Shallow Wedge Research Articles

Slab melting boosts the mantle wedge contribution to Li-rich magmas

The lithium cycling in the supra-subduction mantle wedge is crucial for understanding the generation of Li-rich magmas that may potentially source ore deposition in continental arcs. Here, we look from the mantle source perspective at the geological processes controlling the Li mobility in convergent margins, by characterizing a set of sub-arc mantle xenoliths from the southern Andes (Coyhaique, western Patagonia). The mineral trace element signatures and oxygen fugacity estimates (FMQ > + 3) in some of these peridotite xenoliths record the interaction with arc magmas enriched in fluid-mobile elements originally scavenged by slab dehydration. This subduction-related metasomatism was poorly effective on enhancing the Li inventory of the sub-arc lithospheric mantle, underpinning the inefficiency of slab-derived fluids on mobilizing Li through the mantle wedge. However, major and trace element compositions of mantle minerals in other xenoliths also record transient thermal and chemical anomalies associated with the percolation of slab window-related magmas, which exhibit an “adakite”-type geochemical fingerprint inherited by slab-derived melts produced during ridge subduction and slab window opening event. As these melts percolated through the shallow (7.2–16.8 kbar) and hot (952–1054 °C) lithospheric mantle wedge, they promoted the crystallization of metasomatic clinopyroxene having exceptionally high Li abundances (6–15 ppm). Numerical modeling shows that low degrees (< 10%) of partial melting of this Li-rich and fertile sub-arc lithospheric mantle generates primitive melts having two-fold Li enrichment (~13 ppm) compared with average subduction-zone basalts. Prolonged fractional crystallization of these melts produces extremely Li-enriched silicic rocks, which may stoke the Li inventory of mineralizing fluids in the shallow crust.

Mesh generation for underwater acoustic modeling with KRAKEN

Underwater sound modeling is applied in several environmental studies, from assessing underwater noise induced by offshore wind farms to the influence of climate change on ocean temperature. One of the most well-known underwater acoustics models is KRAKEN, an open-source code requiring a mesh to simulate 3D environments. This paper presents OMesh2KRAKEN, a software toolkit that uses OceanMesh2D to generate unstructured meshes for KRAKEN based on realistic environmental data. Two practical study cases in the North Atlantic are presented and discussed. In addition, an idealized 3D shallow water wedge was simulated. Practically, OMesh2KRAKEN can assist in implementing underwater acoustic modeling studies from deep waters to nearshore regions where, for instance, sound propagation maps are required. Indeed, higher mesh resolutions may be required for areas with complex bathymetric features. In these cases, the new tool presents several advantages as it automatically implements different mesh resolutions in areas of interest and prepares the respective environmental files for acoustic computations.

Three-Dimensional Fault-Fold Growth Deciphered from Combined Seismic and Geological Data: A Case Study from the Xiongpo Anticline, Longmen Shan Piedmont

The Xiongpo fault-fold belt shows prominent NE, ENE- and ~N–S-trending relief, which resulted from multi-stage upper crustal shortening in the Longmen Shan piedmont during the eastward growth of the eastern Tibetan Plateau. Previous studies have determined its 2D structural configurations from seismic profiles and field-based geological cross-sections. Here, we extend this analysis into the entire belt to explore the 3D structural evolution of this complex fault-fold belt and have built a 3D regional fault model. The results reveal along-strike variation of subsurface structural architecture of the Xiongpo fault-fold belt, which is characterized by transformation from a complex superimposition of a deep fault-bend fold beneath a shallow structural wedge in the center segment to a simple shallow fault-bend fold on both ends of the structure, and then to a trishear fault propagation fold on the plunging edges. This structural transformation determines the contrast between the NE-striking relief of the central segment, and the ENE- and ~N-S-striking relief in the two plunging zones. We combine our results with published low-temperature thermochronology and growth strata results to propose a three-stage evolution for the Xiongpo fault-fold belt that closely relates with regional stress field changes, including a NE-striking fault under the NW–SE compression between 40–25 Ma and 15–10 Ma, lateral propagation of the NE-striking fault and initiation of ENE-striking fault by WNW–ESE compression from ~5–2 Ma, ~N–S fault under ~E–W compression until the present. This work enhances our understanding of the stress field changes of eastern Tibet since the Late Eocene. It also can serve as a typical case study deciphering 3D fault-fold growth using seismic and geological imaging, which is helpful to understand 3D structural and landscape evolutions of other complex fault-fold belts worldwide.

