Populating a building Multi Representation Data Base with photogrammetric tools: Recent progress     

Benoit Frdricque  Sylvie Daniel  Yvan Bdard  Nicolas Paparoditis 《ISPRS Journal of Photogrammetry and Remote Sensing》2008,63(4):441-460

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Deformation Patterns of an Accretionary Wedge in the Transition Zone from Subduction to Collision Offshore Southwestern Taiwan   总被引：1，自引：0，他引：1  

Char-Shine Liu  Benoit Deffontaines  Chia-Yu Lu  Serge Lallemand 《Marine Geophysical Researches》2004,25(1-2):123-137

Swath bathymetry data and seismic reflection profiles have been used to investigate details of the deformation pattern in the area offshore southwestern Taiwan where the Luzon subduction complex encroaches on the passive Chinese continental margin. Distinctive fold-and-thrust structures of the convergent zone and horst-and-graben structures of the passive margin are separated by a deformation front that extends NNW-ward from the eastern edge of the Manila Trench to the foot of the continental slope. This deformation front gradually turns into a NNE–SSW trending direction across the continental slope and the Kaoping Shelf, and connects to the frontal thrusts of the mountain belt on land Taiwan. However, the complex Penghu submarine canyon system blurs the exact location of the deformation front and nature of many morphotectonic features offshore SW Taiwan. We suggest that the deformation front offshore SW Taiwan does not appear as a simple structural line, but is characterized by a series of N–S trending folds and thrusts that terminate sequentially in an en-echelon pattern across the passive Chinese continental slope. A number of NE–SW trending lineaments cut across the fold-and-thrust structures of the frontal accretionary wedge and exhibit prominent dextral displacement indicative of the lateral expulsion of SW Taiwan. One of the prominent lineaments, named the Yung-An lineament, forms the southeastern boundary of the upper part of the Penghu submarine canyon, and has conspicuous influence over the drainage pattern of the canyon  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   

The combined use of satellite and seismic monitoring during the 1996 eruption of Pavlof volcano, Alaska     

A.L. Roach  J.P. Benoit  K.G. Dean  S.R. McNutt 《Bulletin of Volcanology》2001,62(6-7):385-399

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Axtell,a new CV3 chondrite find from Texas     

S. B. Simon  L. Grossman  I. Casanova  S. Symes  P. Benoit  D. W. G. Sears  J. F. Wacker 《Meteoritics & planetary science》1995,30(1):42-46

Abstract— We describe a previously unreported meteorite found in Axtell, Texas, in 1943. Based on the mineralogical composition and texture of its matrix and the sizes and abundance of chondrules, we classify it as a CV3 carbonaceous chondrite. The dominant opaque phase in the chondrules is magnetite, and that in refractory inclusions is Ni-rich NiFe metal (awaruite). Axtell, therefore, belongs to the oxidized subgroup of CV3 chondrites, although unlike Allende it escaped strong sulfidation. The meteorite bears a strong textural resemblance to Allende, and its chondrule population and matrix appear to be quite similar to those of Allende, but its refractory inclusions, thermoluminescence properties, and cosmogenic ⁶⁰Co abundances are not. Our data are consistent with a terrestrial age for Axtell of ～100 years and a metamorphic grade slightly lower than that of Allende.  相似文献   

Effect of the processing methodology on satellite altimetry-based global mean sea level rise over the Jason-1 operating period     

Olivier Henry  Michael Ablain  Benoit Meyssignac  Anny Cazenave  Dallas Masters  Steve Nerem  Gilles Garric 《Journal of Geodesy》2014,88(4):351-361

