Relating remotely sensed forest damage data to wind data: storms Lothar (1999) and Vivian (1990) in Switzerland     

Tilo Usbeck  Peter Waldner  Matthias Dobbertin  Christian Ginzler  Christian Hoffmann  Flurin Sutter  Charlotte Steinmeier  Richard Volz  Gustav Schneiter  Martine Rebetez 《Theoretical and Applied Climatology》2012,108(3-4):451-462

This study compares the surface wind speed and forest damage data of two exceptionally severe winter storms, Vivian 1990 and Lothar 1999. The study area comprises the region that suffered damage in Switzerland. The wind speed data were derived from simulations of MeteoSwiss (Federal Office of Meteorology and Climatology), measurements during the storm periods and expert analyses of the data. The remotely sensed forest damage data were provided by the Federal Office for the Environment and the forest cover data by Swiss Federal Statistical Office. We compared data on the peak gust and maximum average wind speed, with data on the spatially related forest area and forest damage area, and found some clear differences in the correlations between the different wind data and forest damage. Our results point generally to the damage-causing role of near-surface gusts at maximum wind speeds during the storm. These tended to be spatially distributed on a fine scale. In only a few cases were the results statistically significant. However, these results could probably be improved with better wind data. For example, gust measurements spatially closer to forests or simulations of gusts at maximum wind speed could be produced with a spatially higher resolution.  相似文献   

Phosphate removal from water by naturally occurring shale,sandstone, and laterite: The role of iron oxides and of soluble species     

Dan Eude Kpannieu  Martine Mallet  Lacina Coulibaly  Mustapha Abdelmoula  Christian Ruby 《Comptes Rendus Geoscience》2019,351(1):37-47

Aqueous phosphate removal by three geomaterials from Ivory Coast was evaluated to determine their potential application as low-cost phosphate adsorbents in wastewater treatment. Batch experiments showed that phosphate uptake strongly depended on pH. Laterite and sandstone dissolution was less pronounced compared to shale. A correlation between concentrations of aqueous cation species released from shale and phosphate uptake was observed. The kinetics were well described using the pseudo-second-order model. Isotherms displayed a saturation level on shale, while phosphate uptake continuously increased for laterite and sandstone. The removal efficiency decreased in the following ranking order: laterite > sandstone > shale. Laterite was also the most efficient adsorbent in column experiments. The high phosphate removal efficiency of laterite (8.3 mg PO₄ g^?1) was attributed to the presence of superparamagnetic low grain sizes of goethite. Laterite is a particularly promising material for further investigation in wastewater treatment technology such as constructed wetlands.  相似文献   

Difference in petrophysical properties between foliated and dilatant fault rocks in deeply buried clastics: The case of the Grès d'Annot Formation,SW French Alps     

Thibault Cavailhes  Pierre Labaume  Jean‐Pierre Sizun  Roger Soliva  Claude Gout  Jean‐Luc Potdevin  Martine Buatier  Aurélien Gay  Alain Chauvet  Delphine Charpentier  Anna Travé 《地学学报》2014,26(4):298-306

This study describes normal fault zones formed in foreland arkosic turbidites (the Grès d'Annot Formation, SW French Alps) under deep diagenesis conditions (~200 °C) and highlights the occurrence of two markedly different fault‐rock types: (1) the foliated fault rocks of the Moutière‐Restefond area; and (2) the dilatant fault rocks of the Estrop area. The deformation of (1) is dominated by intra‐ and transgranular fracturing, pressure solution of quartz and feldspar grains and syn‐kinematic phyllosilicate precipitation resulting from feldspar alteration. The combination of these mechanisms results in a strongly anisotropic strain with intense shortening normal to the foliation (pressure solution) and extension parallel to the foliation (quartz‐ and calcite‐sealed extension veins). This deformation implies local mass transfer that may be achieved without (or with limited) volume change. The deformation of (2) is expressed as dilatant quartz‐sealed veins and breccia textures in which the main mechanisms are transgranular fracturing and quartz precipitation. Type (2) implies fault volume increase, isotropy of deformation and mass transfer at distances larger than in type (1). This study discusses the origins of (1) and (2) and shows that the permeability of (1) is anisotropic, with higher values than the host rocks parallel to the Y main deformation axis (i.e. perpendicular to the slip vector), whereas the permeability of (2) is isotropic and equivalent to that of the host rocks.  相似文献   

A log‐normal spectral analysis of inorganic grain‐size distributions from a Canadian boreal lake core: Towards refining depositional process proxy data from high latitude lakes          下载免费PDF全文