Permafrost and paleoenvironments on the Northeastern Qinghai-Tibet Plateau, China during the local last permafrost maximum

ABSTRACT The Qinghai-Tibet Plateau (QTP) is one of the middle- and low-latitude regions with the most developed and well-preserved periglacial phenomena and remains in the world. On the northeastern QTP, periglacial remains are widespread and vital for investigating the evolution of regional periglacial and permafrost environments. The recently discovered periglacial remains on the northeastern QTP are mostly cryogenic wedges of Late Pleniglacial age (30–10 ka), deep and large cryogenic wedges mostly formed during 30–19 ka ago. Shallow cryogenic wedges have formed between 16 and 12.5 ka. A second wave of cryogenic wedge pseudomorphs seems to have followed, which was ending by about 7 ka. Based on the types of cryogenic wedges and in combination with stratigraphic data for dating, as well as the past Quaternary geological and periglacial landform data, we infer that the mean annual air temperature (MAAT) in this region during the local LPM (30–19 ka) was 7–9°C lower than that at present, and the lower limit of permafrost was lowered to about 2,200–2,500 m a. s. l. During the local LPM, permafrost was extensively and intensively developed on the northeastern QTP, and the continuous permafrost zone extended down to the source area of the Yellow River and the vicinity of the Zoîgé Plateau in the east. Next, discontinuous, sporadic and patchy permafrost occur in cascadingly lowering zones.

Strain Signals Governed by Frictional‐Elastoplastic Interaction of the Upper Plate and Shallow Subduction Megathrust Interface Over Seismic Cycles

AbstractThe behavior of the shallow portion of the subduction zone, which generates the largest earthquakes and devastating tsunamis, is still insufficiently constrained. Monitoring only a fraction of a single megathrust earthquake cycle and the offshore location of the source of these earthquakes are the foremost reasons for the insufficient understanding. The frictional‐elastoplastic interaction between the megathrust interface and its overlying wedge causes variable surface strain signals such that the wedge strain patterns may reveal the mechanical state of the interface. To contribute to this understanding, we employ Seismotectonic Scale Modeling and simplify elastoplastic megathrust subduction to generate hundreds of analog seismic cycles at a laboratory scale and monitor the surface strain signals over the model's forearc across high to low temporal resolutions. We establish two compressional and critical wedge configurations to explore the mechanical and kinematic interaction between the shallow wedge and the interface. Our results demonstrate that this interaction can partition the wedge into different segments such that the anelastic extensional segment overlays the seismogenic zone at depth. Moreover, the different segments of the wedge may switch their state from compression/extension to extension/compression domains. We highlight that a more segmented upper plate represents megathrust subduction that generates more characteristic and periodic events. Additionally, the strain time series reveals that the strain state may remain quasi‐stable over a few seismic cycles in the coastal zone and then switch to the opposite mode. These observations are crucial for evaluating earthquake‐related morphotectonic markers and short‐term interseismic time series of the coastal regions.

Underwater Sound Propagation Modeling in a Complex Shallow Water Environment

Three-dimensional (3D) effects can profoundly influence underwater sound propagation in shallow-water environments, hence, affecting the underwater soundscape. Various geological features and coastal oceanographic processes can cause horizontal reflection, refraction, and diffraction of underwater sound. In this work, the ability of a parabolic equation (PE) model to simulate sound propagation in the extremely complicated shallow water environment of Long Island Sound (United States east coast) is investigated. First, the 2D and 3D versions of the PE model are compared with state-of-the-art normal mode and beam tracing models for two idealized cases representing the local environment in the Sound: (i) a 2D 50-m flat bottom and (ii) a 3D shallow water wedge. After that, the PE model is utilized to model sound propagation in three realistic local scenarios in the Sound. Frequencies of 500 and 1500 Hz are considered in all the simulations. In general, transmission loss (TL) results provided by the PE, normal mode and beam tracing models tend to agree with each other. Differences found emerge with (1) increasing the bathymetry complexity, (2) expanding the propagation range, and (3) approaching the limits of model applicability. The TL results from 3D PE simulations indicate that sound propagating along sand bars can experience significant 3D effects. Indeed, for the complex shallow bathymetry found in some areas of Long Island Sound, it is challenging for the models to track the interference effects in the sound pattern. Results emphasize that when choosing an underwater sound propagation model for practical applications in a complex shallow-water environment, a compromise will be made between the numerical model accuracy, computational time, and validity.

