Paleo-fluids characterisation and fluid flow modelling along a regional transect in Northern United Arab Emirates (UAE)   总被引：1，自引：1，他引：0  

Jean-Paul Callot  Liesbeth Breesch  Nicole Guilhaumou  François Roure  Rudy Swennen  Nadège Vilasi 《Arabian Journal of Geosciences》2010,3(4):413-437

In the Northern Emirates, Jurassic and Lower Cretaceous platform carbonates of the Musandam parautochthonous units are tectonically overlain by siliciclastic units of the Hawasina–Sumeini allochthon, which derive from the former paleo-slope domain and a more distal basinal portion of the Arabian margin of the Tethys, respectively. All these tectonic units display numerous evidences of paleo-fluid circulations, accounting for dolomitisation and recrystallisation of the rock matrix (Musandam Platform units), as well as cementation of fractures. Polymict breccias of Upper Cretaceous Ausaq Formation which underlay the sole thrust of the Hawasina–Sumeini allochthon also record episodes of hydraulic fracturing, whereas fluid inclusion data indicate precipitation at high temperature in relation to paleo-fluid flow. Petrography of thin-sections (conventional and cathodoluminescence microscopic techniques) as well as fluid inclusion and stable isotopes analyses, were combined with micro-tectonic studies. These analytical data document (1) the paragenetic sequence of diagenetic products for the Musandam Platform (which constitutes a carbonate reservoir analogue) and Sumeini units of the Dibba Zone, as well as (2) the nature of the paleo-fluids circulating along fractures and the sole thrust of the Hawasina–Sumeini allochthon. The main results of this petrographic approach are qualitative, evidencing (1) the rapid and vertical transfer of hot fluids in the vicinity of the former slope to platform transition, accounting for episodes of hydrothermal dolomitisation, as well as (2) early (i.e. pre-orogenic) and late (i.e. post-orogenic) episodes of emersion of the carbonate units, accounting for additional interactions with meteoric fluids and karstification. In order to better link these diagenetic events with the overall burial, thermal and kinematic evolution of the Arabian margin, basin modelling with Ceres2D, including fluid flow and pore-fluid pressure modelling, was subsequently performed along a regional transect (D4) located in the vicinity of the samples localities and cross-cutting the Northern Oman Mountains from Dibba in the east up to the Arabian Gulf in the west. New subsurface constraints provided by deep seismic profiles were used to constrain the architecture of the cross-section, and to test various hypotheses on the lateral and vertical connection, timing and hydrodynamic behaviour of the faults. This Ceres basin modelling also provides new quantitative estimates of the paleo-fluid pathways, of the timing and velocities of the fluid transfers and of the evolution of pore-fluid pressures. Ultimately, this integration of petrographic studies on surface samples and coupled kinematic and fluid flow basin modelling provides an updated scenario for the succession of tectonically controlled episodes of fluid rock interactions, namely dolomitisation and karstification recorded in the Mesozoic platform carbonates of the Northern Emirates.  相似文献   

Absolute magnitude calibration for red clump stars     

S. Karaali  S. Bilir  E. Yaz Gökçe 《Astrophysics and Space Science》2013,346(1):89-104

We combined the (K _s , J?K _s ) data in Laney et al. (Mon. Not. R. Astron. Soc. 419:1637, 2012) with the V apparent magnitudes and trigonometric parallaxes taken from the Hipparcos catalogue and used them to fit the $M_{K_{s}}$ absolute magnitude to a linear polynomial in terms of V?K _s colour. The mean and standard deviation of the absolute magnitude residuals, ?0.001 and 0.195 mag, respectively, estimated for 224 red clump stars in Laney et al. (2012) are (absolutely) smaller than the corresponding ones estimated by the procedure which adopts a mean $M_{K_{s}}=-1.613~\mbox{mag}$ absolute magnitude for all red clump stars, ?0.053 and 0.218 mag, respectively. The statistics estimated by applying the linear equation to the data of 282 red clump stars in Alves (Astrophys. J. 539:732, 2000) are larger, $\Delta M_{K_{s}}=0.209$ and σ=0.524 mag, which can be explained by a different absolute magnitude trend, i.e. condensation along a horizontal distribution.  相似文献   

The Corossol structure: A possible impact crater on the seafloor of the northwestern Gulf of St. Lawrence,Eastern Canada     

Patrick Lajeunesse  Guillaume St‐Onge  Jacques Locat  Mathieu J. Duchesne  Michael D. Higgins  Richard Sanfaçon  Joseph Ortiz 《Meteoritics & planetary science》2013,48(12):2542-2558

