Thermo-hydro-mechanical simulation of ATLAS in situ large scale test in Boom Clay     

Bertrand François  Lyesse LalouiClément Laurent 《Computers and Geotechnics》2009

Following the need for understanding and quantifying the effect of temperature on the response of a candidate host formation for radioactive waste disposal, finite element modelling of an in situ thermal experiment has been carried out. Based on a thermo-hydro-mechanical (THM) finite element approach including a consistent thermo-plastic constitutive model, it has been possible to reproduce the THM response of a clay formation submitted to in situ thermal loading. The simulated large-scale experiment, called ATLAS was designed in the underground research facility (HADES-URF) in Mol, Belgium. After an extensive literature analysis on the thermal, hydraulic and mechanical characteristics of Boom Clay, laboratory tests were simulated to calibrate model parameters. The results of the finite element modelling of the ATLAS experiment were compared with in situ measurements and revealed the necessity to account for flow diffusion in all three directions through a 2D axisymmetric analysis. Finally, those results were interpreted in the light of elasto-thermoplasticity, which emphasizes the significant role of thermo-plastic processes in the global THM response of the clay formation.  相似文献   

A wave‐dominated,tide‐modulated model for the Lower Ordovician of the Anti‐Atlas,Morocco          下载免费PDF全文

Romain Vaucher  Bernard Pittet  Hélène Hormière  Emmanuel L. O. Martin  Bertrand Lefebvre 《Sedimentology》2017,64(3):777-807

Hybrid depositional systems are created by the interaction of two or more hydrodynamic processes that control facies distribution and their characteristics in terms of sedimentary structures and depositional geometry. The interaction of wave and tide both in the geological sedimentary record and modern environments has been rarely described in the literature. Mixed coastal environments are identified by the evidence of wave and tidal structures and are well identified in nearshore environments, while their recognition in lower shoreface–offshore environments lacks direct information from modern settings. Detailed field analyses of 10 stratigraphic sections of the Lower Ordovician succession (Fezouata and Zini formations; Anti‐Atlas, Morocco) have allowed the definition of 14 facies, all grouped in four facies zones belonging to a storm‐dominated, wave‐dominated sedimentary siliciclastic system characterized by symmetrical ripples of various scales. Peculiar sedimentary organization and sedimentary structures are observed: (i) cyclical changes in size of sedimentary structures under fair‐weather or storm‐weather conditions; (ii) decimetre‐deep erosional surfaces in swaley cross‐stratifications; (iii) deep internal erosion within storm deposits; (iv) discontinuous sandstone layers in most depositional environments, and common deposition of sandstones with a limited lateral extension, interpreted to indicate that deposition at all scales (metric to kilometric) is discontinuous; (v) combined flow–oscillation ripples showing aggrading–prograding internal structures alternating with purely aggrading wave ripples; and (vi) foreshore environments characterized by alternating phases of deposition of parallel stratifications, small‐scale and large‐scale ripples and tens of metres‐wide reactivation surfaces. These characteristics of deposition suggest that wave intensity during storm‐weather or fair‐weather conditions was continuously modulated by another controlling factor of the sedimentation: the tide. However, tidal structures are not recognized, because they were probably not preserved due to dominant action of storms and waves. A model of deposition is provided for this wave‐dominated, tide‐modulated sedimentary system recording proximal offshore to intertidal–foreshore environments, but lacking diagnostic tidal structures.  相似文献   

Reconciling late faulting over the whole Alpine belt: from structural analysis to geochronological constrains     

Audrey Bertrand  Christian Sue 《Swiss Journal of Geoscience》2017,110(2):565-580

The significance of late-stage fracturing in the European Alps in a large geodynamic context is reappraised by studying brittle deformations over the entire belt. In the internal Western Alps, paleostress datasets display a major occurrence of orogen-parallel extension resulting in normal faulting and associated strike-slip mode. There the direction of subhorizontal extension rotates with the bending of the Alpine belt. In the Central Alps, paleostress tensors also indicate orogen-parallel extensional regimes, both in the Bergell area and the Lepontine Dome, where the brittle structures are associated with ductile structures related to the formation of large-scale upright folds that accommodate most of the collisional shortening due to the north-directed component of the movement of the South-Alpine indenter. This brittle deformation phase is of Miocene age and is coeval with the propagation of the Alpine front toward the external Alpine domains. In the Eastern Alps, brittle deformation of the Tauern Window displays an overwhelming occurrence of orogen-parallel normal faulting and associated strike-slip regimes again, which is inferred to be driven by lateral extrusion of the orogenic wedge toward the Pannonian basin, partly due to indentation on the Dolomites indenter. The major orogen-parallel extensional signal of the brittle Cenozoic deformations appears remarkably stable all over the internal Alps. Extensional brittle structures are part of a late phase of collisional deformation, during which the propagation of the Alpine front of the Western Alps and the northward movement of the Southern Alpine and the Dolomites indenters in the Central and Eastern Alps were accommodated by orogen-parallel extension in the inner zones, at the scale of the entire chain.  相似文献   

