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This study explores the differences of fish assemblages in three macrotidal estuaries of Man-gyeong River Estuary (MRE), Geum River Estuary (GRE), and Han River Esturay (HRE) with similar ranges of seasonal water temperature that are diked with different levels of disconnection from freshwater discharge. The distribution of major species in the three estuaries could generally be grouped into three distinctive patterns based on their cumulative distribution with respect to the salinity gradient. The MRE was geographically closer to the GRE than to the HRE, but the fish community of the MRE more closely resembled that of the HRE. Increased freshness of the water inside the dike and the limit of coastal fish to the river may have led to this result. The results provide clues to how enclosure patterns of estuarine waters could affect fish communities over a long-term period. In addition, the information may provide guidance for how a fish community may return once environmental conditions are restored.

Many coastlines around the world are protected by dikes with shallow foreshores (e.g. salt marshes and mudflats) that attenuate storm waves and are expected to reduce the likelihood and volume of waves overtopping the dikes behind them. However, most of the studies to date that assessed their effectiveness have excluded the influence of infragravity (IG) waves, which often dominate in shallow water. Here, we propose a modular and adaptable framework to estimate the probability of coastal dike failure by overtopping waves (Pf). The influence of IG waves on overtopping is included using an empirical approach, which is first validated against observations made during two recent storms (2015 and 2017). The framework is then applied to compare the Pf values of the dikes along the Dutch Wadden Sea coast with and without the influence of IG waves. Findings show that including IG waves results in 1.1 to 1.6 times higher Pf values, suggesting that safety is overestimated when they are neglected. This increase is attributed to the influence of the IG waves on the design wave period and, to a lesser extent, the wave height at the dike toe. The spatial variation in this effect, observed for the case considered, highlights its dependence on local conditions – with IG waves showing greater influence at locations with larger offshore waves, such as those behind tidal inlets, and shallower water depths. Finally, the change in Pf due to the IG waves varied significantly depending on the empirical wave overtopping model selected, emphasizing the importance of tools developed specifically for shallow foreshore environments.

Magmatism in the passive margin records continuum rift of continental lithosphere and onset of seafloor spreading. The ca. 650 Ma ultramafic-mafic dike swarms are the latest magmatic episode in the South Qinling Belt during the Neoproterozoic, and therefore provide a window to address their mantle sources, and the continental rift to drift transition. These mafic dikes have distinct geochemical signatures, and can be grouped as N-MORB-, E-MORB-, and Arc-affinities. The Shiziyan amphibole gabbros have low Rb/Y (

The 2014–2015 CE rift event associated with the Bárðarbunga eruption at Holuhraun, Iceland, offers a unique opportunity to study the spatial and temporal evolution of a rift graben. We present the first four-dimensional (three-dimensional plus time) monitoring of the formation and evolution of a graben during active magma transport using a suite of digital elevation models spanning from shortly before the eruption throughout 6 months of magma transport and up to 4.5 years after the eruption. This multiscale data set enables investigations of how magma supply and eruption dynamics affect tectonic structures that feed eruptions. After formation (time scale of a few days), the graben is remarkably stable throughout the eruption and for years beyond. It is unaffected by large changes in eruptive activity and effusion and seismicity rates within the plumbing system. These data document that (1) there was no direct feedback between eruptive dynamics and graben topography, and (2) graben formation is near instantaneous on tectonic time scales. These results challenge the overarching role ascribed to magma transport in recent studies of tectonomagmatic relationships in rift events, favoring regional tectonics as the fundamental driving force.

Magmatism accompanies rifting along divergent plate boundaries, although its role before continental breakup remains poorly understood. For example, the magma-assisted Northern Main Ethiopian Rift (NMER) lacks current volcanism and clear tectono-magmatic relationships with its contiguous rift portions. Here we define its magmatic behaviour, identifying the most recent eruptive fissures (EF) whose aphyric basalts have a higher Ti content than those of older monogenetic scoria cones (MSC), which are porphyritic and plagioclase-dominated. Despite these differences, calculations highlight a similar parental melt for EF and MSC products, suggesting only a different evolutionary history after melt generation. While MSC magmas underwent a further step of storage at intermediate crustal levels, EF magmas rose directly from the base of the crust without contamination, even below older polygenetic volcanoes, suggesting rapid propagation of transcrustal dikes across solidified magma chambers. Whether this recent condition in the NMER is stable or transient, it indicates a transition from central polygenetic to linear fissure volcanism, indicative of increased tensile conditions and volcanism directly fed from the base of the crust, suggesting transition towards mature rifting.

Levee-breach-induced flooding occurs occasionally but always causes considerable losses. A serious flood event occurred due to the collapse of a 15 m long levee section in Qianbujing Creek, Shanghai, China, during Typhoon Fitow in October 2013. Heavy rainfall associated with the typhoon intensified the flood severity (extent and depth). This study investigates the flood evolution to understand the dynamic nature of flooding and the compound effect using a well-established 2D hydro-inundation model (FloodMap) to reconstruct this typical event. This model coupled urban hydrological processes with flood inundation for high-resolution flood modeling, which has been applied in a number of different environments, and FloodMap is now the mainstream numerical simulation model used for flood scenarios. Our simulation results provide a comprehensive view of the spatial patterns of the flood evolution. The worst-hit areas are predicted to be low-lying settlements and farmland. Temporal evaluations suggest that the most critical time for flooding prevention is in the early 1–3 h after dike failure. In low-elevation areas, temporary drainage measures and flood defenses are equally important. The validation of the model demonstrates the reliability of the approach.

The stability of a dike is influenced strongly by its water content, by way of changes in effective stress and weight. While flow through porous media is relatively well understood, water flux in and out of a dike through a vegetated surface is not as well understood. This paper presents a numerical study of the soil–vegetation–atmosphere interaction and discusses how it influences the stability of dikes covered with grass. A crop model was used to simulate vegetation growth and infiltration in response to meteorological forcing. The PLAXIS finite-element method model was used to simulate the impact of this infiltration on hydromechanical behaviour and dike stability. Results from a 4-year analysis indicated a strong correlation between root zone water content (WC rz) and factor of safety, although the relationship is not unique. The leaf area index (LAI) was also found to have a strong, lagged correlation with the water flux into the dike. This suggests that monitoring LAI could be a useful tool to identify vulnerable locations along dikes. It is therefore proposed that vegetation and root zone water content could be used as an indication to detect vulnerable dikes in the early stage.

