bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of gestational age using birth certificate data compared with medical record data
Authors: Stanley Emery E. , Eaton Abby , Grether Judith K. , Nelson Karin B.
Published: July 2007

Summary

We assessed the extent to which use of medical record data might improve gestational age estimates compared with reliance on the birth certificate alone. Using population‐based data from four northern Californian counties, we constructed an algorithm to select the best gestational age estimate from antenatal assessments recorded in medical records. A total of 172 singletons with moderate or severe congenital cerebral palsy from the California Cerebral Palsy Project were compared with 472 randomly selected controls with regard to discrepancies between the algorithmderived estimated gestational age (bestgest) and an estimate based solely on the last menstrual period as recorded on birth certificates. Agreement between bestgest and birth certificate estimated gestational age was exact or within one week for at least 60% of both cases and controls in each of the three birth weight strata. In general, the greater the birth weight of the babies, the better the agreement. The mean number of weeks of overestimation by the birth certificate was 0.7 weeks for cases and 1.1 weeks for controls in the lowest birthweight group (< 1500 g). When compared with bestgest, clinical examination of the infant also tended to overestimate gestational age. In the < 1500 g birthweight group, cases were twice as likely as controls to have a bestgest of ‘low certainty’, but antenatal estimates of ‘high certainty’ were obtained for at least a third of very low birthweight babies born during the mid‐1980s. More widespread use of early ultrasound in more recent birth cohorts may result in a greater proportion of accurate antenatal estimates. When a distinction between immaturity and intrauterine growth retardation is important to the understanding of the aetiology of the outcome under investigation, the use of antenatal estimates from medical records may substantially improve the certainty of the data.
Towards a better understanding of time‐dependent geological processes: kinetics of structural transformations in mineraIs
Authors: Salje Ekhard
Published: July 2007

Recent advances in the theoretical understanding of kinetic processes in minerals are outlined. It is shown that relevant temperature‐pressure‐time information on the geological history of rocks can be extracted from a detailed knowledge of the structural states of some of the constituent mineral phases. Kinetic rate laws for the transformation between these structural states have been derived from order parameter theories (Salje; Salje and Wruck); some of the underlying ideas are reviewed in this paper. Recent progress in the experimental determination of the relevant thermodynamic potentials now makes it possible to treat non‐equilibrium features in a similar way to equilibrium states. The conceptual framework of such investigations is explained.
Palaeoseismic (?) liquefaction event in late Quaternary lake sediment at Glen Roy, Scotland
Authors: Ringrose P.S.
Published: July 2007

Late Quaternary lake sediment deposits from a former ice‐dammed lake at Glen Roy, Scotland, contain deformation structures indicative of liquefaction. The distribution of deformation styles reflects a concentric pattern of the degree of liquefaction. A possible fault rupture and several landslides are also observed in the central area. The liquefaction structures, the zonation of the sediment deformation and the association of deformation with landsliding can most simply be interpreted in terms of ground shaking during a major earthquake occurring at the end of the last glacial episode in Scotland (c. 10,000 bp).
The Catak landslide disaster, Trabzon Province, Turkey
Authors: Jones D.K.C. , Lee E.M. , Hearn G.J. , Genc S.
Published: July 2007

The Catak landslide (Trabzon Province, Turkey) developed retrogressively upslope through a series of small slips, culminating with the catastrophic rock avalanche of 23rd June, 1988 when at least 66 people were killed. The landslide was caused by prolonged heavy rainfall triggering a failure in a partially supported 25‐m high road cutting in colluvium, which progressively removed support for the higher parts of the slope and resulted in the catastrophic slide. Such high‐magnitude events are not uncommon in the Black Sea Mountains but the recent disaster highlights the need for systematic landslide hazard assessments in the region.
Non‐Gaussian data expansion in the Earth Sciences
Authors: Journal A.G. , Alabert F.
Published: July 2007

A formalism is proposed to generate alternative equiprobable images of an underlying population spatial distribution. The resulting images honour data values at their locations and reflect important characteristics of the data such as patterns of spatial connectivity of extreme‐values. The formalism capitalizes on a coding of all information available into bits (0‐l), which are then processed all together accounting for their patterns of correlation in space. Such common coding allows accounting for qualitative information, possibly of an interpretative nature, to complement the usually sparse hard data available in Earth Sciences applications. The approach proposed, although of a probabilistic nature, does not call for any Gaussian‐type modelling or hypothesis.
Conodont palaeobiology: recent progress and unsolved problems
Authors: Morris S. Conway
Published: July 2007

