bluuebunny/crossref_metadata_2025 huggingface dataset:
DIELECTRIC PROPERTIES OF POROUS Si3N4-SiO2-BN COMPOSITES
Authors: SUN YINBAO , ZHANG YUMIN , LI DIHONG , HAN JIECAI
Published: April 2009

Porous Si 3 N 4- SiO 2- BN composites were prepared by adding starch as both pore former and consolidator. Bruggeman effective-medium model, Maxwell-Garnett model and logarithmic model were used to describe and predict the dielectric constant of porous Si 3 N 4- SiO 2- BN ceramics. Relative dielectric constant of porous Si 3 N 4- SiO 2- BN composites decreases with the increase of apparent porosity within limits, and these models can forecast the change of the dielectric constant of the porous ceramics quite well. The minimum relative dielectric constant is 2.5 at the apparent porosity of 0.555 at room-temperature. The relationship between dielectric constant and temperature were investigated. It was found dielectric constant varied a lot with the increase of temperature, and Debye relaxation theory was employed to explain the variation of the dielectric constant with temperature increment. But the Debye relaxation theory can not explain the reason of variation of dielectric constant at the temperature range from 300°C to 900°C. To ascertain the cause of changes of dielectric constant at this temperature region, differential scanning calorimentry (DSC) measurement was performed. In this temperature region, phase transition behavior occurs at nearly 300°C in the porous composites. The new phase probably has a tidy large dielectric constant, and the dielectric constant increases sharply.
EFFECT OF BORON ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HOT-ROLLED Nb-ADDED HSLA H-SECTION STEEL
Authors: WANG ZUOCHENG , CUI GUOTAO , SUN TAO , GUO WEIMIN , ZHAO XIULING , GAO JUNQING , DONG CHANGXING
Published: April 2009

In our research, boron was added into the Nb -added high strength low alloy (HSLA) H -section steels. The contents of boron added were 4ppm, 8ppm and 11ppm, respectively. The mechanical properties of H -section steels with/without boron were examined by using uniaxial tensile test and Charpy impact test ( V -notch). The morphologies of the microstructure and the fracture surfaces of the impact specimens were observed by metalloscope, stereomicroscope and electron probe. The experimental results indicate that boron gives a significant increase in impact toughness, especially in low temperature impact toughness, though it leads to an unremarkable increase in strength and plasticity. For instance, the absorbed energy at -40°C reaches up to 126J from 15J by 8ppm boron addition, and the ductile-brittle transition temperature declines by 20°C. It is shown that boron has a beneficial effect on grain refinement. The fracture mechanism is transited from cleavage fracture to dimple fracture due to boron addition.
FABRICATION OF MACH-ZEHNDER INTERFEROMETOR BASED ON PLANAR WAVEGUIDE FOR THE APPLICATION OF BIOSENSORS
Authors: KIM JUN-HYONG , YANG HOE-YOUNG , LEE HYUN-YONG
Published: April 2009

In this paper, designed and simulated Power Splitter (PS) integrated Mach-Zehnder interferometer (MZI) based planar waveguide devices (which is called here a PS-MZI). Moreover, we fabricated optical waveguide based on the PS-MZI for application to the biosensor. The integrated optical structure is sensitive to refractive index change induced due to the interaction of the evanescent field with an immobilized biological sample placed on one of the two arms of the interferometer. The PS-MZI sensor was preceded by a Y -junction, which splits the input power between the sensor and a reference branch to minimize the effect of optical power variations. The waveguide were optimized at a wavelength of 1550 nm and fabricated according to the design rule of 0.45 delta%, which is the difference of refractive index between the core and clad. The fabrication of PS-MZI optical waveguides was performed by a conventional planar lightwave circuit (PLC) fabrication process. The PS-MZI optical waveguides were measured of the optical characteristics for the application of biosensors.
CONTROLLING THE BIODEGRADATION RATE OF MAGNESIUM USING SOL-GEL AND APATITE COATINGS
Authors: ZHANG YAJING , WEI MEI
Published: April 2009

Magnesium is light, biocompatible and has similar mechanical properties to natural bone, so it has the potential to be used as a biodegradable material for orthopedic applications. However, pure magnesium severely corrodes in a physiological environment, which may hinder its use for in vivo applications. Protective coatings are effective method to delay the corrosion of Mg . In this study, sol-gel and hydroxyapatite (HA) coatings were applied onto the surface of pure magnesium substrates using a biomimetic technique. The corrosion rate of surface-treated substrates was tested. It was found that both types of coatings substantially slowed down the corrosion of the substrate, the 60 Ca so-gel and HA coating was more effectively than the 100 Si so-gel and HA coating in hindering the degradation of the substrate. Thus, the corrosion rate of magnesium implants can be closely tailored by coating sol-gel then coating apatite thereby monitoring the release of magnesium ions into the body.
INFLUENCE OF THE GROWTH TEMPERATURE ON THE PROPERTIES OF Mn-DOPED SnO2 THIN FILMS GROWN BY PULSED LASER DEPOSITION
Authors: CHEN YANXUE , JIAO JUN
Published: April 2009