In this paper, the effects of different combinations of permeable spur dikes installed in the bend section of spillway on flow characteristics and energy dissipation rate were experimentally and numerically investigated. The results indicate that the permeable spur dikes installed in the spillway bend appreciably contributes to the improvement on the water surface uniformity, and the water surface uniformity can reach 90.13% with three permeable spur dikes installed in the bend. The permeable spur dike can lead to different degrees of decrease in the time-averaged longitudinal velocity in each zone of spillway bend. Different from previous study, no circulation zone is formed upstream and downstream of permeable spur dike due to the presence of permeable holes, and the flow upstream of permeable spur dikes could be divided into three distinctly different flow modes according to dye tracing. The presence of permeable spur dikes causes the concentration of TKE zone at concave bank of the spillway bend, except for TKE zone immediately next to the bottom plate. The TKE first increases and then decreases with the increase in the vertical distance from the bottom plate of the spillway bend, exhibiting a typical parabolic distribution. The energy dissipation rate in the spillway bend with permeable spur dike was calculated using a modified integral method, and the dissipation rate can reach as high as 21.08% with three spur dikes installed in the bend.

Across Europe, coasts are drastically being changed to adapt to relative sea level rise, which will influence coastal landscapes and heritage in many ways. In this paper, we introduce a methodological starting point for analysing the ways in which landscape architects and spatial planners engage with coastal landscapes and coastal heritage in the context of current climate adaptation projects. We test these methodologies by applying them to the Marconi dike strengthening project in Delfzijl, the Netherlands. This city’s dike fortification is an interesting case, as it offers many opportunities for re-designing heritage. The city borders the Wadden Sea area, a tidal mudflat area protected as a UNESCO World Heritage Site for its natural and geological heritage values. The area also consists of a rich cultural landscape, which is overlooked in the public image and in local policy. We conclude that landscape architects and planners should strengthen not only the dike, but also the interpretation of the past that dominates policy and political debates in the area. We also find that the existing heritage production model of Ashworth and Tunbridge can provide some useful structure for understanding and contextualizing spatial planning for climate change as a way of doing heritage.

Natural hydrogen seeps called fairy circles have been identified in Mali, Brazil, Russia, and United-States. Natural hydrogen is produced from a field in Mali for 7 years. The natural hydrogen system is still poorly understood and needs to be studied in new geological contexts as to streamline hypotheses on the system dynamics and elements into concepts. In Australia, numerous circular surface features, commonly called salt lakes or swaps, are visible from the sky but no existing work shows nor quantifies any hydrogen content in those features. In this study, we reviewed the existing literature on fairy circles as to determine and directly test with soil-gas measurements if hydrogen surface-emitting features are present in Australia. We determined best candidates to test with a multi-disciplinary approach linking geology, multi-physical imaging, and seismic interpretation. Soil-gas measurements showed persistent hydrogen concentration localized in the external ring of circular depressions aligned along the Darling Fault, a major crustal boundary between the granitic, mafic and ultramafic rocks of the Yilgarn Craton from the sedimentary rocks of the Perth Basin. This work is the proof that fairy circles, in the meaning of H2 emitting structures, are present in Australia and opens the door to new prospectivity pathways by evaluating original hypotheses on natural hydrogen generation, migration pathways and entrapment. This geological setting promotes deep serpentinization of ultramafic rocks as well as oxidation of iron-rich Archean rocks and mafic dikes as potential hydrogen sources that are both of massive potential economic value. This hydrogen can circulate and be entrapped as aqueous hydrogen in low-salinity aquifers or migrate in gaseous phase in fault zones up to intermediate structural reservoir or to the surface.

Seepage through dikes under steady-state conditions is a classical problem in geotechnics. Several analytical solutions exist for estimating seepage through 2D dikes. In practice, many dikes have a limited length in the third dimension. This is particularly true for water flow through a waste rock barricade to hold backfill slurry in underground stopes. Three-dimensional solutions are necessary to evaluate seepage through 3D trapezoidal dikes. In this study, existing 2D solutions developed for estimating seepage through 2D dikes under steady-state conditions are presented and generalized for 3D dikes. The validity of these 3D generalized solutions is tested by numerical modeling with FLAC3D. Results show that the 3D solution based on a generalization of the Dupuit solution predicts seepage variation as a function of upstream hydraulic head well, but fails to describe seepage variation as a function of downstream hydraulic head. Further analyses reveal that the Dupuit model involves assumptions by which the flow path can be underestimated and the mean flow cross-section from the bottom to the top surface of the downstream water tends to be overestimated. The 3D generalized Dupuit solution was therefore modified by adding two calibration coefficients, one for the flow path length and another for the mean flow cross-section. The two calibration coefficients were then obtained by calibration against a few 3D numerical results. The validity of the proposed and calibrated analytical solution was then tested against additional numerical results. Finally, both the numerical model and the proposed calibrated analytical solutions were validated by laboratory test results.

Knowledge of the nature of the earliest metamorphism experienced by collisional orogenic belts is essential for reconstruction of tectonic processes that build high mountain chains and their environmental consequences. Understanding the metamorphic nature of Eohimalayan-phase orogeny of the Himalayan orogen, one of the typical examples of orogenic belts worldwide, could provide some important constraints to test different tectonic models (shallow continental subduction vs. slab breakoff) for the early phases of the development of large-scale orogenic belts. As exhumed middle- to lower-crustal rocks in the Kangmar gneiss dome, the garnet amphibolites with a protolith age of 176.4 ± 3.6 Ma experienced a phase of metamorphism at 47.2 ± 1.8 Ma with an increase in pressure as well as temperature from 3–5 kbar and 550–600 °C to over ~11 kbar and 650 °C. This suggests that the middle- to lower-crustal rocks experienced heating at least by ~50 °C while they underwent compression and thickening. Heat-flow estimation further demonstrates that the self-produced heat was high enough to achieve the observed pressure-temperature conditions recorded by the garnet amphibolite. Therefore, an additional heat supply is not required during early Eocene metamorphism. A breakoff of the leading part of the subducting Indian continental slab, if it occurred, should be younger than ca. 47 Ma.

