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Mauffret Alain Leroy Sylvie Vila Jean-Marie Hallot Erwan Mercier de Lépinay Bernard Duncan Robert A. 《Marine Geophysical Researches》2001,22(1):17-45
Using the diving submersible survey NAUTICA we investigated the central part of the Caribbean large igneous province (CLIP) to observe and sample internal portions of this proposed oceanic plateau. Most of the samples are gabbroic and doleritic rocks; basalts are scarce. Radiometric dating by 40Ar/39Ar incremental heating experiments indicate that the intrusive rocks are Campanian in age (81–75 Ma). In some places these intrusive rocks underlie older Santonian (85–83 Ma) extrusive basaltic rocks, suggesting that the Campanian rocks represent a sill injection and an underplating episode. Results of the diving program supplemented by information from ODP and DSDP drilling sites document a 20 m.y. period (94–75 Ma) of igneous activity in the submerged portion of the Caribbean large igneous province (CLIP). In the northern part of the Beata Ridge late Campanian and/or post Campanian uplift is documented by prominent Maastrichtian (71–65 Ma) erosion and the establishment of a Paleocene-middle Eocene (65–49 Ma) carbonate platform. During and after the uplift an extensional period is indicated by seismic images and the subsidence (3 km depth) of the carbonate platform. Paleocene ages (55–56 Ma) determined on some volcanic samples are attributed to localised decompression mantle melting that accompanied the extension. We document a prolonged period of magmatic and tectonic events that do not fit with the current models of short-lived plateau formation during mantle plume initiation but shares many similarities with the constructional histories of other oceanic large igneous provinces. 相似文献
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Wolfram Wobrock Andrea I. Flossmann Marie Monier Jean-Marc Pichon Laurent Cortez Jean-Franois Fournol Alfons Schwarzenbck Stephan Mertes Jost Heintzenberg Paolo Laj Giordano Orsi Loretta Ricci Sandro Fuzzi Harry Ten Brink Piet Jongejan Ren Otjes 《Atmospheric Research》2001,58(4):7907
The second field campaign of the Cloud Ice Mountain Experiment (CIME) project took place in February 1998 on the mountain Puy de Dôme in the centre of France. The content of residual aerosol particles, of H2O2 and NH3 in cloud droplets was evaluated by evaporating the drops larger than 5 μm in a Counterflow Virtual Impactor (CVI) and by measuring the residual particle concentration and the released gas content. The same trace species were studied behind a round jet impactor for the complementary interstitial aerosol particles smaller than 5 μm diameter. In a second step of experiments, the ambient supercooled cloud was converted to a mixed phase cloud by seeding the cloud with ice particles by the gas release from pressurised gas bottles. A comparison between the physical and chemical characteristics of liquid drops and ice particles allows a study of the fate of the trace constituents during the presence of ice crystals in the cloud.In the present paper, an overview is given of the CIME 98 experiment and the instrumentation deployed. The meteorological situation during the experiment was analysed with the help of a cloud scale model. The microphysics processes and the behaviour of the scavenged aerosol particles before and during seeding are analysed with the detailed microphysical model ExMix. The simulation results agreed well with the observations and confirmed the assumption that the Bergeron–Findeisen process was dominating during seeding and was influencing the partitioning of aerosol particles between drops and ice crystals. The results of the CIME 98 experiment give an insight on microphysical changes, redistribution of aerosol particles and cloud chemistry during the Bergeron–Findeisen process when acting also in natural clouds. 相似文献
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Pablo Samaniego Claude Robin Gilles Chazot Erwan Bourdon Joseph Cotten 《Contributions to Mineralogy and Petrology》2010,160(2):239-260
Geochemical studies of long-lived volcanic complexes are crucial for the understanding of the nature and composition of the
subduction component of arc magmatism. The Pichincha Volcanic Complex (Northern Andean Volcanic Zone) consists of: (1) an
old, highly eroded edifice, the Rucu Pichincha, whose lavas are mostly andesites, erupted from 1,100 to 150 ka; and (2) a
younger, essentially dacitic, Guagua Pichincha composite edifice, with three main construction phases (Basal Guagua Pichincha,
Toaza, and Cristal) which developed over the last 60 ka. This structural evolution was accompanied by a progressive increase
of most incompatible trace element abundances and ratios, as well as by a sharp decrease of fluid-mobile to fluid-immobile
element ratios. Geochemical data indicate that fractional crystallization of an amphibole-rich cumulate may account for the
evolution from the Guagua Pichincha andesites to dacites. However, in order to explain the transition between the Rucu Pichincha
andesites and Guagua Pichincha dacites, the mineralogical and geochemical data indicate the predominance of magma mixing processes
between a mafic, trace-element depleted, mantle-derived end-member, and a siliceous, trace-element enriched, adakitic end-member.
