bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pterosaur phylogeny and comments on the evolutionary history of the group
Authors: Kellner Alexander W. A. 
Published: April 2008

Abstract

A cladistic analysis based on 39 terminal taxa and 74 characters (several multistate) using PAUP (Phylogenetic Analysis Using Parsimony) (3.1.1 for MacIntosh and 4.0b10 for Microsoft Windows) presents a new hypothesis of pterosaur inter-relationships. This study suggests that the most primitive taxon is the Anurognathidae, followed by
Sordes
and all remaining pterosaurs.
Dendrorhynchoides
is confirmed as a member of the Anurognathidae, being closely related to
Batrachognathus. Preondactylus
occupies a more derived position than
Sordes
, which questions its previous assignment as the most primitive pterosaur. The hypothesis of rhamphorhynchoid paraphyly is confirmed, with the Rhamphorhynchidae more closely related to the Pterodactyloidea than to more basal forms. The Pterodactyloidea shows a basal dichotomy: the Archaeopterodactyloidea and the Dsungaripteroidea. The Archaeopterodactyloidea is formed by
Pterodactylus
+
Germanodactylus
and a clade formed by Gallodactylidae + Ctenochasmatidae. The Nyctosauridae occupies the basal position within dsungaripteroids and is followed by the Pteranodontoidea and the Tapejaroidea. Pteranodontoids have
Pteranodon
at the base, followed stepwise by
Istiodactylus, Ornithocheirus
and the Anhangueridae. Tapejaroids are composed of the Dsungaripteridae at the base followed by the Tapejaridae and the Azhdarchidae.

Major trends within pterosaur evolutionary history are: general increase in size (wing span and body); increase of wing metacarpal and pteroid; decrease of proportional length of the second and third wing phalanx relative to the first; gradual increase of rostrum (anterior to external nares); and anterior shift of the skull-mandible articulation. Cranial crests are present in most pterodactyloids, but markedly in the Ornithocheiroidea, where all taxa show some sort of crest on the skull. The loss of teeth, previously assumed to have occurred independently in several lineages, seems to be a general trend among dsungaripteroids.
Several nodes recovered by this analysis are supported by very few characters, a result at least partially attributable to the limited available information from several taxa due to poor preservation and/or preparation.
Arc-trench rollback and forearc accretion: 1. A collision-induced mantle flow model for Tethyan ophiolites
Authors: Flower M. F. J. , Dilek Y. 
Published: April 2008

Abstract
Tectonically active remnants of Neo-Tethys represented by Mediterranean and western Pacific marginal seas are characterized by rapidly propagating backarc extension episodes. These appear to be triggered by random subduction nucleation events, commonly signalled by the appearance of refractory boninites in volcanic ‘proto-arcs’. As backarc basins evolve, active arcs separate from their ‘proto-arc’ remnants and may split again if more than one basin-opening episode occurs. Accreting arc-forearc terranes are therefore likely to incorporate proto-arc, backarc, and (in some cases) inherited continental fragments, as evidenced by their structural complexity and lithological diversity. Forearc complexes typically show positive Bouguer gravity anomalies and significant age discrepancies within and between their crustal and mantle components. Where exposed, their lower stratigraphic horizons may include boninite-bearing assemblages along with tectonized fragments of mid-ocean ridge basalt (MORB) basement and hydrated refractory peridotite. These are typically intruded by sodic plagiogranite (adakite) and high-temperature Mn-, Fe-rich hydrothermal veins (‘epidosites’), further indications of subduction nucleation at, or close to a pre-existing spreading axis. Where the arc-trench rollback process is terminated by collision with an approaching continent, or with another retreating forearc complex, MORB-like backarc lithosphere is rapidly reconsumed, in some cases following a change in subduction polarity. In contrast, given their preponderance of ultra-refractory serpentinized peridotite, forearc complexes are relatively buoyant, resist subduction, and are prone to entrapment during early stages of an orogeny. The associated interplay of extension and compression offers a compelling scenario for resolving the so-called ophiolite ‘conundrum’ and explaining the near-ubiquity of ophiolites in orogenic belts. We propose that rapid arc-trench rollback pulses are driven largely by collision-induced mantle flow in addition to commonly cited ‘slab pull’ effects. This is supported by the evidence of isotopic mantle flow tracers, seismic tomography, and the coupled kinematics of marginal basins and continental escape. Model applications to some well-known Tethyan ophiolites are developed in a companion paper.
Tethyan- and Cordilleran-type ophiolites of eastern Australia: implications for the evolution of the Tasmanides
Authors: Spaggiari Catherine V. , Gray David R. , Foster David A. 
Published: April 2008