Wave overtopping at a sea dike was observed using video images during a storm in July 2018 at Rizhao Coast, China. A shore-based video monitoring system was mounted to collect coastal images with a sample frequency of 1 Hz in the beginning 10 min of each hour during daylight. A method to extract the frequency, location, width and duration of individual overtopping events based on the shore-based video monitoring system was developed. A total of 6 252 individual overtopping events were detected over a 360m long sea dike during the storm of 10 h in a safe and labor-saving way, enabling a detailed analysis of the temporal and spatial variation of wave overtopping. The temporal variation of overtopping duration, frequency and volume is basically in sync with the change of tidal level (R = 0.87, 0.82 and 0.76, respectively). The increase of wave height increases the overtopping frequency significantly. We found a high correlation between the hourly observed data and the predicted results of two commonly used formulae. Unlike the previous field measurements of overtopping that were limited in a single location, significant spatial variation of overtopping in the alongshore direction is found. The overtopping volume varies with a factor of 6 within the range of several wave lengths. It is further revealed that the spatial variation of overtopping is highly correlated with the alongshore variation of surf zone width with a correlation coefficient of 0.895. The present study suggests the feasibility of shore-based video monitoring technique to capture the main features of wave overtopping at coastal dikes, providing new possibilities to monitor wave overtopping in the field and to improve prediction tools.

As water damage phenomenon of spur dike exists generally, spur dike must be maintained in order to ensure its regulation function, but its structure changed in the process of maintenance. In order to find out flow structure around the spur dike of different pattens, through generalized flume model tests, variation characteristics of water surface profile and flow velocity around the spur dike of five different pattens were analysed. The results show that the straight head had a greater influence than hook head spur dike on the water surface profile, circular cross-section had smaller effects than trapezoidal cross-section spur dike on the water surface profile; Velocity of Choke area and contraction order from large to small is trapezoidal cross-section and fan straight head dike, trapezoidal cross-section and arc straight head dike, arc section and arc straight head dam, trapezoidal cross-section and fan hook head dike, trapezoidal cross-section arc hook head dike; Cross section vertical velocity distribution from large to small is trapezoidal cross-section and fan hook head dam, trapezoidal cross-section and circular straight head dike, arc cross-section and circular straight head dam, trapezoidal cross-section and circular hook head dike.

Despite decades of research, the mechanisms and processes of subduction initiation remain obscure, including the tectonic settings where subduction initiation begins and how magmatism responds. The Cretaceous Mawgyi Volcanics represent the earliest volcanic succession in the Wuntho-Popa arc of western Myanmar. This volcanic unit consists of an exceptionally diverse range of contemporaneously magmatic compositions which are spatially juxtaposed. Our new geochemical data show that the Mawgyi Volcanics comprise massive mid-oceanic ridge basalt (MORB)-like lavas and dikes, and subordinate island arc tholeiite and calc-alkaline lavas. The Mawgyi MORB-like rocks exhibit flat rare earth elements (REEs) patterns and are depleted in REEs, high field strength elements (except for Th) and TiO2 concentrations relative to those of MORBs, resembling the Izu-Bonin-Mariana protoarc basalts. Our geochronological results indicate that the Mawgyi Volcanics formed between 105 and 93 Ma, coincident with formation of many Neotethyan supra-subduction zone ophiolites and intraoceanic arcs along orogenic strike in the eastern Mediterranean, Middle East, Pakistan, and Southeast Asia. Combined with its near-equatorial paleo-latitudes constrained by previous paleomagnetic data, the Wuntho-Popa arc is interpreted as a segment of the north-dipping trans-Neotethyan subduction system during the mid-Cretaceous. Importantly, our restoration with available data provides new evidence supporting the hypothesis of a mid-Cretaceous initiation of this >8000-km-long subduction system formed by inversion of the ∼E-W–trending Neotethyan oceanic spreading ridges, and that this was contemporaneous with the final breakup of Gondwana and an abrupt global plate reorganization.

New results on the study of the geochemical and Sr–Nd isotopic compositions of effusive and explosive rocks of the Oxfordian–Kimmeridgian Kulpolnei complex and dikes intruding this complex, located in the northwestern part of the South Anyui suture are presented. It is established that effusive and explosive rocks were formed within an intraoceanic convergent boundary (back-arc basin and/or island arc). The volcanics of the Kulpolnei complex are intruded by diorite and plagiogranite dikes, which are deformed together with the host rocks. The concordant U–Th–Pb (SIMS) ages of zircons from dikes are 143 ± 1 to 140 ± 1 Ma. The similarity between the geochemical compositions of volcanics and dikes suggests these units had formed in the same geodynamic setting. If this assumption is correct, the upper age limit of suprasubduction volcanism can be considered to be significantly younger, up until the Berriasian age.

We present geophysical and remote sensing measurements on a flood dike, in the framework of the Polder2C’s Interreg European Project (https://polder2cs.eu/). Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) profiles have been performed alongside and across the dike. The geophysical measurements are then combined with a Digital Terrain Model (DTM) caarried out with a RGB visible camera on board an Unmanned Aerial Vehicle (UAV). Integrated 3D results enrich data interpretation and form the basis for Polder2C’s future experiments.

