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   

Combating Desertification and Improving Local Livelihoods through the GGWI in the Sahel Region: The Example of Senegal     

Salif Diop  Aliou Guisse  Claude Sene  Birane Cisse  Ndeye Rokhaya Diop  Sokhna Di  Ka  Amady Gnagna Cisse  Saly Sambou  Ousmane Ndiaye  Adand  Belarmain Fandohan  FU Chao  WANG Guoqin  WANG Yongdong 《资源与生态学报(英文版)》2018,9(3):257-265

The Great Green Wall Initiative (GGWI) has an overall objective of fighting desert encroachment through proven practices of sustainable management of land, and the reinforcement and protection of natural resources and systems of production and transformation, while also ensuring socio-economic development of local communities through multi-purpose activity platforms. The activities described in the present study are designed to accomplish several goals: (1) generate wealth, (2) strengthen access to basic social services, (3) manage the transition to a green economy as a means of creating suitable conditions for the emergence of rural production centers, (4) integrate sustainable development in order to eradicate poverty and food insecurity, and (5) strengthen adaptation and resilience capacities of local populations. The present study was undertaken on the basis of a wide variety of available publications and documentation, including articles and scientific papers, thesis, meeting summaries and reports, concerning the implementation of the Great Green Wall Initiative/GGWI in Senegal.  相似文献   

Chronology of Quaternary terrace deposits at the locality Hohle Gasse (Pratteln,NW Switzerland)     

Anne Claude  Naki Akçar  Susan Ivy-Ochs  Fritz Schlunegger  Philippe Rentzel  Christine Pümpin  Dmitry Tikhomirov  Peter W. Kubik  Christof Vockenhuber  Andreas Dehnert  Meinert Rahn  Christian Schlüchter 《Swiss Journal of Geoscience》2017,110(3):793-809

The Quaternary stratigraphy of the Alpine Foreland consists of distinct terrace levels, which have been assigned to four morphostratigraphic units: Höhere (Higher) Deckenschotter, Tiefere (Lower) Deckenschotter, Hochterrasse (High Terrace) and Niederterrasse (Lower Terrace). Here, we focus on the terrace gravels at Hohle Gasse, SSE of Pratteln near Basel, which are mapped as Tiefere Deckenschotter. Petrographic and morphometric data established from clasts allowed to infer the transport mechanisms and sources of the gravels. Sedimentological analyses indicate that the gravels were transported by a braided river and deposited in a distal glaciofluvial setting. In addition, it can be shown that the majority of the clasts display multiple reworking and only a minority maintained a distinct glaciofluvial shape. Cosmogenic multi-isotope dating using ¹⁰Be and ³⁶Cl allowed direct dating of the sediments at the study site. A depth-profile age of \(2 70_{ - 1 90}^{ + 8 30}\) ka for ¹⁰Be was achieved for the deposits at Hohle Gasse. Unfortunately, no age could be modelled from the ³⁶Cl concentrations as the blank correction was too high. Furthermore, this age proves that the studied terrace level should be assigned to the morphostratigraphic unit Hochterrasse.  相似文献   

Multiscale modelling in soil and rock mechanics     

Jolanta Lewandowska  Claude Boutin  Moulay Said El Youssoufi 《Acta Geophysica》2014,62(5):991-992

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Retrieval of the boundary layer height from active and passive remote sensors. Comparison with a NWP model     

Livio Belegante  Doina Nicolae  Anca Nemuc  Camelia Talianu  Claude Derognat 《Acta Geophysica》2014,62(2):276-289

In this study, we used boundary layer heights derived from lidar in Romania to validate the Weather Research Forecast (WRF) model improved by ARIA Technologies SA in the framework of ROMAIR LIFE project. Lidar retrievals were also compared to the retrievals from meteorological data, both modeled (Global Data Assimilation System; GDAS) and measured (microwave radiometry). Both the gradient and the wavelet covariance methods were used to compute the boundary layer height (BLH) from the range corrected lidar signal, and their equivalence was shown. The analysis was performed on 102 datasets, spread over all seasons and 3 years (2009–2011). A good agreement was found for the remote sensors (lidar and microwave radiometer) which are co-located and measure simultaneously. The correlation of the measured boundary layer height and the modelled one was 0.66 for the entire dataset, and 0.73 when considering daytime data, i.e., for a well defined boundary layer. A systematic underestimation of the boundary layer height by the WRF during non-convective periods (nocturne, stable atmosphere) was found.  相似文献   

