bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stratigraphic and tectonic implications of Triassic conodonts from northwest Peninsular Malaysia
Authors: Metcalfe I. 
Published: May 2009

AbstractThe Chuping Limestone of northwest Peninsular Malaysia, until recently considered entirely of Permian age, has yielded late Triassic (early Norian) conodonts. TheLimestone thus spans the time interval late Early Permian–Late Triassic and is in part equivalent to the Kodiang Limestone (Late Permian–Late Triassic) in Kedah andsimilar limestone sequences in south Thailand and north Sumatra. Early Late Triassic (Carnian) conodonts are also reported from pelagic limestones associated with bedded chertsof the Chert Member of the Semanggol Formation in Kedah. The Chert Member, previously considered of Middle Triassic age, is re-interpreted to represent Early, Middle and early Late Triassic deposition. The Triassic sedimentary rocks of the Malay Peninsula represent three distinct sedimentary regions: a stable shallow marine carbonate complex (ChupingLimestone, Kodiang Limestone), which forms part of an elongate carbonate platform on theSibumasu block; a deep water pelagic/turbidite basinal sequence (Semanggol Formation) which accumulated in either a foredeep basin or an intracratonic pull-apart basin related to strike-slip faulting; and a volcanic-sourced volcaniclastic basinal sequence on the East Malaya block (Semantan Formation and equivalents) which accumulated in either a forearc/intra-arc setting, or in a post-orogenic rift basin.
Hamrat Duru Group: revised stratigraphy of a Mesozoic deep-water passive margin in the Oman Mountains
Authors: Cooper D. J. W. 
Published: May 2009

AbstractThe stratigraphy of the Hawasina Complex is redefined and rationalized to conform with standard stratigraphical nomenclature. Previously proposed tectono-stratigraphical units are abandoned in favour of a system that relies on the lateral correlation of lithofacies between structural units. To this end, the Dibba, Dhera, Wahrah and Al Ayn Formations are incorporated into an expanded Hamrat Duru Group. This group is divided into five formations, the Zulla, Guweyza Sandstone, Guweyza Limestone, Sid'r and Nayid and spans Triassic to Mid Cretaceous (Cenomanian) time. It locally passes up into the syn-orogenic sediments of the Riyamah Member of the Muti Formation. The nomenclature of the deeper-water, chert-dominated formations is left unaltered.
Archaean strike-slip faulting and related ensialic basins: evidence from the Pilbara Block, Australia
Authors: Krapez B. , Barley M. E. 
Published: May 2009

AbstractArchaean sedimentary and volcanic successions in the Lalla Rookh Basin andc. 2950 Ma old Whim Creek Belt in the Pilbara Block, Western Australia, were deposited in basins with roughly the same configuration as their present outcrop. Basins were fault-bounded and developed in an ensialic setting, overlying older (3500 to 3300 Ma old); deformed and metamorphosed supracrustal rocks and granitoids. The basin margin faults are now part of a pattern of strike–slip faults which were active during the later stages of regional batholith emplacement. In both cases, structural patterns and style of basin filling are similar to younger basins related to strike–slip faulting. The Lalla Rookh Basin was dominated by coarse clastic sedimentation, comprising alluvial–fan, braided–stream, fan–delta and lacustrine facies. The Whim Creek Belt contains bimodal volcanics and clastic sediments, which comprise alluvial, subaqueous fanglomerate, submarine-fan and basinal facies. Regional strike–slip faulting and the development of the Lalla Rookh Basin and Whim Creek Belt, in response to externally imposed deformation, records an important step in the cratonization of the Pilbara Block. Late Archaean sedimentary basins, dominated by coarse clastic facies and situated adjacent to major strike–slip faults, in other cratons may have a similar origin.
Extrusive carbonatites: their origins reappraised in the light of new experimental data
Authors: Gittins John , Jago Bruce C. 
Published: May 2009

AbstractCalcite-rich carbonatites are commonly attributed to calcitization of alkalic carbonatite of Oldoinyo Lengai type. The interpretation arises from the presumption that magmatic crystallization of calcite at atmospheric pressure is not possible. We show that only a small percentage of fluorine, a common element in carbonatite magmas, permits such crystallization, and we argue that most of the calcite in extrusive carbonatites is magmatic. The presence of any more than minor apatite precludes an alkalic carbonatite parentage. While not denying that calcification of alkalic carbonatite can occur, we suggest that it is not generally responsible for the formation of extrusive calcific carbonatites.
Isotopic evidence for the extent of early Proterozoic basement in Scotland and northwest Ireland
Authors: Dickin A. P. , Bowes D. R. 
Published: May 2009

