New evidence of extensive active mud volcanism in the Anaximander mountains (Eastern Mediterranean): The “ATHINA” mud volcano     

V. Lykousis  S. Alexandri  J. Woodside  P. Nomikou  C. Perissoratis  D. Sakellariou  G. de Lange  A. Dahlmann  D. Casas  G. Rousakis  D. Ballas  Chr. Ioakim 《Environmental Geology》2004,46(8):1030-1037

A 3000 km² multibeam survey was carried out on the eastern Anaximander Mountains (Mts), (Eastern Mediterranean). The objective was to obtain detailed bathymetry of known mud volcanoes and identify new sites of active mud volcanism in the area. N-NW of the Amsterdam Mud-Volcano (MV) several mounds and cone-like morphological irregularities with a height of few tens of meters to about one hundred meters were detected and considered as potential MVs on the basis of their distinctive backscattered character. A group of two mounds was selected, the northern mound was sampled, documented as active, and named accordingly Athina MV. These new findings strongly support the presence of extensive active mud volcanism in the Anaximander Mountains especially in the area north of the Amsterdam MV.GEM  相似文献   

Differential aerobic and anaerobic oxidation of hydrocarbon gases discharged at mud volcanoes in the Nile deep-sea fan   总被引：1，自引：0，他引：1  

Vincent Mastalerz  Gert J. de Lange  Anke Dählmann 《Geochimica et cosmochimica acta》2009,73(13):3849-2169

The present study investigates hydrocarbon oxidation processes at Isis and Amon mud volcanoes (MV’s), in the eastern Nile deep-sea fan. In the water column, molecular and carbon isotopic signatures of light hydrocarbons indicate that gases rapidly dissolve in seawater and are partially oxidized.In the upper sediments, anaerobic oxidation of the light hydrocarbons takes place, as clearly shown by their molecular and isotopic composition. These processes lead to the presence of a distinct Sulfate-Hydrocarbon Interface at 120-145 cm and 20-50 cm below the seafloor, for Isis and Amon MV’s, respectively. In contrast to processes occurring in the water column, a clear preferential oxidation of methane, propane and n-butane over ethane and i-butane is observed in the anoxic sediments. Furthermore, for the first time, fractionation factors have been determined for the anaerobic oxidation of propane and butane, being respectively −4.80‰ and −0.7‰ for δ¹³C, and −43.3‰ for δ²H of propane.  相似文献   

Structure and Distribution of Autumn Zooplankton in the Southeastern Baltic Sea in 2015     

Polunina  Ju. Ju.  Lange  E. K.  Krechik  V. A. 《Oceanology》2019,59(1):66-74

Oceanology - Specific features of the structure and distribution of autumn zooplankton in the southeastern Baltic Sea (SEB) in October 2015 have been found taking into account the hydrological and...  相似文献   

Characterisation of Fulvic Acids and Glycyrrhizic Acid by Time‐of‐Flight Secondary Ion Mass Spectrometry     

Wilfried Szymczak  Manfred Wolf  Klaus Wittmaack 《洁净——土壤、空气、水》2001,28(7):350-358

Fulvic acids of different origin, spray deposited on polished silicon after dissolution in high‐purity water without any additives, were analysed by time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) in combination with oblique 24...36 keV SF₅⁺ ion bombardment. The observed, highly reproducible mass spectra cover more than five orders of magnitude in dynamic range, without background subtraction. Apart from lines due to atomic ions and low‐mass ion fragments, the mass spectra exhibit broad maxima between m/z 200...350, mainly due to a beat‐like superposition of lines at every single mass number, up to at least m/z 400. In the negative ion spectra the beats have a spacing of m/z 14, corresponding to a CH₂‐unit. The high‐mass tails of the spectra extend well beyond m/z 5000, with similar slopes in the positive and the negative ion mass spectra. The negative spectra appear to be less affected by fragmentation products than the positive spectra. Fulvic acids (FAs) of different origin show distinctly different spectra, with mean masses ranging between m/z ≈ 450 and 580 (for a low‐mass cut‐off m/z 150). To further verify the ability of TOF‐SIMS to detect molecules and clusters with masses significantly above the maxima of the FA spectra, samples of glycyrrhizic acid (GA, as GA ammonium salt with molecular weight 840) were also analysed. Parent ions as well as multimers (GA)_n were observed as positive and negative ions, up to n = 4 (m/z 3320). The results are compared with spectra recently obtained by other mass spectrometric techniques.  相似文献   

