Reply to the Comment on “Chronology of Vesuvius' activity from A.D. 79 to 1631 based on archeomagnetism of lavas and historical sources” by R. Lanza and E. Zanella     

Claudia Principe  Jean-Claude Tanguy  Simone Arrighi  Maxime Le Goff 《Bulletin of Volcanology》2006,68(4):397-398

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Wavelet analysis of the coherence between Bouguer gravity and topography: application to the elastic thickness anisotropy in the Canadian Shield   总被引：2，自引：0，他引：2  

Pascal Audet  Jean-Claude Mareschal 《Geophysical Journal International》2007,168(1):287-298

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Observed IRIS Profiles of the h and k Doublet of Mg ii and Comparison with Profiles from Quiescent Prominence NLTE Models     

Jean-Claude Vial  Gabriel Pelouze  Petr Heinzel  Lucia Kleint  Ulrich Anzer 《Solar physics》2016,291(1):67-87

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Rapid dome growth at Montagne Pelée during the early stages of the 1902–1905 eruption: a reconstruction from Lacroix’s data     

Jean-Claude?TanguyEmail author 《Bulletin of Volcanology》2004,66(7):615-621

Information obtained from various parts of the two books on Montagne Pelée by Lacroix enables an estimate to be made of the size of l’Etang Sec summit crater, the volume of the 1902–1905 lava dome and its growth rate at various stages of development. During the week preceding the 8 May nuée ardente, dome growth was between 28 and 38 m³ s^–1, leading to a volume of 17–23×10⁶ m³ on the morning of the catastrophe. Considering that significant parts of the dome (~1/3?) were removed by the 8 and 20 May climactic eruptions, a high magmatic flux could have continued until at least 27 May, when the total remaining volume was estimated to 53×10⁶ m³. After moderate activity in June–July (of order 10 m³ s^–1), vigorous dome growth resumed dramatically, leading to the third climactic eruption of 30 August (a true calculation for this period being not feasible because of poor quality of the data). From November 1902 to July 1903 most of the effusive activity was concentrated in the great spine (erupted volume ~15×10⁶ m³, magma flux 1.2 m³ s^–1), which was eventually destroyed by collapse and minor nuées ardentes. The end of the eruption was characterized by a very low effusion rate, <1 m³ s^–1 in average from August 1903 to October 1905.  相似文献   

Isostatic response of the large-offset Atlantic Equatorial fracture zones     

Michel Diament  Jean-Claude Sibuet  Jacques Dubois 《Marine Geophysical Researches》1986,8(3):243-264

Spectral analysis techniques have been applied to data sets of gravity and topography selected across fracture zones with large offset in the Equatorial and Central Atlantic Ocean and processed independently for each fracture zone. Three simple compensation models, two in local isostatic equilibrium (Airy I and II) and one in regional equilibrium (Plate model) have been tested. It is found that the free-air anomalies are primarily controlled by the topography and its isostatic response. For short wavelengths, admittance can be explained either by the effect of uncompensated sea floor topography with high density basement or by the effect of uncompensated sea floor topography with normal oceanic basement density but accompanied by a crust of constant thickness. For intermediate wavelengths, admittance for the Romanche fracture zone agrees best with a local isostatic model in which compensation is achieved by a less dense material in the upper mantle. No such evidence exists for the Vema and Chain fracture zones for which topography could just as well be regionally supported by an elastic plate 3 to 10 km thick. For longer wavelengths, the admittances computed for the three fracture zones are compatible with a thermal compensation of the topography.  相似文献   

Evolution des hydrocarbures dans des sédiments côtiers méditerranéens prélevés à proximité d'un emissaire d'une raffinerie de pétrole     

Gilbert Mille  Jan Yu Chen  Henri Dou  Edgar Azoulay  Maryse Colin  Jean-Claude Bertrand 《Marine environmental research》1985,17(1):65-80

Coastal Mediterranean sediments highly polluted by refinery effluents have been studied for their hydrocarbon content and bacterial activity. The study has taken into account both the distance from the refinery and depth of sampling. Very high hydrocarbon concentrations have been found (1–250 g/kg dry sediment). Micro-organisms in the sediments have a high bacterial activity and a good correlation exists between hydrocarbon concentrations and bacteria able to use these substrates as a carbon and energy source.  相似文献   

Geochemical behaviour and relative mobility of metals (Mn, Cd, Zn and Pb) in recent sediments of a retention pond along the A-71 motorway in Sologne, France     