AbstractTightly clustered Sm–Nd model ages, with an average of 1.96±0.02Ga, for the gneiss complex of Inishtrahull indicate coeval development with the earlyProterozoic gneiss terrane of Islay. The extent of this terrane, largely beneath the Dalradian Supergroup, is argued to be 100×600 km, from northeast Scotland to western Ireland. This is based on the distribution of dated basement in conjunction with Pb, Sr and Nd isotope systematics and inherited zircons in Caledonian granites of the region.
A Cambrian island arc in Iapetus: geochronology and geochemistry of the Lake Ambrose volcanic belt, Newfoundland Appalachians
Authors: Dunning G. R. , Swinden H. S. , Kean B. F. , Evans D. T. W. , Jenner G. A. 
Published: May 2009

AbstractThe Lake Ambrose volcanic belt (LAVB) outcrops as a 45 km long northeast-trending belt of mafic and felsic volcanic rocks along the eastern side of the Victoria Lake Group in south-central Newfoundland. It comprises roughly equal proportions of mafic pillow basalt and high silica rhyolite, locally interbedded with epiclastic turbidites. Volcanic rocks have been metamorphosed in the greenschist facies and are extensively carbonatized.U-Pb (zircon) dates from rhyolite at two, widely separated localities give identical ages of 513 ± 2 Ma (Upper Cambrian), and this is interpreted as the eruptive age of the volcanic sequence. Primitive arc and low-K tholeiites can be recognized on the basis of major and trace element geochemistry, ranging from LREE-depleted to LREE-enriched. Geochemical variation between mafic volcanic types is interpreted predominantly to reflect contrasts in source characteristics and degree of partial melting; some variation within each geochemical type attributable to fractional crystallization can be recognized. Detailed examination of some samples indicates that the heavy REE and related elements have locally been mobile, probably as a result of carbonate complexing.The LAVB is the oldest well-dated island arc sequence in Newfoundland, and perhaps in the Appalachian–Caledonian Orogen. Its age requires modification of widely held models for the tectonic history of central Newfoundland. It is older than the oldest known ophiolite, demonstrating that arc volcanism was extant before the generation of the oldest known oceanic crust in this part of Iapetus. It further demonstrates that there was a maximum of approximately 30 Ma between the rift-drift transition which initiated Iapetus, and the initiation of subduction. This suggests that the oceanic sequences preserved in Newfoundland represent a series of arcs and back arc basins marginal to the main Iapetus Ocean, and brings into question whether the Appalachian accreted terranes contain any remnants of normal mid-ocean ridge type Iapetan crust.
New early Triassic Bryozoa (Trepostomata) from Spitsbergen, with some remarks on the stratigraphy of the investigated horizons
Authors: Nakrem Hans Arne , Mørk Atle 
Published: May 2009

AbstractNew trepostomatous bryozoan species, Paralioclema winsnesi sp. nov., Paralioclema mariaholmensis sp. nov. and Paralioclema sp. cf. mariaholmensis are described from the Lower Triassic succession of Spitsbergen. The investigated bryozoan faunas are associated with coarse sandstones, calcareous siltstones and shelly limestones. The bryozoan colonies are mostly well preserved in situ, and show limited evidence of transportation. Some zoarial fragments show bioerosion. The conodont species Neogondolella elongata, Ellisonia triassica, Neospathodus dieneri and Neospathodus svalbardensis extracted from the investigated horizons are Dienerian–Smithian in age.
A U/Pb age for the Sulitjelma Gabbro, North Norway: further evidence for the development of a Caledonian marginal basin in Ashgill–Llandovery time
Authors: Pedersen Rolf-Birger , Furnes Harald , Dunning Greg 
Published: May 2009