Advective Transport Phenomena to Better Understand Dispersion in Field and Modeling Practice     

Willem J. de Lange 《Ground water》2020,58(1):46-55

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Low‐Resolution Modeling of Dense Drainage Networks in Confining Layers          下载免费PDF全文

P.S. Pauw  S.E.A.T.M. Van der Zee  A. Leijnse  J.R. Delsman  P.G.B. De Louw  W.J. De Lange  G.H.P. Oude Essink 《Ground water》2015,53(5):771-781

Groundwater‐surface water (GW‐SW) interaction in numerical groundwater flow models is generally simulated using a Cauchy boundary condition, which relates the flow between the surface water and the groundwater to the product of the head difference between the node and the surface water level, and a coefficient, often referred to as the “conductance.” Previous studies have shown that in models with a low grid resolution, the resistance to GW‐SW interaction below the surface water bed should often be accounted for in the parameterization of the conductance, in addition to the resistance across the surface water bed. Three conductance expressions that take this resistance into account were investigated: two that were presented by Mehl and Hill (2010) and the one that was presented by De Lange (1999). Their accuracy in low‐resolution models regarding salt and water fluxes to a dense drainage network in a confined aquifer system was determined. For a wide range of hydrogeological conditions, the influence of (1) variable groundwater density; (2) vertical grid discretization; and (3) simulation of both ditches and tile drains in a single model cell was investigated. The results indicate that the conductance expression of De Lange (1999) should be used in similar hydrogeological conditions as considered in this paper, as it is better taking into account the resistance to flow below the surface water bed. For the cases that were considered, the influence of variable groundwater density and vertical grid discretization on the accuracy of the conductance expression of De Lange (1999) is small.  相似文献   

Modeling reactive transport in non-ideal aqueous–solid solution system     

Haibing Shao  Svitlana V. Dmytrieva  Olaf Kolditz  Dmitrii A. Kulik  Wilfried Pfingsten  Georg Kosakowski 《Applied Geochemistry》2009

The numerical simulation of reactive mass transport processes in complex geochemical environments is an important tool for the performance assessment of future waste repositories. A new combination of the multi-component mass transport code GeoSys/RockFlow and the Gibbs Energy Minimization (GEM) equilibrium solver GEM-Selektor is used to calculate the accurate equilibrium of multiple non-ideal solid solutions which are important for the immobilization of radionuclides such as Ra. The coupled code is verified by a widely used benchmark of dissolution–precipitation in a calcite–dolomite system. A more complex application shown in this paper is the transport of Ra in the near-field of a nuclear waste repository. Depending on the initial inventories of Sr, Ba and sulfate, non-ideal sulfate and carbonate solid solutions can fix mobile Ra cations. Due to the complex geochemical interactions, the reactive transport simulations can describe the migration of Ra in a much more realistic way than using the traditional linear K_D approach only.  相似文献   

Rapid crustal uplift in Patagonia due to enhanced ice loss     

R. Dietrich  E.R. Ivins  G. Casassa  H. Lange  J. Wendt  M. Fritsche 《Earth and Planetary Science Letters》2010,289(1-2):22-29

