赫德和中法和约

中法战争期间 ,中国海关总税务司赫德积极插手中法谈判 ,在不同的阶段中扮演了不同的角色。在充当法国侵略者的帮凶遭到中国政府和人民的坚决反对后 ,他在照顾中国利益的基础上 ,促成了中法两国签订了和约 ,结束了战争     

Non-marine selachians from the basal Cretaceous of Charente,SW France

A gypsum quarry at Cherves-de-Cognac in south-western France exposes a large section of Berriasian (basal Cretaceous) sediments deposited in a lagoonal environment. The sediments have yielded rich vertebrate faunas, but only two species of selachians are present; the lonchidiid hybodont Parvodus celsucuspus sp. nov. and the batoid Belemnobatis variabilis. The composition of the fauna, including only a single, seemingly endemic, hybodont species from a time when hybodont faunas are relatively well investigated in Europe, indicate that small hybodonts were not able to migrate longer distances. The recorded batoid species also occurs in southern England, demonstrating that these batoids were primarily marine fishes that regularly explored areas with reduced salinity.     

The Geomorphology of Valley-Floor Troughs Illustrated From Depositional Sequences in the Durance Valley,Southeast France

Three kinds of valley-floor troughs occur in the Durance catchment of southeast France. Details of widths and spatial variations of 10 different sedimentary forms are presented to show how these relate to the present types of troughs and their margins. Internal controls, such as geology, altitude, and available relief, provide a wide variety of conditions, which have been modified through time by external controls such as past and present climates and their hydrological regimes, as well as by anthropogenic activity over several millennia. The 10 sedimentary forms occupy more than 900 km² or 6.4% of the total catchment area, with the present enlarged floodplain having just over 50% of this area. The present channel occupies less than 10%, which is less than the Würm terrace (17.2%) but somewhat more than the marginal colluvia in the lower valley (8.6%). The other forms include older Pleistocene terraces, moraines from the last three glacial stages, and alluvial fans. It is the type of trough and its relative age that condition what, where, and how much of past and present sedimentary forms can survive.     

A study on trade-offs between spatial resolution and temporal sampling density for wheat yield estimation using both thermal and calendar time

Within-season forecasting of crop yields is of great economic, geo-strategic and humanitarian interest. Satellite Earth Observation now constitutes a valuable and innovative way to provide spatio-temporal information to assist such yield forecasts. This study explores different configurations of remote sensing time series to estimate of winter wheat yield using either spatially finer but temporally sparser time series (5daily at 100 m spatial resolution) or spatially coarser but denser (300 m and 1 km at daily frequency) time series. Furthermore, we hypothesised that better yield estimations could be made using thermal time, which is closer to the crop physiological development. Time series of NDVI from the PROBA-V instrument, which has delivered images at a spatial resolution of 100 m, 300 m and 1 km since 2013, were extracted for 39 fields for field and 56 fields for regional level analysis across Northern France during the growing season 2014-2015. An asymmetric double sigmoid model was fitted on the NDVI series of the central pixel of the field. The fitted model was subsequently integrated either over thermal time or over calendar time, using different baseline NDVI thresholds to mark the start and end of the cropping season. These integrated values were used as a predictor for yield using a simple linear regression and yield observations at field level. The dependency of this relationship on the spatial pixel purity was analysed for the 100 m, 300 m and 1 km spatial resolution. At field level, depending on the spatial resolution and the NDVI threshold, the adjusted R² ranged from 0.20 to 0.74; jackknifed – leave-one-field-out cross validation – RMSE ranged from 0.6 to 1.07 t/ha and MAE ranged between 0.46 and 0.90 t/ha for thermal time analysis. The best results for yield estimation (adjusted R² = 0.74, RMSE =0.6 t/ha and MAE =0.46 t/ha) were obtained from the integration over thermal time of 100 m pixel resolution using a baseline NDVI threshold of 0.2 and without any selection based on pixel purity. The field scale yield estimation was aggregated to the regional scale using 56 fields. At the regional level, there was a difference of 0.0012 t/ha between thermal and calendar time for average yield estimations. The standard error of mean results showed that the error was larger for a higher spatial resolution with no pixel purity and smaller when purity increased. These results suggest that, for winter wheat, a finer spatial resolution rather than a higher revisit frequency and an increasing pixel purity enable more accurate yield estimations when integrated over thermal time at the field scale and at the regional scale only if higher pixel purity levels are considered. This method can be extended to larger regions, other crops, and other regions in the world, although site and crop-specific adjustments will have to include other threshold temperatures to reflect the boundaries of phenological activity. In general, however, this methodological approach should be applicable to yield estimation at the parcel and regional scales across the world.     