Mn -Doped SnO 2 thin films were grown on sapphire (012) substrates by pulsed laser deposition. The influence of substrate temperature on the film properties was investigated. X-ray diffraction patterns show that the thin films grown at lower substrate temperatures were amorphous, while those grown at higher temperatures had only a single (101) orientation. Atomic force microscopy results indicate that the films grown at low temperature were extremely flat and they became rougher as substrate temperature (Ts) increased. Optical transmission spectra reveal that the absorption edge shifts towards the blue side and becomes steeper at increasing T s . High-resolution transmission electron microscopy analysis clearly indicates that the samples have a well-arranged tetragonal structure without any detectable secondary phase. Inhomogeneous incorporation of Mn atoms into the SnO 2 lattice was also observed.
COMPOSITION AND NANOHARDNESS OF SiC FILMS DEPOSITED BY ELECTRON BEAM PHYSICAL VAPOR DEPOSITION
Authors: TENG MIN , HE XIAODONG , SUN YUE
Published: April 2009

SiC films with a quantity of carbon and silicon were obtained by electron beam physical vapor deposition (EB-PVD) from a sintered SiC target with different current intensity of EB. The X-ray photoelectron spectroscopy (XPS) was used for characterization of chemical bonding states of C and Si elements in SiC films in order to study the influence of current intensity of EB on the compositions in the deposited films. At the same time, the nanohardness of the deposited films was investigated.
EFFECT OF AL CONTENT ON MICROSTRUCTURE AND PROPERTIES OF AN INTERMETALLIC Ni-Ti (Al) COMPOUND/Ni GRADED COATING DEPOSITED ON COPPER SUBSTRATE
Authors: WANG HONGXING , CHU CHENGLIN , SHENG XIAOBO , LIN PINHUA , DONG YINSHENG
Published: April 2009

Copper and its alloys with high electrical and thermal conductivity are a group of widely used engineering materials in numerous applications. In order to improve the tribological properties of copper substrate, an electroplating nickel layer was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process at 900°C for 12 h using a slurry mixture composed of TiO 2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH 4 Cl and albumen (egg white) as cohesive agent. The effect of Al content on the microstructure and the properties of the coating has been studied. The results showed that an intermetallic Ni - Ti ( Al ) compound/ Ni graded layer was formed on copper substrate after slurry pack cementation process. With the rise of Al content in slurry mixture, the microhardness of the graded coating increased and the friction coefficient decreased from 0.35 to 0.18, at the same time, the slurry pack process gradually transited from the titanizing process to an aluminizing one. Correspondingly the main phases of the coating were changed from Ni - Ti intermetallic compounds into Ni - Al ones.
EFFECT OF VELOCITY OF BALLS ON THE STRAIN AND STRESS OF LOW CARBON STEEL SURFACE LAYER DURING SMAT
Authors: DU HUAYUN , WEI YINGHUI , ZHANG HENGJIN , LIN WANMING , HOU LIFENG , LIU ZENGQING , LIU GANG
Published: April 2009

By means of finite element method, the effect of velocity of balls on the strain and stress of low carbon steel surface layer during the course of surface mechanical attrition treatment (SMAT) are investigated. The effect of different impact velocity on strain rate and grain refinement mechanism is also analyzed. Calculation results confirm that there exists severe plastic deformation in the surface layer: strain, strain rate and stress gradually decrease along the depth of the treated sample during SMAT, which is in agreement with the microstructures observed in corresponding locations. Strain and strain rate play an important role in the grain refinement process and the resultant grain sizes upon plastic deformation.
WRINKLING BEHAVIOR IN HYDROFORMING OF UNSYMMETRICAL TUBULAR PART
Authors: WANG XIAOSONG , YAO YINGXUE , YUAN SHIJIAN
Published: April 2009

Geometrical analysis, numerical simulation and experiment were conducted to investigate wrinkling behavior in hydroforming of unsymmetrical tubular part. The influence of wrinkle parameters on the average thickness reduction rate was demonstrated using geometrical analysis. The wrinkling process and forming results of different loading paths were analyzed especially by means of FE simulation. It is shown from the experiment and simulation results that the unsymmetrical tubular part could be formed through the method of useful wrinkles. The thickness of the sound part is not uniform along the axial direction in the forming area. The internal pressure is the key factor to form the useful wrinkle. The axial stress is near zero in the expanding zone for useful wrinkles. By the method of useful wrinkle, process window of unsymmetrical tubular part can be enlarged for tube hydroforming.
DYNAMIC MEMBRANE TECHNOLOGY FOR PRINTING WASTEWATER REUSE
Authors: LIU LIN , LU XUJIE , CHEN JIHUA
Published: April 2009

