amato Alessandro , de Franco Roberto , Malagnini Luca 
Published: July 2007

ABSTRACTWe describe three study cases in which we used local earthquake and shot travel‐time residuals to investigate the upper crustal structure of three regions in Italy. We inverted for velocity and hypocentral parameters using a damped least‐squares technique making use of parameter (velocity and hypocentre) separation. The three studied regions are in Italy, namely (a) the Vulsinian Volcanic Complex (Latium), where there is an active geothermal field; (b) the Irpinia (Campania–Lucania) region, in the Southern Appennines, site of the strongest earthquake in Italy for at least 65 years (November 1980, Ms= 6.9); (c) the Friuli region, in Northeastern Italy, where another strong earthquake (Ms= 6.5) occurred in 1976. The computed shallow velocity models generally correspond with surface geological structures. For the three studied areas, the main results are, respectively: (a) A low‐velocity anomaly detected in the centre of the Vulsinian Volcanic Complex at a depth of 5–8 km, probably due to anomalous heat flow caused by a partially molten or cooling intrusive body; (b) the identification of a deep (10 km) discontinuity in the crust beneath the Irpinia fault zone, approximately corresponding with the fault extension at depth; (c) the detection of a wedge of high‐velocity, high density material at seismogenic depth (5–10 km) beneath the Friuli region, interpreted as a buried thrust of the metamorphic basement.
Burrowing sculptures as an example in functional morphology
Authors: Savazzi Enrico 
Published: July 2007

ABSTRACTSculptural patterns that aid the burrowing process are found on the exoskeletons of a broad range of fossil and Recent marine invertebrates. A review of these characters is used to illustrate how theoretical principles of functional morphology have been applied to practical cases. The presence of burrowing sculptures has allowed the recognition of burrowing habits and the reconstruction of the burrowing mechanism in several extinct groups, including linguliform brachiopods, trilobites and mitrates.
Rock conductivity and fractal nature of porosity
Authors: Ruffet Clotilde , Gueguen Yves , Darot Michel 
Published: July 2007

ABSTRACTWhile the d.c. electrical properties of a rock, through the volume conductivity, provide information on pore space structure (Formation factor) and pore fluid, the frequency dependence of the electrical parameters allows the characterization of the pore‐matrix interfaces. To illustrate these properties, we present here some results of measurements performed on sedimentary rocks (Vosges and Fontainebleau sandstones). These samples have a classical electrical response, i.e. a ‘Cole and Cole’ frequency behaviour near a certain relaxation frequency and a low‐frequency dispersion. We discuss some of the models that have been proposed in the past to explain this behaviour. It appears that most of them are valid near and above the relaxation frequency, but only Dissado and Hill's model seems to be satisfactory over the whole frequency range. The fractal nature of the interfaces, assumed in two of these models but appropriate only for one of them, could also be a convenient explanation for the frequency dependence.
Modelling Holocene tides on the NW European continental shelf
Authors: Austin Roger M. 
Published: July 2007

ABSTRACTA numerical model of the M2 tide on the NW European continental shelf has been used to estimate the effect of uniform depth changes, of the order of the Holocene eustatic variation, on tidal elevation amplitudes, sand transport paths, and the position of tide‐generated fronts. Minor changes are indicated around the outer shelf, but the Southern Bight of the North Sea is seen to develop from a quiet, shallow sea of low tidal amplitude (< 5m) to its present state of vigorous tidal action with mean coastal amplitudes around 2m. Shifts in the position and strength of amphidromes are shown to cause strong spatial gradients in the rate of change of tidal amplitudes in the Irish Sea and English Channel, but the tidal contribution to absolute changes in mean high water levels is found to be everywhere less than 5% of the eustatic contribution. Development of this modelling approach requires more realistic description of bathymetric variation and an estimate of ocean tidal changes.
Assessment of possible peak accelerations through stochastic variations
Authors: Nava F. Alejandro 
Published: July 2007

