Evidence of sea level drawdown at the end of the Messinian salinity crisis and seismic investigation of the Nahr Menashe unit in the northern Levant Basin,offshore Lebanon     

Kyrre Heldal Kartveit  Heidrun Breiset Ulsund  Stle Emil Johansen 《Basin Research》2019,31(5):827-840

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Coastal Ocean Forecasting Science supported by GODAE OceanView Coastal Oceans and Shelf Seas Task Team (COSS-TT)—Part II     

Cirano  Mauro  Charria  Guillaume  De Mey-Frémaux  Pierre  Kourafalou  Vassiliki H.  Stanev  Emil 《Ocean Dynamics》2021,71(6-7):779-783

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Tidal and wind-driven surface currents in the German Bight: HFR observations versus model simulations     

Alexander Port  Klaus-Werner Gurgel  Joanna Staneva  Johannes Schulz-Stellenfleth  Emil V. Stanev 《Ocean Dynamics》2011,61(10):1567-1585

Tidal and wind-driven surface currents in the German Bight between shallow mudflats of the North Frisian islands and the island of Helgoland are studied using coastal high-frequency radar (HFR) observations and hindcasts from a primitive equation numerical model. The setup of the observational system is described, and estimates of expected measurement errors are given. A quantitative comparison of numerical model results and observations is performed. The dominant tidal components are extracted from the two data sources using tidal harmonic analysis and the corresponding tidal ellipses are defined. Results show that the spatial patterns of different tidal ellipse parameters are consistent in the two data sets. Model sensitivity studies with constant and variable salinity and temperature distributions are used to study density-related mechanisms of circulation. Furthermore, the role of the surface wind field in driving the German Bight circulation is investigated using the complex correlation between wind and surface current vectors. The observed change of the respective correlation patterns from the coastal to open ocean is shown to be due to a combination of density effects, the coastline and topography. The overall conclusion is that HFR observations resolve the small-scale and rapidly evolving characteristics of coastal currents well in the studied area and could present an important component for regional operational oceanography when combined with numerical modelling. Some unresolved issues associated with the complex circulation and large instability of circulation in front of the Elbe River Estuary justify further considerations of this area using dedicated surveys and modelling efforts.  相似文献   

Plio-Pleistocene basanitic and melilititic series of the Bohemian Massif: K-Ar ages,major/trace element and Sr–Nd isotopic data     

Jaromír Ulrych  Lukáš Ackerman  Kadosa Balogh  Ernst Hegner  Emil Jelínek  Zoltan Pécskay  Antonín Přichystal  Brian G.J. Upton  Jiří Zimák  Radana Foltýnová 《Chemie der Erde / Geochemistry》2013