Paul R. Gammon  Lisa A. Neville  R. Timothy Patterson  Martine M. Savard  Graeme T. Swindles 《Sedimentology》2017,64(3):609-630

Better methods for interpreting grain‐size spectra will enhance current understanding of past transport–depositional processes. A high‐resolution inorganic grain‐size dataset has been measured from a freeze core extracted from ‘Alberta Lake E’ a boreal fresh water lake 40 km east of the Athabasca Oil Sands in north‐eastern Alberta, Canada. The grain‐size spectra are remarkably consistent throughout the core, exhibiting a structure comprising six persistent grain‐size distributions below ca 250 μm, plus a rare medium‐sand distribution. Automated deconvolution of the grain‐size spectra produced poor results. Constraining the modes of two of the distributions produced deconvolution solutions that were statistically excellent and consistent with the structure of each spectrum. Statistical analysis of the ‘constrained’ solutions indicates that deconvolution successfully extracted independent grain‐size populations. Conversely, the multimodal spectra generate traditional measures (for example, mean grain size) that are inconsistent combinations of different individual populations and thus are poor proxies of transport–depositional processes. Alberta Lake E is situated in a boreal wetland landscape where sediment delivery is dominated by overland flow transport during spring melt. This context means that the Alberta Lake E grain‐size spectra can be interpreted to reflect: (i) a bedload component transported during short‐duration high discharge events that reflect the intensity of the melt; and (ii) a finer suspended load component representing material whose magnitude is controlled by the volume of the spring melt. Stratigraphically, bedload and suspended load populations demonstrate different short‐wavelength and long‐wavelength cyclicity, suggesting that spring melt is likely to be driven by cyclic external forcing factors. The links between the grain‐size spectra and spring melt have potential for generating proxy records that better capture the external controls over spring melt in boreal systems and the risks associated with these energetic hydrodynamics. This is exemplified by the coarsest Alberta Lake E distributions, which indicate that more intense spring‐melt dynamics occurred in pre‐historical times.  相似文献   

Microtextural investigation (SEM and TEM study) of phyllosilicates in a major thrust fault zone (Monte Perdido, southern Pyrenees): impact on fault reactivation   总被引：1，自引：0，他引：1  

Martine D. Buatier  Brice Lacroix  Pierre Labaume  Virginie Moutarlier  Delphine Charpentier  Jean Pierre Sizun  Anna Travé 《Swiss Journal of Geoscience》2012,105(2):313-324

Thrusting fault zone in foreland basins are characterized by highly foliated zones generally enriched in phyllosilicates which can play a major role on the mechanical behaviour of the fault. In this context, investigations of synkinematic clay minerals permit to determine the origin of the fluid from which they precipitated as well as the mechanisms of deformation. Our study is focused on clay mineral assemblages (illite and chlorite) in a major thrust fault located in the Monte Perdido massif (southern Pyrenees), a shallow thrust that affects upper cretaceous-paleocene platform carbonates and lower Eocene marls and turbidites. It implied 3?km of displacement of the Monte Perdido thrust unit with respect to the underlying Gavarnie unit. In this area the cleavage development by pressure-solution is linked to the Monte Perdido and Gavarnie thrust activity. The core zone of the fault, about 6?m thick, consists of an interval of intensely deformed clay-bearing rocks bounded by major shear surfaces. The deformed sediment is markedly darker than the protolith. Calcite-quartz shear veins along the shear planes are abundant. Detailed SEM and TEM observations of highly deformed fault zone samples indicate that clay mineral enrichment in the core zone of the fault is not only related to passive increase by pressure-solution mechanism but that dissolution?Crecrystallization of phyllosilicates occurs during deformation. A mineral segregation is observed in the highly deformed zone. Newly formed 2M ₁ muscovite is present along the cleavage whereas IIb chlorite crystals fill S_V2 shear veins suggesting syntectonic growth of phyllosilicates in the presence of fluids in low-grade metamorphic conditions. These mineralogical reactions act as weakening processes and would favour Monte Perdido fault creeping.  相似文献   

Microtectonic and geochemical characterization of thrusting in a foreland basin: Example of the South-Pyrenean orogenic wedge (Spain)     

B. Lacroix  M. Buatier  P. Labaume  A. Travé  M. Dubois  D. Charpentier  S. Ventalon  D. Convert-Gaubier 《Journal of Structural Geology》2011,33(9):1359-1377

