bluuebunny/crossref_metadata_2025_split huggingface dataset:
A geological note on the Qir earthquake, SW Iran, April 1972
Authors: McQuillan H. 
Published: May 2009

SummaryThis note outlines some thoughts on the possible significance of the April 1972 Qir earthquake with respect to the geological structure of Fars Province, SW Iran. The area in which the disturbance occurred belongs to a belt of simple folds of the Zagros system. These folds exhibit localized anomalies of structure which are attributed both to renewed movements along deep-seated basement features and to the modifying effects of salt mobility in the subsurface. The absence of surface indications of rupture in the devastated area is puzzling, but the alignment of zones of maximum destruction to buildings suggests a shallow epicentre associated with a concealed N70°W trending thrust fault system. Such seismicity is indicative of the continued activity of the Zagros orogenic movements.
The palaeontology of the Liassic (Lower Jurassic) clay pits at Stonehouse and Tuffley in Gloucestershire
Authors: Palmer C. P. 
Published: May 2009

SummaryThe two pits expose Pliensbachian silty shales and ferruginous limestones and sandstones. Fossils collectedin situare listed and two new morphospecies of fossil bivalve mollusc are described—Hippopodium tuffleyensisandHettangia aperta. A taxonomic discussion is followed by palaeoecological inferences drawn from the essentially bivalve-dominated molluscan fauna. The conclusions indicate that the silty shales were deposited in well oxygenated waters, probably not exceeding 100 m, and the limestones at even shallower depths. Pebbles in the limestones indicate that some erosion preceded each of the limestones in the Margaritatus zone.
Fluviatile fining-upwards cycles and the magnitude of palaeochannels
Authors: Leeder M. R. 
Published: May 2009

SummaryThe bankfull width (w) of modern meandering rivers (sinuosity >1.7) is related to bankfull depth (h) by the equation w = 6.8h1.54. The equation may be used to calculate limits for the bankfull widths of palaeochannels that deposited alluvial fining-upwards cycles. Calculated bankfull widths and measured bankfull widths from epsilon cross stratification are further used to state ranges of values for meander wavelength and mean annual discharge using existing empirical equations. The empirical equations directly relating width/depth ratios to sediment load and sinuosity are shown to be generally valid only for small rivers because of the increase of width/depth ratios as meandering rivers increase in size.
The petrology of the Warsak alkaline granites, Pakistan, and their relationship to other alkaline rocks of the region
Authors: Kempe D. R. C. 
Published: May 2009

SummaryA suite of Tertiary alkaline porphyritic microgranites and hybrid and peralkaline granite from northwest Pakistan is described, with six rock analyses (five of them new). The microgranites, an earlier group of which some contain garnet, have undergone metamorphism, lacking in the granites. The microgranites are shown to be precisely similar to those from the Shewa–Shahbazgarhi area, for which four analyses (two of them new) are presented, and related to a third group from Tarbela. The mineralogy of the rocks is discussed, with seven new analyses of aegirine, riebeckite, ferrohastingsite and astrophyllite, and X-ray determinations of the feldspar compositions. The granites are considered to be related to the undersaturated syenites and associated rocks of Koga, and a petrogenetic scheme for the alkaline province is presented, with a K/Ar age determination, tentatively deriving the source magma (quartz trachytic) from a Himalayan tholeiite.
Felsic plutonic rocks from the southern portion of the New Caledonian Ultramafic Belt
Authors: Rodgers K. A. 
Published: May 2009

SummaryGranodiorite stocks were intruded into the alpine peridotites of southern New Caledonia in the Eocene following overthrusting of the ultramafics onto the sialic core of the island. Strong zoning, from mela-diorite to granodiorite, is developed in one pluton and is believed to be the result of assimilation of ultramafic and mafic rocks by the calc-alkaline magma. Evidence in favour of a consanguineous relationship between the felsic and ultramafic rocks is largely circumstantial. In their petrography, mineralogy and chemistry, the rocks show few differences from other felsic plutonics of Tertiary age in the southwest Pacific.
A marginal Late Proterozoic ocean basin in the Welsh region
Authors: Baker J. W. 
Published: May 2009