The fossilized soft‐parts of conodonts are extraordinarily rare; excluding dubious and refuted examples, only 10 specimens are known. Nine come from the Lower Carboniferous of Granton, Scotland, and represent at least two genera with complex polygnathacean apparatuses. The soft‐parts include well‐defined myotomal segmentation and a probable notochord, thus strongly suggesting affinity with the chordates. The tenth specimen, from the Lower Silurian of Waukesha, Wisconsin, bears a simpler apparatus of panderodontid conodont elements. The soft‐parts are very poorly preserved, but appear to be unlike those of the Granton specimens. In both occurrences the conodont apparatus appears well adapted for grasping and biting, supporting earlier suggestions that conodont elements acted as teeth. Many conodonts were probably predators or scavengers, but other feeding modes are not necessarily excluded. Other aspects of conodont palaeobiology reviewed here include mode of life and possible migration, reproduction and genetics, and palaeopathology. All these topics rely almost exclusively on the study of conodont elements, and many problems of conodont palaeobiology await further research.
San Quintín volcanic field, Baja California, Mexico: ‘within‐plate’ magmatism following ridge subduction
Authors: Storey M. , Rogers G. , Saunders A.D. , Terrell D.J.
Published: July 2007

The Holocene San Quintín volcanic province in northern Baja California comprises spinel‐lherzolite‐bearing alkali basalts. Trace element (La/Nb = 0.57–0.73; K/Rb = 402–479; LaN/YbN= 8.4, 9.9) and isotopic ratios (87Sr/86r = 0.70323–0.70352; 143Nd/144Nd = 0.512924–0.512996; 206Pb/204Pb = 19.108, 19.250; 207Pb/204Pb = 15.567, 15.589; 208Pb/204Pb = 38.82, 38.85) show that the lavas are compositionally indistinguishable from some ocean island, plume‐associated basalts such as Hawaii and the Azores, and testify to an asthenospheric source for the magmas. The occurrence in Baja of such lavas may be related to the nature of the cessation of plate subduction beneath the peninsula; at present, San Quintín (and volcanic provinces to the north) are underlain by a ‘no‐slab window', whereas immediately to the south, remanent oceanic lithosphere may be preserved as a relict slab. This may act as a bamer to the upward passage of diapirs or magmas from the asthenosphere.
Archimedes revisited: a structural test of eclogite emplacement models in the Austrian Alps
Authors: Behrmann J.H. , Ratschbacher L.
Published: July 2007

High‐pressure rocks of the eclogite zone (Tauern Window, Eastern Alps) formed at 20 kb/600°C. Uplift was fast without post‐burial heating. Extensive near‐field and far‐field deformation of the eclogite zone and its surroundings provide evidence for a tectonic uplift mechanism. Published emplacement models (buoyant rise, underplating and extension, wrench faulting) create distinct patterns of crustal deformation, and are therefore testable by structural analysis. We show that emplacement‐related deformation and its kinematics are consistent with underplating and extension. Extension is two‐phased. The first phase may be driven by changes in rate or direction of plate convergence. The second phase is due to large‐scale underplating of continental crust.
On the Chouet model of excitation of a buried magmaticpipe
Authors: Salusti E. , Travaglioni F.
Published: July 2007

Rhythmic motion of the ground (tremor) is often associated with activity before and during a volcanic eruption. Volcanic tremor is characterized by dominant peaks located in the 0.1–10 Hz range of the spectrum. In the light of previous formulations concerning the vibrations of a uniform vertical magma‐filled pipe, this work presents the analysis of the motion when the section of the pipe is not constant but has constrictions and meanders. Our results show that the magma velocity modulus and pressure are inversely proportional to the pipe's cross‐section. Consequently the effect of the motion of the magma gives rise to enlargements of the pipe's constrictions.
Deep‐sea biogenic silica: new structural and analytical data from infrared analysis ‐ geological implications
Authors: Fröhlich François
Published: July 2007