In orogenic systems, thrust faults play a major role in stacking different tectonic units and may act as conduits for the expulsion of large amounts of fluid of different origins (metamorphic, diagenetic, meteoric). This study focuses on the Monte Perdido thrust unit emplaced in the Paleogene Jaca thrust-sheet-top basin, in the SW-central Pyrenees. We aim to decipher the mechanisms and P-T conditions of deformation in fault zones and characterize the related fluid involvement, through combined microstructural, geochemical and microthermometry analyses. Two thrust faults cutting platform limestones, marls and siliciclastic turbidites of the lower part of the basin-fill (Paleocene–lower Eocene) have been studied. The fault zones are characterized by metre-thick shear zones with highly deformed, foliated clay-rich sediments. Foliation is underlined by preferentially oriented phyllosilicates. Several generations of shear and extension calcite, quartz and chlorite-bearing veins attest to fluid-rock interactions during a multi-stage deformation. Microstructural observations and stable isotope analyses on calcite from veins and host sediments suggest that deformation was aseismic and dominated by diffusive mass transfer from pressure solution sites along cleavage and stylolites to the precipitation sites in veins, with mineralizing fluids in equilibrium with the host sediments. Our results suggest an essentially closed hydrologic system, and imply the absence of significant fluid flow along the studied fault zones. Microthermometric study on fluid inclusions present in calcite and quartz veins, and calcite-quartz oxygen isotopic fractionation determined for the first generation shear veins, allow a geothermal gradient of 34 °C/km to be estimated. Analytical results demonstrate an evolution of the fault zones in three stages. The first stage was related to the emplacement of the Monte Perdido thrust unit during the middle Eocene at a temperature of ～208 °C and a burial depth of ～5.7 km. The second stage corresponds to a fault reactivation at a temperature of ～240 °C and a burial depth of ～6.5 km. The latter deformation may have been related to folding of the Monte Perdido thrust unit during the emplacement of the underlying Gavarnie thrust unit during the late Eocene–early Oligocene, with deeper burial resulting from aggradation of the thrust-sheet-top basin-fill. The last event corresponds to the formation of a dilatant vein system likely related to the exhumation of the massif.  相似文献   

A Compilation of Silicon,Rare Earth Element and Twenty‐One other Trace Element Concentrations in the Natural River Water Reference Material SLRS‐5 (NRC‐CNRC)     

Delphine Yeghicheyan  Cécile Bossy  Martine Bouhnik Le Coz  Chantal Douchet  Guy Granier  Alexie Heimburger  Francois Lacan  Aurélie Lanzanova  Tristan C. C. Rousseau  Jean‐Luc Seidel  Mickaël Tharaud  Frédéric Candaudap  Jérôme Chmeleff  Christophe Cloquet  Sophie Delpoux  Marie Labatut  Rémi Losno  Catherine Pradoux  Yann Sivry  Jeroen E. Sonke 《Geostandards and Geoanalytical Research》2013,37(4):449-467

The natural river water certified reference material SLRS‐5 (NRC‐CNRC) was routinely analysed in this study for major and trace elements by ten French laboratories. Most of the measurements were made using ICP‐MS. Because no certified values are assigned by NRC‐CNRC for silicon and 35 trace element concentrations (rare earth elements, Ag, B, Bi, Cs, Ga, Ge, Li, Nb, P, Rb, Rh, Re, S, Sc, Sn, Th, Ti, Tl, W, Y and Zr), or for isotopic ratios, we provide a compilation of the concentrations and related uncertainties obtained by the participating laboratories. Strontium isotopic ratios are also given.  相似文献   

Multivariate statistical analysis of geochemical data as indicative of the hydrogeochemical evolution of groundwater in a sedimentary rock aquifer system   总被引：15，自引：0，他引：15  

Vincent Cloutier  Ren Lefebvre  Ren Therrien  Martine M. Savard 《Journal of Hydrology》2008,353(3-4):294-313

