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Le Touquet – Paris-Plage, France

Dupouy C.,University of New Caledonia | Dupouy C.,CNRS Physics Laboratory | Neveux J.,University Pierre and Marie Curie | Ouillon S.,Toulouse 1 University Capitole | And 4 more authors.
Marine Pollution Bulletin | Year: 2010

The retrieval of chlorophyll-a concentration from remote sensing reflectance (Rrs) data was tested with the NASA OC4v4 algorithm on the inner New Caledonian lagoon (Case 2) and adjacent open ocean (Case 1) waters. The input to OC4v4 was Rrs measured in situ or modeled from water's inherent optical properties (2001-2007). At open ocean stations, backscattering and absorption coefficients were correlated with chlorophyll (R2=0.31-0.51, respectively), in agreement with models for Case 1 waters. Taking spectrofluorometric measurement as reference, the OC4v4 model leads to an average underestimation of 33% of the chlorophyll concentration. For the lagoon waters, OC4v4 performed inadequately because the backscattering coefficient, highly correlated with turbidity and suspended matter (R2=0.98), was poorly correlated to chlorophyll (R2=0.42). The OC4v4 performance was better in deep lagoon waters for stations with a TDT index (Tchla×depth/turbidity) higher than 19mgm-2 NTU-1 (R2=0.974, bias=10.2%). Global Imager Rrs provided a good estimate of Tchla (R2=0.79, N=28) in the deeper part of the lagoon. © 2010 Elsevier Ltd. Source


Allwood A.C.,Jet Propulsion Laboratory | Burch I.W.,University of New South Wales | Rouchy J.M.,Museum National Histoire Naturelle | Coleman M.,Jet Propulsion Laboratory | Coleman M.,NASA
Astrobiology | Year: 2013

The ∼5.3-6.0 million-year-old evaporitic gypsum deposits of Cyprus and Crete contain a variety of stromatolites that formed during the Messinian salinity crisis. We recognize four stromatolite morphotypes, including domical, conical, columnar, and flat-laminated structures. Observations of morphological and textural variations among the different morphotypes reveal significant diversity and complexity in the nature of interactions between microorganisms, gypsum deposition, and gypsum crystal growth. Nonbiological processes (detrital gypsum deposition, in situ crust precipitation, syntaxial crystal growth, subsurface crystal growth, and recrystallization) interacted with inferred microbial processes (including localized growth of biofilms, trapping and binding of grains in mats, nucleation of gypsum on cells) to produce distinct morphological-textural assemblages. Evidence for biological origins is clear in some stromatolite morphotypes and can come from the presence of microfossils, the spatial distribution of organic matter, and stromatolite morphology. In one stromatolite morphotype, the presence of the stromatolite, or the biota associated with it, may have determined the morphology of gypsum crystals. In some stromatolite morphotypes, definitive evidence of a microbial influence is not as clear. There are broad similarities between the Messinian gypsum stromatolites and carbonate stromatolites elsewhere in the geologic record, such as the formation of precipitated and granular layers; the development of domed, columnar, and conical morphotypes; the potential for microbes to influence mineral precipitation; and the recrystallization of deposits during burial. However, in detail the array of microbial-sedimentary-diagenetic process interactions is quite distinct in gypsiferous systems due to differences in the way gypsum typically forms and evolves in the paleoenvironment compared to carbonate. Unique aspects of the taphonomy of gypsum compared to carbonate chemical sediments, generally speaking, include the following: the potential for growth of individual crystals to determine the shape of a stromatolite (and possibly vice versa), a more diverse set of outcomes relating to preservation versus destruction of textures through crystal growth and recrystallization, and a greater likelihood of preserving microfossils through encapsulation in large crystals. These insights gained from the study of terrestrial gypsum sedimentary rocks provide valuable guidance for the search for clues to past life in sulfate chemical sediments on Mars. © Copyright 2013, Mary Ann Liebert, Inc. 2013. Source


Roure F.,French Institute of Petroleum | Roure F.,VU University Amsterdam | Andriessen P.,VU University Amsterdam | Callot J.P.,French Institute of Petroleum | And 17 more authors.
Geological Society Special Publication | Year: 2010

