Does fish scale morphology allow the identification of populations at a local scale? A case study for rostrum dace Leuciscus leuciscus burdigalensis in River Viaur (SW France)   总被引：1，自引：0，他引：1  

Nicolas Poulet  Yorick Reyjol  Hélène Collier  Sovan Lek 《Aquatic Sciences - Research Across Boundaries》2005,67(1):122-127

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Le Viséen supérieur d'Azarhare (Maroc central) : environnements de dépôt,datation et évolution diagénétique     

Atika Karim  Mostafa Berkhli  Daniel Vachard  Nicolas Tribovillard  Beate Orberger 《Comptes Rendus Geoscience》2005,337(5):525-532

The unexplored area of Azarhare in central Morocco is studied thanks to three sections composed of five lithological facies Main biostratigraphical and sedimentological results concern (1) the identification of Late Visean biozones, with important presence of problematic algae Ungdarella, (2) the regional extension of deposit sequences SD5, SD6 and SD7 previously defined, (3) and an analysis of the diagenetic kaolinite. To cite this article: A. Karim et al., C. R. Geoscience 337 (2005).  相似文献   

Apport de l'imagerie satellitaire radar pour l'exploration géologique en zones arides     

Nicolas Baghdadi  Gilles Grandjean  Didier Lahondère  Philippe Paillou  Yannick Lasne 《Comptes Rendus Geoscience》2005,337(8):719-728

The potential of radar imagery in geological exploration was investigated at a study site in Mauritania (Akjoujt region). Compared with optical images, the results obtained show how radar imagery can help not only in detecting surface geological structures such as dykes and veins, but also mapping subsurface structures beneath a shallow layer of sand (palaeochannels). The mapping potential was found to be much better at long wavelengths than at short ones (L-band, compared with C- and X-band). As for optical images, their contribution is much more limited in the mapping of surface geological structures, and inappropriate for detecting subsurface structures. We conclude that spatial remote sensing enables the improvement of existing geological maps and the optimization of cartographic surveying. To cite this article: N. Baghdadi et al., C. R. Geoscience 337 (2005).  相似文献   

CO₂-H₂O mixtures in the geological sequestration of CO₂. II. Partitioning in chloride brines at 12-100°C and up to 600 bar     

Nicolas Spycher  Karsten Pruess 《Geochimica et cosmochimica acta》2005,69(13):3309-3320

Correlations presented by Spycher et al. (2003) to compute the mutual solubilities of CO₂ and H₂O are extended to include the effect of chloride salts in the aqueous phase. This is accomplished by including, in the original formulation, activity coefficients for aqueous CO₂ derived from several literature sources, primarily for NaCl solutions. Best results are obtained when combining the solubility correlations of Spycher et al. (2003) with the activity coefficient formulation of Rumpf et al. (1994) and Duan and Sun (2003), which can be extended to chloride solutions other than NaCl. This approach allows computing mutual solubilities in a noniterative manner with an accuracy typically within experimental uncertainty for solutions up to 6 molal NaCl and 4 molal CaCl₂.  相似文献   

Chronology and stratigraphy of the Magdalen Islands archipelago from the last glaciation to the early Holocene: new insights into the glacial and sea‐level history of eastern Canada          下载免费PDF全文

Audrey M. Rémillard  Guillaume St‐Onge  Pascal Bernatchez  Bernard Hétu  Jan‐Pieter Buylaert  Andrew S. Murray  Benoit Vigneault 《Boreas: An International Journal of Quaternary Research》2016,45(4):604-628

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Does stress transmission in forelands depend on structural style? Distinctive stress magnitudes during Sevier thin‐skinned and Laramide thick‐skinned layer‐parallel shortening in the Bighorn Basin (USA) revealed by stylolite and calcite twinning paleopiezometry     

Nicolas Beaudoin  Olivier Lacombe  Marie‐Elonore David  Daniel Koehn 《地学学报》2020,32(3):225-233

