bluuebunny/crossref_metadata_2025 huggingface dataset:
The late‐glacial climate of North‐West England
Authors: Manley Gordon
Published: February 2007

The combination of geological and botanical evidence with meteorological reasoning leads to the conclusion that in the ninth millenium B.C. small glaciers became re‐established in corries and in the heads of the wetter Lake District valleys, and also in a number of Pennine corries north of Bowland Forest. The meteorological factors giving rise to their distribution and comparative extent are discussed. It is inferred that the amount and distribution of precipitation during this episode resembled that of today. Quantitative estimates are given of the characteristics of the climate during this post‐Alleröd recession, which from the meteorological standpoint appears to be similar to the minor recessions during the post‐Glacial period.
The erosional history of the cliffs around Aberystwyth
Authors: Wood Alan
Published: February 2007

The coastline from Borth to New Quay is described. Three points of general interest emerge. The coastal bevel (hogs back cliffs, fausses falaises) is shown to be the remains of cliffs cut by marine erosion, and degraded by sub‐aerial weathering, at several times in the past. Raised beach platforms occur at different levels, each being backed by degraded cliffs, which merge laterally with the coastal bevel. Later than these, but earlier than the spread of the latest boulder clay in this area by solifluction seawards, are steep “fossil cliffs” cut during apparently two periods of lowered sea‐level. Where the beach platform is cut in solid rocks its outer edge is coincident with the course of one or other of these fossil cliffs.
Nomenclature and diagnostic characters of ignimbrites with reference to Snowdonia
Authors: Beavon R. V. , Fitch F. J. , Rast Nicholas
Published: February 2007

The nomenclature of the welded tufts and ignimbrites is reviewed and it is suggested that the term ignimbrite should include both the welded and the unwelded deposits (sillars) of nuée ardentes. The diagnostic characters of the ignimbrites are examined with special reference to Snowdonia.
Coiled nautiloids from the viséan of Ireland
Authors: Ramsbottom W. H. C. , Moore E. W. J.
Published: February 2007

Species of the genera Subclymenia, Maccoyoceras (= Epidomatoceras Turner), Stroboceras, Epistroboceras, Phacoceras, Liroceras, Ephippioceras, and Knightoceras are described from on and near Dough Mountain, Co. Leitrim, Ireland, and from Cashel, Co. Fermanagh, Northern Ireland. Faunal associations are noted and the occurrence of species of Liroceras, Rineceras (= Pararineceras Turner), and Vestinautilus are recorded.
The metamorphic history of the Loch Tummel area, central Perthshire, Scotland
Authors: Sturt B. A. , Harris A. L.
Published: February 2007

In the Dalradian rocks of the Loch Tummel area it is possible to establish a series of metamorphic events which are both syntectonic and post‐tectonic in relation to the polyphasal sequence of structures established in the area. Mineral assemblages which have developed during successive phases of metamorphism have been distinguished by their textural relationships, and are assigned to the appropriate metamorphic facies. Comparisons have been made with the metamorphic sequence established by Rast in the Schichallion area.
Superposed folding in the Silurian Rocks of Co. Mayo, Eire
Authors: Dewey J. F. , McManus J.
Published: February 2007

Silurian strata of Upper Llandoverian and Wenlockian age, lying in a complex synclinorium south of the Highland Boundary Fault Zone in Co. Mayo, are affected by two main structural episodes. A tight, curving, E–W synclinorium, verging to the south, was developed during the first episode of deformation (F1). Large‐scale cross‐buckling, followed by variable flattening in the axial‐planar schistosity, was responsible for a considerable plunge variation of F1 folds. A mechanism is described whereby primary downward‐facing minor folds may be produced in an upward‐facing major structure. Three slides, of considerable magnitude, are co‐planar with the schistosity. During the second episode of deformation (F2) a slip‐cleavage, dipping steeply to the NNE, was superimposed upon the F1 synclinorium. It is deduced, partly from an analysis of the geometry of F2 minor structures, that the arcuate curvature of the F1 synclinorium is pre‐F2 and was developed during the F1 deformation as a response to the presence of an early or pre‐F1 granite pluton. F2 folds show a great variability in plunge and facing direction, depending upon their position in the F1 major structure.
Iron enrichment and pyroxene fractionation in tholeiites
Authors: Muir I. D. , Tilley C. E.
Published: February 2007

Differentiation in tholeiite magma, particularly iron enrichment and silica variation, as traced in lava successions and dolerite‐granophyre suites, is discussed in the light of analytical data on phenocryst and groundmass pyroxenes and their fractionation. Broadly two trends may be distinguished: (1) an intratelluric equilibrium trend ending in a hedenbergitic pyroxene phase fayalite, such as is exhibited by the Tasmanian Red Hill dolerite‐granophyre suite, and (2) a quench trend characteristic of the subcalcic augite groundmass sequence of the volcanic suites as exemplified in the Hawaiian tholeiite series (e.g. Kilauea). This trend may in more siliceous differentiates be extended to close with assemblages carrying a ferropigeonite phase.
The geology of the Clynnog‐fawr district and Gurn Ddu hills of Northeast Lleyn
Authors: Tremlett W. E.
Published: February 2007

This area of Wales is a westerly continuation of the northern limb of the Snowdon syncline and stretches from the Pre‐Cambrian volcanic series in the north to just above the abbreviated Snowdon Volcanic Series in the south. Large parts of the intervening area consist of Caledonian intrusive rocks, but the middle part of the sedimentary succession has yielded scattered graptolites, most and probably all, of Llanvirn age. The exposed volcanic rocks are largely of ignimbrite character while the Caledonian intrusions are of four types (for which chemical analyses are given). The sequence of these four rock‐types and of the structural events of the district is considered.
The geology of the Chwilog area of Southeastern Lleyn (Caernarvonshire)
Authors: Tremlett W. E.
Published: February 2007

