Comment on ‘Magnetic studies of magma-supply and sea-floor metamorphism: Troodos ophiolite dikes’, by G.J. Borradaile and D. Gauthier     

Jean-Paul Callot  Laurent Geoffroy  Charles Aubourg 《Tectonophysics》2007,433(1-4):141-147

Anisotropy of magnetic susceptibility is used as a proxy for the determination of magmatic flow direction in mafic dykes. Here we take advantage of the dataset from G.J. Borradaile and D. Gauthier to comment three points: (1) the sampling strategy; (2) the geometric relationship between magnetic axis dyke, and, (3) an alternative interpretation to obtain a flow direction. The magnetic lineations published by Borradaile and Gauthier correspond to the zone axis of the dyke and magnetic foliation poles, questioning the reliability of the magnetic lineation as a flow estimate. An alternative interpretation is based on the use of the tiling of the magnetic foliation plane against the dyke wall.  相似文献   

Analysis of karst hydrodynamics through comparison of dissolved and suspended solids' transport     

Danièle Valdes  Jean-Paul Dupont  Nicolas Massei  Benoît Laignel  Joël Rodet 《Comptes Rendus Geoscience》2005,337(15):1365-1374

In karst systems, rain events often result in a decrease of the conductivity (a tracer of dissolved phase transport) and an increase in turbidity (a tracer of suspended solids transport) at wells and springs. This study shows that the comparison of suspended solids and solute transport by the coupled approach of $T\text{–}C$ curves (Turbidity–Conductivity) and autocorrelations gives evidence of the transport processes in the karst network and allows understanding the karst hydrodynamics. To cite this article: D. Valdes et al., C. R. Geoscience 337 (2005).  相似文献   

A multiply imaged, submillimetre-selected ultraluminous infrared galaxy in a galaxy group at z∼ 2.5     

Jean-Paul Kneib  Paul P. van der Werf  Kirsten Kraiberg Knudsen  Ian Smail  rew Blain  Dave Frayer  Vicki Barnard  Rob Ivison 《Monthly notices of the Royal Astronomical Society》2004,349(4):1211-1217

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A site effect study in the Verchiano valley during the 1997 Umbria-Marche (Central Italy) earthquakes     

Stéphane Gaffet  Giovanna Cultrera  Michel Dietrich  Françoise Courboulex  Fabrizio Marra  Michel Bouchon  Arrigo Caserta  Cécile Cornou  Anne Deschamps  Jean-Paul Glot  Robert Guiguet 《Journal of Seismology》2000,4(4):525-541

Strong site effects were observed during the two M _W 5.7 and M _W 6.0 main shocks of the Colfiorito seismic crisis which occured on September 26, 1997 in Umbria-Marche (Central Italy).The most obvious indications of these effects are the dramatic differences in damage shown by buildings of similar construction in neighboring villages.Such observations were specifically made in the Verchiano valley in the fault area, 15 km south of Colfiorito where the Verchiano village and the Colle and Camino hamlets were heavily damaged (MCS intensity IX-X) since the first main shock of 1997/09/26,while in contrast, the Curasci village located 2 km eastwards remains almost intact.In order to study the anomalous ground motion amplifications in this area, an array of 11, 3-components seismo- and accelero-meters was set up during the 1997/10/20-24 period, extending from the western side of the valley, up to the top of Mount San Salvatore, going accross the Colle and Curasci hamlets.During the experiment, 67 aftershocks enlightened the valley from the Colfiorito (10 km north) and the Sellano (6 km south) active swarms.Seismic refraction experiments were conducted at the same time in the 500 m wide, 1500 m long Verchiano valley in order to determine the thickness and main characteristics of the alluvial infilling.The main results are: (i) compared to the valley side ground motion, and for all the events, recordings in the central part of the valley (piana di Verchiano) show relative amplification of 10 with a clear lengthening of the seismogram duration by a factor of 2 – (ii) broad band relative amplification of 6–8 is also clearly identified at the top of the Mount San Salvatore overhanging the valley – (iii) any of the site effect measurements done explains by itself the strongly contrasted damage observed at Colle and Curasci: i.e. the modification of the near-field radiation pattern by interaction with the free heterogeneous surface may have induced local shadow zones that saved Curasci.  相似文献   

Constraining the mass distribution of galaxies using galaxy–galaxy lensing in clusters and in the field     

Marceau Limousin  Jean-Paul Kneib  Priyamvada Natarajan 《Monthly notices of the Royal Astronomical Society》2005,356(1):309-322

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Dynamic patterns of dissolved nitrogen in the Southern Bight of the North Sea     

Willy Baeyens  Jean-Paul Mommaerts  Leo Goeyens  Frank Dehairs  Hugues Dedeurwaerder  Ghislain Decadt 《Estuarine, Coastal and Shelf Science》1984,18(5):499-510