Analysis of the Tilted Shallow Wedge Problem in Couple-Stress Elasticity

Analysis of the Tilted Shallow Wedge Problem in Couple-Stress Elasticity

Explicit and asymptotic solutions for frictional incomplete half-plane contacts subject to general oscillatory loading in the steady-state

This contribution presents an asymptotic formulation for the stick-slip behaviour of incomplete contacts under oscillatory variation of normal load, moment, shear load and differential bulk tension. The asymptotic description allows us not only to approximate the size of the slip zones during the steady-state of a cyclic problem without knowledge of the geometry or contact law, but provides a solution when all known analytical solutions for incomplete contacts reach their limitations, that is, in the presence of a varying moment and a differential bulk tension large enough to reverse the direction of slip at one end of the contact. An insightful comparison between the mathematically explicit analytical solution and the asymptotic approach is drawn using the example geometry of a shallow wedge.

Three-dimensional sound scattering from transversely symmetric surface waves in deep and shallow water using the equivalent source method.

This paper proposes a propagation model to calculate the three-dimensional (3-D) sound scattering from transversely symmetric sea surface waves in both deep and shallow water using the equivalent source method (ESM). The 3-D sound field is calculated by integrating an assembly of two-dimensional (2-D) transformed fields with different out-of-plane wavenumbers through a cosine transform. Each 2-D solution is calculated using the ESM incorporating a complex image method that can efficiently and accurately solve the 2-D water/seabed Green's function. The oscillatory cosine integral is accurately calculated using a segmented integral scheme requiring relatively few 2-D solutions, which can be further improved through the use of parallel computation. The model is validated by comparison with a 3-D Helmholtz-Kirchhoff method for deep water and a finite element method for a shallow water wedge with both a fluid and an elastic seabed. The model is as accurate as the finite element approach but more numerically efficient, which enables Monte Carlo simulations to be performed for random rough surfaces in order to study the scattering effects at a reasonable computational cost. Also, 3-D pulse propagation in the shallow water wedge is demonstrated to understand the out-of-plane scattering effects further.

Modelling the cleaning of viscoplastic layers by impinging coherent turbulent water jets

Impinging liquid jets are widely used to clean unwanted soil layers from the walls of structures and vessels. When the soil is a thin layer of an immiscible viscoplastic material, removal involves the growth of a cleared area (which is circular for a jet impinging normally) bounded by a berm of displaced material. Glover et al. [1] presented a semi-empirical model relating the rate of removal to the momentum flow rate in the liquid film. We present a first-order model for cleaning thin layers of these materials based on the rate of viscous dissipation in a shallow wedge of material at the cleaning front. This yields a result of the form of the model in [1], with expressions linking the kinetic parameters to measurable quantities including the rheology of the soil. The fully coupled problem is not solved: the wedge angle and residual layer thickness need to be specified and were obtained here by fitting to the data. The model is compared with experimental results obtained for three soft solids – two petroleum jellies and a soft paraffin – which exhibited Bingham plastic behaviour and creep, for jet Reynolds numbers between 10,000-37,000, and 0.1<h¯/δo<1.5, where h¯ is the average film depth and δo the layer thickness. The data show reasonable agreement with the model.