The systematic variation of trace element abundances and ratios in primitive samples leads us to propose that the Rucu Pichincha
magmas came from a hydrous-fluid metasomatized mantle wedge, whereas Guagua Pichincha magmas are related to partial melting
of a siliceous-melt metasomatized mantle. This temporal evolution implies a change from dehydration to partial melting of
the slab, which may be associated with an increase in the geothermal gradient along the slab due to the presence of the subducted
Carnegie Ridge at the subduction system. This work emphasizes the importance of studying arc-magma systems over long periods
of time (of at least 1 million of years), in order to evaluate the potential variations of the slab contribution into the
mantle source of the arc magmatism. 相似文献
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Daniel Paradis Laurie Tremblay René Lefebvre Erwan Gloaguen Alfonso Rivera Michel Parent Jean-Marc Ballard Yves Michaud Patrick Brunet 《Environmental Earth Sciences》2014,72(5):1325-1348
Providing a sound basis for aquifer management or remediation requires that hydrogeological investigations carried out to understand groundwater flow and contaminant transport be based on representative data that capture the heterogeneous spatial distribution of aquifer hydraulic properties. This paper describes a general workflow allowing the characterization of the heterogeneity of the hydraulic properties of granular aquifers at an intermediate scale of a few km2. The workflow involves characterization and data integration steps that were applied on a 12-km2 study area encompassing a decommissioned landfill emitting a leachate plume and its main surface water receptors. The sediments composing the aquifer were deposited in a littoral–sublittoral environment and show evidence of small-scale transitional heterogeneities. Cone penetrometer tests (CPT) combined with soil moisture and electrical resistivity (SMR) measurements were thus used to identify and characterize spatial heterogeneities in hydraulic properties over the study area. Site-specific statistical relationships were needed to infer hydrofacies units and to estimate hydraulic properties from high-resolution CPT/SMR soundings distributed all over the study area. A learning machine approach was used due to the complex statistical relationships between colocated hydraulic and CPT/SMR data covering the full range of aquifer materials. Application of this workflow allowed the identification of hydrofacies units and the estimation of horizontal hydraulic conductivity, vertical hydraulic conductivity and porosity over the study area. The paper describes and discusses data acquisition and integration methodologies that can be adapted to different field situations, while making the aquifer characterization process more time-efficient and less labor-intensive. 相似文献
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Hydrodynamics and sediment resuspension events, induced at the shoreline by a deep-draft vessel passing nearby, are described.
Measurements (pressure, currents and turbidity) were obtained at 4 Hz, on a lower beach ~50 m from a channel where large car
ferries operate in Wootton Creek, Isle of Wight. The study focuses on a representative 8-min 32-s-long record, during which
two large vessels passed the channel section. At the shore, the passage of each vessel induced a long-period water-level drawdown,
followed by a water-level oscillation (seiche) of similar period, and the short-period waves of the wake. Both drawdowns were
the main constituents of the prevailing wave pattern. The second drawdown was the largest in amplitude, in response to a higher
speed of the ferry, and the influence of the seiche which had been activated during the preceding event. Two successive peaks
of turbidity were observed shortly after this drawdown. Analyses of current velocity and direction indicate that the sediments
resuspended originated from the shallower upper beach. Anthropogenically induced erosion of the foreshore is predicted at
Wootton Creek. 相似文献
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Comprehensive study of the drying behavior of Boom clay: Experimental investigation and numerical modeling 
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下载免费PDF全文 Julien Hubert Erwan Plougonven Noémie Prime Angélique Léonard Frédéric Collin 《国际地质力学数值与分析法杂志》2018,42(2):211-230
This paper presents a thermo‐hydro‐mechanical framework to model the drying behavior of Boom clay. First, the experimental campaign conducted Noémie Prime is briefly presented because it is used to validate the model. The data acquisition and processing is emphasized because of the use of X‐ray microtomography to be able to more accurately compare experimental and numerical strain fields. The different submodels are introduced. Numerical simulations are performed to illustrate the capability of the proposed model to reproduce the observed behavior. Finally, a comprehensive sensitivity study on several key model parameters associated with the water retention curve, and the permeability of the medium, is performed to get a better understanding of the physics behind the coupled model. 相似文献
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New analysis of Lunar Prospector radio tracking data brings the nearside gravity field of the Moon with an unprecedented resolution 总被引：1，自引：0，他引：1
A new analysis of the Doppler tracking data from the Lunar Prospector mission in 1999 revealed a number of previously-unseen gravity anomalies at spatial scales as small as 27 km over the nearside. The tracking data at low altitudes (50 km or below) were better analyzed to resolve the nearside features without dampening from a power law constraint, by partitioning the gravity parameters concentrated on either the nearside or farside. The resulting model presents gravity anomalies correlated with topography with a correlation coefficient of 0.7 or higher from degree 50 to 150, the widest bandwidth yet. The gravity-topography admittance of ∼70 mGal/km is found from numerous craters of which diameters are 60 km or less. In addition, the new model produces orbits that fit to independent radio tracking data from the Lunar Reconnaissance Orbiter and Kaguya (SELENE) better than previous gravity models. This high-resolution model can be of immediate use to geophysical analysis of small craters. Our technique could be applied to an upcoming mission, the Gravity Recovery And Interior Laboratory and useful to extract short wavelength signals from the MESSENGER Doppler data. 相似文献