AbstractThe Sulitjelma Gabbro in the central Norwegian Caledonides has been dated with the U/Pb zircon/sphene method to 437±2 Ma. Geological relationships as well as trace-element geochemistry and Nd and Sr isotopic compositions suggest that the gabbro and associated dyke swarms and pillow lava formed during the initial stages of back-arc spreading. The age constrains the timing of juxtaposition of an older island-arc terrane and continental-margin lithologies exposed within the Caledonian nappes. The age of the gabbro is similar to that of the Solund–Stavfjord Ophiolite in west Norway, and confirms that spreading-related magmatism and marginal-basin development took place along the margin of Iapetus in late Ordovician–early Silurian times.
Upper Cretaceous (upper Santonian)Boehmocerasfauna from the Gulf Coast region of the United States
Authors: Kennedy W. J. , Cobban W. A. 
Published: May 2009

AbstractAn upper Santonian fauna dominated by the curved baculitidBoehmocerasRiedel, 1931, occurs as phosphatic moulds in the Tombigbee Sand Member of the Eutaw Formation in Mississippi and Alabama, and also is reworked into the base of the Mooreville Chalk; a similar assemblage is present in the middle part of the Pen Formation of the Big Bend area, Texas. The assemblage is:Pseudoschloenbachia(Pseudoschloenbachia)mexicana(Renz, 1936),Placenticeras syrtale(Morton, 1834),Reginaites leei(Reeside, 1927a),Reginaites exilissp. nov.,Texanites(Texanites) sp. juv. cf.gallicusCollignon, 1948,Texanites(Plesiotexanites)shiloensisYoung, 1963, Texanitinaeincertae sedis, Hyphantoceras(?)amapondense(van Hoepen, 1921).Glyptoxocerasspp.,Boehmoceras arculus(Morton, 1834) andScaphites(Scaphites)leeiReeside, 1927a, form I. The assemblage is referred to the uppermost SantonianTexanites(Plesiotexanites)shiloensiszone of the Gulf Coast sequence. Common occurrence ofScaphites(S.)leeiI andReginaites leeisuggest correlation with the Upper SantonianDesmoscaphites erdmannizone of the U.S. Western Interior; common occurrence ofBoehmoceras arculus(= B.loescheriof European authors) suggests correlation with theMarsupites–granulatazone at the top of the North German Santonian. These data strengthen intercontinental correlation of the Santonian–Campanian boundary sequence. They also provide a biostratigraphic link to a numerical age of 84.2±0.9 Ma from a bentonite at a slightly lower level in the Tombigbee Sand Member of the Eutaw Formation in Mississippi.
Mafic dykes from Øksfjord, Seiland Igneous Province, northern Norway: geochemistry and palaeotectonic significance
Authors: Reginiussen H. , Ravna E. J. Krogh , Berglund K. 
Published: May 2009

AbstractMafic dykes from the Øksfjord-Langfjord area were intruded at different stages during the prolonged tectonomagmatic evolution of the Seiland Igneous Province. Field relations, petrography and geochemistry indicate the presence of four dyke generations with alkali basalt composition and one generation of alkaline lamprophyres. The entire dyke suite has geochemical signatures consistent with formation in a within-plate geotectonic environment. Trace elements indicate that the alkali basalt dykes have OIB (ocean island basalt) affinities and we suggest a sublithospheric mantle source. The data support a rift-related origin for the Seiland Igneous Province. Longevity of magmatism in the Seiland Igneous Province (300 m.y.) is difficult to explain within a conventional mantle plume framework. Instead, it is proposed that the intermittent magmatism in the province was predominantly permissive and controlled by lithosphere structure.
Geophysical constraints on the nature of the Highland Boundary Fault Zone in western Scotland
Authors: Dentith M. C. , Trench A. , Bluck B. J. 
Published: May 2009

AbstractPreviously published models of gravity anomalies across the Highland Boundary Fault in western Scotland interpret this structure as a high-angle reverse fault. These gravity anomalies have been re-interpreted in the light of more extensive gravity data now available, and new density data from the Highland Border Complex. The new data suggest that earlier interpretations have overestimated the fault anomaly and used over-simplified density models. New gravity models of the Highland Boundary Fault Zone are presented which show that the interface between the Dalradian and Highland Border Complex dips to the northwest at an angle of about 20°. We interpret the contact between these two formations as a thrust fault. The interface between the Highland Border Complex and the Lower Old Red Sandstone is shown to be vertical as suggested by surface geology, with the latter rocks a few hundred metres thick.
The ichnogenusSchaubcylindrichnus: morphological, temporal, and environmental significance
Authors: Frey Robert W. , George Pemberton S. 
Published: May 2009