Due partly to folding but mainly to faulting, the Caradocian volcanic rocks outcrop in three districts within this area, and this repetition of outcrop reveals the variation shown by this dominantly rhyolitic volcanic series. A thick lower group of submarine bedded tuffs, thinning and fading out northwestwards, is followed unconformably by subaerial andesite and rhyolitic rocks in the north, but these volcanic rocks are absent or represented by bedded tuffs in the southern districts. The overlying sediments are generally poorly exposed but have yielded Upper Longvillian fossils from a number of localities. Caledonian intrusions are neither so numerous nor so varied as in northern Lleyn, but include granodioriteporphyries and felsites. Explosion breccias are present at the margins of some of the felsites. Nine chemical analyses indicate the variety of composition in the volcanic series while two analyses of Caledonian felsites are also supplied.
Geochemistry of an ordovician basalt‐trachybasalt‐subalkaline/peralkaline rhyolite association from the Lleyn Peninsula, North Wales, U.K
Authors: Leat P. T. , Thorpe R. S.
Published: February 2007

The Caradoc volcanic rocks of the Lleyn Peninsula represent a major episode of rhyolite‐dominated eruption (total volume up to 560 km3) within the Southern British Caledonides. New geochemical data reveal the original chemical characteristics of the basic, intermediate, and acid lavas. The basalts are interpreted as having predominantly within‐plate character and are associated with intermediate lavas (trachybasalts) and high‐Zr, originally peralkaline, trachytes, and rhyolites. A low‐Zr, originally high‐K, subalkalic group of rhyolites, and a basalt with transitional island arc tholeiite‐MORB characteristics are unrelated to these lavas. The volcanic rocks are interpreted to have been erupted onto a complex, rapidly evolving, active continental margin dominated by crustal tension.
Eocene sheetflood systems and transitional fan‐deltas, Southern Pyrenees, Spain
Authors: van der Meulen Sjoerd
Published: February 2007

The Eocene Monllobat and Castigaleu Formations in the Southern Pyrenees consist of continental and shallow marine deposits respectively. The Monllobat Formation contains conglomerate sheets with sandstone tails, symmetrical channel fills with wings and various types of lobes, accreted laterally in channels as well as by progradation. These deposits are intercalated in large amounts of flat‐bedded silt and mudstone with mottling and caliche.

The high energy alluvial flow, which deposited these sediments, was initially at right angles to the axis of the elongated basin, becoming near parallel to the axis distally. The deposits are less gravelly distally. Upstream wide, gravelly braidplains were developed. Gravel lobes and muddy sheetfloods prograded over the distal floodplain. Meandering rivers were restricted to a marginal position in the sheetflood environment.

The Castigaleu Formation consists of mudstone with intercalations of sandstone. Lobes of conglomerate and sandstone dominate the contact zone with the Monllobat Formation. Flat sandstone layers with tabular cross beds and parallel lamination and massive sandstone beds are distributed throughout the other parts.

The lobes were formed at the coastline during high energy inflow in the marine basin. Flow deceleration caused the deposition of the coarsest load at this site, building a wedge with an inclined front during major aggradation and progradation. The other deposition types originated during hyperpycnal inflow in a marine environment. Massive sandstones originated partly because of bioturbation. Reworking by physical marine processes did not occur. Synsedimentary tectonics determined the type of sedimentation at times.
The Valley and Ridge Province of eastern Pennsylvania—stratigraphic and sedimentologic contributions and problems
Authors: Epstein Jack B.
Published: February 2007

Many contributions that have led to a better understanding of Appalachian geology have resulted directly from work in the folded Appalachian Mountain and Great Valley sections of the Valley and Ridge physiographic province of eastern Pennsylvania. Disagreements have been common since H.D. Rogers first described the geology of the area in 1858. Many differing opinions still exist regarding the stratigraphy, structural geology, geomorphology, and glacial geology.

The rocks in the area, which range from Middle Ordovician to Late Devonian in age, are more than 25000 feet (7620 m) thick. This diversified group of sedimentary rocks was deposited in many different environments, ranging from deep sea, through neritic and tidal, to alluvial. In general, the Middle Ordovician through Lower Devonian strata are a sedimentary cycle related to the waxing and waning of Taconic tectonism. The sequence began with a greywacke‐argillite suite (Martinsburg Formation) representing synorogenic basin deepening. This was followed by basin filling and pro‐gradation of a sandstone‐shale clastic wedge (Shawangunk Formation and Bloomsburg Red Beds) derived from the erosion of the mountains that were uplifted during the Taconic orogeny. The sequence ended with deposition of many thin units of carbonate, sandstone, and shale on a shelf marginal to a land area of low relief. Another tectonic‐sedimentary cycle, related to the Acadian orogeny, began with deposition of Middle Devonian rocks. Deep‐water shales (Marcellus Shale) preceded shoaling (Mahantango Formation) and turbidite sedimentation (Trimmers Rock Formation) followed by another molasse (Catskill Formation).
Carboniferous (Dinantian and Silesian) and Permo‐Triassic rocks in south County Wexford, Ireland
Authors: Clayton G. , Sevastopulo G. D. , Sleeman A. G.
Published: February 2007

