bluuebunny/crossref_metadata_2025_split huggingface dataset:
A deep-marine ichnofaunal assemblage from Llandovery strata of the Welsh Basin, west Wales, UK
Authors: Orr Patrick J. 
Published: May 2009

AbstractIn the Welsh Basin, turbidites of Llandovery age at Cwmerfyn, near Goginan (Devil’s Bridge Formation) and Neuadd Fawr, near Lampeter, contain similar, diverse, ichnofaunal assemblages, despite strong sedimentological differences between the two localities. The sediments at Cwmerfyn are a series of very thin- to thin-bedded silt/mud couplets. The silt-grade lower half of each couplet is ripple-cross- and/or planar-laminated; the mud-grade upper part is massive. At Neuadd Fawr, the strata are thin- to medium-bedded, and composed of fine- to medium-grained sand; individual beds are parallel-laminated or display pronounced convolute lamination. At both localities, the ichnofaunal assemblage is dominated by endostratal pascichnia observed on intrastratal, bedding-parallel, planes of splitting. All the ichnofauna is post-depositional. Both assemblages are dominated by examples ofNereites cambrensisandmacleayii; examples ofNeonereites uniserialisandbiserialis, Protovirgularia dichotoma, Chondrites, Dictyodora scotica, Helminthoida crassa, two other ichnospecies ofNereitesand examples ofNereitesisp.,Palaeophycus tubularis, Macaronichnus segregatus, Planolites beverleyensisandmontanusand a ‘braided trace’ are also present. In contrast, the diverse ichnofaunal assemblage recorded from the Aberystwyth Grits Group by others is both pre-depositional and post-depositional in origin. The former include agrichnia (PaleodictyonandSquamodictyon) and cubichnia (AsteracitesandBergaueria), observed as secondary casts on the soles of turbidites. The differences in composition between this ichnofaunal assemblage and those at Cwmerfyn and Neuadd Fawr are interpreted to be a result of the degree of oxygenation of the sediment profile. In the Aberystwyth Grits, the producers of the agrichnia and cubichnia would have been able to tolerate reduced oxygen levels in the sediment profile, because they maintained a connection with an oxygenated water column. The post-depositional component of the Aberystwyth Grits assemblage is interpreted to represent opportunistic colonization of the sediment profile during short intervals of elevated oxygen conditions produced by episodic turbidite deposition. The producers of the endostratal pascichnia at Cwmerfyn and Neuadd Fawr did not maintain connections with the water column, implying the presence of oxygenated interstitial porewaters during their emplacement.
Diagenesis of ferriferous phases in the Northampton ironstone in the Cowthick quarry near Corby (England)
Authors: Gehring A. U. 
Published: May 2009

AbstractBerthierine, siderite and pyrite are the major ferriferous phases in the Northampton ironstone (NIS). Mineralogical and chemical data suggest a formation of these phases in a diagenetic marine environment changing from post-oxic to sulphidic conditions. Berthierine was formed first when the Fe2+ activity in the diagenetic system increased. Later, this phase was partially replaced by siderite and/or pyrite. A second stage of the diagenetic development in the NIS with increasing CO2 partial pressure (PCO2 ) is documented by siderite. The isotopic composition (δ18O mean value: –1.7‰PDB; δ13C mean value: –8.6‰PDB) points to siderite precipitation from a marine porewater environment with a microbial CO2 source. The shift from post-oxic to sulphidic conditions is indicated by the occurrence of pyrite and can be considered as a final stage. The diagenetic processes in the marine environment and the formation of the ferriferous phases were stopped by the influx of brackish or fresh water when the Midland Shelf turned estuarine.
Perim Island, a volcanic remnant in the southern entrance to the Red Sea
Authors: Mallick D. I. J. , Gass I. G. , Cox K. G. , De Vries B. V. W. , Tindle A. G. 
Published: May 2009