Spatial and temporal variations of dissolved inorganic nitrogen (DIN) have been assessed in onshore and offshore areas of the Southern Bight on the basis of several years' measurements. They indicate that both the residual flow lines and DIN isoconcentration lines run parallel with the coast except in the vicinity of important freshwater discharge points such as the Scheldt estuary. Evidence was found that the seasonal DIN oscillations are not created through fluctuations in input conditions at the lateral boundaries, despite considerable fluctuations in these inputs which include the English Channel (from 500 tons(t) N day^?1 in June up to approximately 2000 t N day^?1 in February) and also rivers such as the Scheldt estuary (up to 50 t N day^?1 in January but less than 5 t N day^?1 in June–July). In both the onshore and offshore areas the sum of daylight phytoplanktonic nitrogen intake and sediment release of nitrogen corresponds to the observed DIN variations during most of the year. Pelagic N-mineralization from natural or grazing mortality of phytoplankton (220 mg N m^?2 day^?1 onshore at its maximum) can account for the differences (200 mg N m^?2 day^?1 onshore at its maximum), especially at the end of the phytoplankton spring bloom. Although the causes of DIN oscillations onshore and offshore are the same, the results differ because offshore (1) the vegetative season lasts longer, and (2) DIN is exhausted at the end of the phytoplankton spring bloom.  相似文献   

3-D upper mantle shear velocity and attenuation from fundamental mode free oscillation data     

G. Roult  B. Romanowicz  J. P. Montagner 《Geophysical Journal International》1990,101(1):61-80

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Les cinquantes premières années des Eclogae geologicae Helvetiae: au service des géologues suisses et de la géologie     

Jean-Paul Schaer 《Swiss Journal of Geoscience》2007,100(1):5-22

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Cluster lenses     

Jean-Paul Kneib  Priyamvada Natarajan 《Astronomy and Astrophysics Review》2011,19(1):47-100

Clusters of galaxies are the most recently assembled, massive, bound structures in the Universe. As predicted by General Relativity, given their masses, clusters strongly deform space-time in their vicinity. Clusters act as some of the most powerful gravitational lenses in the Universe. Light rays traversing through clusters from distant sources are hence deflected, and the resulting images of these distant objects therefore appear distorted and magnified. Lensing by clusters occurs in two regimes, each with unique observational signatures. The strong lensing regime is characterized by effects readily seen by eye, namely, the production of giant arcs, multiple images, and arclets. The weak lensing regime is characterized by small deformations in the shapes of background galaxies only detectable statistically. Cluster lenses have been exploited successfully to address several important current questions in cosmology: (i) the study of the lens(es)—understanding cluster mass distributions and issues pertaining to cluster formation and evolution, as well as constraining the nature of dark matter; (ii) the study of the lensed objects—probing the properties of the background lensed galaxy population—which is statistically at higher redshifts and of lower intrinsic luminosity thus enabling the probing of galaxy formation at the earliest times right up to the Dark Ages; and (iii) the study of the geometry of the Universe—as the strength of lensing depends on the ratios of angular diameter distances between the lens, source and observer, lens deflections are sensitive to the value of cosmological parameters and offer a powerful geometric tool to probe Dark Energy. In this review, we present the basics of cluster lensing and provide a current status report of the field.  相似文献   

Metacraton: Nature,genesis and behavior     

Jean-Paul Liégeois  Mohamed G. Abdelsalam  Nasser Ennih  Aziouz Ouabadi 《Gondwana Research》2013,23(1):220-237

In this paper, we show with examples that cratons involved in intercontinental collisions in a lower plate position are often affected by orogenic events, leading to the transformation of their margins. In some cases, craton interiors can also be shaped by intense collisional processes, leading to the generation of intracratonic orogenic belts. We propose to call these events “metacratonization” and the resulting lithospheric tract “metacraton”. Metacratons can appear similar to typical orogenic belts (i.e. active margin transformed by collisional processes) but are actually sharply different. Their main distinctive characteristics (not all are present in each metacraton) are: (1) absence of pre-collisional events; (2) absence of lithospheric thickening, high-pressure metamorphism being generated by subduction, leading to high gradient in strain and metamorphic intensity; (3) preservation of allochthonous pre-collisional oceanic terranes; (4) abundant post-collisional magmatism associated with shear zones but not with lithospheric thickening; (5) presence of high-temperature–low-pressure metamorphism associated with post-collisional magmatism; (6) intracontinental orogenic belts unrelated to subduction and oceanic basin closures. Reactivation of the rigid but fractured metacratonic lithosphere will cause doming, asthenospheric volcanism emplacement, and mineralizations due to repetitive mineral enrichments. This paper provides several geological cases exemplifying these different metacratonic features in Scandinavia, Sahara, Central Africa and elsewhere. A special focus is given to the Saharan Metacraton because it is where the term “metacraton” originated and it is a vastly expanded tract of continental crust (5,000,000 km²). Metacratonization is a common process in the Earth's history. Considering the metacraton concept in geological studies is crucial for understanding the behavior of cratons and their partial destruction.  相似文献