Nankai Trough, Japan Trench and Kuril Trench: geochemistry of Fluids sampled by submersible “Nautile”     

Jacques Boulgue  Jean T. Iiyama  Jean-Luc Charlou  Jacques Jedwab 《Earth and Planetary Science Letters》1987,83(1-4)

Deep-water samples collected during the Kaiko project are often associated with biological communities located on geological structures favorable to fluid venting. The evidence of fluid venting are the temperature anomalies, the decrease in sulfate concentrations, the content in methane and the lowC₁(C₂ +C₃) ratio of light hydrocarbons. Because of large dilution by ambiant seawater during sampling it is difficult to compute the composition of the advected end-member pore fluid. Part of this fluid should originate in the “petroleum window”, i.e. at temperature about 60°C. Modeling the upward flow of water, taking into account the anomalies of temperature measured on the seafloor and the geochemical anomalies, leads to non-steady-state advection of the pore fluid. The occurrence of a deep component in the fluid has implications for the geological and tectonic models of the subduction zones off Japan.  相似文献   

Effets thermique et hydrothermal de la coulée de basalte triasico-liasique sur les argiles du bassin d'Argana (Maroc)Thermal and hydrothermal effects of Triassic–Liassic basalt flow deposition on clays (Agana Basin,Morocco)     

Lahcen Daoudi  Jean-Luc Pot de Vin 《Comptes Rendus Geoscience》2002,334(7):463-468

Thermal and hydrothermal effects of Triassic–Liassic basalt flow deposition on sedimentary series of the Argana Basin are responsible for major modifications in detrital clays, until 20 m in depth. It expressed by transformation of detrital smectite to corrensite and moreover to chlorite, and by increasing illite crystallinity. On the 2 m of sediments located immediately under the flow, magnesium-rich hydrothermal fluids have caused precipitation of new mineral phases. To cite this article: L. Daoudi, J.-L. Pot de Vin, C. R. Geoscience 334 (2002) 463–468.  相似文献   

La diatomee marine chaetoceros simplex calcitrans paulsen et son environnement,I. Relations avec le milieu de culture; étude de la fraction insaponifiable,des stérols et des acides gras     

Jean-Luc Boutry  Michel Barbier 《Marine Chemistry》1974,2(3):217-227

Detailed analysis of the lipids present in seawater medium before and after growing cultures of the diatom Chaetoceros simplex calcitrans Paulsen in them has been carried out and compared with the lipids found in the diatom itself.Fatty Acids. The seawater contained 1.0 μg fatty acids/ml, C 16:0, C 18:0 and C 18:1 being the predominant components. After removal of 12-day cultures of the diatom, the medium contained 1.1 μg fatty acids/ml and showed 47% decrease of the C 18:0 acid, and decreases of 37% in the C 13:0 and 56% in the C 15:1 contents. The diatom itself contained 10.7% fatty acids of the dry weight, among which C 16:1, C 16:0 and C 14:0 predominated.Sterols. Cholesterol dominated the sterol composition of seawater, which was found to contain 0.15 μg total sterols/ml. The filtered culture medium contained 0.18 μg total sterols/ml, had lost some of its cholesterol content, but contained a significant amount of 24-methylene-cholesterol. Other minor sterols in seawater both prior to and after growing diatoms cultures in it were β-sitosterol, stigmasterol and campesterol.The diatom itself contained 0.47% total sterols of the dry weight with cholesterol and 24-methylene-cholesterol making up ca. 40% of the total each. Minor sterols found were stigmasterol (or fucosterol), campesterol and β-sitosterol.  相似文献   

Predicting the impact of land use on the major element and nutrient fluxes in coastal Mediterranean rivers: The case of the Têt River (Southern France)     

Javier Garcia-Esteves  Wolfgang Ludwig  Philippe Kerhervé  Jean-Luc Probst  Franck Lespinas 《Applied Geochemistry》2007