Manglaralto parish communities are supplied with drinking water extracted from shallow aquifers (associated with alluvial terraces) recharged by seasonal rivers. The companies responsible for extracting and distributing water are the Manglaralto Regional Drinking Water Administration Board (JAAPMAN, for its acronym in Spanish) and Olon Regional Board of Drinking Water (JRAPO, for its acronym in Spanish). However, due to population growth and tourism (floating population) of Manglaralto parish, water demand has increased. This has meant that, during the dry season, the water stored in these underground reservoirs is not enough to meet the growing demand. The case study presented is that of the Manglaralto community. The aim is to design, in a technical way, an artisanal dyke (tape) by performing geological-geotechnical studies that allow optimal surface storage and artificial recharge of aquifers for the provision of water to communities. The methodology is as follows: i) Analysis of the technical starting information, ii) Recognition of the study site and the choice of sampling sites, iii) Conducting laboratory tests and analysis of information obtained in the field, and iv) Technical design of the tape. According to laboratory results and the field data analysis, the design of a spillway dyke equipped with a dentellon was defined, which acts as a screen to block the subsurface flow. The rescue of ancestral knowledge, used as a solution to current problems in this coastal community, allows storing a volume of 4,641.88 m3 and an artificial recharge of 15%, with low costs and great social acceptance.

The location of the West African craton (WAC) has been poorly constrained in the Paleoproterozoic–Mesoproterozoic supercontinent Nuna (also known as Columbia). Previous Nuna reconstruction models suggested that the WAC was connected to Amazonia in a way similar to their relative position in Gondwana. By an integrated paleomagnetic and geochronological study of the Proterozoic mafic dikes in the Anti-Atlas Belt, Morocco, we provide two reliable paleomagnetic poles to test this connection. Incorporating our new poles with quality-filtered poles from the neighboring cratons of the WAC, we propose an inverted WAC-Amazonia connection, with the northern WAC attached to northeastern Amazonia, as well as a refined configuration of Nuna. Global large igneous province records also conform to our new reconstruction. The inverted WAC-Amazonia connection suggests a substantial change in their relative orientation from Nuna to Gondwana, providing an additional example of large-magnitude cumulative azimuthal rotations between adjacent continental blocks over supercontinental cycles.

Matured continental rift zones that imprint the complete cycle of rifting are rare deformation environments in the globe. The western Afar margin is one that shows such a complete process. This research is aimed to understand the development of the lower part of the western Afar margin and determine the nature of transfer zones that host the mega dike injections, the elliptical scoria cones, and rhyolitic domes around Gulina area. To do so, structural analyses were conducted using intensive field measurements, Landsat ETM+, and SPOT imageries, and digital elevation models (DEM) data to comprehend chronologically distinct structures and magmatic series. The result shows that marginal structures are represented by older rift bounding NNW-SSE trending faults and younger NE-SW oriented transverse structures. Mode of emplacement of these two structurally and chronologically distinct structures are found associated with the evolution of the marginal magmatic series. The study has also investigated NE-SW trending offset faults and NE-SW striking transversal structures. Moreover, this work shows that the marginal structures are inactive but the younger structures (mega dikes and scoria cones are active and controlled by regional transversal structures that separate the Erta’Ale range and Tendaho-MandaHararo rift segment). From the recognition of the cross-cutting relationship, the marginal faults are identified as firstgeneration fractures, whereas the deformed domical silicified rhyolite outcrops situated in the marginal areas are classified under the second generation. The preserved rhyolite dome in the rift floor, the scoria cones, rift floor fractures, and dikes are found to be third-generation structures.

The article presents the first U-Pb (SHRIMP–II) zircon age data on dikes cutting dunite of the Kamenushinsky dunite–clinopyroxenite–gabbroic massif in the Ural Platinum Belt. The dikes are made up of gabbro-pegmatite, hornblendite, and granite, the field relations between which suggest their subsequent intrusion in the dunites. Their geochemical features show that they belong to two different magmatic series. The gabbro–pegmatite is the derivatives of the dunite–clinopyroxenite–gabbro series, while hornblendites are the derivatives of the gabbro series. At the same time, the granite corresponds to anatectic granites developed within the Platinum Belt. U-Pb zircon dating of the gabbro yielded an age of 418.3 ± 4.5 Ma, which can be considered as the upper age limit of the dunite–clinopyroxenite–gabbro series. The age of the hornblendite of 421.0 ± 2.4 Ma is close to the age of the majority of the gabbroic rocks of the Ural Platinum Belt. The U-Pb zircon dating of the granite yielded a relatively young age of 384.9 ± 0.5 Ma. This testifies the continuation of the intrusive magmatic activity within the Ural Platinum Belt after the formation of the youngest volcanic rocks of the Tagil volcanic arc, the gabbro–diorite–granite intrusions of the Auerbakh Complex, and significantly expands the time range of magmatism associated with partial melting of the gabbro protolith directly within the belt.

––A dike of rock similar in composition to carbonatites has been found in the Aikhal diamondiferous pipe of the Alakit–Markha field of the Yakutian kimberlite province (YaKP). The fine-grained rock of essentially carbonate composition (dolomite and calcite) rich in thin-platy phlogopite contains minerals typical of carbonatites: monazite, baddeleyite, and pyrochlore. In the high contents and distribution of incompatible elements the rock differs significantly from kimberlites and is transitional from kimberlites to carbonatites. The content of incompatible elements in this rock is 3–5 times lower than that in carbonatite breccias of the pipes in the Staraya Rechka kimberlite field of the YaKP (Nomokhtookh site). The compositions of accessory trace element minerals from the Aikhal dike rock and the Nomokhtookh carbonatite breccias are compared. An assumption is made that the high contents of incompatible elements in the carbonatite-like rock, which caused the crystallization of accessory minerals, are due to the differentiation of kimberlite melt/fluid. The high Sr isotope ratios indicate that the rock altered during hydrothermal and metasomatic processes. The obtained data on the composition of the carbonatite-like rock cannot serve as an argument for the genetic relationship between the Aikhal kimberlites and typical carbonatites. The genetic relationship between kimberlites and carbonatites in the northern fields of the YaKP remains an open issue.