Determining how the global mean sea level (GMSL) evolves with time is of primary importance to understand one of the main consequences of global warming and its potential impact on populations living near coasts or in low-lying islands. Five groups are routinely providing satellite altimetry-based estimates of the GMSL over the altimetry era (since late 1992). Because each group developed its own approach to compute the GMSL time series, this leads to some differences in the GMSL interannual variability and linear trend. While over the whole high-precision altimetry time span (1993–2012), good agreement is noticed for the computed GMSL linear trend (of $3.1\pm 0.4$  mm/year), on shorter time spans (e.g., ${<}10~\hbox {years}$ ), trend differences are significantly larger than the 0.4 mm/year uncertainty. Here we investigate the sources of the trend differences, focusing on the averaging methods used to generate the GMSL. For that purpose, we consider outputs from two different groups: the Colorado University (CU) and Archiving, Validation and Interpretation of Satellite Oceanographic Data (AVISO) because associated processing of each group is largely representative of all other groups. For this investigation, we use the high-resolution MERCATOR ocean circulation model with data assimilation (version Glorys2-v1) and compute synthetic sea surface height (SSH) data by interpolating the model grids at the time and location of “true” along-track satellite altimetry measurements, focusing on the Jason-1 operating period (i.e., 2002–2009). These synthetic SSH data are then treated as “real” altimetry measurements, allowing us to test the different averaging methods used by the two processing groups for computing the GMSL: (1) averaging along-track altimetry data (as done by CU) or (2) gridding the along-track data into $2^{\circ }\times 2^{\circ }$ meshes and then geographical averaging of the gridded data (as done by AVISO). We also investigate the effect of considering or not SSH data at shallow depths $({<}120~\hbox {m})$ as well as the editing procedure. We find that the main difference comes from the averaging method with significant differences depending on latitude. In the tropics, the $2^{\circ }\times 2^{\circ }$ gridding method used by AVISO overestimates by 11 % the GMSL trend. At high latitudes (above $60^{\circ }\hbox {N}/\hbox {S}$ ), both methods underestimate the GMSL trend. Our calculation shows that the CU method (along-track averaging) and AVISO gridding process underestimate the trend in high latitudes of the northern hemisphere by 0.9 and 1.2 mm/year, respectively. While we were able to attribute the AVISO trend overestimation in the tropics to grid cells with too few data, the cause of underestimation at high latitudes remains unclear and needs further investigation.  相似文献   

Reionization and the Cosmic Dawn with the Square Kilometre Array     

Garrelt Mellema  Léon V. E. Koopmans  Filipe A. Abdalla  Gianni Bernardi  Benedetta Ciardi  Soobash Daiboo  A. G. de Bruyn  Kanan K. Datta  Heino Falcke  Andrea Ferrara  Ilian T. Iliev  Fabio Iocco  Vibor Jelić  Hannes Jensen  Ronniy Joseph  Panos Labroupoulos  Avery Meiksin  Andrei Mesinger  André R. Offringa  V. N. Pandey  Jonathan R. Pritchard  Mario G. Santos  Dominik J. Schwarz  Benoit Semelin  Harish Vedantham  Sarod Yatawatta  Saleem Zaroubi 《Experimental Astronomy》2013,36(1-2):235-318

The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21 cm line from the earliest phases of star and galaxy formation in the Universe. This 21 cm signal provides a new and unique window both on the time of the formation of the first stars and accreting black holes and the subsequent period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope.  相似文献   

Determination of Rare Earth Elements, Sc, Y, Zr, Ba, Hf and Th in Geological Samples by ICP-MS after Tm Addition and Alkaline Fusion   总被引：2，自引：0，他引：2  

Germain Bayon  Jean Alix Barrat  Joël Etoubleau  Mathieu Benoit  Claire Bollinger  Sidonie Révillon 《Geostandards and Geoanalytical Research》2009,33(1):51-62

We present a revised method for the determination of concentrations of rare earth (REE) and other trace elements (Y, Sc, Zr, Ba, Hf, Th) in geological samples. Our analytical procedure involves sample digestion using alkaline fusion (NaOH-Na₂O₂) after addition of a Tm spike, co-precipitation on iron hydroxides, and measurement by sector field-inductively coupled plasma-mass spectrometry (SF-ICP-MS). The procedure was tested successfully for various rock types (i.e., basalt, ultramafic rock, sediment, soil, granite), including rocks with low trace element abundances (sub ng g⁻¹). Results obtained for a series of nine geological reference materials (BIR-1, BCR-2, UB-N, JP-1, AC-E, MA-N, MAG-1, GSMS-2, GSS-4) are in reasonable agreement with published working values.  相似文献   