As environmental regulations become rigid and the cost of freshwater increases, wastewater is considered as a major resource in China. The paper presented a study on the implementation of the advanced treatment process using dynamic membrane (DM) in reusing of printing wastewater. The DM was well formed by circulating 1.5g/L of PAC in 20 minutes, the trans-membrane pressure of 200 kPa and the cross-flow velocity of 0.75m/s. The printing effluents were treated in effluent treatment plants comprising a physicochemical option followed by biological process. The treated effluent contained chemical oxygen demand (COD), color and turbidity in the range of 45-60 mg/L, 0.030-0.045 (absorbance at 420 nm) and 3-5 NTU. The results showed that the COD, color and turbidity removal efficiencies of the DM permeate were 84%, 85% and 80%, respectively. The wastewater treated by DM was reused as process water and the final concentrated retentate could be discharged directly into sewage treatment works with no additional treatments. Cleaning and regeneration of DM were very convenient if necessary. The proper process was that the polluted DM was cleaned with tap water at high cross-flow velocity. When irreversible pollutants accumulate, it would be rinsed with chemicals tested and the membrane flux would be restored up to 95%. The result showed that DM was considered as a promising method for purification aimed at reuse of printing wastewater, resulting in direct environmental and economic benefits.
CONTROLLING AND OPTIMIZATION OF THERMAL PROFILE IN REFLOW SOLDERING
Authors: SHI JIANWEI , HE PENG , LV XIAOCHUN
Published: April 2009

Heating factor, Q is a quantitative parameter describing a process of reflow soldering. It can be used to evaluate a reflow soldering process and the reliability of solder joints. The value of Q is directly related to the energy absorbed by solder joint during heating and the morphology of Intermetallic Compound formed at the interface between solder and pad. Electronic product manufacturers use heating factor as a technical evaluation parameter to guide the adjustment of reflow soldering process and the optimization of reflow soldering curve, to ensure the best reliability of the circuit board. Solder paste manufacturers use heating factor to represent characteristics of their reflow soldering products, and to customize products according to consumer's requests. Equipment manufacturers for reflow soldering use heating factor as an important controlling parameter to establish automatic system for managing solder joint reliability. A reliable soldering result can be achieved using the automatic reflow management system, to control and optimize thermal profile, which leads to the adjustment of the heating factor.
EFFECT OF CHARGE DENSITY ON THE TAYLOR CONE IN ELECTROSPINNING
Authors: STANGER JONATHAN , TUCKER NICK , KIRWAN KERRY , STAIGER MARK P.
Published: April 2009

A detailed understanding of charge density and its origins during the electrospinning process is desirable for developing new electrospinnable polymer-solvent systems and ensuring mathematical models of the process are accurate. In this work, two different approaches were taken to alter the charge density in order to measure its effect on the Taylor cone, mass deposition rate and initial jet diameter. It was found that an increase in charge density results in a decrease in the mass deposition rate and initial jet diameter. A theory is proposed for this behaviour in that an increase in charge density leads to the tip of the Taylor cone forming a smaller radius of curvature resulting in the concentration of electric stresses at the tip. This leads to the electrostatic forces drawing the initial jet from a smaller effective area or "virtual orifice".
PARAMETER EFFECTS ON TEMPERATURES IN THE THIN FILM IRRADIATED BY ULTRAFAST-PULSE LASER
Authors: HO CHING-YEN , WEN MAO-YU , SHIH CHIA-SHENG
Published: April 2009

The effects of parameters on temperatures in thin metal films heated by ultrafast-pulse laser are investigated in this paper. The time scale in which energy transfers from the electrons to lattice is on the order of a picosecond for metals. Therefore when the duration of ultrafast-pulse laser heating metal films is on the order of or shorter than a picosecond, a substantial nonequilibrium can occur between the electron and lattice temperature and the metal lattices stay almost thermally undisturbed in this highly nonequilibrium regime. A parabolic two-temperature heating model is employed to investigate thermal transport in thin metal films irradiated by ultrafast-pulse laser. Using the Laplace transform and assuming the thermal properties to be independent of temperature, a closed form solution of temperature in the thin film is provided. The effects of laser parameters and material properties on temperatures are also discussed.
EFFECT OF HYDRAULIC PRESSURE ON WARM HYDRO MECHANICAL DEEP DRAWING OF MAGNESIUM ALLOY SHEET
Authors: LIU WEI , WU LINZHI , YUAN SHIJIAN
Published: April 2009

The uniaxial tensile test and hydraulic bulging test of AZ31 magnesium alloy sheets were applied to study the influence of temperature on the material properties and obtain the forming limit curves at different temperatures. Numerical simulations of warm hydro mechanical deep drawing were carried out to investigate the effect of hydraulic pressure on the formability of a cylindrical cup, and the simplified hydraulic pressure profiles were used to simulate the loading procedure of hydraulic pressure. The optimal hydraulic pressure at different temperatures were given and verified by experimental studies at temperature 100°C and 170V.
Sequential development of interfering metamorphic core complexes: numerical experiments and comparison with the Cyclades, Greece
Authors: Tirel C. , Gautier P. , van Hinsbergen D. J. J. , Wortel M. J. R.
Published: April 2009