Abstract

The preservation of diverse ophiolitic rocks in the Tasmanides of eastern Australia reflects a period of complex oceanic crust formation off the east Gondwana margin from
c.
560 to 495 Ma. This involved development of oceanic crust possibly at a spreading ridge (now preserved as the
c.
560 Ma Marlborough ophiolite, New England Orogen), development of forearc crust in a suprasubduction zone between
c.
530 and 515 Ma (Tyennan-Delamerian ophiolites), possible synchronous formation of suprasubduction zone crust further outboard (southern New England Orogen ophiolites), emplacement of Tyennan-Delamerian ophiolites onto the Gondwana margin at
c.
515 Ma, followed by development of new forearc and backarc crust between
c.
505 and 495 Ma (Lachlan Orogen). Tasmanide orogenesis has resulted in the production of both Tethyan-type and Cordilleran-type ophiolites. Tethyan types are represented by the Tyennan (Tasmanian) and possibly Delamerian Orogen ophiolites that were emplaced onto the passive continental margin. The Tasmanian ophiolite has been interpreted as having been emplaced as one or more thrust sheets, concurrent with the development of a metamorphic sole. In contrast, Lachlan Orogen ophiolites were emplaced within major fault zones by accretionary processes such as offscraping, underplating, and duplexing via underthrusting and basin closure during Late Ordovician to Silurian times. Cordilleran-type ophiolites, for example the Lachlan Orogen ophiolites, are dominated by disrupted upper oceanic crustal stratigraphies, whereas Tethyan-types tend to be dominated by mantle and gabbroic sequences, or preserve more complete stratigraphies.
Volcanic history of the back-arc region of the Izu-Bonin (Ogasawara) arc
Authors: Ishizuka Osamu , Uto Kozo , Yuasa Makoto 
Published: April 2008

Abstract

The laser-heating
40
Ar/
39
Ar dating method was applied to volcanic rocks systematically collected from the back-arc region of the central part of the Izu-Bonin arc. Dating results combined with whole-rock chemistry and other geological information reveal the volcanic history of the back-arc region of the Izu-Bonin arc. In the back-arc seamount chains area, andesitic-basaltic volcanism initiated at
c.
17 Ma, slightly before the Shikoku Basin ceased spreading, and continued until
c.
3 Ma. Relatively old volcanism (>8 Ma) has been found only from the western part of the seamount chains, and younger volcanism mainly occurs in the eastern part of the chains, indicating the western margin of the active volcanic zone of the Izu-Bonin arc has migrated eastward with time. At around 2.8 Ma, volcanism initiated in the western part of the back-arc knolls zone. This volcanism is characterized by eruption of clinopyroxene-olivine basalt. In the first stage of rifting, this type of basalt erupted from N-S-trending fissures and/or vents aligned in this direction and formed N-S-trending ridges. Between 2.5 and 1 Ma, many small knolls were formed by eruption of basalt and minor felsic rocks. Volcanism younger than 1 Ma occurred only in the currently active rift zone and its adjacent area.

The active volcanic zone in the back-arc seamount chains area converged to the volcanic front with time from 17 to 3 Ma. Active rifting and rifting-related volcanism also migrated or converged eastward after 1 Ma. The observed temporal variation of locus of volcanism may be explained by rapid retreat of the Philippine Sea Plate relative to the Pacific Plate and resulting steepening of the subducting slab.
Metamorphic monazite and the generation of P-T-t paths
Authors: Foster Gavin , Parrish Randall R. 
Published: April 2008