Evolution of calc-alkaline to alkaline magmatism through Carboniferous convergence to Permian transcurrent tectonics,western Chinese Tianshan   总被引：7，自引：0，他引：7  

Bo Wang  Dominique Cluzel  Liangshu Shu  Michel Faure  Jacques Charvet  Yan Chen  Sebastien Meffre  Koen de Jong 《International Journal of Earth Sciences》2009,98(6):1275-1298

Continuous magmatic activity occurred in the western Chinese Tianshan, Central Asia, from the Carboniferous to the Permian, i.e. before and after the Late Carboniferous amalgamation of Junggar and the Yili Blocks. Zircon U–Pb LA-ICPMS and Ar–Ar data reveal a coincidence in time between regional wrench faulting and granitoid emplacement. Permian post-collisional granitoids crop out within or at the margins of large-scale dextral strike-slip shear zones, some of them show synkinematic fabrics. The whole rock geochemical features of the Early-Middle Permian granitoids indicate an evolution from high-K calc-alkaline towards alkaline series. In other places of the North Tianshan, alkaline magmatism occurred together with deep marine sedimentation within elongated troughs controlled by wrench faults. Therefore, in contrast with previous interpretations that forwarded continental rift or mantle plume hypotheses, the coexistence of diverse magmatic sources during the same tectonic episode suggests that post-collisional lithosphere-scale transcurrent shearing tightly controlled the magmatic activity during the transition from convergent margin to intraplate anorogenic processes.  相似文献   

Where do fishmeal and fish oil products come from? An analysis of the conversion ratios in the global fishmeal industry   总被引：1，自引：0，他引：1  

Guillaume Péron  Jean François Mittaine  Bertrand Le Gallic 《Marine Policy》2010

As a result of the stagnation of commercial fishery landings, aquaculture activities are expected to increase over the next decades to match the growing demand for marine protein. Overall, it is expected that the aquaculture sector could reduce some of the fishing pressure applied to wild stocks. However, this development is likely to be limited by the availability of key aquaculture inputs, specifically fishmeal and fish oil products (FMFOP). Aquaculture provided 60 % (fish meal) and 80 % (fish oil) of the world total consumption of these products in 2007. FMFOP are generally derived from small pelagic fish species, but can also be derived from other sources. Identifying the origin of FMFOP is crucial to understanding the effects of this new pressure on marine social-ecological systems. Two factors are of particular importance in the reduction sector transforming wild fish into fishmeal or fish oil: the two “conversion ratios” (i.e. the ratio between the quantity of wild fish harvested and the resulting quantity of FMFOP, and the ratio between the quantity of FMFOP and aquaculture production), and the type of raw material used by the reduction sector. Based on trade and production databases from FAO and the International Fishmeal and Fish oil Organisation (IFFO), this paper proposes an approach to identify the origin of FMFOP. It shows that whereas different countries use different pelagic resources to produce FMFOP, other countries use non-pelagic sources, and some countries use pelagic resources for human consumption.  相似文献   

Evolution des hydrocarbures dans des sédiments côtiers méditerranéens prélevés à proximité d'un emissaire d'une raffinerie de pétrole     

Gilbert Mille  Jan Yu Chen  Henri Dou  Edgar Azoulay  Maryse Colin  Jean-Claude Bertrand 《Marine environmental research》1985,17(1):65-80

Coastal Mediterranean sediments highly polluted by refinery effluents have been studied for their hydrocarbon content and bacterial activity. The study has taken into account both the distance from the refinery and depth of sampling. Very high hydrocarbon concentrations have been found (1–250 g/kg dry sediment). Micro-organisms in the sediments have a high bacterial activity and a good correlation exists between hydrocarbon concentrations and bacteria able to use these substrates as a carbon and energy source.  相似文献   

Furongian (upper Cambrian) Guole Konservat-Lagerst?tte from South China     

ZHU Xuejian  PENG Shanchi  Samuel ZAMORA  Bertrand LEFEBVRE  CHEN Guiying 《《地质学报》英文版》2016,90(1):30-37

The Guole biota contains common shelly fossils and some exceptionally well-preserved soft-bodied fossils. Stratigraphically, it is located in the mudstones and siltstones of the Sandu Formation near Guole Town, Jingxi County, Guangxi, South China. It is the first Furongian (late Cambrian) Burgess Shale-type biota found in the world, thereby filling the gap between middle Cambrian and Lower Ordovician Burgess Shale-type Lagerst?tten. Preliminary studies suggest that the Guole biota includes approximately seven metazoan groups as well as algae. These will provide important new evolutionary and ecological information.  相似文献   