Dating results on sedimentary quartz,bones and teeth from the Middle Pleistocene archaeological site of Coudoulous I (Lot,SW France): A comparative study between TT-OSL and ESR/U-series methods

This study presents palaeodosimetric results from the Middle Pleistocene archaeological site of Coudoulous I (Lot, SW France). Nine sedimentary quartz samples (41–60 μm) have been analyzed using a multiple aliquot protocol based on the measurement of the TT-OSL signal. In addition, 7 teeth and 7 bones have been dated by combining the ESR method with U-series analyses. Both methods gave consistent age results allowing correlation of the Early Middle Paleolithic Human occupation of the site to MIS 6 and part of the Lower Paleolithic tools to MIS 7. Beyond the establishment of a radiometric chronology for the Coudoulous I sequence, this study focuses on the information extracted from the intercomparison of the methods. Our data suggest that 1) the TT-OSL signal is stable over at least the last 230 ka (considering the age range of the studied samples), 2) there are not significant problems of incomplete bleaching leading support to the applicability of the TT-OSL technique for sedimentary deposits associated with karstic contexts. This approach highlights the interest of combining luminescence and ESR/U-series methods to discuss the reliability of the dating results.     

Crystal clustering in magmas: Insights from HP–HT experiments

We have studied by high-resolution X-ray Computed Tomography the effect of crystal clustering on the Shape-Preferred Orientation (SPO) development in synthetic magmas experimentally deformed at 300 MPa and 475–550°C. A fully connected solid network that could potentially induce the onset of yield strength is not achieved in these suspensions containing 16 vol% of crystals. The alumina grain population exhibits a glomeroporphyritic texture made of isolated grains (59.6%) and clusters of touching grains (40.4%). The SPO of the sub-population of isolated grains exhibits foliation and lineation, which are closely parallel to the plane and direction of shear, respectively. The SPO of clustered grains has little influence overall shape fabric. The angular relationships between the average foliation and cluster elongation provide a good indicator of the shear sense. Finally, we highlight the strain partitioning between nearly non-deformed large clusters acting as rigid glomerocrysts and highly sheared zones in low concentrated suspensions.     

Identification of an underfilled foreland basin system in the Upper Devonian of the Central Pyrenees: implications for the Hercynian orogeny

A foreland basin succession has been identified in the Frasnian of the Central Pyrenees. This succession comprises a carbonate-dominated transgressive system which recorded the cratonward migration of the foreland basin subsidence, and siliciclastic depocenters which recorded the progression of the thrust-fold deformation. The foreland basin system has always been maintained in deep-marine environments, i.e., at an underfilled depositional state. It was associated with a thrust wedge which descended toward a deep-marine hinterland, i.e., with a type of orogenic wedge usually related to subduction zones. The Frasnian foreland basin system differs from the one known in the Carboniferous which evolved to overfilled depositional state and was associated with a thrust wedge rising toward a mountainous hinterland. Consequently, the Hercynian orogeny in the Pyrenees seems to result first, from a Frasnian thrusting controlled by a subduction zone located north of the Pyrenees, and second, from a Carboniferous thrusting controlled by the surrection of a frontal thrust belt in the Pyrenees. The association of underfilled foreland basin systems and hinterland-dipping thrust wedges, as exemplified in the Frasnian of the Pyrenees, can be interpreted as illustrative of the initial stages of thrust-wedge growth in deep-marine settings.     