The role of water on melting in the mantle wedge is still debated due to large uncertainty on the estimates of H2O flux beneath arcs. B has been proven as an effective proxy for water flux because B and H2O show similar chemical behaviors during subduction. The Habahe mafic dikes from the Chinese Altai were emplaced within a narrow area (

Aim: This study was conducted to provide data on weed species composition and biodiversity indexes at different rice crops inside and outside of the dike system in An Giang province, Vietnam. Methodology: Weeds were collected from paddy rice of inner and outer side of dike system from six districts of An Giang province, Vietnam. From each sampling sites, two quadrats with 100 m2 (10 m × 10 m) per quadrat were selected to collect weed after 75-80 days of rice planting. Weeds were collected and identified for their scientific name, and the number of each species was defined, followed by calculation of the occurrence frequency and density of samples. Biodiversity indices viz. Shannon-Weaver (H’), Simpson (1- λ), Margalef (d), and similarity index were also studied among three crops and two sides of dike system. Results: The weed composition in the paddy rice in An Giang was diversity with 137 species. Among them, the most species belonged to families Poaceae, Cyperaceae, and Compositae. The species composition of Crop 3 was the highest one. Species occurrence frequency and weed density of groups C, D, E reached the highest value in Crop 1, followed by Crop 2 and 3. The biodiversity indices of weed species composition in the studied sites were high, reaching the highest value in Crop 3. Interpretation: The results of this study enhance the knowledge of weed species composition and biodiversity indexes to effectively manage and control weeds in rice cultivation.

Dikes of primitive olivine melilitites and monchiquites intruded into an Oligocene (Rupelian) potash salt deposit near Buggingen (SW Germany). Ocelli and amygdules reveal distinct mineral assemblages depending on whether the dike rocks are in direct contact with the potash layer or with bituminous shales (Fish Shale). Samples in contact with the potash salt layer show roundish textures that contain smectite ± talc ± chlorite, calcite, and in cases anhydrite and halite, while those close to the bituminous shale mainly comprise smectite, calcite, zeolite group minerals, and analcime. No textural or mineralogical evidence for high-temperature (magmatic) interaction between the dike rocks and the evaporites was observed. This is presumably related to (1) a very low magmatic water activity in the magma, which prevented exsolution of aqueous fluids and appreciable dissolution of the salt, and (2) fast cooling of the magmas, inhibiting melting of the salt deposits and potential liquid mingling and/or assimilation processes. Halite formation in the dike rocks is, rather, related to later, post-magmatic hydrothermal fluids that previously interacted with the salt-rich host rocks. Alteration of the initially glassy groundmass to smectites and zeolites caused an enrichment of Na in the residual fluid, but halite saturation was not attained, as indicated by the absence of groundmass halite. Only fluid–rock interaction in millimeter-sized vugs caused halite precipitation via desiccation by swelling of previously formed clay minerals. Locally, the boron silicate datolite formed in pseudomorphs after olivine. Its precipitation was controlled by the Si and B supply provided by the breakdown of serpentine and smectite.

The relationship among the orebody, volcanic rocks, and a rhyolite dike in the large epithermal Kupol deposit (Western Chukotka) is considered. Almost throughout its entire length (more than 3000 m), the orebody of the deposit is intersected by rhyolite dikes. In the studied profiles in the mine excavations at the horizons 425, 455, 470, 515 m, a rhyolite dike clearly intersects and bisects the orebody, which is a 20-m-thick dominantly quartz vein with some adularia. The rhyolite has a porphyritic structure. The groundmass is devitrified with the formation of an aphanite quartz-feldspar aggregate with a mosaic microstructure. Some patches are fluidized. The rhyolites contain from 72.96 to 74.97 wt % SiO2, and the composition corresponds to biotite granites of the low-alkaline series. The following criteria have been identified to indicate the post-mineralization age of the dike: a clear intersection of a thick ore vein by the dike; vitrification of the dyke material at the contact with the vein; rhyolite cementing the crushed quartz vein material; the emergence of some small tongues from the dike that penetrate the quartz vein; xenoliths of quartz vein material in the dike body; the orebody tongues do not penetrate the dike; increased concentration of vein and ore minerals on the contact surface of the dike or in cracks of the endocontact zone. The formation of obsidian (vitrophyre) in rhyolite at contact with the orebody indicates that the dike was emplaced in a cold system. Preservation of the productive vein thickness, its morphological features, and the Au and Ag contents at the cabs of the rhyolite dike; identical textures and repeated rhythms in the areas of rhythmic-banded layering in the vein on both sides of the dike shows that in the Kupol deposit, post-mineralization dikes do not replace or impoverish the productive vein system, which is probably due to their dilatation nature and the infilling of separation cracks.

Research subject. The gold-sulphide-quartz deposits of Central Chile are typical prospecting objects, having small ore intervals (from the first tens of centimetres to 1 m), intermittent and nested ore distribution and extremely uneven gold contents.Materials and methods. The patterns of ore mineralization distribution are considered against the background of the results of modern geophysical studies of the lithosphere: the Moho surface, density and thermal regime of the upper mantle. Detailed studies were conducted on the Yapin ore field.Results. It was shown that the faults controlling gold-sulphidequartz mineralization are derivatives of shear tectonics under the conditions of a transpression regime along the Chilean active margin. At an early stage, these faults developed in a right-shift environment, which was accompanied by the introduction of diabase dikes into the northeastern faults, and gold-sulfide-quartz mineralization superimposed on the dikes was deposited during the left-shift stage. The geological structure of the deposits in the ore field Yapin was characterized. It was shown that a diverse mineralization is developed in the ore field - copper-porphyry, IOCG-type and gold-sulphide-quartz. According to geochemical data, the latter is characterized by a clear enrichment of chalcophilic elements (Au, As, Ag, Cd, Cu, Bi, Pb, Zn, Te, Co). The marked enrichment of Bi, Te and Co ores indicates the participation of magmatic fluid in ore formation and the similarity of the mineralization of the Escondida deposit with the type of gold deposits associated with granitoid intrusions. According to geochemical features, gold-sulphide-quartz mineralization in the general zoning pattern occupies a boundary position between IOCG-type objects and copper-porphyry deposits.Conclusions. The conclusion is drawn about the independence of gold-sulphide-quartz mineralization and its difference from epithermal gold deposits. It is noted that, in the volcanic belts of the North-East of Russia, the prospects for discovering unconventional gold-sulphidequartz deposits similar to those of Central Chile are rather real.