This study presents a detailed discrimination between the natural and anthropogenic sources of dissolved major elements in the Têt River, a typical small coastal river in the south of France. The main objectives were to quantify the materials that were released by human activities in the basin, and to determine the specific element inputs for the major land use forms. The dissolved material fluxes were estimated by weekly monitoring over a hydrological year (2000–2001) along the major water gauging stations, and the flux relationships were examined in the context of anthropogenic and natural basin characteristics as determined by a Geographical Information System (GIS). Intensive agricultural land use in the form of fruit tree cultures and vineyards has a strong control on the dissolved element fluxes in the river. Area specific element releases for these cultures are greatest for SO₄, with an estimated average of about 430 ± 18 keq km⁻² a⁻¹. This is ?11 times the natural SO₄ release by rock weathering. Also for K, NO₃, PO₄ and Mg, the specific releases were ?6 times the natural weathering rates (respectively about 44, 60, 4 and 265 keq km⁻² a⁻¹). Waste-waters are the other major source of anthropogenic elements in the river. They have an important role for the fluxes of inorganic P and N, but they are also a considerable source of Cl and Na to the river. For example, the average annual release of Cl is around 150 moles/inhabitant in the rural basin parts. Further downstream, however, where population density strongly increases, industrial effluents can enhance this value (>300 moles/inhabitant). The waste-waters contribute more than 70% of the dissolved inorganic N export to the sea, although their contribution to the average DOC export is almost negligible (3%).  相似文献   

Experimental study of D/H isotopic fractionation factor of water adsorbed on porous silica tubes     

Thierry Richard  Lionel Mercury  Marc Massault  Jean-Luc Michelot 《Geochimica et cosmochimica acta》2007,71(5):1159-1169

This paper presents D/H isotopic fractionation factor measurements of water adsorbed on porous silica tubes in isotopic equilibrium with water vapor. The fractionation factor is measured as a function of vapor pressure ranging from 10% to 80% RH (relative humidity) at room temperature. It is shown that the fractionation factor between the adsorption film or nanometrically confined water and vapor is smaller than that between bulk liquid water and vapor. A qualitative analysis relates this deuterium depletion to a modification of the zero-point energy of the water isomers in the adsorbed/confined state. Furthermore, the behavior of the fractionation factor with RH shows two different linear trends. The transition between the two (at 60% RH) may indicate the transition from a two-dimensional adsorbed water to a three-dimensional water network.  相似文献   

Evidence for fault-related directionality and localized site effects from strong motion recordings of the 2003 Boumerdes (Algeria) earthquake: Consequences on damage distribution and the Algerian seismic code   总被引：1，自引：0，他引：1  

Nasser Laouami  Abdennasser Slimani  Youcef Bouhadad  Jean-Luc Chatelain  Ali Nour 《Soil Dynamics and Earthquake Engineering》2006,26(11):991-1003

The Algiers–Boumerdes region has been struck by a destructive magnitude 6.8 (M_w) earthquake on May 21, 2003. The study presented in this paper is based on main shock strong motions from 13 stations of the Algerian accelerograph network. A maximum 0.58g peak ground acceleration (PGA) has been recorded at 20 km from the epicenter, only about 150 m away from a PGA of 0.34g, with both a central frequency around 5 Hz, explained by a strong very localized site effect, confirmed by receiver function technique results showing peaks at 5 Hz with amplitudes changing by a factor of 2. Soil amplifications are also evidenced at stations located in the quaternary Mitidja basin, explaining the higher PGA values recorded at these stations than at stations located on firm soil at similar distances from the epicenter. A fault-related directionality effect observed on the strong motion records and confirmed by the study of the seismic movement anisotropy, in agreement with the N65 fault plan direction, explains the SW–NE orientation of the main damage zone. In the near field, strong motions present a high-frequency content starting at 3 Hz with a central frequency around 8 Hz, while in the far field their central frequency is around 3 Hz, explaining the high level of damage in the 3- to 4-story buildings in the epicentral zone. The design spectra overestimate the recorded mean response spectra, and its high corner frequency is less than the recorded one, leading to a re-examination of the seismic design code that should definitively integrate site-related coefficient, to account for the up to now neglected site amplification, as well as a re-modeling of the actual design spectra. Finally, both the proposed Algerian attenuation law and the worldwide laws usually used in Algeria underestimate the recorded accelerations of the 6.8 (M_w) Boumerdes earthquake, clearly showing that it is not possible to extrapolate the proposed Algerian law to major earthquakes.  相似文献   