AbstractSchaubcylindrichnus, a distinctive sheaf of arcuate, well lined, congruent dwelling tubes, although poorly known in general, is a good indicator of shoreface depositional settings for many Cretaceous rocks of the United States. Until recently, in fact, it was known only from those rocks; but it has now been recognized in Tertiary rocks of Taiwan, possibly in slightly more distal depositional settings. In addition to its distinctive morphological and environmental significance, the ichnogenus also may have substantial biostratigraphical significance. Further reconnaissance is needed to confirm these seemingly unique distributions, that is, to help explain why the trace fossil so far seems to be restricted to certain Cretaceous rocks in North America and certain Tertiary rocks in Asia.
The Lower Pleistocene stratigraphy of the Ormesby Borehole, Norfolk, England
Authors: Harland R. , Bonny Anne P. , Hughes M. J. , Morigi A. N. 
Published: May 2009

AbstractThe sedimentology, micropalaepntology and palynology of Lower Pleistocene sediments recovered from a borehole at Ormesby St Margaret, near Great Yarmouth, Norfolk, have been investigated. The sediments, consisting of a lower clay facies overlain by an upper predominantly sandy facies, were deposited in inner neritic environments. Micropalaeontological and palynologicalevidence allows comparisons with the nearby Ludham sequence but an unequivocal correlation cannot be made. The Ormesby Borehole sequence includes representatives of the Pre-Ludhamian to Early Pastonian stage interval and the presence of a late Pre-Ludhamian to late Baventian/Pre-Pastonian a hiatus. Foraminiferal faunas matched to grain size analysis are indicative of transportation and considerable post-mortem sorting.
The depositional environments and tectonic development of a Mesozoic intra-arc basin, Atacama Region, Chile
Authors: Bell C. M. , Suarez M. 
Published: May 2009

AbstractA thick succession of continental redbeds was deposited in a 50 km wide intra-arc basin on the Andean active continental margin in the Atacama region of northern Chile during early Cretaceous times. Upper Jurassic to early Cretaceous marine limestones were buried by the seaward progradation of a succession of coastal dunes, saline lakes and sandflats. Aeolian dune fields migrating towards the east across these coastal plains became stabilized by the growth of vegetation. Interdune alluvial areas between the sand dunes and dune fields developed into extensive alluvial braid plains which were in turn superimposed by alluvial fans. These fans were inundated by a regionally extensive saline lake produced by tectonic or volcanic damming of the sedimentary basin. This lake dried up leaving a large area of playa-lake mudflats. The climate was warm and semi-arid with a low and seasonal rainfall. Parts of the area supported a substantial vegetation of woody plants, together with a vertebrate fauna of dinosaurs, pterosaurs and crocodiles. The continental redbeds were derived from a volcanic source and were deposited on continental crust in a deep but narrow, north-south elongated, fault-bounded graben. This extensional basin formed in an intra-arc setting within an active andesitic volcanic chain. Upwards-coarsening sedimentary successions were the product of uplift of the fault-bounded margins of the basin.
The Eocene-Oligocene planktic foraminiferal transition: extinctions, impacts and hiatuses
Authors: Molina Eustoquio , Gonzalvo Concepción , Keller Gerta 
Published: May 2009

AbstractBiostratigraphic study and re-examination of 22 late Eocene to early Oligocene sections provides data in support of three and possibly a fourth late Eocene impact events in the G. index Zone during a period of about 1 Ma of the middle Priabonian between 34.7 and 35.7 Ma. No major species extinctions or significant species abundance changes directly coincide with these impact events. Species extinctions are gradual and selective, affecting primarily cool-temperature-intolerant surface dwellers. These extinctions began with the onset of global cooling during the early middle Eocene and culminated near the Eocene/Oligocene boundary. The global cooling was associated with the isolation of Antarctica as Australia moved northward, the development of a circum-Antarctic circulation, growth of Antarctic ice sheet beginning by late middle Eocene time and a change from a thermospheric to thermohaline circulation. We find no evidence that the multiple late Eocene impact events directly contributed to the climatic deterioration already in progress.
Biostratigraphy of the Upper Jurassic-Lower Cretaceous bivalves Buchia and Aucellina of eastern Heilongjiang, northeast China
Authors: Sha Jingeng , Fürsich Franz Theodor 
Published: May 2009