We collected drone data to quantify the kinematics at extensional fractures and normal faults, integrated this information with seismological data to reconstruct the stress field, and critically compared the results with previous fieldwork to assess the best practice. As a key site, we analyzed a sector of the northeast rift of Mt Etna, an area affected by continuous ground deformation linked to gravity sliding of the volcano's eastern flank and dike injections. The studied sector is characterized also by the existence of eruptive craters and fissures and lava flows. This work shows that this rift segment is affected by a series of NNE- to NE-striking, parallel extensional fractures characterized by an opening mode along an average N105.7∘ vector. The stress field is characterized by a σHmin trending northwest–southeast. Normal faults strike parallel to the extensional fractures. The extensional strain obtained by cumulating the net offset at extensional fractures with the fault heave gives a stretching ratio of 1.003 in the northeastern part of the study area and 1.005 in the southwestern part. Given a maximum age of 1614 CE for the offset lavas, we obtained an extension rate of 1.9 cm yr−1 for the last 406 years. This value is consistent with the slip along the Pernicana Fault system, confirming that the NE rift structures accommodate the sliding of the eastern flank of the volcano.

The Dahongliutan rare-metal pegmatite deposit, associated with the pegmatite dikes hosted by Dahongliutan pluton and metasedimentary rocks, is a new discovered Li–Be deposit in the the West Kunlun ...

The widespread W-(Mo)-Sn-Nb-Ta polymetallic mineralization in Southeast (SE) China is genetically associated with Mesozoic highly fractionated granitic rocks. Such rocks have enigmatic mineralogical and geochemical features, making its petrogenesis an intensely debated topic. To better understand the underlying magma evolution processes, petrography, garnet chemistry and whole-rock major and trace element data are reported for Jurassic highly fractionated granitic rocks and associated microgranite and aplitepegmatite dikes from Macao and compared with coeval similar granitic rocks from nearby areas in SE China. Despite the fact that the most evolved rocks in Macao are garnet-bearing aplite-pegmatite dikes, the existence of coeval two-mica and garnet-bearing biotite and muscovite granites displaying more evolved compositions (e.g, lower Zr/Hf ratios) indicates that the differentiation sequence reached higher degrees of fractionation at a regional scale. Although crystal fractionation played an important role, late-stage fluid/melt interactions, involving F-rich fluids, imparted specific geochemical characteristics to Macao and SE China highly fractionated granitic rocks such as the non-CHARAC (CHArge-and-RAdius-Controlled) behavior of trace elements, leading, for example, to non-chondritic Zr/Hf ratios, Rare Earth Elements (REE) tetrad effects and Nb-Ta enrichment and fractionation. Such process contributed to the late-stage crystallization of accessory phases only found in these highly evolved facies. Among the latter, two populations of garnet were identified in MGI (Macao Group I) highly fractionated granitic rocks: small grossular-poor euhedral grains and large grossular-rich skeletal garnet grains with quartz inclusions. The first group was mainly formed through precipitation from highly evolved Mn-rich slightly peraluminous melts under low-pressure and relatively low temperature (∼700 °C) conditions. Assimilation of upper crust metasedimentary materials may have contributed as a source of Mn and Al to the formation of garnet. The second group has a metasomatic origin related to the interaction of magmatic fluids with previously crystallized mineral phases and, possibly, with assimilated metasedimentary enclaves or surrounding metasedimentary strata. The highly fractionated granitic rocks in Macao represent the first stage in the development of granite-related W-(Mo)-Sn-Nb-Ta mineralization associated with coeval more evolved lithotypes in SE China.

Heavy rain and river flooding due to Typhoon No. 19 in October 2019 led to overflow and a dike breach on the left bank of the Chikuma River that caused large-scale inundation damage in Nagano City, Japan. To devise countermeasures, an inundation analysis model is an important tool. In this study, an inundation analysis model was developed to examine the inundation water behavior. The calculated inundation water depth and inundation area showed good agreement with the observed inundation water depth and the inundated area, confirming the validity of the analysis model. In addition, temporal changes of the inundation state were calculated considering the drainage process. However, the sewerage system, waterway, and drainage pump car were not taken into consideration in this analysis, and future issues for model improvement were also revealed. In addition, an analysis model with a 2 m grid was developed in the dike breach site, and the inundation water flow on roads and the fluid force around houses were obtained after taking into consideration the effect of houses. In paticular, the calculated value of the specific force exerted on damaged houses was very high. Moreover, it was proposed that house hazard should be evaluated while taking into consideration the loss of houses around the dike.

Maar volcanoes are produced by subsurface phreatomagmatic explosions that can move vertically and laterally during an eruption. Constraining the distances that maar-forming explosions move laterally, and the number of relocations common to these eruptions, is vital for informing hazard scenarios and numerical simulations. This study uses 241 intact Quaternary maar crater shapes to establish global trends in size and spacing of explosion position relocations. Maar craters are sorted into shape classes based on the presence of uniquely identifiable combinations of overlapping circular components in their geometry. These components are used to recognize the minimum number of explosion locations responsible for observed crater shapes. Craters with unique solutions are then used to measure the size and spacing of the explosion footprints, the circular area of the largest crater produced by a single explosion of a given energy, that produce the crater shape. Thus, even in the absence of abundant observations of maar-type eruptions, the typical range, size and spacing of explosion positions are derived from maar crater shapes. This analysis indicates that most Quaternary maar eruptions involved at least three different explosion locations spanning distances of 200–600 m that did not always follow the trend of the dike feeding the eruption. Additional evaluation of larger maars, consistent with stratigraphic studies, indicates that centers of explosive activity, and thus the origin of ballistic and density current hazards, can move as many as twenty times during a maar-forming eruption. These results provide the first quantitative constraints on the scale and frequency of lateral migration in maar eruptions and these values can directly contribute to hazard models and eruption event trees in advance of future maar-type eruptions.