Boreholes drilled in the Wexford Outlier have proved Permo‐Trias conglomerate and red beds (Killag Formation), Westphalian D sandstone and mudrock. including at least one thin coal (Richfield Formation), and probable Namurian mudrock (Park Formation). The Killag Formation rests on the Westphalian, the Namurian, and on Dinantian (probably Asbian) limestone in different boreholes. The Westphalian contains horizons with bivalves, conchostracans, and plants and has yielded miospore assemblages which, in addition to indigenous taxa, contain reworked material of three different ages: Devonian or early Carboniferous; late Viséan or early Namurian; and Westphalian A. The western end of the Welsh massif of previous palaeogeographical reconstructions was of very low relief during the Silesian and probably was more often a site of deposition than of erosion.
An unusual crinoid columnal from salthill quarry, Clitheroe, Lancashire
Authors: Donovan S. K.
Published: February 2007

An unusual crinoid pluricolumnal from the Lower Carboniferous of Salthill Quarry, Clitheroe, Lancashire, has a tetrastellate lumen. This may be derived from either a cupressocrinitid or a gasterocomid, two families of cladid inadunate which have previously only been reported from the Devonian. Large inadunate cups are relatively rare at Salthill but columnals are varied and numerous, so it is not surprising that the first indications of such a crinoid at this locality should be given by dissociated ossicles. However, it is also possible that this columnal represents an aberrant individual of a species with an axial canal that is usually pentastellate.
Rb‐Sr whole‐rock isochron studies of the Barnesmore and Fanad plutons, Donegal, Ireland
Authors: O'Connor P. J. , Long C. B. , Evans J. A.
Published: February 2007

Results of Rb‐Sr whole‐rock isochron studies of the Barnesmore and Fanad plutons of Co. Donegal are presented. The Barnesmore pluton yields an age of 397 ± 7 My and initial 87Sr/86Sr ratio of 0·7063 ± 0·0005 (MSWD 10·2) while the Fanad pluton yields an age of 402 ± 10 My and initial 87Sr/86Sr ratio of 0·7050 ± 0·0001 (MSWD 1·6).

These studies supplement recent Rb‐Sr dating of the Donegal granitoid batholith by Halliday et al. (1980) and O'Connor et al. (1982), and confirm that the entire suite was emplaced during a short interval spanning mid‐Silurian to earliest Devonian time. The relatively low and restricted range of initial Sr isotope ratios suggests small, but significant, differences in the composition of the source region of these ‘Caldedonian I‐type’ magmas.

The Rb‐Sr data indicate that contamination processes have not played a significant role in the petrogenesis of the Fanad rocks and their intermediate character and high Sr content are considered primary features of the parent dioritic magma. At Barnesmore, late stage devolatilization of evolved granitic magmas has resulted in the development of desilicated zones within the pluton: the granite of such zones may exhibit elevated 87Sr/86Sr ratios.
Macrofloral biostratigraphy of the Newent Coalfield, Gloucestershire
Authors: Cleal C. J.
Published: February 2007

Boreholes recently drilled by the British Geological Survey provide the first extensive collection of fossil plants from the Newent Coalfield, Gloucestershire. They belong to the Lobatopteris vestita Biozone, indicating a late Westphalian D age. The Newent sequence is thus homotaxial with part of the Forest of Dean Coalfield, and supports the view of Wills (1956) that there was a ‘strait’ extending across St George's Land during the late Westphalian.
Gravity anomalies associated with the Cefn‐y‐Fedw Sandstone Group, northeast Wales, and their geological significance
Authors: Cornwall J. D.
Published: February 2007

Regional and detailed gravity surveys over Carboniferous rocks in northeast Wales have revealed an elongated Bouguer anomaly low over part of the outcrop of the Cefn‐y‐Fedw Sandstone Group. The anomaly has a pronounced gradient over the boundary of these sediments with the limestones of the underlying Viséan Series, but downdip, to the east, the anomaly merges with the general decrease of Bouguer anomaly values. The anomaly can be explained if the thickness of the lower density Cefn‐y‐Fedw Sandstone Group increases abruptly along the margin of the outcrop of these rocks. Various explanations for this are considered including faulting, a syncline. and channel‐like deposits. The interpretation is further complicated by the presence of sandstones with densities varying between 2·2 Mg m−1 and 2·6 Mg m−3

Although a full explanation is not possible without further evidence, the existence of the Bouguer anomaly low necessitates a review of the nature of the Cefn‐y‐Fedw Sandstone Group.
Late Pan‐African magmatism and crustal development in northeastern Egypt
Authors: Abdel‐Rahman Abdel‐Fattah M. , Martin Robert F.
Published: February 2007

The voluminous Pan‐African calc‐alkaline granitic suite of the Ras Gharib crustal segment in northeastern Eygpt provides a typical example of orogenic magmatism. The 552 ± 7 Ma‐old granodiorite–adamellite and leucogranite suite is compositionally broad (58 to 77 wt.% SiO2) and exhibits calc‐alkaline geochemical trends and trace‐element characteristics typical of the volcanic‐arc granites. The rocks contain oligoclase, albite, K‐feldspar, calcic amphibole, biotite, titanite, zircon, and magnetite. The suite exhibits typical features characteristic of I‐type granites.