The mechanics of metamorphic core complex (MCC) development and the associated process of lower crustal flow have been the topic of several modelling studies. The model setup usually includes a local heterogeneity forcing deformation to localize at a given site, enabling only one MCC to develop. This paper presents numerical lithospheric-scale experiments in which deformation is not
a priori
localized in a specific place, in order to examine whether multiple MCCs could develop during extension, at which conditions, and how. Configurations with either a single MCC or several far-distant MCCs aligned in the section parallel to extension are obtained for a relatively wide range of initial conditions, the only firm requirement being that the lower crust and the sub-Moho mantle both have very low strengths. In contrast, only a narrow range of conditions leads to the development of closely spaced MCCs. In this case, the MCCs interfere with one another (the domes are partly superimposed or/and share a shear zone in common) and develop in sequence. This configuration is compared with the Cyclades archipelago, where closely spaced chains of MCCs have been described in the literature. A review of available data on the islands documents a good agreement with the experiments in terms of final depth of the Moho, geometry and kinematic pattern of the MCCs, and timing of exhumation of the metamorphic rocks. Based on this agreement, we tentatively deduce from the numerical results some of the conditions that prevailed at the initiation of, and during, post-orogenic MCC-type extension in the Cyclades. The most likely initial thickness of the crust is between 40 and 44 km. A thermal lithospheric thickness of only
c
. 60 km is also likely, which might be a condition at the onset of extension or may have been obtained during early stages of extension while the lithosphere was warmed up. Either a backarc subduction setting or a process of mantle delamination may account for this situation. The numerical results also suggest a boundary velocity of 2.0–2.3 cm/a, which should basically reflect the rate at which the South Hellenic subduction zone retreated. Considering
c
. 500 km as an upper bound for the amount of retreat balanced by Aegean extension and assuming that this retreat mostly occurred during MCC-type extension in the Cyclades, we find that the boundary velocity could have been as high as 2.1 cm/a if MCC-type extension lasted 24 Ma, starting at
c
. 30 Ma and finishing at
c
. 6 Ma, as suggested by available geochronological data. A velocity of 2.1 cm/a agrees well with the numerical results.
The Itea–Amfissa detachment: a pre-Corinth rift Miocene extensional structure in central Greece
Authors: Papanikolaou Dimitrios , Gouliotis Leonidas , Triantaphyllou Maria
Published: April 2009

The Itea–Amfissa valley, separating Giona Mountain to the west from Parnassos Mountain to the east, is related to an extensional detachment observed along the eastern slopes of Giona. The detachment is traced for 30 km north of the Corinth Gulf and dips 25°–40° to the east, showing an east–west extension parallel to the Hellenic arc. The lower nappes of Pindos, Penteoria, Vardoussia and mainly the basal thrust of the Parnassos unit form part of the footwall, whereas the upper thrusts of the Parnassos unit and the Western Thessaly–Beotia nappe form part of the hanging wall. The eastern slopes of Giona are controlled by the detachment and several hundred metres of syn-tectonic breccia-conglomerates are observed at the top of the hanging wall rocks and are back-tilt towards the detachment plane. Two conglomeratic sequences are distinguished: the lower one consists of argillaceous matrix and abundant ophiolite detritus whereas the upper one bears carbonate matrix with carbonate detritus together with large olistholites of Mesozoic limestones. Based on calcareous nannofossils a middle Miocene age has been determined for the lower formation and a middle–upper Miocene age is probable for the upper. Planation surfaces cut on top of the sediments rise from south to north starting from sea level at Galaxidi to about 1400 m at Prosilio. The throw of the detachment is about 2.5–4.2 km measured mainly from the structural omission of the Alpine tectono-stratigraphic units. A contrast between the footwall and the hanging wall structure is described, with monoclinic sequence of the Parnassos nappe dipping to the west in the footwall but a complex synsedimentary horst and graben structure of sliding blocks of Alpine formations within the Miocene clastic sequences in the hanging wall. The detachment has been deformed by the east–west-trending steep normal faults that have created the Corinth rift during late Pliocene–Quaternary time showing a north–south extension. The Itea–Amfissa detachment forms the northern tip of the broader East Peloponnesus detachment, observed south of the Corinth rift structure from Feneos to Kyparissi. Similar geodynamic phenomena with large olistholites and breccia conglomerates are known from the Serravalian of Crete, related to the activity of the Cretan detachment.
Neogene brittle detachment faulting on Kos (E Greece): implications for a southern break-away fault of the Menderes metamorphic core complex (western Turkey)
Authors: van Hinsbergen Douwe J. J. , Boekhout Flora
Published: April 2009

The southern limit of the Menderes metamorphic core complex has recently been proposed to be formed by an Oligocene–early Miocene top-to-the-north breakaway detachment fault, the Datça–Kahle fault running across the Lycian nappes in southwestern Turkey. Proving a breakaway detachment fault as opposed to a ‘simple’ local high-angle normal fault is generally hampered by absence of a metamorphic contrast between hanging wall and footwall. The island of Kos lies close to the inferred southern breakaway fault. It exposes Permo- Carboniferous anchimetamorphic rocks, intruded and contact-metamorphosed at upper crustal levels by a 12 Ma old monzonite during or close to peak-burial conditions. Here, we show that exhumation of these rocks occurred along a top-to-the-north brittle extensional detachment fault underneath upper Mesozoic and Palaeogene non-metamorphic carbonates after 12 Ma, and that any (undocumented) earlier extension did not lead to significant exhumation of the Permo-Carboniferous rocks. Kos should thus be placed within the Cyclades–Menderes extensional province since 12 Ma. The age of exhumation is younger than the proposed activity of the breakaway fault, the existence of which we cannot corroborate. We conclude that the brittle detachment of Kos cannot be straightforwardly correlated to any ductile-to-brittle detachments of the Menderes or eastern Cycladic metamorphic core complexes further to the north and may represent a relatively isolated structure.
The structure of the Kythira–Antikythira strait, offshore SW Greece (35.7°–36.6°N)
Authors: Kokinou Eleni , Kamberis Evangelos
Published: April 2009