Pegmatite dikes in the Malayer–Boroujerd–Shazand magmatic complex, located in the Sanandaj-Sirjan zone of the Zagros orogen, are hosted in both granitoid rocks and their contact and regional metamorphic aureoles. In this study, we report the geochronology, geochemistry and mineral chemistry of these pegmatite dikes. The granitoid rocks in the Malayer–Boroujerd–Shazand magmatic suites are mainly monzogranite, quartz diorite, granodiorite and quartz monzonite characterized by metaluminous to peraluminous I-type compositions of the calc-alkaline series and display the geochemical characteristics of volcanic arc granites related to an active continental margin. The pegmatite dikes mainly consist of quartz, feldspar (albite and orthoclase), tourmaline, muscovite and less common biotite and garnet. The tourmaline content in the igneous-hosted pegmatite dikes is higher than those of metamorphic rocks, whereas the muscovite content is lower in the igneous-hosted pegmatite dikes. The K/Rb ratio and the Rb content of pegmatite dikes and their minerals (K-feldspar and muscovite) indicate that they are less evolved. Pegmatite dikes display a typical calc-alkaline affinity of I-type granites and are classified as peraluminous Lithium-Caesium-Tantalum (LCT) family (barren sub-type) to muscovite class. The tourmaline is a schorl-foitite type, which is common in the early crystallization stage of less evolved pegmatites. U–Pb zircon dating of the Boroujerd and Shazand pegmatite dikes yield weighted mean 206Pb/238U ages of 160.2 ± 1.8 and 121.8 ± 1.5 Ma, respectively. In contrast, U–Pb zircon dating of the Malayer pegmatite dike gives a mean 206Pb/238U age of 43.2 ± 1.5 Ma. Our new geochronological data indicate that the first group of pegmatite dikes (older pegmatite dikes) in the Boroujerd district (160.2 ± 1.8 Ma) shows an overlap with the main and first magmatic episode in the Sanandaj–Sirjan zone during Jurassic times, simultaneous with the Middle Cimmerian Orogenic phase, and formed during the subduction initiation. The second group of pegmatite dikes in the Shazand district (121.8 ± 1.5 Ma) formed in the Early Cretaceous and shows a temporal overlap with previously reported ages (ca. 130–114 Ma) during the early Alpine tectonic movements (Late Cimmerian Orogenic phase). Finally, the younger group of pegmatite dikes in the Malayer district (43.2 ± 1.5 Ma) formed in the Eocene overlapping with previously reported ages (ca. 34–52 Ma) which is equivalent to the Laramian phase. These data reveal that the magmatism in the Malayer–Boroujerd–Shazand magmatic complex started in the Early-Middle Jurassic resembling adjacent areas in the Sanandaj–Sirjan zone (e.g., Hamedan region) by melting of crustal protoliths in a subduction tectonic setting. The second and third groups of pegmatite dikes formed during the late subduction to syn-collisional process, respectively. These pegmatite generation marked the subduction initiation to syn-collisional span in the region. The zircon geochemistry (negative Ce anomalies and positive Eu anomalies) is indicative of the relatively oxidized conditions of the parent magma and shows characteristics of continental crust zircon.

The natural radioactivity data revealed that eU reached up to 157.4, 1625 and 178 ppm in microgranite and dolerite dikes as well as japer vein, respectively, whereas the two-mica granite possesses ...

The Early Cretaceous New England-Quebec igneous province is a classic example of postrift magmatism along the eastern North American passive margin. Although a suite of 40Ar/39Ar ages has been available for the Monteregian Hills lobe in the Quebec portion of the New England-Quebec igneous province for many years, only a single high accuracy radiometric age has been published for the Burlington lobe and none for the Taconic lobe in the New England portion of the province. As a result, the timing of and driving mechanisms behind the magmatism have remained unresolved, and a hotspot origin for the entire province persists in the literature. We have dated four dikes and one pluton in the Burlington and Taconic lobes using 40Ar/39Ar and U–Pb geochronology to improve understanding of the age of magmatism in the New England portion of the province. In the Burlington lobe, 40Ar/39Ar plateau ages include a 137.55 ± 1.80 Ma biotite age and a 136.9 ± 4.2 Ma amphibole age for a lamprophyre dike from Charlotte, Vermont, and a 133.6 ± 2.2 Ma biotite age for a lamprophyre dike from Colchester, Vermont. In the Taconic lobe, ages include an 40Ar/39Ar plateau amphibole age of 107.09 ± 1.32 Ma for a lamprophyre dike from Castleton, Vermont, a 122 Ma minimum 40Ar/39Ar biotite age for a lamprophyre dike from Poultney, Vermont, and a 103.13 ± 0.53 Ma LA-ICP-MS U–Pb zircon age from the quartz syenite of the Cuttingsville complex. These results show that magmatism spanned at least 35 Ma, from ∼138 to 103 Ma, which is broadly consistent with the span of magmatism suggested by workers in the 1970s and 1980s based on K–Ar and Rb–Sr ages. This extended span of magmatism for the Burlington and Taconic lobes is in contrast to the brief 1 to 2 Ma episode of magmatism at ∼124 Ma inferred for the Monteregian Hills lobe. The New England-Quebec igneous province has traditionally been attributed to passage of the Great Meteor hotspot. However, given the close proximity of the Burlington and Taconic lobes, the magmatism in these lobes should span only a few Ma if the product of a hotspot. The age data are also difficult to reconcile with a more complex expression of hotspot magmatism in continental lithosphere related to either plume head magmatism or long-distance migration of plume material. Instead, the extended duration of Early Cretaceous New England-Quebec igneous province magmatism in New England may represent an expression of edge-driven convection, a process known to occur along passive margins and inferred to be operating beneath the eastern North American margin today.

This publication offers an overview of the latest cross-disciplinary developments in the field of Building with Nature (BwN) for the protection of coastal regions. The key philosophy of BwN is the employment of natural processes to serve societal goals, such as flood safety. The starting point is a systems-based approach, making interventions that employ the shaping forces of the natural system to perform measures by self-regulation. Initial pilots of this innovative approach originate from coastal engineering, with the Sand Motor along the coast of South Holland as one of the prime examples. From here, the BwN approach has evolved into a new generation of nature-based hydraulic solutions, such as mangrove forests, coastal reefs, and green dikes.