210Pb and 137Cs dating methods in lakes: A retrospective study   总被引：1，自引：0，他引：1  

Gaboury Benoit  Tim F. Rozan 《Journal of Paleolimnology》2001,25(4):455-465

²¹⁰Pb has been used for more than two decades to provide the geochronology of annually deposited sediments and to construct pollution histories. Evidence from some lakes suggests that this radionuclide may be adequately mobile to compromise dating reliability. This study provides one test of that possibility by comparing recent measurements of ²¹⁰Pb and trace metals to ones carried out more than 20 yrs in the past. ¹³⁷Cs dating is used to confirm sediment accumulation rates in the recent cores. In the three Connecticut, USA, lakes studied, sediment accumulation rates changed abruptly to higher values between 40-50 yrs ago (increasing by factors of 2.2, 2.9, and 3.0). In all three lakes, rates calculated from ²¹⁰Pb distributions both above and below this horizon agreed, within measurement uncertainty, in recent and older cores. Furthermore, when the older data were corrected for 20 yrs of burial, the changes in slope in ²¹⁰Pb distributions occurred at the same depth in each pair of cores. The depth of sharp peaks in concentrations of trace metals also matched. In general, this evidence supports the idea that sediments in these lakes have simply been buried, without significant diagenetic remobilization of ²¹⁰Pb and trace metals . Nevertheless, some important differences were also observed. For two of the three lakes, there was a significant difference in average sediment accumulation rate during the past 33 yrs as calculated from ¹³⁷Cs and ²¹⁰Pb in the recent cores. Most potential causes for this difference can be ruled out, and it appears that one of the two nuclides is remobilized compared to the other. There were also significant differences in the total inventories of both ²¹⁰Pb and trace metals (both up to 2 ×) between recent and older cores in some cases. This may be due to dissimilar sediment focusing, since it is not known for certain whether the new cores were collected at exactly the same sites as in the past.  相似文献   

Equilibrium state of diopside-bearing harzburgites from ophiolites: Geobarometric and geodynamic implications   总被引：5，自引：0，他引：5  

Jean -Claude C. Mercier  Vincent Benoit  Jacques Girardeau 《Contributions to Mineralogy and Petrology》1984,85(4):391-403

The bulk compositions of coexisting enstatite and diopside in basal lherzolites and clinopyroxene-bearing harzburgites from ophiolitic complexes are typical of solidus/subsolidus equilibria, but for a few texturally distinct magmatic diopsides. They would presumably reflect the state of equilibrium at the time they last coexisted with liquid as the rocks reentered subsolidus conditions. The total lack of correlation between Al and Ca concentrations shows that the compositional scatter observed for any given massif, results from analytical errors related to extensive exsolution and serpentinization, rather than from differences in equilibrium conditions. However, significant differences are found between the residual ophiolitic lherzolites from Hare Bay, Newfoundland, and from Xigaze, Tibet, two massifs selected for their distinct structural and textural features. As for thermobarometry techniques relevant to these rocks, the best barometer found is an empirical relation for the expression of pressure as a virtually temperature-independent function of the ratioK _f=(X _Di ^opx )/(1 –X _Di ^cpx ), in agreement with semi-quantitative models based on natural solid solutions. Temperatures are then simply derived from a surface-fitting expression relating pressure, temperature and diopside-solvus compositions, according to a regularX _En ^cpx solution model (CMS) corrected for the effect of Al in the spinel facies. Application of these techniques yield pressures of 0.4 and 1.4 GPa, i.e. depths from sea-bottom of about 13 and 43 km, for temperatures of 1,170 and 1,300° C for the ophiolitic lherzolites of Tibet and New-foundland, respectively, in good agreement with dry-solidus data by radioactive tracing and with geothermal-model estimates for ridges.  相似文献