Zarafasaura oceanis, a new elasmosaurid (Reptilia: Sauropterygia) from the Maastrichtian Phosphates of Morocco and the palaeobiogeography of latest Cretaceous plesiosaurs     

Peggy Vincent  Nathalie Bardet  Xabier Pereda Suberbiola  Badi Bouya  Mbarek Amaghzaz  Saïd Meslouh 《Gondwana Research》2011,19(4):1062-1073

Though the Maastrichtian Phosphates of Morocco have yielded very rich marine vertebrate assemblages, plesiosaurs remain very scarce in these strata. The only hitherto recognized taxon was Plesiosaurus mauritanicus Arambourg, 1952, regarded here as a nomem dubium. Here we describe a new genus and species of elasmosaurid plesiosaur, Zarafasaura oceanis, which represents the first valid elasmosaurid plesiosaur described from the latest Cretaceous of Africa, and the second one from this continent. A phylogenetic analysis of plesiosauroids indicates that Zarafasaura oceanis has close affinities with elasmosaurids from the Late Cretaceous of North America and Japan. Among its distinctive suite of characters, the general shape and organisation of its squamosal and palate are unique among elasmosaurids. This new taxon completes our understanding of Late Cretaceous plesiosaur palaeobiodiversity and palaeobiogeography, and shows that Maastrichtian plesiosaurs were characterized by a quite high degree of endemism. They were also highly diversified and distributed worldwide, which supports the hypothesis of a catastrophic extinction of plesiosaurs at the K/T boundary.  相似文献   

Overview on the formation of paleolakes and ponds on Mars     

Nathalie A. Cabrol  Edmond A. Grin 《Global and Planetary Change》2003,35(3-4):199-219

Lakes on Mars were formed under periglacial to glacial climates. Extreme conditions prevailed including freezing temperatures, low atmospheric pressure, high evaporation/sublimation rates, and liquid water reservoirs locked in aquifers below a thick cryosphere. Although many of the Martian paleolakes display evidence of a short period of activity consistent with these conditions, others display clear evidence of lifetimes ranging from 10⁴ to 10⁵ years. The discovery of young seeping processes in impact craters and pole-facing valley slopes along with young volcanic activity raise questions about the conditions and limitations of liquid water flow and potential lacustrine activity today on Mars. Current climate models show that in today's conditions there exist regions on Mars of sols above the triple point and below boiling point of water that could provide hydrogeological conditions comparable to these of the Antarctic Dry Valley lakes (with the exception of the atmosphere pressure). The locations of the most recent Martian paleolakes are correlated with these regions. Throughout the history of Mars, lakes generated diversified environments, which could have provided potential habitats for life. The recent discovery of young energy sources from volcanism and the potential for liquid water reinforces the possibility of extant life on Mars, and suggests recent ponds and ancient paleolakes as primary targets for rover and sample return missions.  相似文献   

Investigating the nexus of climate,energy, water,and land at decision-relevant scales: the Platform for Regional Integrated Modeling and Analysis (PRIMA)     

Ian Kraucunas  Leon Clarke  James Dirks  John Hathaway  Mohamad Hejazi  Kathy Hibbard  Maoyi Huang  Chunlian Jin  Michael Kintner-Meyer  Kerstin Kleese van Dam  Ruby Leung  Hong-Yi Li  Richard Moss  Marty Peterson  Jennie Rice  Michael Scott  Allison Thomson  Nathalie Voisin  Tristram West 《Climatic change》2015,129(3-4):573-588

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Reconstructed density and velocity fields from the 2MASS Redshift Survey     

Pirin Erdo&#;du  Ofer Lahav  John P. Huchra †  Matthew Colless  Roc M. Cutri  Emilio Falco †  Teddy George  Thomas Jarrett  D. Heath Jones  Lucas M. Macri  Jeff Mader  Nathalie Martimbeau  Michael A. Pahre  Quentin A. Parker  Anaïs Rassat  Will Saunders 《Monthly notices of the Royal Astronomical Society》2006,373(1):45-64

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Some consequences of a spatially varying cosmological constant in a spherically symmetric distribution of matter     