P.-K. Lee  Patrick Baillif  Jean-Claude Touray 《Environmental Geology》1997,32(2):142-152

 Retention ponds have been dug along some of the motorways in France to minimize environmental pollution by keeping pollutants from spreading over the surrounding area. In the current work, eight core samples were collected from the bottom of a retention pond located along the A-71 motorway in Sologne to study the pollution of sediment by heavy metals and their diagenetic behaviour. The vertical concentration profiles of metals (Pb, Zn, Cd, Fe and Mn) in sediment as well as in interstitial water were determined. Especially in the case of the sediment, a sequential extraction method was employed to investigate how the movement of each metal is associated with the other metals and with other solid phases such as organic matter. In addition, to investigate the relative mobility of the metals, the distribution coefficients (K_D) were also determined. The concentrations of the metals were always found to be highest in the topmost layer of sediment. This so-called surface enrichment is caused by a substantial increase of the non-detrital fraction of these metals at the sediment surface. For instance, the accumulation of Pb and Zn is associated with the increase in the "fraction II" in the sequential extraction. The accumulation of Cd at the surface (0–2 cm) is partly due to the liberation of Cd from the particles during early diagenesis. However, the major factor contributing to the accumulation of Cd at the sediment surface is attributed to the dissolution of Cd from polluted roadside soil during the periods of rainstorms and its subsequent redeposition on the sediment surface after being carried to the retention pond. K_D values for Zn and Cd were found to decrease with depth, while K_D values for Pb increased. Based on the K_D values, the relative mobilities of the studied metals were determined to be as follows: Mn>Zn>Cd>Pb, for the upper layer, and Mn>Cd>Zn>Pb, for the layers below. Received: 28 October 1996 / Accepted: 21 November 1996  相似文献   

Transition between the Okinawa trough backarc extension and the Taiwan collision: New insights on the southernmost Ryukyu subduction zone   总被引：4，自引：0，他引：4  

Shu-Kun Hsu  Jean-Claude Sibuet  Serge Monti  Chuen-Tien Shyu  Char-Shine Liu 《Marine Geophysical Researches》1996,18(2-4):163-187

Located between the Okinawa trough (OT) backarc basin and the collisional zone in Taiwan, the southernmost Ryukyu subduction zone is investigated. This area, including the southwestern portions of the OT and Ryukyu island arc (RA) and located west of 123.5° E, is named the Taiwan-Ryukyu fault zone (TRFZ). West of 123.5° E, the OT displays NNW-SSE structural trends which are different in direction from the ENE-WSW trending pattern of the rest of the OT. Using joint analysis of bathymetric, magnetic, gravity and earthquake data, three major discontinuities, that we interpret as right-lateral strike-slip faults (Faults A, B and C), have been identified. These faults could represent major decouplings in the southern portion of the Ryukyu subduction zone: each decoupling results in a decrease of the horizontal stress on the portion of the RA located on the eastern side of the corresponding fault, which allows the extension of the eastern side of OT to proceed more freely.We demonstrate that the 30° clockwise bending of the southwestern RA and the consecutive faulting in the TRFZ are mainly due to the collision of the Luzon arc with the former RA. After the formation of Fault C, the counterclockwise rotated portion of the ancient RA located west of the Luzon arc was more parallel to the Luzon arc. This configuration should have increased the contact surface and friction between the Luzon arc and the ancient RA, which could have reduced the northward subduction of the Luzon are. Thus, the westward component of the compressive stress from the collision of the Luzon arc should become predominant in the collisional system resulting in the uplift of Taiwan. Presently, because the most active collision of the Luzon arc has migrated to the central Taiwan (at about 23° N; 121.2° E), the southwestern OT has resumed its extension. In addition, the later resistent subduction of the Gagua ridge could have reactivated the pre-existing faults A and B at 1 M.y. ago and present, respectively. From 9 to 4 M.y., a large portion of the Gagua ridge probably collided with the southwestern RA. Because of its large buoyancy, this portion of the ridge resisted to subduct beneath the Okinawa platelet. As a result, we suggest that a large exotic terrane, named the Gagua terrane, was emplaced on the inner side of the present Ryukyu trench. Since that period, the southwestern portion of the Ryukyu trench was segmented into two parallel branches separated by the Gagua ridge: the eastern segment propagated westward along the trench axis while the western segment of the trench retreated along the trench axis.  相似文献   

Paleomagnetism,magnetic fabric,and <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating of Pliocene and Quaternary ignimbrites in the Arequipa area,southern Peru     