A multi-dimensional statistical rainfall threshold for deep landslides based on groundwater recharge and support vector machines     

A. Vallet  D. Varron  C. Bertrand  O. Fabbri  J. Mudry 《Natural Hazards》2016,84(2):821-849

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Molecular dynamics simulations of the orthoclase (0 0 1)- and (0 1 0)-water interfaces     

Sebastien Kerisit  Chongxuan Liu  Eugene S. Ilton 《Geochimica et cosmochimica acta》2008,72(6):1481-1497

Molecular dynamics simulations of water in contact with the (0 0 1) and (0 1 0) surfaces of orthoclase (KAlSi₃O₈) were carried out to investigate the structure and dynamics of the feldspar-water interface, contrast the intrinsic structural properties of the two surfaces, and provide a basis for future work on the diffusion of ions and molecules in microscopic mineral fractures. Electron density profiles were computed from the molecular dynamics trajectories and compared with those derived experimentally from high-resolution X-ray reflectivity measurements by Fenter and co-workers [Fenter P., Cheng L., Park C., Zhang H. and Sturchio N. C. (2003a) Structure of the orthoclase (0 0 1)- and (0 1 0)-water interfaces by high-resolution X-ray reflectivity. Geochim. Cosmochim. Acta67, 4267-4275]. For each surface, three scenarios were considered whereby the interfacial species is potassium, water, or a hydronium ion. Excellent agreement was obtained for the (0 0 1) surface when potassium is the predominant interfacial species; however, some discrepancies in the position of the interfacial peaks were obtained for the (0 1 0) surface. The two surfaces showed similarities in the extent of water ordering at the interface, the activation energies for water and potassium desorption, and the adsorption localization of interfacial species. However, there are also important differences between the two surfaces in the coordination of a given adsorbed species, adsorption site densities, and the propensity for water molecules in surface cavities and those in the first hydration layer to coordinate to surface bridging oxygen atoms. These differences may have implications for the extent of dissolution in the low-pH regime since hydrolysis of Si(Al)OSi(Al) bonds is a major dissolution mechanism.  相似文献   

Age and pyrite Pb-isotopic composition of the giant Sukhoi Log sediment-hosted gold deposit, Russia   总被引：2，自引：0，他引：2  

Sebastien Meffre  Ross R. Large  Jon Woodhead  Sarah E. Gilbert  Valeriy Maslennikov 《Geochimica et cosmochimica acta》2008,72(9):2377-2391

Sukhoi Log is one of the largest gold deposits in Russia (1100 t Au at 2.45 g/t). Like many other sediment-hosted gold deposits throughout the world, Sukhoi Log preserves textural, structural and geochemical evidence for multiple generations of Au enrichment and pyrite growth.The deposit is located in the Lena gold province of Siberia, on the edge of the Siberian Craton and occurs in the core of a recumbent anticline in a Neoproterozoic black shale and quartz-rich siltstone-sandstone turbidite succession. Temporal constraints on pyrite paragenesis at the deposit have been determined using laser ablation inductively coupled mass spectrometry (LA-ICPMS) measurements of U, Th and Pb isotopes in pyrite, monazite and zircon. LA-ICPMS age determinations on detrital zircons indicate the host rocks were deposited after 600 ± 10 Ma and derived from a mixture of Palaeoproterozoic and Neoproterozoic sources. The U, Th and Pb isotopic systematics indicate the cores of large monazite crystals, which predate obvious tectonic fabric development in the host rocks, began growing at 573 ± 12 Ma. The rims of the same monazite crystals formed at 516 ± 10 Ma, during peak metamorphism and deformation. Small monazite crystals also grew in the sedimentary rocks during the Devonian (374 ± 20 Ma) and the Carboniferous or Early Permian (288 ± 22 Ma), possibly in response to fluid movements triggered by synchronous granite intrusion in the area. Multi-collector and quadrupole LA-ICPMS Pb isotopic determination on pyrite, combined with overprinting criteria, show that the earliest (stratiform) Pb and Au-bearing pyrite formed prior to metamorphism—possibly during sedimentation or early diagenesis (575-600 Ma). Small Au-rich pyrite nodules preserved as cores to folded bedding-parallel pyrite-quartz veins probably grew during late diagenesis or early metamorphism. Large pyrite euhedra, which overgrow the strong axial planar cleavage in the host rocks, have more radiogenic Pb-isotopic compositions and formed either late during or after deformation. Framboidal pyrite that is overgrown by both the late diagenetic-early metamorphic and syn- to post-metamorphic pyrite has the most radiogenic Pb-isotopic composition suggesting exchange with radiogenic Pb in the matrix may have continued until late in the history of the deposit.The dating and Pb isotopes support a multistage origin for the gold deposit with Au first introduced during or prior to growth of the earliest stratiform pyrite and progressively re-concentrated (with or without addition of further gold) during later metamorphic events.  相似文献