Abstract
Monazite is the mineral of choice in pelitic rocks for providing time constraints on metamorphic rocks and metamorphic processes. However, unlike rock-forming mineral chronometers such as garnet, the petrogenesis of monazite is relatively poorly understood. Consequently, although it is possible to generate precise monazite ages, the significance of the age in metamorphic rocks is often uncertain. In this contribution, we show how the petrogenesis of monazite can be linked to pressure and temperature information. Four complementary approaches, each illustrated by examples, are discussed: (i) the textural relationships of accessory minerals are used to relate the petrogenesis of monazite to that of the rock-forming mineral assemblage, and through this to P-T; (ii) monazite composition, in particular Y content, is used to relate monazite to the rock-forming mineral assemblage, and thus, to P-T; (iii) the bulk compositional control on monazite stability has been empirically determined and this relationship allows the temperature of initial monazite growth to be estimated in a given bulk composition; (iv) monazite-xenotime thermometry is utilized to provide estimates of the temperature of monazite growth. Either individually or combined, these approaches successfully enable monazite age data to be placed in a P-T framework.
Stacking fault-enhanced argon diffusion in naturally deformed muscovite
Authors: Kramar Nicolas , Cosca Michael A. , Buffat Philippe-André , Baumgartner Lukas P. 
Published: April 2008

Abstract

Recent advances in microscale
40
Ar/
39
Ar geochronology have revealed argon concentration gradients in naturally deformed muscovite that are incompatible with volume diffusion uniquely, and have been interpreted to result from intragranular defect-enhanced diffusion. Defects and heterogeneously spaced stacking faults observed by transmission electron microscopy in such muscovites are evaluated as potential fast pathways for argon diffusion.

Two-dimensional defects, such as stacking faults, are of particular interest for noble gas diffusion because of the net dilatation effect that a stacking fault is able to generate in minerals. In micas, partial dislocations (and the area between them known as stacking faults) within the interlayer displace the potassium atoms from a stable hexagonally centred position between opposing tetrahedral layers to an unstable position relative to one of the tetrahedral layers such that repulsive forces lead to a localized net dilatation effect within the interlayer. Such a dilatation effect may have direct consequences for argon retention in micas. Numerical modelling of the effects stacking faults have on argon diffusion was performed on the basis of the calculated interlayer spacing, measured isotope data, and observed linear stacking fault density. These calculations result in effective diffusivity ratios defined by volume diffusion to defect-enhanced diffusion of 10
6
to 10
7
, which are comparable with diffusivity ratios in other materials (ceramics or metals).

In the absence of defects causing physical grain size reduction (e.g. kink bands or subgrain boundaries), stacking faults are potentially the main defect in sheet silicates exerting a measurable influence on intragranular argon diffusion. Stacking-fault-enhanced argon diffusion differs from pipe diffusion, whose significance on bulk diffusion depends on high dislocation densities, by the small volume fraction of dislocations required to affect bulk diffusivities. In contrast to pipe diffusion, the linked occurrence of dislocations and stacking faults within mica interlayers represents a potentially significant volume fraction, even in samples that do not have high apparent dislocation densities.
Foreland basin evolution around the western Alpine Arc
Authors: Ford Mary , Lickorish W. Henry 
Published: April 2008

Abstract
The arcuate form of the external western Alps was generated during Tertiary NW-directed collision between the Apulian indentor and the southward-subducting European passive margin. The evolution of peripheral syn-collisional depocentres around this arcuate orogen (in France and Switzerland) is reconstructed using a compilation of stratigraphic and tectonic data. This reveals fundamental changes in the flexural behaviour of the European lithosphere during collision. During early collision (Eocene), an increasingly arcuate, peripheral flexural basin migrated rapidly NW across the European plate. During peak collision (early Oligocene), frontal flexure, recorded in the North Alpine Foreland Basin (NAFB), steepened markedly, while lateral flexure of the European plate, affecting SE France, effectively ceased. Here, Oligocene sedimentation was confined to small thrust-sheet-top basins. Two rift systems initiating in the late Eocene, the West European rift system and the West Mediterranean oceanic basin (that created the Gulf of Lion passive margin), are superimposed in space and time on the outer margins of the alpine flexural depocentres. During waning collision (Mio-Pliocene) the NAFB became overfilled, then uplifted and abandoned while, in SE France, a local depocentre (Digne-Valensole) developed between uplifting blocks and continued to accumulate sediments until the late Pliocene.
The turbidite fill of the Annot sub-basin (SE France): a sequence-stratigraphy approach
Authors: Callec Y. 
Published: April 2008