Investigating the Failure Mechanism of Jointed Rock Slopes Based on Discrete Element Method

This paper presents a comprehensive engineering method to investigate the failure mechanism of the jointed rock slopes. The field geology survey is first carried out to obtain the slope joint data. A joint network model considering the structural complexity of rock mass is generated in the PFC software. The synthetic rock mass (SRM) approach for simulating the mechanical behavior of jointed rock mass is employed, in which the flat‐jointed bonded‐particle model (FJM) and smooth joint contact model (SJM) represent intact rock and joints, respectively. Subsequently, the effect of microparameters on macromechanical properties of rock is investigated for parameter calibration. Moreover, the scale effect is analyzed by multiscale numerical tests, and the representative elementary volume (REV) size in the selected research area is found as 16 m × 16 m × 16 m. The microparameters of the SRM model are calibrated to match the mechanical properties of the engineering rock mass. Finally, an engineering case from Shuichang open‐pit mine is analyzed and the failure process of the slope during the excavation process from micro‐ to macroscale is obtained. It has been found that failure occurs at the bottom of the slope and gradually develops upwards. The overall failure of the slope is dominated by the shallow local tension fracture and wedge failure.

Evidence for three Cenozoic phases of upper crustal shortening of the Xiongpo structure in the Longmen Shan fold-and-thrust belt, China: Implications for the eastward growth of the eastern Tibetan Plateau

Cenozoic crustal shortening across the Longmen Shan (LMS) fold-and-thrust belt records the eastward growth of the Tibetan Plateau. Although the structural geometries of individual structures in the region have been studied, the kinematics and rates of deformation across these structures remain unclear. In this study, we construct a geological cross section to derive the subsurface structural architecture of the Xiongpo structure in the LMS piedmont using one seismic reflection profile, and data from two boreholes. The structure displays a superimposed deep fault-bend fold and shallow structural wedge with three splay thrust faults. Using two-dimensional kinematic models, based on fault-bend folding algorithm, we reconstruct three episodes of upper crustal shortening, with 7.0 ± 0.3 km of total shortening. Combining with previously published low-temperature thermochronology data, we further estimate that the structure has experienced an average shortening rate of ∼ 0.2 mm/yr since 40–25 Ma. We infer that the structure acted as the deformation front of the LMS fold-and-thrust belt between 40 and 25 Ma and 15–10 Ma driven by the eastward growth of the Tibetan Plateau. Finally, we review the shortening rates of other five structures within the LMS piedmont, and find that these six structures (including the Xiongpo structure) individually have undergone an average shortening rate < 0.5 mm/yr on each fault, suggesting that strain is partitioned along several structures within the LMS fold-and-thrust belt. We also show that the southern LMS piedmont has absorbed more upper crustal shortening than the central LMS, ∼0.5–0.7 mm/yr, since ∼2.6 Ma.

Researches on very low frequency acoustic signal propagation characteristics in different shallow elastic wedge bottoms

Targeted at the issue of extremely low-frequency (&lt;100Hz) acoustic propagation in complex shallow elastic bottom environments. The influence law of different complex elastic bottoms on the acoustic signal propagation at very low frequency by acoustic energy flux has been analyzed with the simulation, which is based on the finite element method. The elastic bottoms which have been studied are the shallow horizontal elastic bottom, and the up-sloping and the down-sloping elastic bottom. The results show that the acoustic signal propagating in the up-sloping and down-sloping elastic bottom environments is more complex than that propagating in the horizontal elastic bottom, and the acoustic energy leaking into those elastic bottoms has very different influence on the acoustic signal propagation, especially in the up-sloping bottom.

Design of plate and screw anchors in dense sand: failure mechanism, capacity and deformation

Plate and screw anchors provide a significant uplift capacity and have multiple applications in both onshore and offshore geotechnical engineering. Uplift design methods are mostly based on semi-empirical approaches assuming a failure mechanism, a normal and a shear stress distribution at failure and empirical factors back-calculated against experimental data. However, these design methods are shown to under- or overpredict most of the existing larger scale experimental tests. Numerical FE simulations are undertaken to provide new insight into the failure mechanism and stress distribution which should be considered in anchor design in dense sand. Results show that a conical shallow wedge whose inclination to the vertical direction is equal to the dilation angle is a good approximation of the failure mechanism in sand. This shallow mechanism has been observed in each case for relative embedment ratios (depth/diameter) ranging from 1 to 9. However, the stress distribution varies non-linearly with depth, due to the soil deformability and progressive failure. A sharp peak of normal and shear stress can be identified close to the anchor edge, before a gradual decrease with increasing distance along the shear plane. The peak stress magnitude increases almost linearly with embedment depth at larger relative embedment ratios. Although further research is necessary, these results lay the basis for the development of a new generation of design criteria for determining anchor capacity at the ultimate limiting state.