The Sheep Mountain‐Little Sheep Mountain Anticlines, Bighorn Basin (USA) formed as basement‐cored Laramide structures in the formerly undeformed foreland of the thin‐skinned Sevier orogen. We take advantage of the well‐constrained microstructural network there to reconstruct differential stress magnitudes that prevailed during both Sevier and Laramide layer‐parallel shortening (LPS), before the onset of large‐scale folding. Differential stress magnitudes determined from tectonic stylolites are compared and combined to previous stress estimates from calcite twinning paleopiezometry in the same formations. During stress loading related to LPS, differential stress magnitudes transmitted from the distant Sevier thin‐skinned orogen into the sedimentary cover of the Bighorn basin (11–43 MPa) are higher than the differential stress magnitudes accompanying the early stage of LPS related to the thick‐skinned Laramide deformation (2–19 MPa). This study illustrates that the tectonic style of an orogen affects the transmission of early orogenic stress into the stable continental interior.  相似文献   

Chemical and textural equilibration of garnet during amphibolite facies metamorphism: The influence of coupled dissolution–reprecipitation          下载免费PDF全文

Tim J Dempster  Julie La Piazza  Andrew G Taylor  Nicolas Beaudoin  Peter Chung 《Journal of Metamorphic Geology》2017,35(9):1111-1130

Metamorphic equilibration requires chemical communication between minerals and may be inhibited through sluggish volume diffusion and or slow rates of dissolution in a fluid phase. Relatively slow diffusion and the perceived robust nature of chemical growth zoning may preclude garnet porphyroblasts from readily participating in low‐temperature amphibolite facies metamorphic reactions. Garnet is widely assumed to be a reactant in staurolite‐isograd reactions, and the evidence for this has been assessed in the Late Proterozoic Dalradian pelitic schists of the Scottish Highlands. The 3D imaging of garnet porphyroblasts in staurolite‐bearing schists reveals a good crystal shape and little evidence of marginal dissolution; however, there is also lack of evidence for the involvement of either chlorite or chloritoid in the reaction. Staurolite forms directly adjacent to the garnet, and its nucleation is strongly associated with deformation of the muscovite‐rich fabrics around the porphyroblasts. “Cloudy” fluid inclusion‐rich garnet forms in both marginal and internal parts of the garnet porphyroblast and is linked both to the production of staurolite and to the introduction of abundant quartz inclusions within the garnet. Such cloudy garnet typically has a Mg‐rich, Mn‐poor composition and is interpreted to have formed during a coupled dissolution–reprecipitation process, triggered by a local influx of fluid. All garnet in the muscovite‐bearing schists present in this area is potentially reactive, irrespective of the garnet composition, but very few of the schists contain staurolite. The staurolite‐producing reaction appears to be substantially overstepped during the relatively high‐pressure Barrovian regional metamorphism reflecting the limited permeability of the schists in peak metamorphic conditions. Fluid influx and hence reaction progress appear to be strongly controlled by subtle differences in deformation history. The remaining garnet fails to achieve chemical equilibrium during the reaction creating distinctive patchy compositional zoning. Such zoning in metamorphic garnet created during coupled dissolution–reprecipitation reactions may be difficult to recognize in higher grade pelites due to subsequent diffusive re‐equilibration. Fundamental assumptions about metamorphic processes are questioned by the lack of chemical equilibrium during this reaction and the restricted permeability of the regional metamorphic pelitic schists. In addition, the partial loss of prograde chemical and textural information from the garnet porphyroblasts cautions against their routine use as a reliable monitor of metamorphic history. However, the partial re‐equilibration of the porphyroblasts during coupled dissolution–reprecipitation opens possibilities of mapping reaction progress in garnet as a means of assessing fluid access during peak metamorphic conditions.  相似文献   

Segmentation and kinematics of the North America‐Caribbean plate boundary offshore Hispaniola          下载免费PDF全文