SummaryRe-assessment of the idea that the Monian and Longmyndian accumulated along the margin of a palaeo-ocean suggests that Monian sedimentation occurred near the eastern shoreline of a micro-continent. If Monian igneous activity, metamorphism and deformation are attributed to an underlying subduction zone, this must have dipped northwestwards away from a small ocean basin to the southeast. Consumption of this ocean floor brought about collision with the continental shield and simple deformation of the Longmyndian.
Petrology of the alkali syenites of the Mundwara magmatic suite, Sirohi, Rajasthan, India
Authors: Bose M. K. , Gupta D. K. Das 
Published: May 2009

SummaryThe alkali syenites of the Mundwara magmatic suite, Sirohi district, Rajasthan, in north-western India, are chiefly developed in the Musala hill of the complex. They comprise three principal varieties representing different stages of crystallization, viz. nepheline-sodalite syenite, nepheline-barkevikite microsyenite, and nepheline poor leucosyenite. The dominant constituent of these hypersolvus syenites is alkali feldspar, an orthoclase microperthite showing a variable degree of exsolution. The chief mafic mineral is a distinctly green and zoned sodic pyroxene, close to aegirine-augite in composition. A brown calciferous amphibole, identified as a barkevikite, is developed in addition in the microsyenites. Reddish brown biotite of the phlogopite-annite series is common to all the syenites. The petrography and mineralogy of the syenites are discussed, and a comparative study of the Mundwara syenites with similar rocks of the Deccan volcanic province is presented. Chemistry and mineralogy of the syenites of the Mundwara suite suggest that they are related to those associated with the Deccan volcanic province.
An extension of the granophyric quartz-dolerite intrusion of Centre 2, Ardnamurchan, Argyllshire
Authors: Butchins C. S. 
Published: May 2009

SummarySheet-like bodies of dolerite with granophyre within the Hypersthene-gabbro on the NE shore of Sanna Bay are shown to be akin to the granophyric quartz-dolerite, and suggest that the latter originally extended for a considerable distance N of its previously mapped limits.
The role of CO2 in alkali rock genesis
Authors: Rock N. M. S. 
Published: May 2009

SummaryThe extreme rarity of alkaline rock suites bearing both calcic plagioclase and magmatic carbonatites is believed to reflect a fundamental bifold division between Gabbroic and Carbonatitic types, plagioclase being present only in the former and carbonatite only in the latter. Alkali basalt magma may be parental to both lineages, the gabbroic lineage deriving from normal differentiation under low CO2 pressure, and the carbonatitic by suppression of plagioclase crystallization under high pressures of CO2, leading through pyroxene fractionation to a ‘secondary parental’ olivine-poor nephelinite magma. Support for this hypothesis is found in evidence for the suppression of plagioclase in CO2-rich alkali basaltic magmas and for the secondary origin of olivine-poor nephelinites, in the nature of xenoliths and cumulates at carbonatite complexes, in Sr isotopic data, and in major and trace element compositions of the magmas. The possible origin of melilitic rocks at carbonatite complexes is also briefly discussed.
Vertical igneous layering in the Ewarara layered intrusion, central Australia
Authors: Goode A. D. T. 
Published: May 2009

SummaryThe Ewarara Intrusion of central Australia contains two vertical fine-banded horizons within a sequence of sub-horizontal ultramafic cumulates. The horizons are arranged in an en échelon pattern adjacent to a steep intrusional contact, and consist of an alternation of two layer types which correspond to the two major lithologies present in the horizontal sequence. The horizons are up to 5 m thick. A number of possible origins, including folding of originally horizontal cumulates, flow differentiation and multiple injection, do not satisfactorily explain the formation of the layering. The most likely origin appears to involve differential viscous flow along the steep contact of an inhomogeneous crystal mush derived from the horizontal layered sequence. This mobilization is related to fresh injections along a feeder zone trending 060µ, the only such zone recognized in the Giles Complex.
The Iglesia Irca intrusion and the role of gas brecciation in the emplacement of the Coastal Batholith of Peru
Authors: Bussell M. A. , McCourt W. J. 
Published: May 2009

SummaryIn the Iglesia Irca intrusion early undifferentiated pulses of granitic magma were emplaced at pressures of approximately 1 kb as narrow dykes of vesicular felsite. These dykes are associated with penecontemporaneous burst breccias and gas breccias and are themselves sometimes brecciated. Subsequently a large dyke of granophyre, representing a more fractionated composition, was emplaced by subsidence and stoping along the line of earlier microbreccias, explosion breccias and felsites. The dyke cooled relatively slowly at low structural levels and retained its volatiles while at higher levels more rapid cooling accompanied the greater escape of volatiles. This resulted in marked potassium enrichment of the upper levels of the dyke and the country rocks of the hanging wall. It is argued that the Iglesia Irca intrusion provides an example of the association of gas brecciation with vesiculating and volatile-rich magma which is atypical of the Coastal Batholith as a whole.
Newly discovered Tremadoc rocks in the Carmarthen district, South Wales
Authors: Cope J. C. W. , Fortey R. A. , Owens R. M. 
Published: May 2009

