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Felix V. Kaminsky Sergei M. Sablukov Elena A. Belousova Paulo Andreazza Mousseau Tremblay William L. Griffin 《Lithos》2010,114(1-2):16-29
The Juina diamond field, in the 1970–80s, was producing up to 5–6 million carats per year from rich placer deposits, but no economic primary deposits had been found in the area. In 2006–2007, Diagem Inc. discovered a group of diamondiferous kimberlitic pipes within the Chapadão Plateau (Chapadão, or Pandrea cluster), at the head of a drainage system which has produced most of the alluvial diamonds mined in the Juina area. Diamonds from placer deposits and newly discovered kimberlites are identical; they have super-deep origins from the upper-mantle and transition zone. Field observations and petrographic studies have identified crater-facies kimberlitic material at seven separate localities. Kimberlitic material is represented by tuffs, tuffisites and various epiclastic sediments containing chrome spinel, picroilmenite, manganoan ilmenite, zircon and diamond. The diamond grade varies from 0.2–1.8 ct/m3. Chrome spinel has 30–61 wt.% Cr2O3. Picroilmenite contains 6–14 wt.% MgO and 0.2–4 wt.% Cr2O3. Manganoan ilmenite has less than 3 wt.% MgO and 0.38–1.41 wt.% MnO. The 176Hf/177Hf ratio in kimberlitic zircons is 0.028288–0.28295 with εHf = 5.9–8.3, and lies on the average kimberlite trend between depleted mantle and CHUR. The previously known barren and weakly diamondiferous kimberlites in the Juina area have ages of 79–80 Ma. In contrast, zircons from the newly discovered Chapadão kimberlites have a mean 206Pb/238U age of 93.6 ± 0.4 Ma, corresponding to a time of magmatic activity related to the opening of the southern part of the Atlantic Ocean. The most likely mechanism of the origin of kimberlitic magma is super-deep subduction process that initiated partial melting of zones in lower mantle with subsequent ascent of proto-kimberlitic magma. 相似文献
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Eric Heinen De Carlo Laure Mousseau Ornella Passafiume Patrick S. Drupp Jean-Pierre Gattuso 《Aquatic Geochemistry》2013,19(5-6):399-442
The Service d’Observation de la Rade de Villefranche-sur-Mer is designed to study the temporal variability of hydrological conditions as well as the abundance and composition of holo- and meroplankton at a fixed station in this bay of the northwest Mediterranean. The weekly data collected at this site, designated as “Point B” since 1957, represent a long-term time series of hydrological conditions in a coastal environment. Since 2007, the historical measurements of hydrological and biological conditions have been complemented by measurements of the CO2–carbonic acid system parameters. In this contribution, CO2–carbonic acid system parameters and ancillary data are presented for the period 2007–2011. The data are evaluated in the context of the physical and biogeochemical processes that contribute to variations in CO2 in the water column and exchange of this gas between the ocean and atmosphere. Seasonal cycles of the partial pressure of CO2 in seawater (pCO2) are controlled principally by variations in temperature, showing maxima in the summer and minima during the winter. Normalization of pCO2 to the mean seawater temperature (18.5 °C), however, reveals an apparent reversal of the seasonal cycle with maxima observed in the winter and minima in the summer, consistent with a biogeochemical control of pCO2 by primary production. Calculations of fluxes of CO2 show this area to be a weak source of CO2 to the atmosphere during the summer and a weak sink during the winter but near neutral overall (range ?0.3 to +0.3 mmol CO2 m?2 h?1, average 0.02 mmol CO2 m?2 h?1). We also provide an assessment of errors incurred from the estimation of annual fluxes of CO2 as a function of sampling frequency (3-hourly, daily, weekly), using data obtained at the Hawaii Kilo Nalu coastal time-series station, which shows similar behavior to the Point B location despite significant differences in climate and hydrological conditions and the proximity of a coral reef ecosystem. 相似文献
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S. Chakhar V. Mousseau 《International journal of geographical information science》2013,27(11-12):1159-1196
Multicriteria analysis is a set of mathematical tools and methods allowing the comparison of different alternatives according to many criteria, often conflicting, to guide the decision maker towards a judicious choice. Multicriteria methods are used in spatial context to evaluate and compare spatial decision alternatives, often modeled through constraint‐based suitability analysis and represented by point, line, and polygon features or their combination, and evaluated on several space‐related criteria, to select a restricted subset for implementation. Outranking methods, a family of multicriteria methods, may be useful in spatial decision problems, especially when ordinal evaluation criteria are implied. However, it is recognized that these methods, except those devoted to multicriteria classification problems, are subject to computational limitations with respect to the number of alternatives. This paper proposes a framework to facilitate the incorporation and use of outranking methods in geographical information systems (GIS). The framework is composed of two phases. The first phase allows producing a planar subdivision of the study area obtained by combining a set of criteria maps; each represents a particular vision of the decision problem. The result is a set of non‐overlapping spatial units. The second phase allows constructing decision alternatives by combining the spatial units. Point, line and polygon feature‐based decision alternatives are then constructed as an individual, a grouping of linearly adjacent or a grouping of contiguous spatial units. This permits us to reduce considerably the number of alternatives, enabling the use of outranking methods. The framework is illustrated through the development of a prototype and through a step‐by‐step application to a corridor identification problem. This paper includes also a discussion of some conceptual and technical issues related to the framework. 相似文献