The main parameters of infrared spectra have been investigated for marine siliceous skeletons and for silica polymorphs. From infrared (IR)data, the mean values for the Si‐O bond length (1.62 Å) and for the Si‐O‐Si angle (about 142°6) are inferred for biogenic silica. A model is proposed for the molecular structure of biogenic, amorphous silica, which consists of a discontinuous, three‐dimensional framework of short chains of [SiO4] tetrahedra, bounded with apical hydroxyls. According to the relationship between the structure of the silica polymorphs and their infrared spectra, it is shown that a quantitative analysis of biogenic silica seems to be possible in quartz‐rich sediments. Some geological implications of these data are emphasized, including the processes of siliceous skeleton sedimentation and diagenetic evolution.
Viscosity ratio estimates from natural Rayleigh‐Taylor instabilities
Authors: Rönniund Peter
Published: July 2007

The geometry of natural gravity‐driven overturns potentially contains information on viscosity ratios of the material involved. Irregularities at the interface between two superposed horizontal fluid layers tend to amplify and grow with time with a regular wavelength if the top iayer is more dense, Published formulas (Woidt), for such Rayleigh‐Taylor (R‐T) instabilities have been used to construct graphs which can constrain the effective viscosity ratio at the onset of the overturn. Only the initial thicknesses of the two layers and the final wavelength of the structures need be known. The theory is based on an infinite two‐layer system of Newtonian fluids between rigid boundaries with no slip or free slip at contacts.

Geological examples included are; soft‐sediment dewatering on the scale of decimetres in northern Norway, an unusual instability between basalt and sand in Australia of hundreds of metres, salt diapirism of kilometres in Germany and the Persian Gulf, and granitic diapirism from northern Sweden of tens of kilometres. Viscosity ratios in the order of 1–10 are found for soft sediments with the top layer as the more viscous. Ratios inferred from patterns of salt diapirs are very large, with the overburden approximately 103‐−105 times more viscous than the salt. The viscosities of granites are indicated as lower than their overburden and with ratios of 103.
Evidence from Mössbauer spectroscopy for intense localization of metamorphic fluid flow during the formation of spaced cleavage
Authors: Boulter C.A. , McConchie D.M. , Clarke E.M.
Published: July 2007

Arenites in the low‐grade metasedimentary rocks of the Stirling‐Barren Group, Western Australia, contain discrete spaced cleavages. These in part are pure white mica, but up to 30% of the cleavage zones consists of fine‐grained quartz resulting from crystal plastic deformation. A modified Gresens analysis shows that the cleavage domains formed by a 50% volume loss associated primarily with SiO2 and MgO concentration decreases of 58% and 37%, respectively, and a 12% decrease in Fe2O3. Mössbauer spectroscopy shows that the Fe2+: Fe3+ ratio from lithon to cleavage changed from 50:SO to 15:85. This substantial difference cannot be accounted for by loss of iron. The data are best explained by the focusing of a highly oxidizing fluid through the cleavage domains where volumetric fluid rock ratios around 150 to 1 are indicated. In this example advectic processes appear to be important in low‐grade regional metamorphism.
A psittacosaurid dinosaur from the Cretaceous of Thailand and its implications for the palaeogeographical history of Asia
Authors: Buffetaut Eric , Sattayarak Nares , Suteethorn Varavudh
Published: July 2007

Primitive ceratopian dinosaurs of the family Psittacosauridae were hitherto known only from central and northern Asia, from northern China to Mongolia and Siberia. This paper reports the discovery of psittacosaurid jaws in Early Cretaceous rocks of the Khorat Plateau in north‐eastern Thailand. These fossils are clearly referrable to the genusPsittacosaurusOsborn and may represent a new species. They constitute a significant new element of the hitherto poorly known Cretaceous continental vertebrate fauna of South‐East Asia, suggesting that it was basically similar to that of northern and central Asia. This in turn confirms that, contrary to some recent palaeogeographical reconstructions, by Early Cretaceous times the Indochina block, on which the Thai psittacosaurids have been found, had become part of mainland Asia.
Outcrop to subsurface cycle correlation in the Milankovitch frequency band: Middle Cretaceous, central Italy
Authors: Melnyk David H. , Smith David G.
Published: July 2007

Time series analysis of the Cenomanian through Aptian interval, in well logs from offshore Adriatic boreholes, facilitates a cycle‐by‐cycle correlation with measured sections of equivalent age in Umbria, central Italy. The cycle‐by‐cycle match can be demonstrated between filtered spontaneous potential logs and filtered bed thickness data, but is unequivocal only at wavelengths of greater than 10 metres, which are believed to represent a 2 Myr eccentricity signal; at shorter wavelengths tool resolution becomes a limiting factor. As a result of low sedimentation rates the 100, 41, and 21 kyr Milankovitch signals all appear to be aliased to longer wavelengths in the sonic and gamma ray log records and tend to blend with the 400 kyr signal; this is especially true in the Aptian‐Albian interval. Attempts to filter and correlate on the bases of these shorter wavelengths were therefore unsuccessful.