Optical studies of natural deformation microstructures in feldspars (gneiss and pegmatites from Occitania,southern France)     

Pierre Debat  Jean-Claude Soula  Ladislas Kubin  Jean-Luc Vidal 《Lithos》1978,11(2):133-145

Natural deformation microstructures of feldspars have been investigated optically in augen gneisses and pegmatites from southern France that exhibit microstructures due to polyphase deformation. This deformation was produced in both cases under a pressure of about 2 Kb and a temperature decreasing from about 550° to 200–300°C.In microcline, recrystallization, tension gashes and shear planes are the most important microstructures observed. In plagioclase, shear planes and kink-bands prevail. The development of these structures is controlled primarily by three parameters: temperature, influence of the surrounding material and amount of bulk strain. The orientation of the planes of anisotropy of the minerals with respect to the compression axis is also important. Some perthitic patterns are ascribed to deformation.  相似文献   

Metal corrosion and argillite transformation at the water-saturated,high-temperature iron–clay interface: A microscopic-scale study     

Michel L. Schlegel  Christian Bataillon  Keltoum Benhamida  Cécile Blanc  Denis Menut  Jean-Luc Lacour 《Applied Geochemistry》2008

In this study, microscopic and spectroscopic techniques (scanning electron microscopy coupled with energy-dispersive X-ray analysis, Raman microspectroscopy, micro X-ray fluorescence spectroscopy, micro X-ray fine structure adsorption spectroscopy, and micro laser-induced breakdown spectroscopy) were combined to decipher the chemical and mineralogical properties of a saturated Fe–clay interface reacted at 90 °C and 50 bar for 8 months. The results collectively confirm the presence of a corrosion layer and a clay transformation layer. The corrosion layer is made of a magnetite-containing internal sublayer and a Fe-phyllosilicate external sublayer enriched in Na, with traces of goethite presumably resulting from sample reaction with air. The clay transformation layer is made of predominantly Ca-rich siderite (FeCO₃). It is depleted in Al and K, suggesting dissolution of rock-forming minerals. The corroded thickness determined from the amount of Fe in corrosion and transformation layers and assuming zero porosity equals 19 ± 9 μm. These data indicate that the interfacial clay was transformed by dissolution of calcite and clay minerals and precipitation of siderite close to the original surface. Silica released upon clay dissolution diffused into the corrosion layer and coprecipitated with oxidized Fe to form Fe-phyllosilicate.  相似文献   

Adapting to climate change: a comparison of two strategies for dike heightening     

Arjen Y. Hoekstra  Jean-Luc De Kok 《Natural Hazards》2008,47(2):217-228

In the Netherlands the current dike design policy is to design flood defence structures corresponding to an agreed flooding probability with an extra safety board of at least 0.5 m. For river dikes a return period of 1,250 years is used to determine the design water levels. A problem with this strategy is that it builds on assumptions with regard to the intrinsically uncertain probability distributions for the peak discharges. The uncertainty is considerable and due to (1) the measuring records that are limited to about 100 years and (2) the changing natural variability as a result of climate change. Although the probability distributions are regularly updated based on new discharge data the nature of the statistics is such that a change in the natural variability of the peak discharge affects the probability distribution only long after the actual change has happened. Here we compare the performance of the probabilistic dike design strategy with the older strategy, referred to as the ‘self-learning dike’. The basic principle of the latter strategy is that the dike height is kept at a level equal to the highest recorded water level plus a certain safety margin. The two flood prevention strategies are compared on the basis of the flooding safety over a 100-year period. The Rhine gauge station at Lobith serves as case study. The results indicate that the self-learning dike performs better than the probabilistic design in terms of safety and costs, both under current and climate change conditions.  相似文献   

Eruptive parameters and dynamics of the April 2015 sub-Plinian eruptions of Calbuco volcano (southern Chile)     

Angelo Castruccio  Jorge Clavero  Andrea Segura  Pablo Samaniego  Olivier Roche  Jean-Luc Le Pennec  Bárbara Droguett 《Bulletin of Volcanology》2016,78(9):62

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