The Kythira–Antikythira strait, within the SW Hellenic Arc, forms a 100 km long NNW–SSE trending ridge between Peloponnesus and Crete and represents the submarine continuation of the Hellenic Alpine belt. In order to present the shallow as well as the deeper structure of Kythira–Antikythira strait we studied five seismic sections, oriented either parallel or perpendicular to the inner part of the Hellenic Arc. This information was complemented with velocity analyses from a dense network of seismic lines and information concerning the bathymetry.

Contractional structures recognized on the seismic profiles indicate that this part of the Gavrovo–Tripolitza geotectonic zone was involved in the Miocene shortening related to the westward propagation of the Hellenic fold-and-thrust system. East-dipping thrust faults which root in the top of the crystalline basement were identified on the seismic profiles. The deepest reflector identified on the profiles corresponds to the crystalline basement. Shallower reflectors include those corresponding to the contacts between the Mesozoic/Miocene, Upper Miocene/Lower Pliocene and Pliocene/Pleistocene sedimentary sequences. The Upper Cenozoic to Quaternary sequence rests unconformably upon Mesozoic carbonates. Messinian intrusions, forming small scale domes, deform the Pliocene–Quaternary sedimentary succession. West- and east-dipping normal faults were also recognised both within the Palaeozoic and Cenozoic successions, and are related to regional extension during sedimentation.
Tectono-stratigraphy of the Çankırı Basin: Late Cretaceous to early Miocene evolution of the Neotethyan Suture Zone in Turkey
Authors: Kaymakci Nuretdin , Özçelik Yakup , White Stanley H. , Van Dijk Paul M.
Published: April 2009

The Çankırı Basin straddles the İzmir–Ankara–Erzincan Suture Zone which demarcates the former position of the northern branch of the Neotethys. It includes more than 3 km of pre-Middle Miocene in-fill related to late Cretaceous to pre-Middle Miocene evolution of the region. The basin has developed on the upper Cretaceous subduction complex and arc related basins of the Neotethys Ocean. The basin fill includes an upper Cretaceous forearc sequence overlain by Paleocene with a local unconformity. The upper Cretaceous configuration of the Çankırı basin is interpreted as a part of a forearc basin. The Paleocene and younger history is interpreted as a foreland sequence dominated by progressively southwards migrated depocenters in front of southward migrating thrust faults upon which a series of piggy-back basins were developed. Termination of the forearc setting and beginning of foreland basin conditions indicates complete subduction of the Neotethyan oceanic crust and onset of collision between the Pontides (Laurasia) and the Taurides (Gondwana) in the Paleocene. Thrusting and related sedimentation continued until the Aquitanian (Early Miocene).
Oligocene–Miocene basin evolution in SE Anatolia, Turkey: constraints on the closure of the eastern Tethys gateway
Authors: Hüsing Silja K. , Zachariasse Willem-Jan , van Hinsbergen Douwe J. J. , Krijgsman Wout , Inceöz Murat , Harzhauser Mathias , Mandic Oleg , Kroh Andreas
Published: April 2009

The Oligocene–Miocene was a time characterized by major climate changes as well as changing plate configurations. The Middle Miocene Climate Transition (17 to 11 Ma) may even have been triggered by a plate tectonic event: the closure of the eastern Tethys gateway, the marine connection between the Mediterranean and Indian Ocean. To address this idea, we focus on the evolution of Oligocene and Miocene foreland basins in the southernmost part of Turkey, the most likely candidates to have formed this gateway. In addition, we take the geodynamic evolution of the Arabian–Eurasian collision into account.

The Muş and Elazığ basins, located to the north of the Bitlis–Zagros suture zone, were most likely connected during the Oligocene. The deepening of both basins is biostratigraphically dated by us to occur during the Rupelian (Early Oligocene). Deep marine conditions (between 350 and 750 m) prevailed until the Chattian (Late Oligocene), when the basins shoaled rapidly to subtidal/intertidal environment in tropical to subtropical conditions, as indicated by the macrofossil assemblages. We conclude that the emergence of this basin during the Chattian severely restricted the marine connection between an eastern (Indian Ocean) and western (Mediterranean) marine domain. If a connection persisted it was likely located south of the Bitlis–Zagros suture zone. The Kahramanmaraş basin, located on the northern Arabian promontory south of the Bitlis–Zagros suture zone, was a foreland basin during the Middle and Late Miocene, possibly linked to the Hatay basin to the west and the Lice basin to the east. Our data indicates that this foreland basin experienced shallow marine conditions during the Langhian, followed by a rapid deepening during Langhian/Serravallian and prevailing deep marine conditions (between 350 and 750 m) until the early Tortonian. We have dated the youngest sediments underneath a subduction-related thrust at
c
. 11 Ma and suggest that this corresponds to the end of underthrusting in the Kahramanmaraş region, i.e. the end of subduction of Arabia. This age coincides in time with the onset of eastern Anatolian volcanism, uplift of the East Anatolian Accretionary Complex, and the onset of the North and East Anatolian Fault Zones accommodating westward escape tectonics of Anatolia. After
c
. 11 Ma, the foreland basin south of the Bitlis formed not (or no longer) a deep marine connection along the northern margin of Arabia between the Mediterranean Sea and the Indian Ocean. We finally conclude that a causal link between gateway closure and global climate change to a cooler mode, recorded in the Mi3b event (δ
18
O increase) dated at 13.82 Ma, cannot be supported.
Long-term evolution of the North Anatolian Fault: new constraints from its eastern termination
Authors: Hubert-Ferrari Aurélia , King Geoffrey , Woerd Jérome van der , Villa Igor , Altunel Erhan , Armijo Rolando
Published: April 2009