Constraining the Dip of Shallow, Shallowly Dipping Thrust Events Using Long‐Period Love Wave Radiation Patterns: Applications to the 25 October 2010 Mentawai, Indonesia, and 4 May 2018 Hawaii Island Earthquakes

AbstractConstraining precise faulting geometry for shallow, shallowly dipping thrust earthquakes is a common challenge. Plate boundary megathrust faults near the trench and décollement faults beneath volcanic islands and nappes may dip only a few degrees. Long‐period point source moment tensor waveform inversions provide limited resolution of shallow fault dip angle. The possibility of splay faulting requires precise dip estimation. High sensitivity to dip is provided by long‐period Love wave amplitude azimuthal radiation patterns, which undergo rapid change from four lobed to two lobed as dip decreases from 10° to 0°. Modeling variability in Love wave nodal amplitudes allows the dip to be determined to within a few degrees. This is demonstrated for the 25 October 2010 Mentawai (MWW 7.8) tsunami earthquake, which ruptured the 2.0–5.0° dipping megathrust beneath the shallow sedimentary wedge offshore of Indonesia, and the 4 May 2018 Hawaii Island (MWW 6.9) thrust earthquake, which ruptured the 2.5–7.5° dipping décollement under the island flank.

Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges.

Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (~1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to ~3 × 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 × 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 ± 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.

V12-01 TRANSURETHRAL VENTRAL BUCCAL MUCOSA GRAFT (BMG) INLAY URETHROPLASTY FOR DISTAL URETHRAL STRICTURES

You have accessJournal of UrologyReconstruction1 Apr 2016V12-01 TRANSURETHRAL VENTRAL BUCCAL MUCOSA GRAFT (BMG) INLAY URETHROPLASTY FOR DISTAL URETHRAL STRICTURES Mourad Abouelleil, Michael Daneshvar, and Dmitriy Nikolavsky Mourad AbouelleilMourad Abouelleil More articles by this author , Michael DaneshvarMichael Daneshvar More articles by this author , and Dmitriy NikolavskyDmitriy Nikolavsky More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2016.02.2127AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Traditional options for distal urethral stricture repair involve penile skin incision to achieve access to urethra for various forms of external urethrotomy and subsequent repair with flaps or grafts. These incisions then require meticulous closure and are at risks of fistula formation, glans dehiscence and poor cosmetic outcomes. We introduce a novel surgical technique to repair fossa navicularis stricture without a need for skin incision. Our approach, a modified Naude technique, employs a ventral internal urethrotomy and precise transurethral delivery and fixation of BMG to the surface of the urethrotomy. METHODS Surgical technique: a ventral urethrotomy is performed transurethrally and a shallow wedge of the obstructive tissue is removed to achieve access to a proximal patent lumen. Appropriate size BMG is then harvested and prepared for delivery. A double arm 6-0 polydioxanone suture is used: each arm of the suture is passed through the proximal apex of the graft then through the urethra at the proximal apex of the urethrotomy and externalized through the skin. By pulling on the arms of the suture externally the graft is delivered precisely into its place in the urethra. Additional 6-0 double armed sutures are used to quilt the graft at its mid portion and their knots tied externally. The distal edge of the graft is sutured to the edge of the meatotomy with absorbable sutures. A retrospective chart review was conducted of all the patients after a fossa navicularis/ distal urethral stricture repair since March 2014 by a single surgeon (DN). Surgical and functional outcomes including complications were reviewed. Uroflow and SHIM scores were evaluated pre- and post-operatively. RESULTS This surgery was performed for 7 patients including 3 circumcised males, 2 uncircumcised males with lichen sclerosus (LS) and 2 transgender patients with neophallus. Mean patient age was 39 years (25-55), mean stricture length 2.6 cm (1-4). At a mean follow up of 8.8 month (4-18), there were no stricture recurrences, fistula, penile chordee or adverse effects on sexual function. Mean uroflow pre-op was 5.5 (0-13), post-op 22 (16-37). SHIM score pre-op 19 (23-25), post-op 23 (22-25). CONCLUSIONS We demonstrated the feasibility of incisionless distal urethral/fossa navicularis stricture repair with ventral inlay BMG. This single stage technique allows avoiding skin incision or urethral mobilization. It prevents glans dehiscence or fistula formation. It avoids the use of genital skin flaps in patients affected with LS and is a viable option for patients with distal strictures in a neophallus. © 2016FiguresReferencesRelatedDetails Volume 195Issue 4SApril 2016Page: e1066 Advertisement Copyright & Permissions© 2016MetricsAuthor Information Mourad Abouelleil More articles by this author Michael Daneshvar More articles by this author Dmitriy Nikolavsky More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