SummaryNewly discovered Tremadoc rocks in South Wales are described from outcrops south of Carmarthen. The faunas suggest that both the Clonograptus tenellus and Shumardia pusilla Zones are represented, together with possible higher Tremadoc strata.
Sri Lanka in Gondwanaland and the evolution of the Indian Ocean
Authors: Katz M. B. 
Published: May 2009

SummaryThe present position of Sri Lanka and its past fit in Gondwanaland are investigated in relation to the development of the Indian Ocean. The 3 stages in the evolution of the Indian Ocean are shown to be controlled by fundamental NW, NS, and NE Precambrian lineament directions in Sri Lanka and South India. These older lineaments were rejuvenated in the Mesozoic–Tertiary to form oceanic transform faults which determined the phases of Indian Ocean floor spreading.
The trachybasaltic volcanics of the Adrano area, Mount Etna, Sicily
Authors: Duncan A. M. 
Published: May 2009

SummaryThe Adrano area covers approximately 150 km2 of the tower SW flanks of Mount Etna, Sicily. A wide selection of the rocks that occur on the volcano are represented in the area. Lavas of alkalic affinity form by far the greater proportion of the volcanics in the area, and comprise a trachybasaltic suite of lavas ranging from hawaiite through mugearite to benmoreite. There appears to be no overall progressive variation in the chemistry of these trachybasaltic lavas with time; rather that the parental magma has remained fairly constant in composition. Periodically, however, this parental magma has been able to differentiate into more evolved products. The chemical variation shown by the trachybasaltic lavas can be largely explained by crystal fractionation of augite, olivine, plagioclase and titanomagnetite at moderate to low pressures. Crystal fractionation, however, cannot explain the variation in the alkalis which is thought to be affected by volatile transfer.
Mesopotamia: the Tigris—Euphrates delta and its Holocene Hammar fauna
Authors: Macfadyen W. A. , Vita-Finzi C. 
Published: May 2009

SummaryIn 1957, Hudson, Eames & Wilkins proposed the name of Hammar Formation for a series of sands and silts below the surface alluvium of the Mesopotamian Plains near Basrah, Iraq, which yielded a marine molluscan fauna of Holocene age. This paper shows that deposits yielding a very similar molluscan fauna are present at shallow depths at Amarah and Qurmat Ali, and lists the numerous foraminifera recovered from these deposits. Marine or brackish water conditions are thus shown to have prevailed in recent times over a distance of at least 250 km NW of the present head of the Persian Gulf.
K-Ar age determinations of some Miocene–Pliocene basalts in Israel: their significance to the tectonics of the Rift Valley
Authors: Steinitz G. , Bartov Y. , Hunziker J. C. 
Published: May 2009

SummaryThirty samples of Upper Tertiary basalts intruding marine and continental sequences were by the K-Ar method. Four volcanic phases are recorded: (a) 24.8±1.5 Ma of the Raqabat e Na'ame dike in Central Sinai; (b) 20.4±0.7 Ma of basalt intrusions in Central Sinai and the Arava. Some of these are offset by E-W to NE-SW dextral faults of the Central Sinai – Negev Shear Zone; (c) 14.5±0.3 to 4.9±1.3 Ma of basalt flows in the Eastern Galilee and the Coastal Plain; (d) 2.7±0.6 Ma of ‘En Yahav dike. These results contribute to the correlation between Tertiary continental formations from different areas, and put limits on the age of tectonic events, such as folding in the Syrian arc, faulting in the Central Sinai - Negev Shear Zone and shearing along the Jordan Rift.
Comparison of the San Andreas Fault System with the Highland Boundary Fault System of Scotland
Authors: Lambert R. St J. , McKerrow W. S. 
Published: May 2009