We contend that the magma was formed by partial melting of a modified oceanic crust at an active continental margin during the late stage of the Pan‐African orogeny. The process may have involved assimilation of Early Pan‐African dioritic country rocks. The more felsic units were produced by progressive fractionation of that magma. The petrological–geochemical evidence suggest that the Pan‐African crust in northeastern Egypt did not develop in an extensional tectonic regime, as proposed recently.
The Moel‐y‐Golfa Andesite: An Ordovician (Caradoc) intrusion into unconsolidated conglomeratic sediments, Breidden Hills Inlier, Welsh borderland
Authors: Dixon R. J.
Published: February 2007

The Moel‐y‐Golfa Andesite is a discordant intrusive body of porphyritic pyroxene andesite, 1 km across and at least 200 m thick. Textural variation defines a central facies and a marginal facies, the latter displaying well‐formed lobes, tubes, and pillows. The vertically stacked lobes, brecciated tubes, and elongate pillows of andesite intrude and locally enclose enclaves of altered host sediment and are cut by steeply dipping slide scars. The host sediments are locally strongly silicified and cut by numerous, anastomosed vertical and subvertical fissures. Fissures are filled by disrupted host sediment and fragments of brecciated andesite. The formation and filling of each fissure system was probably concomitant with the brecciation of an intrusive magma lobe. The complex relationship of igneous and sedimentary material indicates that the Moel‐y‐Golfa Andesite was emplaced into the host sediments whilst they were unconsolidated or only partly lithified.
A sedimentological study of diamondiferous Quaternary sediments in Southern Shandong, China
Authors: Dobbs P. N. , Yaping Guo , Siyi Hu , Jianrong Lin , Lianquan Luo , Jinsong Zang , Xiongying Zhao , Harris J. W.
Published: February 2007

A sedimentological study of the lower Quaternary sediments in southern Shandong Province suggests that they were derived from a northern highland area of Archaean gneiss and Palaeozoic sediments. Diamond‐bearing kimberlites, intruded during the Ordovician, occur in the highland area and are a possible source of diamonds found in the Quaternary sediments. A warm and humid climate prevailed at the beginning of the Quaternary and braided rivers carried gravel and sand southeast towards the Yellow Sea. Cooler and drier conditions in Q2 times reconcentrated diamonds from the underlying Q1 gravels. Post‐Q2 faulting deflected the drainage to the south and subsequent erosion left only small remnants of diamondiferous Q2 gravel. A study of diamond shape characteristics suggests that the diamonds in the Quaternary sediments were derived from the known kimberlites to the north, although the possibility of undiscovered kimberlites occurring beneath the Quaternary sediments cannot be ruled out.
The Burkinian orogenic cycle, precursor of the Eburnian orogeny in West Africa
Authors: Lemoine S. , Tempier P. , Bassot J. P. , Caen‐Vachette M. , Vialette Y. , Touré S. , Wenmenga U.
Published: February 2007

In the best known areas of the West African craton structural, petrographic, and geochronological data provide a distinction between two separate units of the Lower Proterozoic in West Africa. A lower unit was metamorphosed from low to medium grade around 2170 Ma by horizontal shearing. This unit is mainly composed of dominantly basic bimodal magmatic rocks, and some trondhjemitic to tonalitic anatectic gneisses, and locally mesozonal mica schists known in Ivory Coast as the ‘Kounoukou formation’ which has been dated as 2183 Ma old. An upper unit, which frequently begins with polygenic conglomerates, also shows important bimodal vulcanism, but in contrast to the lower unit is dominantly silicic. This unit is affected by lower grade conditions of metamorphism and is weakly deformed. These two units correspond to the classic Eburnian I/Eburnian II succession. However, a clearer distinction is possible, with the recognition of two successive orogenic cycles. In the basal part of each of the two units a major episode of tholeiitic magmatism is evidence for separate periods of lithospheric thinning and fracturing. This was followed by the deposition of various lithological sequences, then by one or more tectonometamorphic events. Later uplift led to the emplacement of anorogenic subvolcanic granitic massifs which are displayed occasionally as ring complexes.

This suggests that ‘Eburnian I’ is actually an independent orogenic cycle appearing in the West African formations between 2400 and 2150 Ma, for which we propose the name ‘Burkinian cycle’. This cycle has affected the lower magmatic and sedimentary formations, which we designate Dabakalian. This implies a restricted time span for the Eburnian cycle from 2100–2150 to 1800 Ma.

The stratigraphic term ‘Birimian’ is applied to the sedimentary and magmatic formations of the upper unit.

This scheme proposed for the Lower Proterozoic in West Africa is probably applicable to other Lower Proterozoic terranes in Africa.
Typology, evolution, and origin of the Kerguelen Plutonic Series, Indian Ocean: A review
Authors: Giret André
Published: February 2007

The Kerguelen Islands (6,500 km2) are the third largest oceanic archipelago after Iceland and Hawaii. One of their most remarkable geological features is the existence of several igneous complexes thought to represent the deep levels of volcano‐plutonic structures of which the upper part has been eroded. These plutonic bodies have ring shapes with diameters ranging from 1 to 15 km. The oldest (39–23 Ma) have transitional petrological features while the youngest (26 Ma–Recent) are typically alkaline. This sequence is also observed in the surrounding flood‐basalts. Both the basalts and the plutonic rocks have a mantle origin. The alkaline plutonic suites evolve towards silica‐over or undersaturated rock types depending on whether they are located to the west or to the east of a NNW–SSE boundary. The divergence in alkaline trends may be related to magmatic differentiation or linked to the evolution of two different initial magmas, one being mid‐alkaline and the other high‐alkaline. In both hypotheses fluids, particularly H2O, play a major role.
Granitoid suites
Authors: Whitten E. H. T.
Published: February 2007

The concept of suites within granitoid batholiths must be treated with extreme caution, especially when petrogenic interpretation of identified suites is involved (e.g. infrastructural control of granitoid suite composition). Without stated, necessary, and sufficient operational definitions of the parameters (and their weighting) used in suite definition, suite/s should be avoided.
Analcime: A characteristic authigenic phase of andean alluvium, northern chile
Authors: Hartley Adrian , Flint Stephen , Turner Peter
Published: February 2007

Analcime (NaAlSi2O6.H2O) forms a characteristic authigenic phase in Andean alluvium of northern Chile. Three stratigraphic units ranging from the lower Cretaceous to the Miocene were studied in order to investigate the presence of analcime in diagenetic assemblages of different ages. The units were deposited in forearc, foreland/back‐arc, and intra‐arc basinal settings.