Basin modelling tools are now more efficient to reconstruct palinspastic structural cross sections and compute the history of temperature, pore-fluid pressure and fluid flow circulations in complex structural settings. In many cases and especially in areas where limited erosion occurred, the use of well logs, bottom hole temperatures (BHT) and palaeo-thermometers such as vitrinite reflectance (Ro) and Rock-Eval (Tmax) data is usually sufficient to calibrate the heat flow and geothermal gradients across a section. However, in the foothills domains erosion is a dominant process, challenging the reconstruction of reservoir rocks palaeo-burial and the corresponding calibration of their past thermal evolution. Often it is not possible to derive a single solution for palaeoburial and palaeo-thermal gradient estimates in the foothills, if based solely on maturity ranks of the organic matter. Alternative methods are then required to narrow down the error bars in palaeo-burial estimates, and to secure more realistic predictions of hydrocarbon generation. Apatite fission tracks (AFT) can provide access to time-temperature paths and absolute ages for the crossing of the 120 °C isotherm and timing of the unroofing. Hydrocarbon-bearing fluid inclusions, when developing contemporaneously with aqueous inclusions, can provide a direct access to the pore-fluid temperature and pressure of cemented fractures or reservoir at the time of cementation and hydrocarbon trapping, on line with the tectonic evolution. Further attempts are also currently made to use calcite twins for constraining reservoir burial and palaeo-stress conditions during the main deformational episodes. Ultimately, the use of magnetic properties and petrographical measurements can also document the impact of tectonic stresses during the evolution of the layer parallel shortening (LPS). The methodology integrating these complementary constraints will be illustrated using reference case studies from Albania, sub-Andean basins in Colombia and Venezuela, segments of the North American Cordillera in Mexico and in the Canadian Rockies, as well as from the Middle East. © The Geological Society of London 2010. Source


Russo Ermolli E.,University of Naples Federico II | Di Donato V.,University of Naples Federico II | Martin-Fernandez J.A.,University of Girona | Orain R.,Museum National Histoire Naturelle | And 2 more authors.
Review of Palaeobotany and Palynology | Year: 2014

Pollen data from five palaeo-lacustrine basins are used in this study to correlate floral and vegetation patterns along a NW-SE transect in the Southern Apennines (Italy) during Marine Isotope Stage (MIS) 13. Compositional Data Analysis (CoDA) is applied to pollen data in order to better define and explain the main differences in the pollen composition of coeval records. Pollen data belonging to MIS 13, chosen on the basis of a constrained cluster analysis on each entire record, have been analyzed through a non-constrained cluster analysis. The relative variation biplot, the parametric and the non-parametric MANOVA computed for the MIS 13 pollen data, show that samples belonging to the different sites are distinct by their average composition. This means that each site has a distinctive character of forest landscape, which could have been the result of local environmental (physical) factors, such as mesoclimate, topography and edaphic humidity, and/or of historical factors such as species composition of refuges and temporary changes in environmental conditions due to disturbance ecology. © 2014 Elsevier B.V. Source


Amato V.,University of Molise | Aucelli P.P.C.,Parthenope University of Naples | Cesarano M.,University of Molise | Jicha B.,University of Wisconsin - Madison | And 5 more authors.
Rendiconti Lincei | Year: 2014

An integrated morpho-stratigraphic approach has been used to reconstruct the Quaternary history of the Boiano basin, the largest tectonic depression of the Molise Apennine (Italy). Lacustrine, marshy and fluvial environments alternate all along the investigated infilling succession as a response to tectonic subsidence, volcaniclastic inputs and climate changes, from ca. 500 ka. Two tephra layers 40Ar/39Ar have been dated and referred to the Middle Pleistocene explosive activity of the Roccamonfina volcano, while a younger tephra layer has been related to the Campi Flegrei Neapolitan Yellow Tuff (ca. 15 ka). Pollen analysis has highlighted the vegetation changes related to the 100 ka glacial-interglacial cyclicity, between MIS 13 and 2. From 500 to 350 ka, a strong subsidence led to lacustrine deposition, while between 350 and 250 ka, a decrease in subsidence rates caused the transition to fluvial-marshy conditions and, at a later stage, to floodplain environments. The analysis of palaeosurfaces allowed the geomorphological evolution of the basin to be reconstructed since the Middle Pleistocene and the morpho-sedimentary events to be related to the SW-NE extensional tectonics affecting this sector of the central-southern Apennine. This tectonic behavior is also testified by the differential subsidence rates recorded within the basin through the analysis of two deep cores drilled in the center of the Boiano town. © 2014 Accademia Nazionale dei Lincei. Source

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