The deformation and
40
Ar–
39
Ar dating of recent volcanism, that remarkably sits across the North Anatolian Fault eastern termination in Turkey, together with previous studies, put strong constraints on the long-term evolution of the fault. We argue that after a first phase of 10 Ma, characterized by a slip rate of about 3 mm/a, and during which most of the trace was established, the slip rate jumped to about 20 mm/a on average over the last 2.5 Ma, without substantial increase of the fault length. The transition correlates with a change in the geometry at the junction with the East Anatolian Fault that makes the extrusion process more efficient.
Mediterranean snapshots of accelerated slab retreat: subduction instability in stalled continental collision
Authors: Edwards M. A. , Grasemann B.
Published: April 2009

This review of Mediterranean geodynamics highlights that the Mediterranean region captures at a fortuitous moment in time, a picture of the fate of foundering, old, cold oceanic lithosphere of limited area due to being landlocked in an all-but-stalled continental collision (Africa with Europe). We synthesize the geological spatial and temporal data for stretched crust as well as the 3D distribution of old abyssal plains and new oceanic lithosphere segments in concert with heat flow, palaeomagnetic data, geodetic velocity data, earthquake hypocentre distributions and seismic tomography. We use three Mediterranean subduction system settings (the western Mediterranean, the Hellenic and the Pannonian–Carpathian) that nicely reflect the slab instability and retreat. We assume that mantle slab dynamics best explains the observations. The dispersal and segmentation of the foundering landlocked ocean results in a series of discontinuous subduction zones whose individual lengths gradually diminish while retreat accelerates as slab progressively narrow and tear (i.e. along-strike laterally-propagating slab break-off) due to imminent total consumption of available oceanic lithosphere. We suggest that the Mediterranean region offers a lucid series of snapshots of accelerated slab retreat that, additionally, is globally unique as the only present day example of what we term intra-collisional landlocked ocean subduction.
Evolution of the southern Tyrrhenian slab tear and active tectonics along the western edge of the Tyrrhenian subducted slab
Authors: Argnani Andrea
Published: April 2009

The evolution of the southern Tyrrhenian subduction has been possibly controlled by distinct episodes of slab break-off as indicated by a critical review of the geological literature and by the analysis of purposely acquired multichannel seismic profiles. Within the proposed interpretation the first episode occurred from 8.5 to 4.0 Ma and affected the segment of the slab located in the Sardinia Channel, causing the abandonment of the Adventure thrust front in western Sicily. The second episode occurred between 2.5 and 1.6 Ma, affecting the segment of slab located north of Sicily, and was preceeded by rifting in the Strait of Sicily. The space and time location of these episodes appear controlled by discontinuities pre-existing within the subducted African plate that trend at high angle to the advancing subduction front. These discontinuities delimit segment of subducted slab that can be affected by slab break-off and can act as wayouts for magma and mantle derived He. The major of these discontinuities, the Malta Escarpment, has been reactivated in the Quaternary as a trench-perpendicular tear (STEP faults). Ultimately, the hierarchy in strength of these trench-perpendicular features could have affected the timing and amount of trench retreat and backarc opening.
Insights from the Apennines metamorphic complexes and their bearing on the kinematics evolution of the orogen
Authors: Vignaroli Gianluca , Faccenna Claudio , Rossetti Federico , Jolivet Laurent
Published: April 2009

The Apennine belt represents a typical orogenic segment of the western Mediterranean, characterized by the tectonic convergence between European and Africa plates after oceanic subduction. Both oceanic- and continent-derived metamorphic complexes, considered as the remnants of the subduction-exhumation cycle, crop out in the inner sectors of the Apennine belt, where extensional deformation has dominated since the Early Oligocene. We review the available structural, metamorphic and geochronological data coming from these metamorphic complexes in order to provide a kinematics reconstruction accounting for the tectono-metamorphic evolution of the Apennines, from oceanic subduction to final extensional reworking. During the Eocene, oceanic rocks were progressively subducted down to eclogite-facies conditions following a subduction-type metamorphic gradient. The transition from oceanic- to continental-subduction was coeval with a transition from subduction-type to Barrovian-type metamorphic gradient. Continental collision, at the Eocene–Oligocene boundary, post-dated the syn-orogenic exhumation of HP-rocks and was synchronous with the onset of post-orogenic extension in the hinterland domains. Extensional deformation migrated to the east, following the forelandward migration of the thrust system at the trench. The concomitance of extension and compression is here related to fast rollback of the subducting plate and delamination of the lithospheric mantle below the subducted continental crust. Implications on how the subduction tectonics, syn-orogenic exhumation and post-orogenic extension could have controlled the circulation of HP-rocks in the developing Apennines are also discussed.
Middle Devonian microfloras from the Chigua Formation, Precordillera region, northwestern Argentina
Authors: Amenábar C. R.
Published: April 2009