Sylvie Leroy  Nadine Ellouz‐Zimmermann  Jordane Corbeau  Frédérique Rolandone  Bernard Mercier de Lépinay  Bertrand Meyer  Roberte Momplaisir  José‐Luis Granja Bruña  Anne Battani  Céline Baurion  Evgueni Burov  Valérie Clouard  Rémy Deschamps  Christian Gorini  Youri Hamon  Manfred Lafosse  Jottin Leonel  Laetitia Le Pourhiet  Pilar Llanes Estrada  Nicolas Loget  Francis Lucazeau  Daniel Pillot  Jeffrey Poort  Kevin R. Tankoo  José‐Luis Cuevas  José‐Fernando Alcaide  Claude Jean Poix  Alfonso Muñoz‐Martin  Serge Mitton  Yamil Rodriguez  Julien Schmitz  Leonardo Seeber  Andres Carbo‐Gorosabel  Santiago Muñoz 《地学学报》2015,27(6):467-478

We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high‐resolution multibeam echo‐sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate‐boundary structures are a series of strike‐slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre‐existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike‐slip regime. Along the most recent trace of the SOFZ, we measured a strike‐slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS‐derived motion of 9.8 ± 2 mm a^?1 has remained stable during the entire Quaternary.  相似文献   

Development of a rain‐on‐snow detection algorithm using passive microwave radiometry          下载免费PDF全文

Caroline Dolant  Alexandre Langlois  Benoit Montpetit  Ludovic Brucker  Alexandre Roy  Alain Royer 《水文研究》2016,30(18):3184-3196

Currently observed climate warming in the Arctic has numerous consequences. Of particular relevance, the precipitation regime is modified where mixed and liquid precipitation can occur during the winter season leading to rain‐on‐snow (ROS) events. This phenomenon is responsible for ice crust formation, which has a significant impact on ecosystems (such as biological, hydrological, ecological and physical processes). The spatially and temporally sporadic nature of ROS events makes the phenomenon difficult to monitor using meteorological observations. This paper focuses on the detection of ROS events using passive microwave (PMW) data from a modified brightness temperature (T_B) gradient approach at 19 and 37 GHz. The approach presented here was developed empirically for observed ROS events with coincident ground‐based PMW measurements in Sherbrooke, Quebec, Canada. It was then tested in Nunavik, Quebec, with the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR‐E). We obtained a detection accuracy of 57, 71 and 89% for ROS detection for three AMSR‐E grid cells with a maximum error of 7% when considering all omissions and commissions with regard to the total number of AMSR‐E passes throughout the winter period. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

<Emphasis>H</Emphasis>ydrological variability of the <Emphasis>S</Emphasis>oummam watershed <Emphasis>(N</Emphasis>ortheastern <Emphasis>A</Emphasis>lgeria<Emphasis>)</Emphasis> and the possible links to climate fluctuations     

Imen?TurkiEmail author  Benoit?Laignel  Nicolas?Massei  Zeneddine?Nouaceur  Nadir?Benhamiche  Khodir?Madani 《Arabian Journal of Geosciences》2016,9(6):477

The long-term variability of rainfall in the Soummam watershed (NE Algeria) has been analysed over the past 108 years using continuous wavelet method in order to identify the interannual modes controlling the rainfall variability. Statistical analyses of rainfall timeseries have shown its distribution following five periods of time, limited by a series of discontinuities around 1935, 1950, 1970 and 1990. The continuous wavelet transform have demonstrated different low frequency modes: 2–4, 4–8, 8–16 and 16–32 years.The annual band is expanded during the full study period with some pics around 1905, 1920–1935 and 1960; it shows a negative long-term trend, in particular since the period 1970–1990 when a major change has been identified. Then, the relationships between climate patterns of North Atlantic Oscillation (NAO) and Southern Oscillation Index (SOI) and the hydrological variability in the frequency domain have been investigated; they have shown a mean explained variance of 40 and 24 %, respectively. Such variances are less obvious for the annual mode and increase for the interannual frequencies. The coherence suffer from high perturbations since the period 1970–1990 when the NAO (SOI) shifts from negative (positive) phases to positive (negative) ones. Such anomalies are responsible for significant changes of rainfall variability, emphasising the global warming effects.  相似文献