Accepting a 2 Myr duration for each cycle permits an estimation of less than 7 Myr to be made for the duration of the Cenomanian Stage.
Primary versus diagenetic origin of Blue Lias rhythms (Dorset, UK): evidence from sulphur geochemistry
Authors: Bottrell Simon , Raiswell Robert
Published: July 2007

The question of a primary versus diagenetic origin for the limestone‐shale rhythms of the Blue Lias has been addressed through a study of pyrite abundance and isotopic composition. Pyrite is relatively abundant and isotopically light in the central portions of the bioturbated limestones as compared to adjacent, less calcareous, sediment. The abundance of pyrite shows that the limestones were a focus for prolonged sulphate reduction and pyrite formation. The isotopic data indicate that bioturbation oxidized some pyrite to produce isotopically light sulphate, part of which was subsequently reduced back to pyrite before preservation by burial. Acidity generated by pyrite oxidation was buffered in the limestones by carbonate dissolution, hence supersaturation of sulphides could be maintained. By contrast, in adjacent less calcareous sediments, carbonate dissolution was unable to buffer acidity and bioturbational oxidation of pyrite formed iron‐rich pore solutions. Continued sulphate reduction in the limestones acted as a sink for iron from the adjacent sediments and, with burial below the zone of bioturbation, the alkalinity so generated caused cementation of the limestones. Diagenetic cementation would be enhanced during an hiatus in sedimentation, an event which might be related to a Milankovitch forcing mechanism, but which would not be recorded in bioturbated, less calcareous sediment, thus leaving an imperfect record. Only cyclicity in pre‐diagenetic sedimentation patterns may be safely related to a Milankovitch forcing mechanism as proposed by Weedon.
Cyclic sedimentation patterns in Lower Lias mudstones of Yorkshire (GB)
Authors: van Buchem F.S.P. , McCave I.N.
Published: July 2007

Distinct stratification patterns in Lower Liassic mudstones are due to the regular occurrence of shell beds, silty/sandy layers and concretionary horizons. The mudstones formed in four depositional environments: (1) a storm dominated shallow marine system; (2) a hemipelagic system; (3) a shallow marine system influenced by climatic changes at astronomical frequencies; and (4) a pro‐deltaic offshore transition/shallow marine system. The tectonic setting played an important role in determining the facies sequence, whereas eustatic sea‐level changes were of lesser influence.
Milankovitch type cycles in the Lower Carboniferous of NW Ireland
Authors: Schwarzacher W.
Published: July 2007

A short description of the Lower Carboniferous near Sligo (NW Ireland) is given. Limestones and mark in four measured sections in the Glencar Limestone were numerically coded as plus and minus one, respectively. Such sequences show good and persistent cyclicity with a basic wave length of 200 cm. Filtered sections have been adjusted to give each cycle a constant length. Such records show a much longer cycle in the form of amplitude modulation of the basic cycle.

The 200 cm cycle is very regular and its approximate duration is around 100 kyr. It could, therefore be the result of eccentricity variations in the earth's orbit. The longer cycle represents approximately 1–1.5 Myr and may be equivalent to the Yoredale cycles in the northern England.
The project ‘Marine‐environmental development of Danish Waters’ at the Geological Survey of Denmark
Authors: Konradi Peter B.
Published: July 2007

Research in marine geology at the Geologcal Survey is primarily related to environmental problems. At present several projects are concerned with sedimentation in the inner Danish waters during the Holocene. A primary objective is a subdivision of the sea‐floor into areas of erosion, reworking and accumulation. In the accumulation area the exact sedimentation processes and sedimentary environments are elucidated. Here, also, the organo‐chemical processes are investigated, especially with regard to the biological transformations and diagenesis of par‐ticulate organic matter, by utilizing well‐known techniques from industry.