AbstractThe biostratigraphic significance of the bivalves Buchia and Aucellina in northeast China is assessed. Buchia is abundant in four assemblages of the Dong'anzhen Formation, spanning the Jurassic-Cretaceous boundary: B. russiensis-B. fischeriana (Middle Volgian), B. fischeriana-B. unschensis (Upper Volgian), B. volgensis-B. cf. subokensis-B. cf. okensis-B. unschensis (Berriasian), and B. pacifica (Lower Valanginian). Aucellina is common in two Middle Barremian-Aptian assemblages: A. caucasica-A. aptiensis-A. jeletzkii in the lower part of the Upper Yunshan Formation, Longzhaogou Group, and in the lower part of the Chengzihe Formation, Jixi Group; A. cf. caucasica-A. cf. aptiensis in the upper part of the Upper Yunshan Formation. These assemblages can be correlated on a global scale and are particularly significant in dating the Early Cretaceous coalbearing measures of eastern Heilongjiang.
Integrated geophysical/geological modelling of the Caledonian and Precambrian basement of southern Britian
Authors: Busby J. P. , Kimbell G. S. , Pharaoh T. C. 
Published: May 2009

AbstractQuantitative modelling of potential field data has been used to test and extend geological sections constructed for the new British Geological Survey Tectonic Map of Britain and Ireland. Three of the profiles cross part of the Anglo-Brabant Massif and provide new information on the nature of the pre-Mesozoic basement. A profile across southern England (passing just to the west of London) suggests that a significant contribution to observed gravity variations in the region results from changes in the thickness of relatively low density Lower Palaeozoic rocks. It also identifies a major deep-seated body with relatively high magnetic susceptibility and low density which is interpreted as a Precambrian cratonic core underlying the southeastern part of the Midlands Microcraton. Profiles across central and eastern England reveal major boundaries within the Precambrian basement, some of which coincide with structures mapped at surface. A number of intrusions of probable Caledonian age have been recognized, including bodies beneath the Widmerpool Gulf and The Wash. Those beneath The Wash appear to lie in a discrete basement region which separates belts of more magnetic basement lying to the northwest and southeast.
Structural evolution of the Skiddaw Group (English Lake District) on the northern margin of eastern Avalonia
Authors: Hughes R. A. , Cooper A. H. , Stone P. 
Published: May 2009

AbstractThe Skiddaw Group comprises a marine sedimentary sequence deposited on the northern margin of eastern Avalonia in Tremadoc to Llanvirn times. It is unconformably overlain by subduction-related volcanic rocks (the Eycott and Borrowdale Volcanic groups) of mid-Ordovician age, and foreland basin marine strata of late Ordovician and Silurian age. The Skiddaw Group has a complex deformation history. Syn-depositional deformation produced soft sediment folds and an olistostrome. Volcanism was preceded (in late Llanvirn to Llandeilo times) by regional uplift and tilting of the Skiddaw Group, probably caused by the generation of melts through subduction-related processes. The Acadian (late Caledonian) deformation event produced a northeast- to east-trending regional cleavage, axial planar to large scale folds, and a later set of southward-directed thrusts with associated minor folds and crenulation cleavages. This event affected the northern Lake District probably in the late Silurian and early Devonian. The Skiddaw Group structures contrast strongly with those formed during the same event in the younger rocks of the Lake District inlier. The contrasts are attributed to differing rheological responses to varying and possibly diachronous stresses, and to possible impedence of thrusting by the combined mass of the Borrowdale Volcanic Group and the Lake District batholith.
A preliminary study of Ashgill carbonate beds from the lower part of the Fosses Formation (Condroz, Belgium)
Authors: Tourneur Francis , Vanguestaine Michel , Buttler Caroline , Mamet Bernard , Mouravieff Nicolas , Poty Edouard , Préat Alain 
Published: May 2009

AbstractThe sedimentology and palaeontology of carbonate beds in the lower part of the Fosses Formation (Ashgill of the Condroz area, central Belgium) have been investigated. Two depositional interpretations are suggested: deposition either near a platform-ramp margin as bioclastic turbidites and interbedded shales or on a shelf as a transgressive sequence following a regressive event. Faunal affinities with the Baltic area and Wales are confirmed, and the location of Belgium in the tropics during the Ashgill is supported by the calcareous algae and the coral fauna.