Rich palynological assemblages have been obtained from the Middle Devonian Chigua Formation (Chinguillos Group, San Juan Province), western Precordillera, Argentina, at two new localities (Del Chaco and Don Agustín creeks). From the palyniferous levels at Del Chaco Creek, there are two assemblages: one is very rich in microplankton (assemblage 1) whereas the other is dominated by spores (assemblage 2). The level obtained from Don Agustín Creek, poorest in overall taxa, is also rich in microplankton (assemblage 3). Compared with coeval microfloras elsewhere, a late Emsian–early Eifelian, and an early Givetian age are proposed for the first and the second assemblages respectively. A third assemblage (assemblage 3) tentatively represents a timespan around the Givetian–Frasnian boundary. The proposed age based on the palynomorphs reinforces previous palaeontological records. Variation in the microplankton diversity, fluctuations in the microplankton/spore ratio and differences in acritarch morphology are used here to interpret changing proximity to palaeoshoreline and so to recognize fluctuations in relative sea level that occurred during the deposition of the Chigua Formation.
Middle Devonian microfloras and megafloras from western Argentina and southern Bolivia: their importance in the palaeobiogeographical and palaeoclimatic evolution of western Gondwana
Authors: di Pasquo M. , Amenábar C. R. , Noetinger S.
Published: April 2009

The study of microfloras and megafloras from western Argentina and southern Bolivia presented here extends our knowledge of the biodiversity and succession of floristic events during the Middle Devonian, and hence improves the current biostratigraphy. Among floral remains, species attributable to ‘
Haplostigma
’ are mostly recorded from the same
Grandispora pseudoreticulata
and other palynomorph-bearing sections at Balapuca (southern Bolivia) and Del Chaco and La Cortadera creeks in the Precordillera of Argentina. The northernmost record of
Grandispora pseudoreticulata
is recorded from a third palynoassemblage from the Pando x-1 corehole of northern Bolivia. A great similarity among all these assemblages (notably abundant
Grandispora pseudoreticulata
) suggests the identification of terrestrial connections, or at least proximity, of these local areas and other regions in South America during the Givetian. Comparison with other contemporary Gondwanan palynofloras shows cosmopolitan species (e.g.
Geminospora lemurata
,
Samarisporites triangulatus
,
Archaeozonotriletes variabilis
,
Chelinospora concinna
) along with some others with more restricted distribution (e.g.
Grandispora pseudoreticulata
,
Leiotriletes balapucensis
,
Acinosporites ledundae
). This pattern defines an Afro-South American Subrealm, which most likely results from the effects of palaeolatitude and, in a lesser way, local palaeoenvironmental conditions. On the other hand, such a level of cosmopolitanism supports previous palaeogeographical reconstructions where a narrow Rheic Ocean was developed between Euramerica and the northern parts of Africa and South America.
Late Devonian echinoderms from the Hongguleleng Formation of northwestern China
Authors: Webster G. D. , Waters J. A.
Published: April 2009

The Late Devonian, Famennian, Hongguleleng Formation of northwestern China has yielded one of the most diverse echinoderm faunas known from China. New collections and re-evaluation of earlier collections results in recognition of new taxa, increases the known diversity, provides new morphological information on some of the previously reported taxa, and provides new information on the affinity of the Late Devonian echinoderms of the Hongguleleng Formation.

New crinoid taxa introduced are
Gnarycrinus lanei
n. gen., n. sp.,
Anamesocrinus tieni
n. sp.,
Histocrinus
?
chenae
n. sp.,
Eumhacrinus tribrachiatus
n. gen., n. sp.,
Sostronocrinus aberratus
n. sp. and
Labrocrinus granulatus
n. gen., n. sp. One new species of blastoid,
Hadroblastus liaoi
, n. sp. is described.

Previous reports listed 46 echinoderms from the Hongguleleng Formation, including 13 blastoids and 33 crinoids. An additional 11 crinoid species bring the total crinoids to 44 species assigned to 32 genera. Similarly, the one additional species of blastoid brings the totals to 14 species assigned to 12 genera. The new echinoderms described herein include the first report of a dimerocrinitid, amphoracrinid, allagacrinid, glossocrinid, histocrinid, cercidiocrinid, dactylocrinid and neoschismatid from the Devonian of northwestern China. Additional morphologic information is provided for three of the previously described taxa and a revision of species assigned to
Grabauicrinus
is proposed.