Internal erosion is one of the main causes of dike failures. Their failure mechanism is related to the physical characteristics (distribution of particle size, permeability characteristics, clay co...

Coastal reclamation projects have been extensively constructed along the coastline of the East China Sea over the past decades. To investigate the impact of reclamations on the Rui’an coastal zone, regional tidal and sediment dynamics were studied by combining field data and numerical modeling. Field data of tidal elevation and currents, suspended sediment concentration (SSC), and bottom erosion were obtained during both spring and neap tides from 2014 to 2019. Data analysis suggested that the reclamation and construction of the dike reduced the currents in the tidal flat and subsequently reduced the SSC values. The sediment was mainly deposited in the tidal flat after construction. The largest annual deposition rate was approximately 1 m, occurring in the southern part near the dike, while the deposition rate was only 0.08 m/a in the middle part of the tidal flat. In addition, the results of the numerical experiment proved that the reclamation and dike construction contributed to the variations in currents and SSC, thus altering the deposition in the tidal flat. It is suggested that the construction of coastal works and social facilities in macro-turbid coastal zones, such as the Rui’an coast, require the evaluation of possible impact on sediment dynamics.

The paper presents isotope–geochronological data on zircons from a granite–aplite dike that cuts garnet–hypersthene gneisses of the Kuzeyev unit of the Neoarchean–Paleoproterozoic Kan Group in the southern extension of the Ishimba–Tatarka regional shear zone, Kan River. The morphology and internal structure of most of the zircon grains indicate that the zircons are metamorphic and xenogenic and were captured by the acidic magma from the host rocks when the magma intruded the granulites. Based on these data, the obtained Paleoproterozoic U–Pb age of 1784 ± 6 Ma can be interpreted as the age of granulite metamorphism. The interpretation of available geological and isotopic data confirms a postcollisional age of the aplite, which was emplaced nearly synchronously with the formation of anorogenic leucogranites of the late phase of the Tarak complex, during the final stage of the formation of the Nuna supercontinent.

The Qingchengzi orefield is an important Pb-Zn-Au-Ag polymetallic orefield in NE China. The Indosinian magmatism has formed the Shuangdinggou batholith and the Xinling stock, as well as dikes of quartz monzonite porphyry and lamprophyre. According to petrographic characteristics, the Shuangdinggou intrusion can be divided into the main suite and the central suite. Zircon U-Pb dating yielded crystallization ages of 215.0–220.9 Ma for these various Qingchengzi magmatic units, which are within analytical error and represent coeval magmatism. The Shuangdinggou main suite contains abundant mafic microgranular enclaves (MMEs) and shows features of magma mixing. Geochemically, the major oxide contents of the MMEs and their quartz monzonite host show well-defined linear fractionation trends. The REE and trace element patterns of the MMEs and their host are similar, which demonstrates certain degree of geochemical homogenization between the two during magma mixing. The Shuangdinggou main suite shares similar geochemical characteristics with typical high Ba-Sr granites (Ba=1 082 ppm–2 051 ppm, Sr=803 ppm-886 ppm), and was likely originated from the mixing between a melt derived from partial melting of the thickened lower crust and the enriched mantle. The central suite was likely formed by fractional crystallization of the main-suite magma. The Xinling intrusion may represent a branch of the Shuangdinggou intrusion and has the same genesis as the central suite. The quartz monzonite porphyries geochemically mimic the Shuangdinggou main suite, and may also be an epioic facies of the Shuangdinggou intrusion. The MMEs and lamprophyres may have been derived from incomplete magma mixing. Formation of the Pb-Zn and Au-Ag deposits in the Qingchengzi orefield may have been related to the granite/quartz monzonite porphyries near the Shuangdinggou intrusion, which were formed by magma mixing and fractional crystallization.

For large rivers with a compound cross section, the downstream channel has a very wide water surface during the flood season. A wide water surface, high water level, and larger wind speed will cause higher waves, increasing the threat of flooding to the dike. The design of a combined-vegetation wave break forest was put forward to achieve better wave attenuation effect. The main idea of this concept is to plant different types of vegetation at different locations in front of the dike. Three single-vegetation and four combined-vegetation forest schemes were tested under seven different water depth conditions. Both physical experiments and wave numerical simulations were carried out for each scheme to study the wave attenuation effect. The results showed that the wave attenuation effect of the single-vegetation wave break forest was significantly different under different water depth conditions, and the overall effect of the combined-vegetation of wave forest was better. Combined-vegetation wave break forests combine the advantages of different types of vegetation in different water levels, which makes it more economical and reasonable to plant by rivers with large water level variation. The proposed design ideas and methods could provide theoretical support for ecological revetment engineering of large rivers and insights for practical applications.

In this study, numerical simulations were performed to investigate the flow and turbulence characteristics of rectangular spur dikes with varying permeability using the Reynolds stress turbulence model developed by three-dimensional (3-D) numerical code FLUENT (ANSYS). In this research, both permeable and impermeable spur dikes were investigated with varying permeability (25%, 37%, 49%, 62%, and 74%) to show its effect on the flow structure. At zh=3.5 cm (where z is the maximum flow depth, and zh is mid of flow depth), 3-D flow velocities and depth-averaged velocities were measured in the horizontal plane. Different velocity profiles and contours, turbulent intensities (T.I), and turbulent kinetic energy (TKE) were analyzed at various selected positions. The findings indicate that an increase in the permeability of the spur dikes up to 74% had a reciprocal effect on the mean stream-wise velocity. Moreover, the recirculation regions created within the impermeable spur dike field decreased with increased permeability of spur dikes. The permeable spur dike head showed a significant decrease in T.I, and TKE compared to the impermeable spur dike. Therefore, to protect the spur dike head from severe turbulent flow during floods and reduce the spur dike field’s recirculation region, a permeable spur dike is preferred.