Characteristics of other sedimentary analcime occurrences were examined in order to define conditions favourable for analcime precipitation. Zeolite zonation and evidence for the original presence of volcanic glass, common to many sedimentary analcime occurrences, are absent in the studied units. Analcime precipitation requires a high Na+/H+ ratio, relatively low Si4+/Al3+ activity and low H2O activity.

Diagenetic examination of the three stratigraphic units revealed early quartz and feldspar overgrowths, mechanical clay infiltration, and dissolution of labile rock and mineral fragments, particularly intermediate plagioclase (An30–80). Conditions for these processes are favoured by oxidizing groundwater at near neutral pH. Later diagenesis involved the precipitation of analcime, non‐ferroan calcite, quartz, and authigenic clays as the main cementing phases. These formed due to the concentration of oxidizing groundwater and resulted from its continued reaction with detrital feldspars and rock fragments of andesitic and dacitic composition.

Analcime precipitation in Andean alluvium resulted from the evolution of saline, alkaline brines under an arid, evaporative climate in closed hydrographic basins with circulating groundwater systems.
Aspects of dinantian sedimentation in the edale basin, north derbyshire
Authors: Gutteridge Peter
Published: February 2007

The Dinantian Edale Basin is located to the north of the Derbyshire carbonate platform and underlies the Upper Carboniferous of the central Pennines. The Edale Basin was thought to be part of a large basin which extended from the Derbyshire carbonate platform to the Askrigg Block. The presence of aggregate grains and ooids in the Alport Borehole suggests that a carbonate platform, possibly located on the Holme structural high, was present underneath the central Pennines. This platform is called the Holme Platform.

The Arundian to early Asbian section of the Alport Borehole represents deposition of resedimented shallow‐water carbonates with occasional bioturbated periplatform carbonates and basinal shales on the middle part of a carbonate ramp. Volcaniclastic sediments may have been derived from a volcanic centre within the Edale Basin.

A change in sedimentation during the mid‐Asbian to the deposition of basinal shales and distal carbonate turbidites is attributed to starvation of the basin. This may have been caused by a combination of the development of accretionary rimmed carbonate shelves and the repeated emergence of shelf carbonates deposited on surrounding carbonate platforms. The late Asbian/early Brigantian section of the Edale Borehole is interpreted as a distal equivalent of the ‘Beach Beds’ which outcrop at the north margin of the Derbyshire carbonate platform. The ‘Beach Beds’ represent bioclastic turbidites derived from the Derbyshire carbonate platform.

Throughout the Brigantian, sedimentation in the Edale Basin was dominated by the deposition of distal carbonate turbidites and basinal shales. Variation of dip through the Alport Borehole indicates the common occurrence of slumps throughout the sequence and the presence of either an angular unconformity or a fault within the early Brigantian section.
Early Devensian interstadial and glacigenic sediments in Gwynedd, North Wales
Authors: Addison K. , Edge M. J.
Published: February 2007

Recent excavations at Pen‐y‐bryn, Caernarfon have revealed a series of organic deposits below and within a glacial till of Welsh ice provenance. This paper presents the results of 14C analyses carried out on tree wood and organic peaty muds, together with a description of the site stratigraphy. Pen‐y‐bryn is the first Welsh site from which in situ biogenic deposits directly enclosed by glacigenic sediments and yielding finite radiocarbon dates have been recovered. Radiocarbon, plant macrofossil, palynological, fossil coleopteran and lithostratigraphic evidence suggest that this is the first site in Wales at which at least one Early Devensian interstadial episode followed by an Early Devensian stadial ice advance may be represented. Snowdonian glacier ice appears to have buried some of the organic deposits beneath till and incorporated other organic material within the till before a later advance of Irish Sea ice. This evidence is used to construct a Devensian chronostratigraphy which may involve two glacial stadia rather than a single Late Devensian glaciation.
Ordovician volcanism of the Peloritan Mountains (Sicily): Implications for evolution of Palaeozoic basins in the Calabrian‐Peloritan Arc
Authors: Acquafredda P. , Lorenzoni S. , Lorenzoni E Zanettin
Published: February 2007

The palaeontologically dated Ordovician associations of the Peloritan Mountains consist of metasilts, metapelites, calc‐schists and metavolcanic rocks. These rocks form a portion of a terrigenous‐volcanic‐carbonate sequence of Cambro‐Ordovician to Carboniferous age. This Palaeozoic sequence occupies the lower tectonic position in a Variscan orogen, affected by later Alpine deformation. The upper portion of this orogen is formed by low to high grade metamorphic rocks and some rare magmatic rocks.