Modelling colloid association with plutonium: The effect of pH and redox potential     

Claude Degueldre  Magdalena Bolek 《Applied Geochemistry》2009,24(2):310-318

An analytical expression that evaluates the effect of pH and the redox potential (E) on Pu-colloid association was studied on a model basis. It includes surface complexation with one type of surface site and its formulation leads to a distribution coefficient (K_d) as a function of the pH (hydrolysis) and E (redox sensitive species). The formulation also considers the values of the stability and hydrolysis constants for all species present in solution and associated at the surface. Correlations between hydrolysis and surface complexation constants reported in the literature have been applied systematically to evaluate sorption of all species for each colloid system. The presence of ligands in solution was also taken into account. The model was applied to study the association of Pu onto colloids coated with AlOH, FeOH or SiOH groups in the presence and in the absence of carbonates in solution. The tests performed with the model suggest that the oxidation of Pu(III) to Pu(IV) has the potential to increase sorption, as demonstrated by the increased K_d values. Under natural conditions Pu may be present at oxidation states of (III)--(VI), and the effect of redox potential is significant because of the differences in the sorption of each oxidation state. When carbonates are present in the solution, the calculated values of distribution coefficient were lower than those calculated in the absence of carbonates, particularly in the case of Pu(VI). The K_d values obtained with the developed model are compared with experimental values reported for the sorption of Pu onto colloids. This model can equally be applied to study the sorption of other redox sensitive elements.  相似文献   

Book reviews     

Jim Renwick  Marie‐Claude Larivière  Ian Hawes 《新西兰海洋与淡水研究杂志》2013,47(6):1339-1344

Climate change in contrasting river basins: adaptation strategies for water, food and environment. Edited by J Aerts and P Droogers. Published in 2004 by CABI Publishing, 288 p., hardcover. ISBN: 0–85199–835–6. Price: US$100 (orders: services@dadirect.com.au).

Australian water bugs. Their biology and identification (Hemiptera‐Heteroptera, Gerromorpha &; Nepomorpha). By Nils M Andersen? and Tom A Weir. Published in 2004 by CSIRO Publishing/Apollo Books, P.O. Box 1139, Collingwood, VIC 3066, Australia. 344 p., hardcover. ISBN: 0–643–090517. Price: AU$135.00 (orders: publishing.sales@csiro.au).

The Lakes Handbook. Volume I: Limnology and Limnetic Ecology. Volume II: Lake restoration and rehabilitation. Edited by Patrick O'Sullivan and Colin Reynolds. Published by Blackwell Publishing Ltd., 109 Cowley Road, Oxford OX4 1JF, United Kingdom (http//www.blackwellpublishing.com). Volume I (published in 2003) 712 p., hardcover. ISBN: 0632047976. Price: £125. Volume II (published in 2004) 568 p., hardcover. ISBN: 063204795X. Price: £125.  相似文献   

From outwash to coastal systems in the Portneuf–Forestville deltaic complex (Québec North Shore): Anatomy of a forced regressive deglacial sequence          下载免费PDF全文

Pierre Dietrich  Jean‐François Ghienne  Mathieu Schuster  Patrick Lajeunesse  Alexis Nutz  Rémy Deschamps  Claude Roquin  Philippe Duringer 《Sedimentology》2017,64(4):1044-1078