The Plio-Pleistocene volcanic rocks of the Bohemian Massif comprise a compositional spectrum involving two series: an older basanitic series (6.0–0.8 Ma) and a younger, melilititic series (1.0–0.26 Ma). The former consists of relatively undifferentiated basaltic rocks, slightly silica-undersaturated, with Mg# ranging from 62 to almost primitive mantle-type values of 74. The major and trace element characteristics correspond to those of primitive intra-plate alkaline volcanic rocks from a common sub-lithospheric mantle source (European Asthenospheric Reservoir – EAR) including positive Nb, and negative K and Pb anomalies. ⁸⁷Sr/⁸⁶Sr ratios of 0.7032–0.7034 and ¹⁴³Nd/¹⁴⁴Nd of 0.51285–0.51288 indicate a moderately depleted mantle source as for other mafic rocks of the central European volcanic province with signs of HIMU-like characteristics commonly attributed to recycling of subducted oceanic crust in the upper mantle during the Variscan orogeny. The melilititic series is characterized by higher degrees of silica-undersaturation, and high Mg# of 68–72 values, compatible with primitive-mantle-derived compositions. The high OIB-like Ce/Pb (19–47) and Nb/U (32–53) ratios indicate that assimilation of crustal material was negligible. In both series, concentrations of incompatible elements are mildly elevated and ⁸⁷Sr/⁸⁶Sr ratios (0.7034–0.7036) and ¹⁴³Nd/¹⁴⁴Nd ratios (0.51285–0.51288) overlap. Variations in incompatible element concentrations and isotopic compositions in the basanitic series and melilititic series can be explained by a lower degree of mantle melting for the latter with preferential melting of enriched mantle domains. The Sr and Nd isotopic compositions of both rock series are similar to those of the EAR. Minor differences in geochemical characteristics between the two series may be attributed to: (i) to different settings with respect to crust and lithospheric mantle conditions in (a) Western Bohemia (WB) and (b) Northeastern Bohemia (NEB) and the Northern Moravia and Silesia (NMS) areas, (ii) a modally metasomatized mantle lithosphere in WB in contrast to cryptically metasomatized domains in the NEB and NMS, (iii) different degrees of partial melting with very low degrees in WB but higher degrees in NEB and NMS. The geochemical and isotopic similarity between the Plio-Pleistocene volcanic rocks and those of the late Cretaceous and Cenozoic (79–6 Ma) suggests that their magmas came from compositionally similar mantle sources, that underwent low degrees of melting over an interval of ∼80 Ma. The Oligocene to Miocene basanitic series that accompanied the Plio-Pleistoicene basanitic series in the NMS region indicate that they shared a common mantle source. There is no geochemical evidence for thermal erosion of the lithospheric mantle or significant changes in mantle compositions within the time of a weak thermal perturbation in the asthenospheric mantle. These perturbations were caused by a dispersed mantle plume or passively upwelling asthenosphere in zones of lithospheric thinning.  相似文献   

Discrete fracture model for simulating waterflooding processes under fracturing conditions          下载免费PDF全文

Emil Gallyamov  Timur Garipov  Denis Voskov  Paul Van den Hoek 《国际地质力学数值与分析法杂志》2018,42(13):1445-1470

In our study, we develop a model for simulating fracturing processes in a poroelastic medium. The proposed approach combines the discrete fracture model enriched with contact plane mechanics. The model captures mechanical interactions of fractures and a deformable medium, fluid, and heat transfer in fractures and in a porous medium. Both effects of poroelasticity and thermoelasticity are accounted in our model. Mass and heat conservation equations are approximated by the finite volume method, and mechanical equilibrium equations are discretized by means of the Galerkin finite element approach. Two‐dimensional grid facets between 3‐dimensional finite elements are considered as possible fracture surfaces. Most of these facets are inactive from the beginning and are activated throughout the simulation. A fracture propagation criterion, based on Irwin's approach, is verified on each nonlinear iteration. When the criterion is satisfied, additional contact elements are added into finite element and discrete fracture model formulations respectively. The proposed approach allows modeling of existing natural and artificially created fractures within one framework. The model is tested on single‐ and multiple‐phase fluid flow examples for both isothermal and thermal conditions and verified against existing semianalytical solutions. The applicability of the approach is demonstrated on an example of practical interests where a sector model of an oil reservoir is simulated with different injection and production regimes.  相似文献   

Tidal wave transformations in the German Bight   总被引：2，自引：2，他引：0  

Emil V. Stanev  Rahma Al-Nadhairi  Joanna Staneva  Johannes Schulz-Stellenfleth  Arnoldo Valle-Levinson 《Ocean Dynamics》2014,64(7):951-968

Mesoscale and submesoscale dynamics associated with tidal wave transformations were addressed in the German Bight using numerical simulations. Tidal gauge and velocity observations in several locations were used to validate the numerical model. A downscaling approach included analysis of simulations with horizontal resolutions of 1, 0.4, and 0.2 km. It was shown that the modified tidal wave lost most of its energy after reflection or refraction over the eastern part of the German Bight. Energy loss resulted in a pronounced change of the wave’s spectral composition and generation of overtides. Tidal oscillations were modified by mesoscale processes associated with bathymetric channels. Semidiurnal and quarterdiurnal tides revealed very different spatial patterns. The former were aligned with the bathymetric channels, while the latter were rather “patchy” and had about half the spatial scales. In numerous areas around the bathymetric channels, the major axis of the M₄ ellipses was normal or at some angle with the major axis of the M₂ ellipses. Thus, higher harmonics developed “orthogonal” patterns that drove secondary circulations. Moreover, the ratio between spring and neap tidal amplitudes was relatively low in the Wadden Sea, showing reduced sensitivity of this very shallow area to fortnightly tidal variations. It was demonstrated that simulated hydrodynamics patterns help explain the physical mechanism shaping the median grain size distribution in the German Bight.  相似文献   