A vertical crustal uplift rate of 39 mm yr^? 1 is measured between 2003 and 2006 using Global Positioning System (GPS) measurements at the northeastern edge of the Southern Patagonia Icefield (SPI). This is the largest present-day glacial isostatic rate ever recorded. The combination of SPI's rapid melting and the unique regional slab-window tectonics that promotes a relatively low viscosity, is central to our interpretation of the observations. The two effects lead to a strong interaction of short relaxation times with ice loads that change on a comparable time scale. The profile of GPS observations link ice loss to the soft viscoelastic isostatic flow response over the time scale of the Little Ice Age (LIA), including ice loss in the period of observation. The agreement of the results with our model predictions strongly suggests the large crustal uplift in Patagonia is due an accelerated glacier wasting since the termination of the LIA and that the effective regional mantle viscosity is near 4.0–8.0 × 10¹⁸ Pa s. A century-long diminution of the icefields, at rates that are about 1/4 – 1/2 the contemporary loss rates, is consistent with multidecadal-scale temperature trends estimated for the past 50–100 years and is, in fact, a key feature in any model capable of explaining the uplift data.  相似文献   

Statement to comment by K. Föllmi on ,,Neubenennungen lithostratigraphischer Einheiten in der helvetischen Kreide“     

Schweizerisches Komitee für Stratigraphie  Thierry Adatte  Jean-Pierre Berger  Hansruedi Bläsi  Reto Burkhalter  Stephan DallAgnolo  Danielle Decrouez  Hanspeter Funk  Heinz Furrer  Yves Gouffon  Hansruedi Graf  Werner Heckendorn  Wilfried Winkler 《Swiss Journal of Geoscience》2009,102(3):519-519

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Phenocryst complexity in andesites and dacites from the Tequila volcanic field,Mexico: resolving the effects of degassing vs. magma mixing     

Holli M. Frey  Rebecca A. Lange 《Contributions to Mineralogy and Petrology》2011,162(2):415-445

The petrology of five phenocryst-poor (2–5%) andesites and dacites, all of which were erupted from different short-lived, monogenetic vents, is compared to that of phenocryst-rich (10–25%) andesites erupted from the adjacent stratovolcano, Volcán Tequila, in the Mexican arc. Despite differences in phenocryst abundances, these magmas have comparable phase assemblages (plagioclase + orthopyroxene + titanomagnetite + ilmenite + apatite ± augite ± hornblende), and similarly wide variations in phenocryst compositions, coupled to complex zoning patterns. For the phenocryst-poor lavas, equilibrium pairs of two Fe–Ti oxides lead to a narrow range of calculated temperatures for each sample that range from 934 (±24) to 1,073 (±6)°C and oxygen fugacities that range from +0.1 to +0.7 log units relative to the Ni–NiO buffer. Application of the plagioclase-liquid hygrometer to each sample at these calculated temperatures leads to maximum melt water concentrations of 4.6–3.1 wt% during plagioclase crystallization, indicating that the magmas were fluid saturated at depths ≥6.4–4.5 km. There is a wide, continuous range in the composition of plagioclase (≤44 mol% An) and orthopyroxene (≤16% Mg#) phenocrysts in each sample, which is consistent with a loss of dissolved water (≤2.8 wt%) from the melt phase during degassing as the magmas ascended rapidly to the surface. Evidence is presented that shows the effect of dissolved water is to reduce the activity of MgO relative to FeO in the melt phase, which indicates that degassing will also affect the Mg# of pyroxene phenocrysts, with higher melt water concentrations favoring Fe-rich pyroxene. Both plagioclase and orthopyroxene commonly display diffusion-limited growth textures (e.g., skeletal and hopper crystals, large interior melt hollows, and swallow tails), which are consistent with large undercoolings produced by degassing-induced crystallization. Therefore, degassing is proposed as a possible cause for the phenocryst compositional diversity documented in the phenocryst-poor andesite and dacite lavas erupted from peripheral vents, including the coexistence of normally zoned plagioclase and reversely zoned orthopyroxene. Degassing-induced crystallization may also explain some of the phenocryst complexity in crystal-rich andesites erupted from large stratovolcanoes, including Volcán Tequila.  相似文献