AbstractPerim Island is an eroded fragment of the southwest flank of a late Miocene (10.5 ± 1.0 Ma) volcano whose centre lay on the southwesternmost tip of Arabia. The volcano is the westernmost of the E–W line of six central vent volcanoes (the Aden Line) that extends 200 km along the south coast of Arabia from Perim to Aden. Major oxide and trace element abundances are given for 35 Perim specimens and these show that the volcano has within-plate trace element characteristics and consists of a petrographically and geochemically simple suite of alumina-poor olivine basalts, andesites, and transitional andesite–trachyandesites. Six specimens, however, are markedly enriched in Al2O3 and CaO, and contain abundant (20–30 mode %) highly calcic (An77–83) plagioclase phenocrysts. Geochemical modelling suggests that the main Perim volcanic sequence was produced by the fractional crystallization (o1 + cpx + Ti-mt + plag) of a silica saturated (SiO2 c. 45%) basic melt. The high A1, high Ca, magmas appear to be mixing products of plagioclase-enriched basic magmas with more evolved melts. Perim is the oldest volcano of the Aden line, which becomes increasingly younger and alkalic eastward. It is suggested that the volcanism is related to an eastwards-propagating rift produced before the most recent stage of sea-floor spreading in the Gulf of Aden (4.5 Ma–present).
Elastic flexure with compressive thrusting of the Green River Basin, Wyoming, U.S.A.
Authors: Jie Tang , Lerche Ian , Cogan Jeff 
Published: May 2009

AbstractAn inverse elastic flexural model with compressive thrusting is applied to the northern Green River Basin, Wyoming. A combination of six parameters in the model determines the deformational processes of basement due to sediment load and compressive thrusting: flexural rigidity, lateral stress, bending moment, initial load, dip angle of the basement, and length. The results suggest that the northern Green River Basin develops dominantly as an elastic flexural response to the deformation of basement due to compressive thrusting of the Wind River Mountains. From the unloaded basement configuration we estimate that by latest Cretaceous time the thrust fault activity of the Wind River Mountains led the basement to uplift about 7 km above the hinge point at the margin of the basin and to form a complex faulted mountain system. The maximum uplift rate is about 100 m/Ma at the Wind River Mountains. Also we predict the sedimentary pattern, and provenance of sediments of Tertiary units, from the unloaded basement geometry. Thus the inverse elastic flexural model can be used to assess the evolutionary processes involved in a basin under compressive thrusting.
Vendian strata in their type area
Authors: Yakobsan K. E. 
Published: May 2009

AbstractIn the Eastern European region Vendian strata are divisible into two complexes: the lower one, only locally developed, is composed of alternating tillites, volcanics, sandy–clay rocks and dolomites; and the upper one, of alternating sandstone, siltstone, and mudstone strata with medusoid fauna, resting transgressively on the lower complex and older rocks. The lower complex is associated with sheet glaciation; the upper one was formed in a post-glacial isostatic basin. The name ‘Vendian’ should be applied only to the upper complex; the lower one should be called ‘Waranger’.
Systematic status of Pseudohibolites Blüthgen, 1936 (Belemnitida, Coleoidea) from Kong Karls Land, Svalbard
Authors: Doyle Peter 
Published: May 2009

AbstractThe belemnite genus Pseudohibolites Blüthgen, 1936 was erected without designation of a type species and is invalid according to Article 13b of the International Code of Zoological Nomenclature. The species P. nathorsti Blüthgen and P. caroli Blüthgen are reinterpreted using topotypes from Kong Karls Land and are considered species of Hibolithes Montfort, 1808.
Upper Triassic to Lower Cretaceous continental and coastal saline lake evaporites inthe Atacama region of northern Chile
Authors: Suarez M. , Bell C. M. 
Published: May 2009

AbstractEvaporites within Upper Triassic to Lower Cretaceous sequences in the Atacama region of northern Chile are interpreted as the deposits of continental and coastal saline lakes. Halite casts and finely laminated calcareous evaporites, intercalated with alluvial and fluvial sediments, are probably playa lake deposits. These continental evaporites have been recognized in Upper Triassic alluvial sediments (Cifuncho Formation), in Upper Triassic–Lower Jurassic braided river deposits (basal unit of the Pan de Azúcar Formation), and within a sequence of Lower Cretaceous aeolian, alluvial and playa lake mudflat sediments (Quebrada Monardes Formation). Lower Cretaceous evaporites between marine limestones (Lautaro Formation) and continental redbeds (Quebrada Monardes Formation) were probably deposited in coastal saline lagoons, produced during a regionally extensive marine regression.These sequences, and other similar successions in northern Chile, provide a record of almost continuous evaporite deposition, and hence of arid to semi-arid conditions, since Upper Triassic times. These conditions were primarily the result of a constant latitudinal position within the subtropical zone. A contributary factor was the geographical position of the area, initially on the west coast of Gondwanaland and subsequently on the coast of South America, with cold, northward-flowing ocean currents and offshore winds.
Stratigraphy and age of the ammonoid Durvilleoceras woodmani from the Greville Subgroup, New Zealand
Authors: Waterhouse J. B. 
Published: May 2009