LP/HTmetamorphism as a temporal marker of change of deformation style within the Late Palaeozoic accretionary wedge of central Chile

AbstractA Late Palaeozoic accretionary prism, formed at the southwestern margin of Gondwana from Early Carboniferous to Late Triassic, comprises the Coastal Accretionary Complex of central Chile (34–41°S). This fossil accretionary system is made up of two parallel contemporaneous metamorphic belts: a high‐pressure/low temperature belt (HP/LT– Western Series) and a low pressure/high temperature belt (LP/HT– Eastern Series). However, the timing of deformation events associated with the growth of the accretionary prism (successive frontal accretion and basal underplating) and the development of theLP/HTmetamorphism in the shallower levels of the wedge are not continuously observed along this paired metamorphic belt, suggesting the former existence of local perturbations in the subduction regime. In the Pichilemu region, a well‐preserved segment of the paired metamorphic belt allows a first order correlation between the metamorphic and deformational evolution of the deep accreted slices of oceanic crust (blueschists andHPgreenschists from the Western Series) and deformation at the shallower levels of the wedge (the Eastern Series).LP/HTmineral assemblages grew in response to arc‐related granitic intrusions, and porphyroblasts constitute time markers recording the evolution of deformation within shallow wedge material. IntegratedP–T–t–danalysis reveals that theLP/HTbelt is formed between the stages of frontal accretion (D1) and basal underplating of basic rocks (D2) forming blueschists atc. 300 Ma. A timeline evolution relating the formation of blueschists and the formation and deformation ofLP/HTmineral assemblages at shallower levels, combined with published geochronological/thermobarometric/geochemistry data suggests a cause–effect relation between the basal accretion of basic rocks and the deformation of the shallowerLP/HTbelt. The S2foliation that formed during basal accretion initiated near the base of the accretionary wedge at ~30 km depth atc. 308 Ma. Later, the S2foliation developed atc. 300 Ma and ~15 km depth shortly after the emplacement of the granitoids and formation of the (LP/HT) peak metamorphic mineral assemblages. This shallow deformation may reflect a perturbation in the long‐term subduction dynamics (e.g. entrance of a seamount), which would in turn have contributed to the coeval exhumation of the nearby blueschists atc. 300 Ma. Finally,40Ar–39Ar cooling ages reveal that foliated LP/HT rocks were already at ~350 °C atc. 292 Ma, indicating a rapid cooling for this metamorphic system.

Filling transitions in acute and open wedges.

We present numerical studies of first-order and continuous filling transitions in wedges of arbitrary opening angle ψ, using a microscopic fundamental measure density functional model with short-ranged fluid-fluid forces and long-ranged wall-fluid forces. In this system the wetting transition characteristic of the planar wall-fluid interface is always first order regardless of the strength of the wall-fluid potential ɛ(w). In the wedge geometry, however, the order of the filling transition depends not only on ɛ(w) but also on the opening angle ψ. In particular we show that even if the wetting transition is strongly first order the filling transition is continuous for sufficient acute wedges. We show further that the change in the order of the transition occurs via a tricritical point as opposed to a critical end point. These results extend previous effective Hamiltonian predictions which were limited only to shallow wedges.

Interactions between the shallow wedge mantle and subducted slab ~ the Shiraga ultramafic body, Kochi prefecture ~

Interactions between the shallow wedge mantle and subducted slab ~ the Shiraga ultramafic body, Kochi prefecture ~