The study of groundwater hydrogeochemistry of the Paleozoic Basses-Laurentides sedimentary rock aquifer system in Québec produced a large geochemical dataset. Groundwater samples were collected at 153 sites over a 1500 km² study area and analyzed for major and minor ions. The large number of data can lead to difficulties in the integration, interpretation and representation of the results. Two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal components analysis (PCA), were applied to a subgroup of the dataset to evaluate their usefulness to classify the groundwater samples, and to identify geochemical processes controlling groundwater geochemistry. This subgroup consisted of 144 samples and 14 parameters (Ca²⁺, Mg²⁺, Na⁺, K⁺, , Cl⁻, , Fe²⁺, Mn²⁺, Br⁻, Sr²⁺, F⁻, Ba²⁺, HS⁻). Seven geochemically distinct clusters, C1–C7, resulted from the HCA. Samples from clusters C3, C4, C6 and C7 are mostly located in preferential recharge areas. The majority of these samples have Ca–Mg–HCO₃ recharge groundwater (C3, C6, C7) and Na–HCO₃ evolved groundwater (C4). Samples from the other three clusters (C1, C2, C5) are characteristic of an aquifer system under confined conditions. The majority of these samples have Na–HCO₃ evolved groundwater (C1, C5) and Na–Cl ancient groundwater that exhibits elevated concentrations in Br⁻ (C2). In addition to recognizing the importance of hydrogeological conditions on groundwater geochemistry, the distribution of clusters also showed the importance of the geological formations on minor and trace elements, such as Fe²⁺, Mn²⁺, Sr²⁺, F⁻ and Ba²⁺. The first five components of the PCA account for 78.3% of the total variance in the dataset. Component 1 is defined by highly positive loadings in Na⁺, Cl⁻ and Br⁻ and is related to groundwater mixing with Champlain Sea water and solute diffusion from the marine clay aquitard. The high positive loadings in Ca²⁺ and Mg²⁺ of component 2 suggest the importance of dissolution of carbonate rocks in this aquifer system. From their characteristic loadings, the first two components are defined as the “salinity” and “hardness” components, respectively. Components 3–5 are related to more local and geological effects. The integration of the HCA and the PCA, with conventional classification of groundwater types, as well as with the hydrogeological and geological contexts, allowed the division of the region into four main geochemical areas, providing an improved regional picture of the aquifer system dynamics and hydrogeochemical evolution of groundwater. The following factors were recognized as influencing the evolution of groundwater identified in every geochemical area: (1) geological characteristics including sedimentary rock type and till mineralogy; (2) hydrogeological characteristics represented by the level of confinement and the hydraulic gradient; and (3) the geological history including the latest glaciation and the Champlain Sea invasion. With its integrated approach, this hydrogeochemical study contributes to the characterization and understanding of complex groundwater flow systems, and provides an example of the long-term geochemical evolution of hydrogeological systems after a major perturbation, in this case seawater invasion.  相似文献   

The essential contribution of indigenous knowledge to understanding natural hazards and disaster risk: historical evidence from the Rwenzori (Uganda)     

Bwambale  Bosco  Nyeko  Martine  Sekajugo  John  Kervyn  Matthieu 《Natural Hazards》2022,110(3):1847-1867

Natural Hazards - The integration of indigenous knowledge into understanding disasters from natural hazards is hitherto hampered by the limited conceptualization of the process that shapes...  相似文献   

Development of crystallographic preferred orientations by nucleation and growth of new grains in experimentally deformed quartz single crystals   总被引：1，自引：1，他引：0  

Martine G.C. Vernooij  Bas den Brok  Karsten Kunze 《Tectonophysics》2006,427(1-4):35

Deformation experiments have been carried out to investigate the effect of dynamic recrystallisation on crystallographic preferred orientation (CPO) development. Cylindrical samples of natural single crystals of quartz were axially deformed together with 1 vol.% of added water and 20 mg of Mn₂O₃ powder in a Griggs solid medium deformation apparatus in different crystallographic orientations with compression direction: (i) parallel to <c>, (ii) at 45° to <c> and 45° to <a> and (iii) parallel to <a>. The experiments were performed at a temperature of 800 °C, a confining pressure of 1.2 GPa, a strain rate of  10^− 6 s^− 1, to bulk finite strains of  14–36%. The deformed samples were analysed in detail using optical microscopy, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). Two different microstructural domains were distinguished in the deformed samples: (i) domains with undulatory extinction and deformation lamellae, and (ii) domains with new recrystallised grains. Within the domains of undulatory extinction, crystal-plastic deformation caused gradual rotations of the crystal lattice up to  30° away from the host orientation. New recrystallised grains show a strong CPO with c-axis maxima at  45° to the compression direction. This is the case in all experiments, irrespective of the initial crystallographic orientation. The results show that c-axes are not continuously rotated towards the new maxima. The new grains thus developed through a mechanism different from subgrain rotation recrystallisation. New grains have a subeuhedral shape and numerous microcavities, voids, fluid channels and fluid inclusions at their grain boundaries. No host control is recorded in misorientation axes across their large angle grain boundaries. New grains might have been created by nucleation from solution in the μm-scale voids and microfractures. The CPO most likely developed due to preferred growth of the freshly precipitated grains with orientations suitable for intracrystalline deformation at the imposed experimental conditions.  相似文献