The crinoids and blastoids suggest closer affinity with Mississippian faunas than with Devonian faunas, and with North American faunas than European faunas. Collectively the blastoid and crinoid faunas from the Hongguleleng indicate that rediversification happened rapidly after extinction in contrast to current suggestions of a long interval of lowered origination following these extinction events.
Devonian ecological-evolutionary subunits in the Appalachian Basin: a revision and a test of persistence and discreteness
Authors: Brett C. E. , Ivany L. C. , Bartholomew A. J. , DeSantis M. K. , Baird G. C.
Published: April 2009

New data compilations for successive formation scale intervals, approximately third-order sequences, permit a statistical characterization of the ecological–evolutionary subunits (EESUs) or faunas of the Latest Silurian to mid-Late Devonian interval in the Appalachian Basin. Cluster analysis using the Jaccard coefficient of similarity show that certain formations cluster tightly together on the basis of faunal composition while in other cases units are sharply set off from superseding units. This result indicates both the coherence of faunal composition within EESUs and the discreteness of their boundaries. The results also require minor revision of EESUs previously delineated, including the addition of three new units. The Esopus Formation is designated as a distinct unit separate from the Schoharie on the basis of brachiopods from shallow water facies of the Skunnemunk outlier in New York; in addition, a short-lived Stony Hollow fauna is recognized in shallow shelf facies of the Union Springs Formation and coeval units (formerly referred to as the lower Marcellus Formation) and the lower transgressive beds of the overlying Oatka Creek Formation. This fauna, consisting of subtropical Old World Realm (OWR) emigrants, is distinctive from both the underlying Onondaga fauna and that of the overlying Hamilton Group. Moreover, the Tully Formation presents another case of a short-lived incursion of tropical OWR taxa followed by the extermination of this fauna and reappearance of a suite of typically Hamilton taxa. This case illustrates that EESUs may persist globally despite their local extermination or emigration from a large region, such as the Appalachian Basin.

Review of the broader context of EESU turnover suggests that these crises are geologically rapid and synchronous. Moreover, most of the Devonian EESU boundaries coincide with recognized global bioevents, within the limits of combined biostratigraphic and sequence stratigraphic resolution. Hence, these crises, although perhaps locally accentuated in the Appalachian Basin, are allied to global causes. They appear mostly to be associated with rapid rises in sea level, periods of widespread climatic change and hypoxic events in basinal areas.
The Siegenian delta: land-sea transitions at the northern margin of the Rhenohercynian Basin
Authors: Stets J. , Schäfer A.
Published: April 2009

Analysis, interpretation and reconstruction of different depositional palaeoenvironments in the land–sea transition zone of the huge Lower Devonian siliciclastic delta system at the northern margin of the Rhenohercynian Basin (Central European Variscides, Germany) are the main subjects of this paper. Seven representative columnar sections have been taken at larger outcrops in the Mid-Rhine region. They furnished the main criteria for this analysis. The understanding and interpretation of the different depositional palaeoenvironments have been supported by regional geological lithological and biostratigraphical data.

The sedimentary processes of distal meandering fluvial systems that gradually passed into fluvial-dominated deltaic systems of the elongate bird-foot type have been recognized. Lower delta slope to delta-foot plain conditions have been detected in a subtidal environment probably down to 100 m of former water depth. Thus, the Siegenian delta must have had a low inclined but wide slope down to the basin floor.

Palaeoclimatic conditions at a latitude of about 10 to 30° south, in the basinal as well as in the source area of the Old Red Continent in the north, controlled the input of siliciclastic detritus as well as the depositional processes in the basin. Moreover, steady subsidence and an intermittent sea level played a prominent role during sedimentation. They held this system in balance for more than seven million years.
Frasnian reef evolution and palaeogeography, SE Lennard Shelf, Canning Basin, Australia
Authors: George Annette D. , Trinajstic Kate M. , Chow Nancy
Published: April 2009

Frasnian reef complexes of the southeastern Lennard Shelf (northern Canning Basin) developed on tilt-block highs and their evolution was controlled by fault-related subsidence. Tectonic control on relative sea-level changes was, therefore, a major factor influencing Early–Middle Frasnian palaeogeography of the Lennard Shelf. However, palaeogeographic reconstruction is not consistent with simple landward (northward) backstepping and younging of reef complexes in response to basin extension and subsidence of fault blocks. Using a sequence-stratigraphic approach, in conjunction with sedimentological and biostratigraphic data, we propose that two neighbouring fault blocks (Lawford area on the eastern side of Bugle Gap and the Hull platform to the north) record a similar history and that the reef complexes on those blocks were initiated at similar times. Seven phases of Early–Middle Frasnian platform growth (Fr2–8) are identified. All are bounded by third-order flooding surfaces associated with backstepping of platform margins and three surfaces (defined by conodont Zone 4, Zone 6 and late Zone 6) correlate across the two fault blocks. Only one sequence boundary has been clearly identified and a second relative sea-level fall is proposed based on a major collapse event following progradation and associated coarse siliciclastic facies. We propose that the correlation of flooding events across the SE Lennard Shelf is related to episodes of basin-margin faulting centred on the large, long (
c
. 25 km) faults which border these blocks (shelf-parallel faults for the Lawford block and an oblique north-trending transfer zone for the Hull block). There is limited evidence for relative sea-level falls and those recognized most likely resulted from eustatic events. The correlation between the Lawford block and Hull platform suggests linkage between major NW-trending shelf-parallel and oblique transfer faults and an evolved rift system by the Early Frasnian.