The Ordovician section of the sequence is divisible into a lower part (probably Arenigian), characterized by frequent and extensive within‐plate alkaline metabasalts, and an upper part characterized by metadacites and metarhyolites intercalated with metasediments, commonly carbonates. The chemical characteristics of the metavolcanic rocks and the composition and structure of the metasediments indicate the persistence of tensional conditions during the Lower Ordovician. In contrast, the Upper Ordovician was marked by reducing tension, stagnation of basaltic magmas at different crustal levels, and consequent formation of dacitic and rhyolitic melts by partial melting of the surrounding crust.

A comparison of the Ordovician sequences of the Peloritan Mountains with those of the Calabrian Palaeozoic basins shows several geodynamic similarities. Among other circum‐Mediterranean basins, only that of north‐western Bulgaria shows good analogies.
Middle Westphalian plant fossils from the West Cumberland Coalfield, UK
Authors: Thomas B. A. , Cleal C. J.
Published: February 2007

Twenty‐six form‐species of plant macrofossils occur in the Coal Measures exposed in the Howgill Head Quarry, Whitehaven, Cumbria, UK. They belong to the Neuropteris semireticulata Subzone in the lower part of the Paripteris linguaefolia Zone, indicating the uppermost Duckmantian. They confirm that the sandstones exposed in this part of the West Cumberland Coalfield are part of the Whitehaven Sandstone Formation, and not a stratigraphically lower unit as previously suggested. The Howgill head fossils represent the only well documented example of a N. semireticulata Subzone assemblage in Britain, although comparable assemblages are known from coeval strata in northern France, Belgium, northern Germany and Poland.
An iron‐bearing wave‐dominated siliciclastic shelf: Facies analysis and palaeogeographic implications (Silurian‐Lower Devonian Sierra Grande Formation, Southern Argentina)
Authors: Spalletti Luis A.
Published: February 2007

The Sierra Grande Formation (Silurian‐Early Devonian) consists of quartz arenites associated with clast supported conglomerates, mudstones, shales and ironstones. Eight sedimentary facies are recognized: cross‐stratified and massive sandstone, plane bedded sandstone, ripple laminated sandstone, interstratified sandstone and mudstone, laminated mudstone and shale, oolitic ironstone, massive conglomerate and sheet conglomerate lags. These facies are interpreted as shallow marine deposits, ranging from foreshore to inner platform environments. Facies associations, based on vertical relationships among lithofacies, suggest several depositional zones: (a) beach to upper shoreface, with abundant plane bedded and massive bioturbated sandstones; (b) upper shoreface to breaker zone, characterized by multistorey cross‐stratified and massive sandstone bodies interpreted as subtidal longshore‐flow induced sand bars; (c) subtidal, nearshore tidal sand bars, consisting of upward fining sandstone sequences; (d) lower shoreface zone, dominated by ripple laminated sandstone, associated with cross‐stratified and horizontal laminated sandstone, formed by translatory and oscillatory flows; and (e) transitional nearshore‐offshore and inner platform zones, with heterolithic and pelitic successions, and oolitic ironstone horizons. Tidal currents, fair weather waves and storm events interacted during the deposition of the Sierra Grande Formation. However, the relevant features of the siliciclastics suggest that fair weather and storm waves were the most important mechanisms in sediment accumulation.

The Silurian‐Lower Devonian platform was part of a continental interior sag located between southern South America and southern Africa. The Sierra Grande Formation was deposited during a second order sea level rise, in which a shallow epeiric sea flooded a deeply weathered low relief continent.
The Humphrey Head Borehole: Evidence for Carboniferous vulcanicity and Permian dolomitization in the southern Lake District
Authors: Adams A. E. , Wadsworth W. J.
Published: February 2007

In south Cumbria, Permo‐Triassic breccias and conglomerates (‘brockram’) are exposed only at Rougholme Point on the Cartmel peninsula. In 1973 the Institute of Geological Sciences Humphrey Head borehole penetrated 257 m of brockram before entering probable Upper Carboniferous sediments. The brockram consists of pebbles of carbonate, chert and basalt in a matrix of haematite‐stained quartz sand. Carbonate and chert fragments were derived from the upper part of the Carboniferous Limestone sequence exposed today nearby. Basalt clasts were derived from lavas, which appear to have cooled in a subaqueous environment, at least in part. They were locally derived and are the only certain evidence for Carboniferous volcanic activity in south Cumbria. As volcanic fragments increase in abundance towards the base of the borehole they must have been derived from the top of the succession being eroded and are probably of Brigantian age.

Carbonate fragments were dolomitized soon after incorporation in the brockram, probably by saline fluids derived from the evaporative Zechstein Sea. The dolomitization was incomplete, leaving remnant limestone cores to clasts which were subsequently dissolved. The resultant vugs were infilled by dolomite, calcite and gypsum cements, which have been partially weathered from outcropping brockram, leaving hollow pebbles.
Mantle‐derived heat recorded by conodont colour alteration in the Carboniferous of the Isle of Man
Authors: Swift A.
Published: February 2007

A range of colour alteration index (CAI) values between 3.0 and 6.0 is recorded for conodont elements recovered from the Arundian to Brigantian (Dinantian, Lower Carboniferous) sequence around Castletown, Isle of Man. Mantle‐derived heat, channelled through the Caledonian South Barrule pluton, is proposed as the major cause of these elevated values. A lower CAI of 2.5 is obtained from elements recovered from a borehole sunk into the concealed Namurian (Upper Carboniferous) deposits near Shellag Point; the Glen Mona pluton acted as the medium for mantle‐derived heat in this instance. The CAI values which may have been established during a late Dinantian volcanic episode around Castletown were overprinted by the greater effects of heat emanating from the South Barrule pluton. The record of CAI 6.0 for a sample taken from the immediate vicinity of a dyke indicates a high level of very localized CAI elevation in the early Tertiary.
Structural arcuation in the Berwyn Hills, North Wales
Authors: Awan M. A. , Woodcock N. H.
Published: February 2007