AbstractDurvilleoceras woodmani of debated Late Permian or Early Triassic age is accompanied by other ammonoids, deemed to belong to Araxoceratidae, Xenodiscidae, and Goniatitida, of chiefly Late Permian age. The ammonoids are found principally in the Deserter Bay and especially Tongue Point Members (new names) of the newly named South Arm and Wells Arm formations of the Greville Subgroup, which are overlain, apparently in normal stratigraphic succession, by the Waiua Formation and newly named formations of the Te Mokai Group, with three successive faunas of Permian appearance.
Origin and emplacement of an inferred late Jurassic subduction-accretion complex, Euboea, eastern Greece
Authors: Robertson A. H. F. 
Published: May 2009

AbstractIn northern Euboea, central eastern Greece, an up to 3 km-thick polygenetic melange (Pagondas complex) is structurally interleaved between a Triassic–Jurassic carbonate platform (Pelagonian Zone) and an overriding harzburgitic ophiolite. The melange mainly comprises late Triassic shallow-water limestone and calciturbidites, radiolarites, Triassic–Jurassic tholeiites, alkaline basalts and minor andesites. The units concerned range from kilometre-sized thrust sheets, and detached blocks, to broken formation and structureless, or bedded matrix-supported conglomerates (diamictite). The melange includes remnants of Neotethyan oceanic lithosphere, overlain by radiolarites, hemipelagic carbonates and distal calciturbidites derived from a Mesozoic carbonate platform. Tholeiites were erupted at a Triassic–Jurassic spreading axis, whilst within-plate-type alkali basalts are interpreted mainly as seamounts. Kilometre-scale detached blocks of shallow-water coralline limestone are identified as collapsed atolls, formed within an ocean and/or along the rifted continental margin. Volcaniclastic sediments are locally interbedded with radiolarite, and reflect post-volcanic erosion of the ocean floor. Intra-oceanic convergence began, apparently in late early Jurassic time, giving rise to the Euboea ophiolite above an inferred westwards-dipping subduction zone. The Pagondas Complex then developed as an accretionary prism. The subduction trench later collided with the Pelagonian passive margin, driving the hot Euobea ophiolite over the accretionary complex, to produce amphibolites and greenschists of the metamorphic sole. Trench–margin collision then drove the entire supra-subduction zone complex, apparently eastwards, downflexing the Pelagonian carbonate platform to form a foredeep in which late Jurassic (Kimmeridgian–Tithonian) radiolarian sediments accumulated. During emplacement, the accretionary complex was disrupted and partly resedimented as debris flows, turbiditic volcaniclastic sandstone and shale in a foredeep, or foreland basin setting.
An ankylosaurid dinosaur from the Upper Cretaceous of Shandong (China)
Authors: Buffetaut Eric 
Published: May 2009

AbstractIn 1923, H. C. T’an and O. Zdansky collected remains of an ankylosaurid dinosaur in the Late Cretaceous Wangshi Group of the Laiyang region, in eastern Shandong (China). Apart from a few caudal vertebrae, this material, which is kept at the Palaeontological Institution of the University of Uppsala (Sweden), was never described or figured. It includes a well-preserved sacrum with the attached right ilium and part of the presacral rod, caudal vertebrae, a left femur and a dermal scute. This material is referred to an ankylosaurid of the genus Pinacosaurus Gilmore, 1933, on the basis of the widely divergent ilium bearing a strong ventral ridge and of the slenderness of the femur. In the absence of cranial material, a specific attribution is difficult and the Uppsala material is referred to as Pinacosaurus cf. grangeri (P. grangeri being the only generally accepted species of Pinacosaurus). This is the first record of Pinacosaurus outside the Gobi Basin of Mongolia and northwestern China. In the Gobi Basin, Pinacosaurus has been reported only from the Djadokhta Formation or its equivalents, of supposed Campanian age, and it is suggested that at least the part of the Wangshi Group which yielded the Shandong Pinacosaurus may be of roughly the same age as the Djadokhta Formation.
An atheloptic trilobite assemblage from the Carboniferous of North Devon
Authors: Owens R. M. , Tilsley J. W. 
Published: May 2009