The aim is to explain the natural development of the environment at the sea‐floor and to get a better understanding of the elements of the oxygen consumption at the waterisediment interface. A primary objective is to produce a new measuring‐technique for organic matter diagenesis in the sea bed that will provide fast and reproducible results in the monitoring of the environmental parameters of the sea‐floor. Special attention will be given to the various potentials of different types of organic matter in relation to oxygen consumption during bacterial decomposition in the sediment.
On the quantitative interpretation of magnetic anomalies by pseudo‐gravimetric integration.
Authors: Fedi Maurizio
Published: July 2007

Poisson's theorem relates linearly the derivative of the gravity potential (taken along the total magnetization vector direction) and the magnetic potential due to a common, isolated source with constant density and magnetization distributions.

From that theorem, two very useful functional transformations for magnetic anomalies were formulated by Baranov, that is the ‘pseudo‐gravimetric integration’ and the ‘reduction to the pole'.

In this paper, it is shown that the first transformation is, in some sense, more useful than the reduction to the pole and, further, that its utilization presents noticeable advantages as regards the interpretation of magnetic anomalies. In fact, the pseudo‐gravimetric integration, in contrast to the reduction to the pole, also provides a smoothing of the anomaly map and, in particular, reduces the degree of non‐linearity existing in the mathematical relationship between the data and the source depth.

In order to show this last property of the transformation, spectral expansion inversions by 21/2D structures were performed on both magnetic and pseudo‐gravimetric synthetic anomalies and the respective speed and precision were compared. The tests clearly indicate that very accurate estimates of the geometric parameters of the known source can be more easily and rapidly calculated by the transformed anomalies. Furthermore, due to its smoothing property, the method seems particularly useful when data are noisy. Tests on real anomalies confirm these results.
Do carbonate reefs form due to fluid seepage?
Authors: Hovland Martin
Published: July 2007

Buried carbonate reefs are favoured hydrocarbon prospecting targets, mainly due to their high porosity and potential for containing large quantities of petroleum. The question of the true relationship between reef structure and the internally trapped fluids (hydrocarbons) is here raised as one of cause ‐ and effect. In other words, which came first, the hydrocarbons or the carbonate reef itself?

Modern bioherms and seabed carbonate reefs in, amongst other locations, the North Sea and the Gulf of Mexico, are shown to form in close association with active hydrocarbon seepages. Mainly based on results from ecological studies at deep‐ocean vent communities, a new model for carbonate reef formation is promoted: that such reefs form at locations containing high concentrations of bacteria and other microorganisms suspended in the water column as a result of seeping fluids (solutions and gases) that provide some of the energy basis and carbon source for ecosystems independently of photosynthesis. Therefore, on burial and effective sealing (‘capping’), these carbonate reefs become hydrocarbon reservoirs, trapping and accumulating the very minerals on which they ‐ in the first place ‐ were dependent.
Gold‐bearing listwaenites in the Araç Massif, Kastamonu, Turkey
Authors: Aydal Doǧan
Published: July 2007

The mineralogy and chemistry of gold‐bearing listwaenites of Gemiköy in the Araç massif (southern part of the Daday‐Devrekâni massif) were investigated in detail. The process of listwaenitization and the reasons for gold enrichment in the area are discussed.

The listwaenites have no direct contact with any magmatic intrusion or extrusion. Detailed chemical analysis showed that the listwaenitized rocks contain silica‐, silica and carbonate‐, and carbonate‐rich parts. Each part is different chemically from the others, even in terms of accessory mineral content. In general, the listwaenites differed chemically and mineralogically from the surrounding ultramafic rocks. In particular, SiO2 and CaO contents of listwaenites were higher and MgO and Al2O3 contents were lower than in the surrounding ultramafic rocks. Furthermore, Ni, As, Mn, Zn, Pb and Co enrichment occurred during listwaenitization, while K was absent and Ni enrichment was detected especially in silica and carbonate‐, and carbonate‐rich parts.