New mapping has better defined the well known arc in Acadian (late Caledonian) structures centred in the Berwyn Hills. This arc, convex to the north‐west and about 20 km across, is defined by the strikes of bedding and cleavage and the trends of fold hinges. In contrast, a mineral lineation within the cleavage has a north‐north‐westerly plunge throughout the arc. It approximates to the long (X) axes of measured strain ellipsoids. A primary origin for the arcuation is implied by this consistency, by the absence of secondary cleavages and by opposing senses of fold transection across the arc. The new data favour the hypothesis of shortening of the Lower Palaeozoic cover against and over a pre‐existing basement high inferred from geophysical data and from metamorphic and sedimentary facies.
Low pressure‐high temperature metamorphism in the Vredefort Dome, South Africa: Anticlockwise pressure‐temperature path followed by rapid decompression
Authors: Gibson R. L. , Wallmach T.
Published: February 2007

Pelitic metasediments of the Witwatersrand Supergroup in the Vredefort Dome contain textural evidence for a two‐stage metamorphic history. The pressure‐temperature (P‐T) path derived for the rocks indicates that they were subjected to a high geothermal gradient (≈40°C km‐1), mid‐amphibolite facies, Mla metamorphic event concomitant with thickening of the overlying upper crust. Peak temperatures of 570–600°C were reached during Mla at depths of 14–16 km. After initial isobaric cooling following Mla, the rocks experienced rapid exhumation during a high strain rate deformation event associated with the formation of the dome. This event led to the development of abundant pseudotachylite and a brittle cleavage in these rocks. These features are overgrown. together with the Mla assemblages, by a low P M1b paragenesis comprising microporphyroblastic cordierite+biotite. Estimated P‐T conditions during Mlb were < 3.5 kbar, ≈500–;530°C.

The two‐stage P‐T path is incompatible with existing contact metamorphic and diapiric models that have attempted to link the mid‐amphibolite facies metamorphism with the formation of the Vredefort Dome. Instead, it indicates that the doming event occurred some time after the peak of a regional low P‐high T metamorphic event, during cooling of the terrain. Given an age of 2.02 Ga for the doming event, the Mla event is attributed to a widespread magmatic‐thermal event on the Kaapvaal Craton that accompanied the formation of the Bushveld Complex at 2.05–2.06 Ga. The Mlb event developed in response to the localized exhumation of deep parts of this terrain while the crustal geotherm was still elevated (≈30°C km‐1). The association, elsewhere in the dome, of pseudotachylite with shock metamorphic features generated at pressures in excess of 20–120 kbar indicates that exhumation was accomplished by the impact of a large meteorite into the terrain.
Molecular markers of extracellular matrix remodeling in glioblastoma vessels: Microarray study of laser‐captured glioblastoma vessels
Authors: Pen Ally , Moreno Maria J. , Martin Joel , Stanimirovic Danica B.
Published: February 2007

Glioblastoma multiforme (GBM) are the most malignant and vascularized brain tumors. The aberrant vascular phenotype of GBM could be exploited for diagnosis or therapeutic targeting. This study identified new molecular markers of GBM vessels, using a combination of laser capture microdissection (LCM) microscopy, RNA amplification, and microarray analyses to compare vessels from nonmalignant human brain and GBM tumors. Forty‐two genes were differentially expressed in GBM vessels compared to nonmalignant brain vessels. Validation of differentially expressed genes was performed by literature mining, Q‐PCR, and immunohistochemistry. Among the differentially expressed genes, only 64% were previously associated with vessels, angiogenesis, gliomas, and/or cancer. The upregulation of genes encoding secreted extracellular proteins IGFBP7 and SPARC was confirmed by Q‐PCR in LCM‐captured vessels. Whereas SPARC and IGFBP7 protein were absent in nonmalignant brain vessels, a distinct immunoreactivity patterns were observed in GBM sections whereby SPARC was strongly expressed in perivascular cells adjacent to GBM vessels while GBM endothelial cells were immunostained for IGFBP7. IGFBP7 immunoreactivity was also detected on the abluminal side of GBM vessels deposited between strands of vascular basal lamina. The study discerns unique molecular characteristics of GBM vessels compared with nonmalignant brain vessels that could potentially be used for diagnostic or therapeutic purposes. © 2007 Wiley‐Liss, Inc.
Dissociation of response inhibition and performance monitoring in the stop signal task using event‐related fMRI
Authors: Chevrier Andre D. , Noseworthy Michael D. , Schachar Russell
Published: February 2007