AbstractNew collections of trilobites have been made from Dinantian rocks in North Devon, distributed among seven genera. Of these,Wagnerispina, Archegonus (Phillibole), Liobole, Aprathia, and probablyLichanocoryphegen. nov., are primitive phillipsiids belonging to the subfamily Archegoninae. Reasons are given here for the others,TawstockiaandSpatulina, previously considered to be primitive phillipsiids of the subfamily Cystispininae, to belong to the higher phillipsiids, as effaced, blind members respectively of the Linguaphillipsiinae and Cummingellinae. The species of these genera from North Devon discussed here, three of which are new, are either small-eyed or blind, and form an atheloptic assemblage; they occur in hemipelagic sediments of the Codden Hill Chert Group in the Barnstaple district, and the Kersdown Chert Formation in the Bampton district. Ammonoids associated with the trilobites indicate an early Viséan, late Chadian age for the fauna, and the same or similar trilobite species and subspecies occur in the Březina Shales of Moravia, suggesting that they are approximately coeval.
The oldest known dinosaur from southeast Asia: a prosauropod from the Nam Phong Formation (late Triassic) of northeastern Thailand
Authors: Buffetaut Eric , Martin Valérie , Sattayarak Nares , Suteethorn Varavudh 
Published: May 2009

AbstractThe distal part of the fused ischia of a prosauropod from the Nam Phong Formation (late Triassic) of Phetchabun Province, in northeastern Thailand, is described. Comparisons with various prosauropods, as well as with an early sauropod, show that the Thai specimen is especially robust. However, the available material is too incomplete to warrant a precise identification. It is the first vertebrate fossil found in the Nam Phong Formation, the oldest known dinosaur from southeast Asia, and the first prosauropod to be reported from that region.
Denudation chronology from cave and river terrace levels: the case of the Buchan Karst, southeastern Australia
Authors: Webb J. A. , Fabel D. , Finlayson B. L. , Ellaway M. , Shu Li , Spiertz H.-P. 
Published: May 2009

AbstractDetailed mapping of surface and underground karst features at Buchan, in eastern Victoria, has shown that the three river terraces along the Buchan River can be correlated with three levels of epiphreatic development in the nearby caves. Each level represents a stillstand in the denudational history of the area. Uranium series dating of speleothems and palaeomagnetic studies of cave sediments indicate that all three stilistands are more than 730 ka old. The periods of incision separating the stillstands were probably the result of active tectonic uplift. This contrasts with some northern parts of the Southeastern Highlands, which have been stable since the Eocene. The overall amount of incision and uplift at Buchan is small, indicating that the majority of scarp retreat in this section of the highlands must have occurred earlier. The denudation history of the Buchan area over the last 730 ka has seen only 2–3 m of incision, despite the major climatic and sea-level changes that have occurred in that time. Whereas most karst landscapes in the Northern Hemisphere have been extensively modified during the late Pleistocene, the Buchan karst was little affected, and its geomorphology has an older origin.
Azolla tegeliensis Florschütz from the early Pleistocene of the British Isles
Authors: Field Michael H. 
Published: May 2009

AbstractFossil megaspores of the aquatic fern Azolla tegeliensis Florschütz have been recovered from sediments of early Pleistocene age at Great Blakenham, Suffolk, England. This discovery is the first record for this taxon in the British Isles. The find reinforces a recently suggested correlation of the British early Pleistocene sediments with those from con tinental northwest Europe. In the long continuous Pleistocene sequences in The Netherlands the megaspores of A. tegeliensis have been recovered from early Pleistocene sediments, where they are restricted to the Tiglian Stage. Sediments at Great Blakenham can now be correlated with the Tiglian sediments of The Netherlands.
Evidence for extensive post-Caledonian karst development in southwestern Spitsbergen
Authors: Bjørnerud M. 
Published: May 2009