Abstract
New sedimentological and biostratigraphical data on the Annot sub-basin (southern Alps, France) provide a good overview of a fore-deep basin infill with well-known Annot turbiditic complex. This basin shows a total thickness of more than 1100 m, where the Grès d’Annot exceeds 500m with well-longitudinal and transversal outcrops. Our study is to define a chronostratigraphical framework, which allows comparisons of local signatures of sea-level fluctuations with eustatic curve, and also identification of tectonic effects. The Annot succession could be interpreted as a second-order cycle. We identify a deepening and transgressive Priabonian interval, represented by the transition from platform of the Calcaires Nummulitiques to hemipelagic marls of the Marnes Bleues where tectonic subsidence rate outpaces third-order eustatic fluctuations and sedimentary influx. Priabonian to early Rupelian Annot turbidites progressively appear with a thickening- and coarsening-upward stacking pattern of four different sand-rich turbiditic systems with lobes, megaslide, channelized lobes and erosional/depositional channel. Each prograding system is separated by an erosive surface corresponding to a third sequence boundary. A possible sequence stratigraphy interpretation may be modelled as a forced regression during foreland basin closure, where the upper turbiditic systems correspond to lowstand prograding complexes from basin floor fan to proximal slope fan.
The influence of syndepositional basin floor deformation on the geometry of turbiditic sandstones: a reinterpretation of the Côte de L’Âne area (Sanguinière-Restefonds sub-Basin, Grès d’Annot, Late Eocene, France)
Authors: Broucke Olivier , Guillocheau François , Robin Cécile , Joseph Philippe , Calassou Sylvain 
Published: April 2008

Abstract
The Côte de l’Âne section has been previously interpreted as shallow marine deposits (deltaic system with delta-front to bay head and back-barrier environments). The purpose of this article is (1) to suggest a reinterpretation of these facies of the Grès d’Annot in this area as deep marine deposits and (2) to discuss the effect of an evolving seafloor topography during sedimentation on the stacking pattern of turbiditic deposits. The facies analysis of the sedimentary succession is based on eight measured sedimentological logs and on the visual correlation of identified surfaces. Detailed sedimentological observations permitted the identification of a turbidite facies spectrum, schematized in nine facies associations. Outcrop-scale analysis highlights a downstream thickening of the sedimentary sequence resulting from a strong control by tectonic deformation. This deformation is mainly a flexure with a half-wavelength longer than 500m. Associated normal faults may be related to a gravity slide of unconsolidated sediments accommodated within the flexure. Finally, detailed correlations based on the genetic unit model in the Restefonds-Sanguinière system establish the effect of an evolving seafloor topography during sedimentation on the stacking pattern of turbiditic deposits.
The influence of a lateral basin-slope on the depositional patterns of natural and experimental turbidity currents
Authors: Amy L. A. , McCaffrey W. D. , Kneller B. C. 
Published: April 2008

Abstract
Understanding topographic effects upon the depositional processes of turbidity currents and the resulting deposit characteristics is key to producing reliable depositional models for turbidity currents. In this study, the effect on depositional patterns of a lateral slope whose strike is parallel to the principal direction of flow is explored using field and experimental results. This type of basin topography is commonly found in confined turbidite systems. Field data from the Peïra Cava turbidite system of the Tertiary Alpine Foreland Basin (SE France) and experimental data show that a characteristic depositional pattern is produced by surge-type waning flows that interact with a lateral slope. This pattern comprises beds that thin (and fine in the field study) not only downstream but also markedly away from the lateral slope (Type I beds). In the Peïra Cava system, this pattern is also observed in average values of sandstone bed thickness, sandstone percentage and grain-size, derived from measured sections, demonstrating that the processes responsible for this pattern also control gross properties within this sheet system. The characteristic thinning-away-from-slope deposit geometry is interpreted as an effect of the lateral slope via its influence on spatial variations in flow properties and on the suspended load fallout rate (SLFR) from currents. Flow velocity non-uniformity cannot explain thinning into the basin because flow has a higher deceleration along streamlines away from the slope that should cause higher SLFR and thicker deposits away from the slope instead of close to the slope. A concentration non-uniformity mechanism is invoked that has the effect of maintaining relatively high flow concentrations and hence SLFR in medial and distal locations close to the slope. Experiments suggest that this may arise due to different rates of flow expansion on the obstructed and unobstructed sides of the current in proximal regions. Velocity non-uniformity can, however, explain the geometry of deposits that thicken away from slope. Beds of this type do occur occasionally in the Peïra Cava system (Type II beds). Flow velocity non-uniformity patterns have been used previously to successfully explain the spatial distributions of depositional facies of turbidity currents that have interacted with topography. The analysis in this study demonstrates that velocity non-uniformity, by itself, cannot explain depositional patterns in all basin settings. Future depositional models need to incorporate the effects of spatial changes in other flow properties, such as flow concentration, upon deposition to be able to predict turbidite facies in many different types of basin setting.
Factors controlling foredeep turbidite deposition: the case of Northern Apennines (Oligocene-Miocene, Italy)
Authors: Cibin U. , Di Giulio A. , Martelli L. , Catanzariti R. , Poccianti S. , Rosselli C. , Sani F. 
Published: April 2008