Finally, Gemiköy listwaenites are interpreted as autometamorphic, even though they show similarities to allometamorphic listwaenites according to Ploshko's (1963) classification.
Hydrothermal mobility of Ti, Zr and REE: examples from the Bergell and Adamello contact aureoles (Italy)
Authors: Gieré Reto
Published: July 2007

Contact metamorphic marbles, affected by metasomatic fluids at the contact to the Bergell and Adamello Intrusives, contain various accessory minerals (zirconolite, allanite, titanite, rutile, geikielite, hoegbomite), which provide new evidence for the hydrothermal mobility of Ti and Zr. In both examples, Ti and Zr migrated along with U, Th, Y and REE in a metasomatic fluid rich in potassium. The composition of the main minerals (fluorine‐rich phlogopite, pargasite and titanian clinohumite) and the abundance of fluor‐apatite demonstrate that fluorine and phosphorus were important components of the fluid. The textural relationships indicate that the formation of the accessory phases is linked to the crystallization of the hydrous minerals.
Upper Devonian tetrapod palaeoecology in the light of new discoveries in East Greenland
Authors: Bendix‐Almgreen Svend Erik , Clack Jennifer Alice , Olsen Henrik
Published: July 2007

For the first time, new material of one of the world's oldest known tetrapods,Acanthostega, has been studied in its sedimentological context. The reported evidence suggests thatAcanthostegawas primarily aquatic and inhabited active fluvial channels in fluvial‐dominated environments.
Growth of ferruginous oncoliths in the Bajocian (Middle Jurassic) of Europe
Authors: Palmer Timothy J. , Wilson Mark A.
Published: July 2007

Limonitic oncoliths from the Bajocian of Europe, widely known as ‘snuff‐boxes’, grew by accretion of bundles of laminae on one side, followed by overturning and accretion of laminae on the other side. A diverse hard‐substrate encrusting fauna grew interleaved with the ferruginous laminations. The palaeoecological preferences of this fauna indicate that its growth, and hence the accumulation of the laminations, took place on the gloomy undersides of the oncoliths. This upsidedown growth is supported by characteristics of the lamination bundles themselves, and by the predominant present‐day orientations of the snuff‐boxes. The abundance of the associated fauna and the lack of carbonate‐dissolving macroborers cutting the laminae suggest an original ferric composition. Precipitation was probably under the control of non‐photosynthetic microorganisms that inhabited the microenvironments represented by the oncoliths' lower surfaces.
The gold mineralization of Baccu Locci (Sardinia, Italy): origin, evolution and concentration processes
Authors: Bakos F. , Carcangiut G. , Faddat S. , Mazzella A. , Valera R.
Published: July 2007

As‐Fe‐Cu‐Pb‐Zn‐Ag‐Sb sulphides and sulphosalts, with native gold as a frequent accessory (locally concentrated with high values) are the ore minerals of a deposit occurring in a Silurian volcanosedimentary sequence, either as concordant bedded orebodies, or as discordant veins and split fillings at the contact between shales and lamprophyres of the late Hercynian magmatism. Scheelite, mainly bound to acid metavolcanics, is occasionally scattered as isolated grains in the sulphides. The local geological setting together with correlations with other deposits occurring along the same regionally distributed Lower Paleozoic sequence, permit the proposal of the following scheme for the origin and evolution of the Baccu Locci Au‐bearing mineral deposit:

(1) Base‐metal sulphide deposition, with gold, in the Silurian volcanosedimentary sequence: protore.

(2) Hercynian tectonometamorphic activity, accompanied by multiphase ore mobilization and concentration processes, stratabound.

(3) Hercynian magmatism, locally represented by lamprophyre dikes and by the effects of multiphase hydrothermal activity: ore mobilization and redeposition.
The metallotectonics in Eastern Shandong gold metallogenetic province, China
Authors: Enhuai Liu
Published: July 2007

Based 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

Sedimentological 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

In 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

A 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

Ophiolitic 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

On 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.
THE MUD VOLCANOES OF RAMRI AND CHEDUBA (ARAKAN, WESTERN BURMA)
Authors: Mallet F.R.
Published: July 2007

In this, the seventh in an occasional series of earth phenomena the author recounts tales of sudden flames issuing from the ground, paroxysmal eruptions and serpent spirits presiding over volcanoes.
Continental drift and a theory of convection
Authors: Wilson J. Tuzo
Published: July 2007

Early 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

Tomographic 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

Teleseismic 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

The 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

We 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

Sculptural 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

While 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

A 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

A 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

The 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.