AbstractProterozoic limestones at several localities in southwestern Spitsbergen contain karst-related features (layered clastic infillings, collapse breccias, deeply weathered depressions) which overprint the Caledonian deformational fabric in the rocks. These features apparently developedbetween middle Devonian and mid-Carboniferous time when the Precambrian basement complex stood high above sea level. Recognition of these karst features may shed light on depositional and tectonic events in post-Caledonian Spitsbergen.
Crystallization of solid solutions from aqueous solutions in a porous medium: zoning in (Ba, Sr)SO4
Authors: Prieto Manuel , Putnis Andrew , Fernandez-Diaz Lurdes 
Published: May 2009

AbstractBarite-celestite solid solutions have been synthesized under controlled conditions by the counter-diffusion of Ba2+, Sr2+and SO42–ions through a porous transport medium (silica gel), to investigate the factors which control compositionalzoning. The equilibrium compositions of solid solution and aqueous solutionhave been determined from the relative solubilities of barite and celestite, predicting that virtually pure barite should precipitate from Sr-rich solutions. However, nucleation and growth in a porous medium, where mass transport is by diffusion, takes place at very high supersaturations. The threshold supersaturation for nucleation is inversely related to the solubility and is therefore much higher for barite than celestite. The balance between the thermodynamics and kinetics of nucleation and growth at high supersaturations leads to zoning patterns the reverse of those predicted at equilibrium. At high supersaturations the zoning is periodic and sector-controlled with many of the general features observed in natural minerals. Oscillatory zoning with compositional gaps can take place without the need to invoke miscibility gaps or periodic variations in externally controlled intensive parameters.
A preliminary petrographic study of the Chilean nitrates
Authors: Searl Alison , Rankin Sharon 
Published: May 2009

AbstractThe nitrate deposits of the northern Atacama Desert occurin a narrow zone between the low-lying Pampa del Tamarugal to the east and the hills of the Coastal Range to the west. High purity nitrate ore occurs as stratiform seams about 20 cm thick, present at depths of 3–7 m below thedesert surface. The ore is hosted by a variety of lithologies and overlain by salt-cemented regolith. The ore is largely composed of nitratite (= sodanitre or Chilean salt peter) and halite with locally abundant humberstonite, polyhalite and mirabilite. Other salts present include Ca iodates and a variety of sulphate, borate and chromate minerals. Textural relationships can be used to deduce paragenetic sequences for individual salt samples and these combined to produce a generalized paragenetic web for the nitrate ore.These textural data can be combined with published solubility data to investigate the course of fluid evolution during ore genesis. The multiplicity of paragenetic relationships within the ore reflects the derivation of precipitating fluids from a variety of sources: westwards flowing Andean groundwater, coastal fogs, occasional rainfall and Andean-derived surface floodwaters. The unusual mineralogy of the nitrate ore reflects the extreme chemical evolution of the precipitating brines through multiple episodes of salt precipitation and remobilization during transport to the nitrate horizons. The formation of high purity nitrate ore appears to be the result of multiple phases of dissolution, reprecipitation and recrystallization, that have separated the highly soluble nitrate salts from less soluble salts in the overlying profile. Salts have largely accumulated through displacive growth, but some of the host silicate and carbonate lithologies have also undergonea small degree of salt replacement.
Carbon isotope and magnetic polarity evidence for non-depositional events within the Cambrian-Ordovician Boundary section near Dayangcha, Jilin Province, China
Authors: Ripperdan R. L. , Magaritz M. , Kirschvink J. L. 
Published: May 2009

AbstractCarbon isotope and magnetic polarity stratigraphic results from the Cambrian-Ordovician Boundary section at Xiaoyangqiao, near Dayangcha, Jilin Province, China, in comparison to a contemporaneous section at Black Mountain, Australia, indicate strata equivalent to major portions of the Australian sequence are either absent or are restricted to highly condensed intervals. These intervals are correlative with regressive sea level events identified in Australia and western North America, suggesting regional or eustatic sea level changes strongly influenced deposition of the Xiaoyangqiao sequence. These results also suggest the Xiaoyangqiao section is unfavourable as the site of the Cambrian-Ordovician Boundary Global Stratotype Section and Point.