ABSTRACTA method is presented for the estimation of possible maximum accelerations, as well as of other accelerogram or seismogram characteristics, based on the stochastic variation of the spectral phase of pulses from an observed time series of interest, possibly the ‘design earthquake’. For a seismic source with the same spectral amplitude the variations are caused by slight differences in source time function, source or receiver location, etc.A large number of variations define the range of possible time series, as well as clear and stable relationships between the standard deviations of phase variation distributions (here considered Gaussian) and possible values of the studied features, as well as their distributions and probabilities.
Sea‐level changes and tectonics in the Quaternary extensional basin of the South Evvoikos Gulf, Greece
Authors: Perissoratis C. , van Andel T.H. 
Published: July 2007

ABSTRACTThe tectonically active South Evvoikos Gulf forms the submerged part of a young basin produced by Neogene fragmentation of the Hellenides, so furnishing an opportunity to study the earliest stages of an extensional rift. Reflection profiles show three seismo‐stratigraphic units: a thin Holocene unit A, a thick Late and Middle Pleistocene unit B, and a deformed Mesozoic‐Cenozoic basal unit C. In the eastern Gulf, at least seven alternatingly stratified and acoustically transparent subunits are related to Pleistocene sea‐level changes that episodically isolated the Gulf. Correlation with the global eustatic sea‐level curve indicates that deposition in the Gulf, formed by southeastward divergence of its northern and southern boundary faults, began during the last million years. Subsequent glacio‐eustatic sea‐level changes superimposed major variations in depositional conditions on long‐term subsidence. Lack of Pleistocene marine beds on the adjacent land implies that a high rate of subsidence confined lacustrine and marine deposition to the basin itself.
The 1988 Orange River flood, Upington Region, Northwestern Cape Province, RSA
Authors: Zawada P.K. , Smith A.M. 
Published: July 2007

ABSTRACTThis paper describes aspects of the 1988 Orange River flood. The Orange River is a perennial, bedrock‐controlled river which experienced severe flooding (flood peak: 8300 m3 s‐1) during February‐April of 1988. This flood resulted in the loss of life and damage in excess of $126 million. Negligible bank erosion took place in the main channel margins due to the stabilizing effect of tree‐lined banks. In contrast, areas removed from the channel margin were characterized by erosion and deposition.Within the confines of the natural flood channels, macroturbulence gave rise to scour holes which sometimes amalgamated into large erosion fields acres in extent. In many cases scour holes were present but macroturbulence‐originating obstacles were not, and it is suggested that these were removed by flood‐erosion processes. In some instances amalgamation of scour‐hole trails (orientated down‐current) led to the formation of steep‐sided flood channels. Deposition took the form of large sandsheets constructed from fluvial‐dune fields and braid‐bar accumulations. Post‐flood winds reworked some of the deposited sand into aeolian dunes.
Glacial rebound and sea‐level change in the British Isles
Authors: Lambeck Kurt 
Published: July 2007

ABSTRACTObservations of sea levels around the coastline of the British Isles for the past 10,000–15,000 years exhibit a major regional variation and provide an important data base for testing models of glacial rebound as well as models of the Late Devensian ice sheet. A high‐resolution rebound model has been developed which is consistent with both the spatial and temporal patterns of sea‐level change and which demonstrates that the observations are the result of (i) the glacio‐isostatic crustal rebound in response to the unloading of the ice sheet over Britain and, to a lesser degree, of the ice sheet over Fennoscandia, and (ii) the rise in sea‐level from the melting Late Pleistocene ice sheets, including the response of the crust to the water loading (the hydro‐isostatic effect). The agreement between model and observations is such that there is no need to invoke vertical crustal movements for Great Britain and Ireland of other than glacio‐hydro‐isostatic origin. The rebound contributions are important throughout the region and nowhere is it sufficiently small for the sea‐level change to approximate the eustatic sea‐level rise. The observational data distribution around the periphery as well as from sites near the centre of the former ice sheet is sufficient to permit constraints to be established on both earth model parameters specifying the mantle viscosity and lithospheric thickness and the extent and volume of the ice sheet at the time of the last glaciation. Preliminary solutions are presented which indicate an upper mantle viscosity of (3–5)1020 Pas, a lithospheric thickness of about 100 km or less, and an ice model that was not confluent with the Scandinavian ice sheet during the last glaciation and whose maximum thickness over Scotland is unlikely to have exceeded about 1500 m.