We report on a 4.1 (±0.2) km diameter and 185 m deep circular submarine structure exposed on the seabed in >40 m water depths in the northwestern Gulf of St. Lawrence (Eastern Canada) from the analysis of high‐resolution multibeam bathymetric and seismic data. The presence of a circular form characterized by a central uplift and concentric rings resembles the morphology and geometry of complex meteorite impact structures. Also, other origins, such as kimberlites, intrusions, karsts, or diapirs, can be eliminated on geological criteria. A single 4 cm long breccia fragment recovered from the central uplift has numerous glassy droplets of fluorapatite composition, assumed to be impact melts, and a single quartz grain with planar intersection features thought to be shock‐induced planar deformation features (PDFs). The absolute age of this possible impact structure is unknown, but its geological setting indicates that it was formed long after the Mid‐Ordovician and before regional pre‐Quaternary sea‐level lowstands. Present results outline the need for further examination to confirm an impact origin and to precisely date the formation of the structure.  相似文献   

Anthropic Exposure Indicator for River Basins Based on Landscape Characterization and Fuzzy Inference     

Elfany Reis do Nascimento Lopes  Carlos de Souza  José  Paixão de Sousa  Jocy Ana  Filho  José Luiz Albuquerque  Lourenço  Roberto Wagner 《Water Resources》2021,48(1):29-40

Water Resources - The objective of this study is to develop an anthropic exposure indicator for river basins using quantitative and qualitative aspects of the landscape and morphometric analysis...  相似文献   

The Weierbach experimental catchment in Luxembourg: A decade of critical zone monitoring in a temperate forest - from hydrological investigations to ecohydrological perspectives     

Christophe Hissler  Núria Martínez-Carreras  François Barnich  Laurent Gourdol  Jean François Iffly  Jérôme Juilleret  Julian Klaus  Laurent Pfister 《水文研究》2021,35(5):e14140

The Weierbach experimental catchment (0.45 km²) is the most instrumented and studied sub-catchment in the Alzette River basin in Luxembourg. Within the last decade, it has matured towards an interdisciplinary critical zone observatory focusing on a better understanding of hydrological and hydro-geochemical processes. The Weierbach catchment is embedded in an elevated sub-horizontal plateau, characterized by slate bedrock and representative of the Ardennes Massif. Its climate is semi-marine, with precipitation being rather evenly distributed throughout the year. Base flow is lowest from July to September, essentially due to higher losses through evapotranspiration in summer. The regolith is composed of Devonian slates, overlaid by Pleistocene slope deposits and entirely covered by forest with 70% deciduous and 30% coniferous trees. Since 2009, the Weierbach has been extensively equipped for continuously monitoring water fluxes and physico-chemical parameters within different compartments of the critical zone. Additionally, these compartments are sampled fortnightly at several locations to analyze δ¹⁸O and δ²H isotopic composition of water including rainfall, throughfall, soil water, groundwater and streamwater. This ongoing monitoring and sampling programme is used for answering pressing questions related to fundamental catchment functions of water infiltration, storage, mixing and release in forest ecosystems. A recently started research line aims at investigating interactions between forest eco-hydrosystems with the atmosphere and understanding how catchments will respond to a non-stationary climate.  相似文献   

Evaluation of the Risk of Marine Slope Instability: A Pseudo-3D Approach for Application to Large Areas     

Nabil Sultan  Pierre Cochonat  Jean François Bourillet  Florence Cayocca 《Marine Georesources & Geotechnology》2013,31(2):107-133

Abstract

This article presents a methodology developed to evaluate the instability of submarine slopes that extend over a large area. Special attention was paid to (1) the complex geometry (bathymetry) and the expanse of the slope, (2) the heterogeneity of the sediment, and (3) the distribution of the pore pressure. The safety factor was considered as a spatially varying quantity. The General Formulation (GLE, Fredlund and Krahn 1977), which fully satisfies equilibrium conditions, was used for evaluating the stability of the marine slope. The submarine slope failure, which occurred on 16 October 1979 during the construction of the new Nice airport, was studied in order to test the developed model. Geotechnical parameters were taken from experimental tests carried out by IFREMER on 19 cores extracted at different depths (from 27 m to 1300 m) (Cochonat, Bourillet, and Savoye, 1993; Mulder et al., 1994). Many scenarios were proposed in order to explain the cause of the Nice slope failure (Habib, 1994). In this article, two of those scenarios were tested. Simulation results are presented and discussed.  相似文献   