We examined the neural substrate of motor response inhibition and performance monitoring in the stop signal task (SST) using event‐related functional magnetic resonance imaging (fMRI). The SST involves a go task and the occasional requirement to stop the go response. We posit that both the go and the stop phases of the SST involve components of inhibition and performance monitoring. The goal of this study was to determine whether inhibition and performance monitoring during go and stop phases of the task activated different networks. We isolated go‐phase activities underlying response withholding, monitoring, and sensorimotor processing and contrasted these with successful inhibition to identify the substrate of response inhibition. Error detection activity was isolated using trials in which a stop signal appeared but the response was executed. These trials were modeled as a hand‐specific go trial followed by error processing. Cognitive go‐phase processes included response withholding and monitoring and activated right prefrontal and midline networks. Response withdrawal additionally activated right inferior frontal gyrus and basal ganglia (caudate). Error detection invoked by failed inhibition activated dorsal anterior cingulate cortex (dACC) and right middle frontal Brodmann's area 9. Our results confirm that there are distinct aspects of inhibition and performance monitoring functions which come into play at various phases within a given trial of the SST, and that these are separable using fMRI. Hum Brain Mapp, 2007. © 2007 Wiley‐Liss, Inc.
Prognostic factors for Korean patients with anaplastic thyroid carcinoma
Authors: Kim Tae Yong , Kim Kyung Won , Jung Tae Sik , Kim Jung Min , Kim Sun Wook , Chung Ki‐Wook , Kim Eun Young , Gong Gyungyub , Oh Young Lyun , Cho Soo Youn , Yi Ka Hee , Kim Won Bae , Park Do Joon , Chung Jae Hoon , Cho Bo Youn , Shong Young Kee
Published: February 2007

Background.

Anaplastic thyroid carcinoma (ATC), although rare, is one of the most aggressive human cancers, and patients with ATC have extremely poor prognoses despite various therapeutic measures. We wished to determine the prognostic factors of survival and effect of treatment on survival rate in patients with ATC.

Methods.

We retrospectively reviewed the medical records of the 121 patients (41 men and 80 women) diagnosed with ATC from January 1995 to June 2004 at 5 major referral centers in Korea.

Results.

Mean patient age at diagnosis was 64 ± 11 years (range, 17–84 years). Of the 121 patients, 11 (9%) had intrathyroidal tumors, 69 (57%) had extrathyroidal tumors or lymph node involvement, 29 (24%) had distant metastases, and 12 had no data about staging (9%). The mean tumor diameter was 5.5 ± 2.5 cm (range, 0.5–17.0 cm). At a median follow‐up of 41 months (range, 26–122 months), 8 patients were alive. Median survival time was 5.1 months. The disease‐specific survival rates were 42% at 6 months, 16% at 12 months, and 9% at 24 months. Sixteen patients (13%) received only supportive care, 25 (21%) received surgery alone, 20 (16%) received radiation treatment or chemotherapy without surgery, and 60 (50%) received surgery plus radiation treatment or chemotherapy. Multivariate analysis showed that age less than 60 years, tumor size less than 7 cm, and lesser extent of disease were independent predictors of lower disease‐specific mortality.

Conclusions.

Long‐term survival is possible for ATC patients less than 60 years old and with small localized tumors. Although aggressive multimodal therapy, including surgery, radiation treatment, and chemotherapy, was not significantly associated with improved survival, we advocate aggressive multimodal therapy in selected ATC patients with good prognostic factors. © 2007 Wiley Periodicals, Inc. Head Neck 2007
Effect of tobacco deprivation on the attentional blink in rapid serial visual presentation
Authors: Heinz Adrienne , Waters Andrew J. , Taylor Richard C. , Myers Carol S. , Moolchan Eric T. , Heishman Stephen J.
Published: February 2007

When two targets are imbedded in rapid serial visual presentation (RSVP), identification of the second target (T2) is impaired if it occurs within 500 ms of the first target (T1). This attentional blink (AB) is thought to involve interference of resources in processing T1 and T2. The deleterious effect of tobacco deprivation on attention has been documented, but no studies have examined the AB. Nonsmokers (n = 30), 12‐h tobacco‐deprived smokers (n = 30), and nondeprived smokers (n = 30) were randomly assigned to perform the RSVP with one of three stimulus‐duration conditions (96, 113, or 130 ms). Participants completed 48 RSVP trials. Each trial consisted of 16 individually presented words (T1, T2, and 14 distractors), and T2 lagged T1 at serial positions 1—8. Participants verbalized T1 and T2 in order immediately after each trial. Identification of T2 (for correct T1 trials) was impaired at early versus late lag positions, which was especially pronounced in the most difficult (96 ms) condition. There was no evidence for group differences on the AB; however, deprived smokers were worse identifying T1 in the 113‐ms condition. These results suggest that the AB is influenced by stimulus duration, but not by 12 h of tobacco deprivation. Copyright © 2007 John Wiley & Sons, Ltd.
Non‐point source pollution estimation using a modified approach
Authors: Jha Ramakar , Ojha C. S. P. , Bhatia K. K. S.
Published: February 2007

Non‐point source (NPS) pollution from agricultural land is increasing exponentially in many countries of the world, including India. A modified approach based on the conservation of mass and reaction kinetics has been derived to estimate the inflow of non‐point source pollutants from a river reach. Two water quality variables, namely, nitrate (NO3) and ortho‐phosphate (o‐PO4), which are main contributors as non‐point source pollution, were monitored at four locations of River Kali, western Uttar Pradesh, India, and used for calibration and validation of the model. Extensive water quality sampling was done with a total of 576 field data sets collected during the period from March 1999 to February 2000. Remote sensing and geographical information system (GIS) techniques were used to obtain land use/land cover of the region, digital elevation model (DEM), delineation of basin area contributing to non‐point source pollution at each sampling location and drainage map.

The results obtained from a modified approach were compared with the existing mass‐balance equations and distributed modelling, and the performances of different equations were evaluated using error estimation viz. standard error, normal mean error, mean multiplicative error and correlation statistics. The developed model for the River Kali minimizes error estimates and improves correlation between observed and computed NPS loads. Copyright © 2007 John Wiley & Sons, Ltd.