The uppermost Middle and Upper Albian succession at the Col de Palluel, Hautes-Alpes, France: An integrated study (ammonites, inoceramid bivalves, planktonic foraminifera, nannofossils, geochemistry, stable oxygen and carbon isotopes, cyclostratigraphy)

An integrated study of the ammonites, inoceramid bivalves, planktonic foraminifera, calcareous nannofossils, geochemistry, stable carbon isotopes, and cyclostratigraphy is provided for the upper Middle to upper Upper Albian sucession exposed in the Col de Palluel section east of Rosans in Hautes-Alpes, France. The Albian-Cenomanian boundary interval described by Gale et al. at Mont Risou is re-examined, a total thickness of 370 m of the Marnes Bleues Formation. Zonal schemes based on ammonites, inoceramid bivalves, planktonic foraminifera, and calcareous nannofossils are integrated with the stable carbon isotope curve and key lithostratigraphic markers to provide a sequence of more than 70 events in the uppermost Middle Albian to basal Cenomanian interval. Time series analysis of the Al₂O₃ content of the 500 m Albian sequence present in the Col de Palluel and Risou sections reveals the presence of the 20 kyr precession, 40 kyr tilt, 100 kyr short eccentricity, and 406 kyr long eccentricity cycles. Correlation using planktonic foraminiferan and nannofossil data provide a link between the Col de Palluel and Risou sections and the Italian sequence at Gubbio, and in the Piobbico core. This provides a basis for the extension of the orbital time scale of Grippo et al. to the sequence. It reveals a major break in the Col de Palluel succession at the top of the distinctive marker bed known as the Petite Vérole that may represent as much as 2 Ma. It also provides a basis for the estimation of the length of the Albian Stage at 4.12 Ma, 0.8 Ma for the early Albian, 2.84 Ma for the Middle Albian, and 3.68 Ma for the late Albian substages.     

A methodological approach of fluvial dynamics oriented towards hydrosystem management: case study of the Loire and Allier rivers

Abstract

This study was conducted as part of the European LIFE Loire Nature program for the conservation and management of a 110-km-long section of the Loire and Allier rivers, an area renowned for its ecological richness. The methodological approach is based on statistical analysis (bivariate and multivariate analyses) of hydro-geomorphologic and biogeographical variables, complemented by reach typology and mapping. The main results show, on the one hand, the great spatial variability of fluvial mosaic complexity along the river continuum and on the other hand, some independence between the riparian forest characteristics and the channel forms. The fluvial pattern (e.g. anabranching) and the forest establishment along the Loire river register specific features. © 2000 Éditions scientifiques et médicales Elsevier SAS     

Progressive shortening axis rotation recorded by Variscan synkinematic granites : example of the South Armorican shear zone in the Vendée (France)

The Variscan continental collision is expressed by large shear zones in Western Europe. The synthesis of granite ages, related to different deformation fields in the Vendée area, suggests a geodynamic model for the tectonic evolution of this part of the Variscan belt between 370 Ma – 320 Ma. After the first step of the continental collision, leading to high temperature and anatexis at 375-360 Ma, the south-eastern part of the Armorican massif underwent large dextral shearing along N110-N125 trending shear zones, related to a bulk NNW-SSE shortening direction, up to early Visean time. Large-scale displacements progressively decreased at around 345-340Ma. During middle Visean time, the shortening axis direction rotated towards a NNE-SSW position implying changes in the regional deformation field. The occurrence of N70-N100 sinistral and N110-N130 dextral conjugate shear zones within leucogranites are related to that epoch. Finally, a new dextral shear zone system, trending N130-N150 along the Parthenay shear zone, occurs during late Visean time. This progressive middle Visean change of shortening direction probably corresponds to a major change in the Iberian plate motion and indentation during the Mississipian collision.