Perrine Paquereau-Lebti  Michel Fornari  Pierrick Roperch  Jean-Claude Thouret  Orlando Macedo 《Bulletin of Volcanology》2008,70(8):977-997

⁴⁰Ar/³⁹Ar ages and paleomagnetic correlations using characteristic remanent magnetizations (ChRM) show that two main ignimbrite sheets were deposited at 4.86 ± 0.07 Ma (La Joya Ignimbrite: LJI) and at 1.63 ± 0.07 Ma (Arequipa Airport Ignimbrite: AAI) in the Arequipa area, southern Peru. The AAI is a 20–100 m-thick ignimbrite that fills in the Arequipa depression to the west of the city of Arequipa. The AAI is made up of two cooling units: an underlying white unit and an overlying weakly consolidated pink unit. Radiometric data provide the same age for the two units. As both units record exactly the same well-defined paleomagnetic direction (16 sites in the white unit of AAI: Dec = 173.7; Inc = 31.2; α95 = 0.7; k = 2749; and 10 sites in the pink unit of AAI; Dec = 173.6; Inc = 30.3; α95 = 1.2; k = 1634), showing no evidence of secular variation, the time gap between emplacement of the two units is unlikely to exceed a few years. The >50 m thick well-consolidated white underlying unit of the Arequipa airport ignimbrite provides a very specific magnetic zonation with low magnetic susceptibilities, high coercivities and unblocking temperatures of NRM above 580°C indicating a Ti-poor titanohematite signature. The Anisotropy of Magnetic Susceptibility (AMS) is strongly enhanced in this layer with anisotropy values up to 1.25. The fabric delineated by AMS was not recognized neither in the field nor in thin sections, because most of the AAI consists in a massive and isotrope deposit with no visible textural fabric. Pumices deformation due to welding is only observed at the base of the thickest sections. AMS within the AAI ignimbrite show a very well defined pattern of apparent imbrications correlated to the paleotopography, with planes of foliation and lineation dipping often at more than 20° toward the expected vent, buried beneath the Nevado Chachani volcanic complex. In contrast with the relatively small extent of the thick AAI, the La Joya ignimbrite covers large areas from the Altipano down the Piedmont. Ti-poor titanomagnetites are the dominant magnetic carriers and AMS values are generally lower than 1.05. Magnetic foliations are sub horizontal and lineations directions are scattered in the LJI. The AMS fabrics are probably controlled by post-depositional compaction and welding of the deposit rather than transport dynamics. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

A report card and quality indicators for the Seine estuary: from scientific approach to operational tool     

Dauvin JC  Fisson C  Garnier J  Lafite R  Ruellet T  Billen G  Deloffre J  Verney R 《Marine pollution bulletin》2008,57(1-5):187-201

The scientific teams from the interdisciplinary Seine-Aval (SA) research program and the SA's operational pole, GIPSA (Groupement d'Intérêt Public Seine-Aval) have worked together to create a report card designed to help the Estuary Council (Conseil de l'Estuaire) revitalize its original functions: maintaining functional links between the various estuarine ecosystems, comprehending and managing the estuary's natural habitats and biological populations, and monitoring and improving the physical-chemical quality of the estuarine waters. The report card will be able to synthesize the information obtained from several system performance variables and available operational indicators. This approach, intended to guide the estuary managers, is the oeuvre of several scientific teams; it is particularly important in the context of the Water Framework Directive because it facilitates the elaboration of a group of relevant indicators, which can then be used as operational tools. A report card will provide decision-makers (e.g., political authorities; national, regional and local institutions and industries) with the key indicators for evaluating the system and predicting changes in terms of selected objectives, such as the preservation and restoration of the estuary's environmental functionalities. The final objective of the research is to choose among the available indicators to approximate potential ecological risks. Integrating the socio-economical data will perhaps lead to setting risk acceptability thresholds for the different uses of the Seine estuary. In the end, collaboration between the scientists, the managers, and the GIPSA operational pole will be essential to produce a viable report card about the environmental status of the Seine estuary. To illustrate the research now under way, this article presents the results for three actions undertaken, concerning: (i) physical indicators (i.e., an inventory of the estuary first as a whole, and then section by section); (ii) benthic indicators (i.e., seven indices which show a moderate EcoQ for the lower part of the estuary); and (iii) a eutrophication indicator (i.e., an indicator for coastal eutrophication potential (ICEP), which helps to limit the nutrient fluxes (N or P) that exceed the silica flux delivered by the Seine network, based on the Redfield ratios for algal propagation).  相似文献