Deglacial sequences typically include backstepping grounding zone wedges and prevailing glaciomarine depositional facies. However, in coastal domains, deglacial sequences are dominated by depositional systems ranging from turbiditic to fluvial facies. Such deglacial sequences are strongly impacted by glacio‐isostatic rebound, the rate and amplitude of which commonly outpaces those of post‐glacial eustatic sea‐level rise. This results in a sustained relative sea‐level fall covering the entire depositional time interval. This paper examines a Late Quaternary, forced regressive, deglacial sequence located on the North Shore of the St. Lawrence Estuary (Portneuf Peninsula, Québec, Canada) and aims to decipher the main controls that governed its stratigraphic architecture. The forced regressive deglacial sequence forms a thick (>100 m) and extensive (>100 km²) multiphased deltaic complex emplaced after the retreat of the Laurentide Ice Sheet margin from the study area ca 12 500 years ago. The sedimentary succession is composed of ice‐contact, glaciomarine, turbiditic, deltaic, fluvial and coastal depositional units. A four‐stage development is recognized: (i) an early ice‐contact stage (esker, glaciomarine mud and outwash fan); (ii) an in‐valley progradational stage (fjord head or moraine‐dammed lacustrine deltas) fed by glacigenics; (iii) an open‐coast deltaic progradation, when proglacial depositional systems expanded beyond the valley outlets and merged together; and (iv) a final stage of river entrenchment and shallow marine reworking that affected the previously emplaced deltaic complex. Most of the sedimentary volume (10 to 15 km³) was emplaced during the three‐first stages over a ca 2 kyr interval. In spite of sustained high rates of relative sea‐level fall (50 to 30 mm·year^?1), delta plain accretion occurred up to the end of the proglacial open‐coast progradational stage. River entrenchment only occurred later, after a significant decrease in the relative sea‐level fall rates (<30 mm·year^?1), and was concurrent with the formation and preservation of extensive coastal deposits (raised beaches, spit platform and barrier sands). The turnaround from delta plain accretion to river entrenchment and coastal erosion is interpreted to be a consequence of the retreat of the ice margin from the river drainage basins that led to the drastic drop of sediment supply and the abrupt decrease in progradation rates. The main internal stratigraphic discontinuity within the forced regressive deglacial sequence does not reflect changes in relative sea‐level variations.  相似文献   

Spatial Variation in the Optical Properties of Dissolved Organic Matter (DOM) in Lakes on the Canadian Precambrian Shield and Links to Watershed Characteristics   总被引：1，自引：0，他引：1  

Kristin K. Mueller  Claude Fortin  Peter G. C. Campbell 《Aquatic Geochemistry》2012,18(1):21-44

In the present study, we explored the use of various optical parameters to detect differences in the composition of the dissolved organic matter (DOM) in a set of lakes that are all located on the Canadian Precambrian Shield, but within which Cu and Ni speciation predictions were previously shown to diverge from measured values in some lakes but not in others. Water samples were collected with in situ diffusion samplers in 2007 (N = 18 lakes) and 2008 (N = 8 lakes). Significant differences in DOM quality were identified between the sampling regions (Rouyn-Noranda, Québec and Sudbury, Ontario) and among lakes, based on dissolved organic carbon concentrations ([DOC]), specific UV absorbance (SUVA₂₅₄), fluorescence indices (FI), and excitation–emission matrix (EEM) fluorescence measurements. Parallel factor analysis (PARAFAC) of the EEM spectra revealed four components, two of which (C3, oxidized quinone fluorophore of allochthonous origin, and C4, tryptophan-like protein fluorescence of autochthonous origin) showed the greatest inter-regional variation. The inter-lake differences in DOM quality were consistent with the regional watershed characteristics as determined from satellite imagery (e.g., watershed-to-lake surface area ratios and relative percentages of surface water, rock outcrops vegetative cover and urban development). Source apportionment plots, built upon PARAFAC components ratios calculated for our lakes, were used to discriminate among DOM sources and to compare them to sources identified in the literature. These results have implications for other areas of research, such as quantifying lake-to-lake variations in the influence of organic matter on the speciation of trace elements in natural aquatic environments.  相似文献   

Estimation of viscoelastic attenuation of real seismic data by use of ray tracing software: Application to the detection of gas hydrates and free gas     

Fateh Bouchaala  Claude Guennou 《Comptes Rendus Geoscience》2012,344(2):57-66

Analysis of P wave velocity profiles and seismic data recorded over the 2002 Hydratech cruise conducted in the Storegga region, North of Norway, has shown the existence of anomalies (a velocity decrease) in some layers of the medium. An elastic propagation model is not sufficient to explain clearly these anomalies, since the viscoelastic attenuation, represented by the quality factor Q_P, is sensitive to physical phenomena of geological media. The combination of the quality factor profile with the velocity profile leads to realistic explanations of these anomalies. In this article, we explain the procedure which we developed for determining the Q_P profile from the P wave velocity profile and the seismic data recorded during Hydratech cruise. Both the Q_P and velocity profiles indicate anomalies in the same layers. Based on previous studies, we interpret that these anomalies are being due to existence of gas hydrates and free gas within these layers.  相似文献