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Dynamic characteristics of buildings are of utmost importance in earthquake engineering. The vibration periods are required to determine design loads, and damping is necessary in time‐history analysis. These parameters are generally obtained through forced‐vibration tests (FVTs) or after a seismic event in the case of permanently instrumented structures. However, for large civil engineering structures, FVTs are often too costly or practically difficult, and ambient or output‐only methods are used. This paper describes a comparison between ambient and FVTs carried out on a two‐story building. Results from both testing methods are compared and discussed in order to assess the vibration properties estimates obtained with the frequency domain decomposition technique. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Nicolas Bourguet Madeleine Goutx Jean-Franois Ghiglione Mireille Pujo-Pay Genevive Mvel Andr Momzikoff Laure Mousseau Catherine Guigue Nicole Garcia Patrick Raimbault Romain Pete Louise Oriol Dominique Lefvre 《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(18):1454-1469
This study investigated the relationships between dissolved organic matter (DOM) composition and bacterial dynamics on short time scale during spring mesotrophic (March 2003) and summer oligotrophic (June 2003) regimes, in a 0–500 m depth water column with almost no advection, at the DYFAMED site, NW Mediterranean. DOM was characterized by analyzing dissolved organic carbon (DOC), colored dissolved organic matter (CDOM) and lipid class biotracers. Bacterial dynamic was assessed through the measurement of in situ bacterial lipase activity, abundance, production and bacterial community structure. We made the assumption that by coupling the ambient concentration of hydrolysable acyl-lipids with the measurement of their in situ bacterial hydrolysis rates (i.e. the free fatty acids release rate) would provide new insights about bacterial response to change in environmental conditions. The seasonal transition from spring to summer was accompanied by a significant accumulation of excess DOC (+5 μM) (ANOVA, p<0.05, n=8) in the upper layer (0–50 m). In this layer, the free fatty acids release rate to the bacterial carbon demand (BCD) ratio increased from 0.6±0.3 in March to 1.3±1.0 in June (ANOVA, p<0.05, n=8) showing that more uncoupling between the hydrolysis of the acyl-lipids and the BCD occurred during the evolution of the season, and that free fatty acids contributed to the excess DOC. The increase of lipolysis index and CDOM absorbance (from 0.24±0.17 to 0.39±0.13 and from 0.076±0.039 to 0.144±0.068; ANOVA, p<0.05, n=8, respectively), and the higher contribution of triglycerides, wax esters and phospholipids (from <5% to 12–31%) to the lipid pool reflected the change in the DOM quality. In addition to a strong increase of bacterial lipase activity per cell (51.4±29.4–418.3±290.6 Ag C cell−1 h−1), a significant percentage of ribotypes (39%) was different between spring and summer in the deep chlorophyll maximum (DCM) layer in particular, suggesting a shift in the bacterial community structure due to the different trophic conditions. At both seasons, in the chlorophyll layers, diel variations of DOM and bacterial parameters reflected a better bioavailability and/or DOM utilization by bacteria at night (the ratio of free fatty acids release rate to bacterial carbon demand decreased), most likely related to the zooplankton trophic behaviour. In mesotrophic conditions, such day/night pattern was driving changes in the bacterial community structure. In more oligotrophic period, diel variations in bacterial community structure were depth dependent in relation to the strong summer stratification. 相似文献
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Climate change and warm‐water species at the north‐western boundary of the Mediterranean Sea 
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下载免费PDF全文 Valeriano Parravicini Luisa Mangialajo Laure Mousseau Andrea Peirano Carla Morri Monica Montefalcone Patrice Francour Michel Kulbicki Carlo Nike Bianchi 《Marine Ecology》2015,36(4):897-909
The effects of global change are particularly serious in areas where range shifts of species are physically constrained such as the Ligurian Sea, which is one of the coldest sectors of the Mediterranean. In this basin, historical information on water temperature (from the sea surface down to 75 m depth) dates back to the 1950s. Early studies also recorded warm‐water species occurrence. Thanks to these data we provide the first detailed characterization of water temperature variation from 1958 up to 2010 in the layer 0–75 m depth. We coupled this analysis with the available information on rocky reef epibenthic communities (literature review from 1955 to 1964 and field data from 1980 to 2010). The analysis of water temperature revealed several patterns of variation: a cooling phase from 1958 to 1980, a phase of rapid warming from 1980 to 1990 and a phase of slower warming from 1990 to 2010. Inter‐annual variation in temperature increased over the entire period for the water layer down to 20 m. Warm‐water native and alien species richness increased during the warming phases. Literature estimates suggest a decrease in warm‐water native species richness during the cooling phase. The analysis of quantitative data collected in the early 1990s and late 2000s indicated a decrease in the cover of warm‐water native species on shallow rocky reefs and an increase in deeper waters. We argue that increased inter‐annual variation in water temperature may disadvantage native warm‐water species in shallow waters. Our results indicate that the effect of temperature rises in cold, constrained basins may be more complex than the simple prediction of species changing their geographical range according to their thermal limits. 相似文献
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