SummaryThere are close geometrical and dimensional similarities between the faults in Scotland north of the Highland Boundary Fault and faults in southern California east of the San Andreas Fault. It is argued that the Moine Thrust and Oarlock Fault are equivalents and that the Great Glen Fault and the Rosamund Lineament are also equivalent, implying corresponding senses of movement and that the Highland Boundary Fault originated as a dextral transform. The comparison cannot be extended yet to the terrains to the N of the Oarlock Fault or W of the San Andreas or to the corresponding areas in the Caledonides.
The Arctic Caledonides and earlier Oceans
Authors: Harland W. B. , Gayer R. A. 
Published: May 2009

SummaryConsideration of the arctic configuration of the Caledonides leads to a distinction between eastern and western geosynclinal belts. The western belt, comprising the East Greenland, East Svalbard and southern Barents Sea Caledonides is postulated to continue northwards into the Lomonosov Ridge, whilst the western Spitsbergen Caledonides are thought to have originated as part of the North Greenland geosyncline which is also thought to continue northwards to form the western part of the Lomonosov Ridge. The eastern Caledonian geosynclinal belt comprising the Scandinavian Caledonides appears to swing eastwards to link with the Timan Chain and possibly the Urals.The already postulated (‘Proto-Atlantic’) ocean concept is reviewed in the light of the Arctic Caledonides and named Iapetus. Faunal provincialism suggests that the ocean was in existence up to early Ordovician but had substantially closed by mid Ordovician times. Possible relics of the suture marking the closure of this ocean suggest that it lay to the west of the Arctic Scandinavian Caledonides trending NE to latitude 70° N and thence veered eastwards separating the southern Barents Sea Caledonides from those of Arctic Scandinavia, possibly connecting with the northern Uralian ocean. A previous branch of the ocean may have separated East Svalbard and East Greenland as an ocean-like trough. A further (pre-Arctic) ocean may have existed to the north of the North Greenland–Lomonosov Ridge geosynclines. This is named Pelagus.The closure of these oceanic areas and the deformation of the bordering geosynclines delineates three principal continental plates, namely, Baltic, Greenland and Barents Plates. Their relative dominantly E–W motion up to Silurian times produced compression between the Greenland and both the Baltic and Barents plates but dextral transpression and transcurrence between the latter plates. In Late Silurian to Devonian times an increasing northward component controlled late Caledonian transpression and sinistral transcurrence between the Greenland plate and the combined Baltic and Barents plates.
The significance of primary structures in the Ordovician pillow lava sequence of Western Norway in an understanding of major fold pattern
Authors: Furnes H. , Skjerlie F. J. 
Published: May 2009

SummaryThe present paper deals with the Lower Ordovician–Silurian rocks between Fördefjord and Sognefjord on the western coast of Norway. During the Caledonian orogeny this sequence was subjected to several phases of Silurian deformation, the first of which resulted in the formation of a large-scale anticline (the Stavfjord Anticline), which now occupies part of an overthrust unit. On the basis of ‘way-up’ criteria in the partly well-preserved Lower Ordovician pillow lavas it has been possible to determine with some confidence the geometry of the Stavfjord Anticline, its probable regional extension and the position of the axial plane trace. Arcuate deflections in the trend of this axial plane trace are a result of large-scale refolding, the later fold axes having WNW–ESE trends.
The Eller Beck Formation (Bajocian) of the Ravenscar Group of NE Yorkshire
Authors: Knox R. W. O'B. 
Published: May 2009

SummaryThe Eller Beck Formation is a thin marine intercalation in a predominantly non-marine Middle Jurassic sequence of coal measures facies. The formation consists of thin transgressive ironstones and siltstones at the base which are overlain by a thicker regressive sequence of shale passing upwards into sandstone. The close association between changes in the local subsidence pattern and the transgression suggest that the incursion resulted from epeirogenic movement rather than from eustatic rise in sea level or a purely sedimentation-controlled change in delta distributary pattern. Facies distribution was greatly affected by local synsedimentary tectonic movement. Water depths were probably very small throughout, and tidal effects on sedimentation minimal.
The Phillipsinella Parabola—Staurocephalus Clavifrons fauna and Upper Ordovician correlation
Authors: Price D. 
Published: May 2009