Erratum to: Role of Stranded Gas from Central Asia and Russia in Meeting Europe’s Future Import Demand for Gas     

Emil D. Attanasi  Philip A. Freeman 《Natural Resources Research》2012,21(3):411-411

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First- and higher-order dynamical controls on water exchanges between tidal basins and the open ocean. A case study for the East Frisian Wadden Sea     

Emil V.?Stanev Email author  G?tz?Fl?ser  J?rg-Olaf?Wolff 《Ocean Dynamics》2003,53(3):146-165

Observational data, high-resolution numerical modelling results and a simple analytical theory are combined in this paper to demonstrate the dependence of the volume transports through tidal inlets on topographical or morphological parameters of a Wadden Sea system. The area of interest covers the East Frisian Wadden Sea and consists of seven weakly connected tidal basins. The observations include time series of tidal gauge data and surface currents measured at a pile station in the backbarrier basin of the island Langeoog, as well as several ADCP transects in the Accumer Ee tidal inlet. The numerical simulations are based on the 3-D primitive equation General Estuarine Transport Model (GETM) with a horizontal resolution of 200 m and terrain following vertical coordinates. The model is forced at its open boundaries with sea-level data from an operational model for the German Bight (German Hydrographic Office). The simple theoretical concepts presented illustrate the effect of topography (hypsometry) in the tidal basins on the temporal variability of the exchange of water. This topographic control is effectuated through the bottom slope in the areas prone to drying and flooding. For our study area it takes about twice as long from slack water to maximum flood current than from slack water to maximum ebb current. The underlying physics of this signal modulation from a more or less harmonic forcing at the open-sea boundary and the quantification of the contributing physical processes are the major results of this paper. Estimates based simply on volume conservation are consistent with observations and results from numerical modelling, but they do not completely capture the actual non-linear tidal response. Our analysis shows that at least during part of the tidal cycle characteristic topographic parameters of the inlet/bay system have a major impact on the rate of exchange of waters between the Wadden Sea and the open ocean. This impact is especially strong during the transition between flood and ebb conditions. The possible morphodynamic responses are also addressed focusing on some common (universal) topographic features in seven tidal basins.Responsible Editor: Hans Burchard  相似文献   

Barium isotopes in individual presolar silicon carbide grains from the Murchison meteorite     

Michael R. Savina  Andrew M. Davis  C.Emil Tripa  Michael J. Pellin  Roy S. Lewis  Roberto Gallino 《Geochimica et cosmochimica acta》2003,67(17):3201-3214

Barium isotopic compositions of single 2.3-5.3 μm presolar SiC grains from the Murchison meteorite were measured by resonant ionization mass spectrometry. Mainstream SiC grains are enriched in s-process barium and show a spread in isotopic composition from solar to dominantly s-process. In the relatively coarse grain size fraction analyzed, there are large grain-to-grain variations of barium isotopic composition. Comparison of single grain data with models of nucleosynthesis in asymptotic giant branch (AGB) stars indicates that the grains most likely come from low mass carbon-rich AGB stars (1.5 to 3 solar masses) of about solar metallicity and with approximately solar initial proportions of r- and s-process isotopes. Measurements of single grains imply a wide variety of neutron-to-seed ratios, in agreement with previous measurements of strontium, zirconium and molybdenum isotopic compositions of single presolar SiC grains.  相似文献   

Big geospatial data analysis for Canada’s Air Pollutant Emissions Inventory (APEI): using google earth engine to estimate particulate matter from exposed mine disturbance areas     

Meyra Fuentes  Emil Laurin 《地理信息系统科学与遥感》2020,57(2):245-257

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