Abstract

Three major controlling factors affect turbidite deposition in foredeep basins: tectonics in the source area, tectonics in the belt-basin system, and variations of sea-level (local or global). These factors are expected to have different effects on the volume, grain size, provenance and distribution of clastic sediments during the evolution of the basin. The interplay of these factors is investigated for the latest Oligocene-Middle Miocene Northern Appennines Foredeep turbidite wedges by means of turbidite-system-based lithostratigraphy and field mapping, integrated with nannoplankton biostratigraphy and sedimentary petrography. Almost all recognized turbidite systems, unless tectonically truncated, show an overall stacking pattern formed by a lower sand-rich, thickly bedded stage (
depocentre stage
) passing upward into mud-rich, thinly bedded stages, eventually grading up to mostly mudstone units (
abandonment stage
). This rhythmically repeated pattern is interpreted as the result of the abrupt switching on and off of coarse-grained input, coupled with an alternating increase/decrease of depositional rate recorded in all detected systems. Biostratigraphy makes it possible to distinguish the switching-off of turbidite systems due to depocentre migration (a new system is switched on basinward) from that due to a regional decrease of clastic input. Sandstone petrography records the compositional variation related to tectonically induced source reorganization. In the latest Oligocene-Middle Miocene NAF foredeep wedges, this integrated dataset allows us to recognize: two different phases of source tectonics in the latest Oligocene and the middle Burdigalian; two major episodes of basin tectonics and related depocentre shift in the latest Oligocene and the Langhian, plus a minor middle Aquitanian phase; and three intervals of reduced regional turbidite deposition during the Late Aquitanian, Middle Burdigalian and Early Serravallian, possibly linked to sea-level rises.
Comparing the depositional architecture of basin floor fans and slope fans in the Pab Sandstone, Maastrichtian, Pakistan
Authors: Eschard R. , Albouy E. , Gaumet F. , Ayub A. 
Published: April 2008

Abstract
Basin-floor fans and slope fans present major differences in their internal architecture related to changes in: (1) margin morphology, (2) relative sea-level change, and (3) sediment supply. These variations are illustrated in the outcrops of the Pab Sandstone in Pakistan. The Pab Sandstone third-order sequence was deposited on the Indo-Pakistani margin during the Upper Maastrichtian. Uplift of the margin induced erosion on the shelf, incision of submarine canyons on the slope and the development of a sand-rich, high-efficiency basin-floor fan extending over hundreds of kilometres on the basin floor. During transgression, sediment accumulated in backstepping shoreface deposits on the shelf, and a minor mud-rich slope fan was deposited in the basin. Finally, a sand-rich braided delta prograded across the shelf, feeding a sand-rich slope fan where it reached the shelf margin. This slope fan was of more limited lateral extent. The Lower Pab basin-floor fan shows the effects of flow funnelling and confinement due to a canyon incised into the slope. It consists mainly of channel complexes deposited by superconcentrated density flows to low-density turbidity currents. In contrast, the Upper Pab slope fan shows little confinement and low transport efficiency. It consists of tabular lobes, aggrading mid-fan channels and conglomeratic channels in the upper fan. The low transport efficiency of the gravity flows probably explains the low degree of organization of the slope fan.