SummaryHorizons characterized by the trilobites Staurocephalus clavifrons and/or Phillipsinella parabola have long been regarded as significant in Upper Ordovician correlation. From time to time this idea has been formalized by the erection of Phillipsinella parabola or Staurocephalus clavifrons Zones or by equating the range of a ‘Phillipsinella parabola fauna’ with Series sub-divisions within the Standard Ordovician succession. At the present time the Phillipsinella parabola-Staurocephalus clavifrons fauna is widely regarded as indicating a Rawtheyan age (Ashgill Zones 5–7).Recent work by the author, however, together with a review of available evidence from the literature casts grave doubts on the validity of such concepts. It is suggested that in some areas the Phillipsinella parabola-Staurocephalus clavifrons fauna may range at least as low as basal Cautleyan (Ashgill Zone 1).
Plateau phonolite lava flows, Kenya
Authors: Lippard S. J. 
Published: May 2009

SummaryThe Miocene phonolite succession of the Uasin Gishu Plateau comprises seven flows totalling about 600 km3 in volume and covering an area of some 6500 km2. Each flow has a number of recognizable and laterally persistent features which permit it to be recognized over a wide area (thousands of square kilometres). These flows originated within the Rift Valley and flowed westwards for distances of up to 60 km across the marginal plateau area.
The geology of the Katete carbonatite, Rhodesia
Authors: Lee C. A. 
Published: May 2009

SummaryThe Katete carbonatite is situated in an area of rifting in the NW of Rhodesia. It consists of varieties of carbonatite and of agglomerates. There is little alteration of the surrounding sandstones and there are no associated alkaline rocks. The age of the complex is mid-Cretaceous, which is about the same as the later stages of carbonatite activity in the Rufunsa Valley in Zambia.
The Manubriate Isograptids
Authors: Beavis F. C. 
Published: May 2009

SummaryThe reference of Isograptus manubriatus (T. S. Hall) to the genus Maeandrograptus Moberg by Skevington (1968) is argued to be invalid. A new genus, Pseudisograptus has been introduced to which the manubriate isograptids I. manubriatus, I. hastatus, and I. dumosus are referred.
A contribution to the geology of the Annapurna and Nilgiri Himals, Nepal
Authors: Waltham A. C. 
Published: May 2009

SummaryWithin the Tethyan Zone of Central West Nepal, the Nilgiri Limestone is the dominant unit. The significance of the separation of the Larjung Formation is questioned in the light of new outcrops examined, and the Nilgiri Sandstone is described. Recumbent fold structures are correlated between Annapurna, Nilgiri and Dhaulagiri. Between these mountains the Thakkhola graben faults are continued southwards, and estimates are made of the magnitude of their throws.
Penecontemporaneous folding from the Lower Palaeozoic of the Trondheimsfjord region, Norway
Authors: Roberts D. 
Published: May 2009

SummaryOccurrences of penecontemporaneous folds of varying style and amplitude are described from low-metamorphic flysch sediments from an area in the Central Norwegian Caledonides. A short discussion of the mode of formation of these folds is presented, and from geometrical considerations it is suggested that, in several cases, both foundering and slumping have contributed to the overall deformation. The significance of the presence of these structures in the stratigraphical sequence is outlined, and the inherent danger of their possible misrepresentation as tectonic folds in higher metamorphic areas is briefly discussed.
Age of the Eycott Volcanic Group and its conformable relationship to the Skiddaw Slates in the English Lake District
Authors: Downie C. , Soper N. J. 
Published: May 2009

SummaryAn earliest Llanvirn age is established on micropalaeontological grounds for the interbedded lava–pelite sequence at the base of the Binsey Volcanic Formation in the northern Lake District. The northern volcanic sequence, here termed the Eycott Volcanic Group, is earlier than, and chemically distinct from, the main Borrowdale Volcanic Group. The evidence precludes a regional unconformity between the Skiddaw Slates and the overlying volcanic rocks, but is compatible with the hypothesis that the vulcanicity occurred in an island arc environment.
The analysis of en-échelon veins
Authors: Hancock Paul L. 
Published: May 2009

SummaryMeasurements of en-échelon veins cutting small chevron folds in Carboniferous greywackes, near Hartland in Devon, allow the following new conclusions about naturally occurring second-order fractures to be stated. 1. Veins may be initiated between 10° and 46° to the shear zone in which they occur. Previous studies of en-échelon fractures have generally classified them as either tension gashes formed at 45° to an array, or Riedel shears at 15° to an array. 2. Veins at about 20° to 40° to an array probably occupy surfaces which are transitional between shear and extension fractures. 3. Proof of a component of shear, in addition to dilation, on many of the veins at less than 40° to an array is provided by crystal fibres at acute angles to vein margins, and third-order en-échelon veins in arrays which are parallel to and part of a set of second-order veins.