The detached eclipsing binary TX Her revisited     

A. Erdem  F. Aliçavuş  F. Soydugan  S.S. Doğru  E. Soydugan  C. Çiçek  O. Demircan 《New Astronomy》2011,16(8):498-502

This paper presents new CCD Bessell BVRI light curves and photometric analysis of the Algol-type binary star TX Her. The CCD observations were carried out at Çanakkale Onsekiz Mart University Observatory in 2010. New BVRI light curves from this study and radial velocity curves from Popper (1970) were solved simultaneously using modern light and radial velocity curves synthesis methods. The general results show that TX Her is a well-detached eclipsing binary, however, both component stars fill at least half of their Roche lobes. A significant third light contribution to the total light of the system could not be determined. Using O–C residuals formed by the updated minima times, an orbital period study of the system was performed. It was confirmed that the tilted sinusoidal O–C variation corresponds to an apparent period variation caused by the light travel time effect due to an unseen third body. The following absolute parameters of the components were derived: M₁ = 1.62 ± 0.04 M_⊙, M₂ = 1.45 ± 0.03 M_⊙, R₁ = 1.69 ± 0.03 R_⊙, R₂ = 1.43 ± 0.03 R_⊙, L₁ = 8.21 ± 0.90 L_⊙ and L₂ = 3.64 ± 0.60 L_⊙. The distance to TX Her was calculated as 155 ± 10 pc, taking into account interstellar extinction. The position of the components of TX Her in the HR diagram are also discussed. The components are young stars with an age of ～500 Myr.  相似文献   

Impact of Boundary-Layer Processes on Near-Surface Turbulence Within the West African Monsoon   总被引：1，自引：1，他引：0  

Fabienne Lohou  Frédérique Saïd  Marie Lothon  Pierre Durand  Dominique Serça 《Boundary-Layer Meteorology》2010,136(1):1-23

High frequency measurements of near-surface meteorological data acquired in north Benin during the 2006 West African monsoon seasonal cycle, in the context of the African Monsoon Multidisciplinary Analysis (AMMA) experiment, offer insight into the characteristics of surface turbulence in relation to planetary boundary-layer (PBL) processes. A wide range of conditions is encountered at the lower and upper limits of the PBL: (i) from water-stressed to well-fed vegetation, and (ii) from small to large humidity and temperature jumps at the PBL top inversion, due to the Saharan air layer overlying the monsoonal flow. As a result, buoyant convection at the surface and entrainment at the PBL top play very different roles according to the considered scalar. We show that, when the boundary-layer height reaches the shear level between the monsoonal and Harmattan flows, the temperature source and humidity sink at the boundary-layer top are sufficient to allow the entrainment to affect the entire boundary layer down to the surface. This situation occurs mainly during the drying and moistening periods of the monsoon cycle and affects the humidity statistics in particular. In this case, the humidity turbulent characteristics at the surface are no longer driven solely by buoyant convection, but also by entrainment at the boundary-layer top. Consequently, the Monin–Obukhov similarity theory appears to fail for the parameterisation of humidity-related moments.  相似文献   

Turbulent Dispersion of Non-uniformly Emitted Passive Tracers in the Convective Boundary Layer     

Jean-François Vinuesa  Stefano Galmarini 《Boundary-Layer Meteorology》2009,133(1):1-16

The impact of spatially non-uniform emissions on the turbulence dispersion of passive tracers in the convective boundary layer is studied by means of large-eddy simulation. We explicitly calculated the different terms of the budget equations for the concentrations, fluxes and variances, and used sub-domain averaging where each sub-domain is the typical size of a large-scale model grid cell. We found that the concentration profiles in the sub-domain where the emission takes place are lightly affected by the size of the emission release. This effect becomes more relevant in the downwind sub-domain. Although sub-domain averaged fluxes are not affected by the emission source size, concentration variances are dramatically increased when the emission shrinks. This increase originates from the mixing of highly concentrated air parcels with those of low concentrations. We also found that the concentration variance at the surface is driven neither by the position of the emission source nor the strength of the shear forcing but solely by the emission variance.  相似文献   

A Mixed Spectral-Integration Model for Neutral Mean Wind Flow Over Hills     

Jean-François Corbett  Søren Ott  Lars Landberg 《Boundary-Layer Meteorology》2008,128(2):229-254

A linear model for neutral surface-layer flow over orography is presented. The Reynolds-Averaged Navier-Stokes and E– turbulence closure equations are expressed in a terrain-following coordinate system created from a simple analytical expression in the Fourier domain. The perturbation equations are solved spectrally horizontally and by numerical integration vertically. Non-dimensional solutions are stored in look-up tables for quick re-use. Model results are compared to measurements, as well as other authors’ flow models in three test cases. The model is implemented and tested in two-dimensional space; the equations for a full three-dimensional version are presented.  相似文献