J. V. Narlikar  J. -C. Pecker  J. -P. Vigier 《Journal of Astrophysics and Astronomy》1991,12(1):7-16

This paper investigates the effects of the spatial variation of the cosmological constant λ on the spacetime geometry within and outside a massive object. It is seen that the variation of λ with the radial coordinate introduces non-trivial changes leading to spacetime closing on itself around a massive object. It may also be possible to generate interior solutions that lead to flat rotation curves of galaxies  相似文献   

Magnesium Isotope Compositions of Natural Reference Materials   总被引：1，自引：0，他引：1  

Emile B. Bolou-Bi  Nathalie Vigier  Agnès Brenot  Anne Poszwa 《Geostandards and Geoanalytical Research》2009,33(1):95-109

This study presents a chemical protocol for the separation of Mg that is particularly adapted to alkali‐rich samples (granite, soil, plants). This protocol was based on a combination of two pre‐existing methods: transition metals were first removed from the sample using an AG‐MP1 anion‐exchange resin, followed by the separation of alkalis (Na, K) and bivalent cations (Ca²⁺, Mn²⁺ and Sr²⁺) using a AG50W‐X12 cation‐exchange resin. This procedure allowed Mg recovery of ～ 10 0 ± 8%. The [Σcations]/[Mg] molar ratios in all of the final Mg fractions were lower than 0.05. The Mg isotope ratios of eleven reference materials were analysed using two different MC‐ICP‐MS instruments (Isoprobe and Nu Plasma). The long‐term reproducibility, assessed by repeated measurements of Mg standard solutions and natural reference materials, was 0.14‰. The basalt (BE‐N), limestone (Cal‐S) and seawater (BCR‐403) reference materials analysed in this study yielded δ²⁶Mg mean values of ?0.28 ± 0.08‰, ?4.37 ± 0.11‰ and ?0.89 ± 0.10‰ respectively, in agreement with published data. The two continental rocks analysed, diorite (DR‐N) and granite (GA), yielded δ²⁶Mg mean values of ?0.50 ± 0.08‰ and ?0.75 ± 0.14‰, respectively. The weathering products, soil (TILL‐1) and river water (NIST SRM 1640), gave δ²⁶Mg values of ?0.40 ± 0.07‰ and ?1.27 ± 0.14‰, respectively. We also present, for the first time, the Mg isotope composition of bulk plant and organic matter. Rye flour (BCR‐381), sea lettuce (Ulva lactuva) (BCR‐279), natural hairgrass (Deschampsia flexuosa) and lichen (BCR‐482) reference materials gave δ²⁶Mg values of ?1.10 ± 0.14‰, ?0.90 ± 0.19‰, ?0.50 ± 0.22‰ and ?1.15 ± 0.27‰ respectively. Plant δ²⁶Mg values fell within the range defined by published data for chlorophylls.  相似文献   

Elemental characterization and source identification of PM_2.5 using Positive Matrix Factorization: The Malraux road tunnel, Nice, France   总被引：1，自引：0，他引：1  

Jean-Franois Fabretti  Nathalie Sauret  Jean-Franois Gal  Pierre-Charles Maria  Urs Schrer 《Atmospheric Research》2009,94(2):320-329

This work was dedicated to the characterization of the elemental composition of atmospheric particles associated with urban traffic. PM_2.5 sampling campaigns were conducted in an urban road tunnel within the area of Nice: the Malraux tunnel. Samples were analyzed by ICP-MS-DRC for the determination of 16 metallic trace elements: Na, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Rb, Cd, Sn, Sb and Pb. An in depth study was carried out on the PM_2.5 dataset collected with specific characterisation tools (enrichment factors, elemental ratio) and a receptor model: the Positive Matrix Factorization (PMF). The model showed that different profiles of emission could influence the ambient air of the tunnel and their contribution to the metal concentration in the air. Elemental fingerprints were used to attribute to each profile a specific emission source linked to road traffic. Finally, results showed that road traffic emissions could be divided into 3 main “subcategory” sources of emission: “soil resuspension” by automobile movement, “vehicular wear” and “fuel combustion”.  相似文献   

Implications of 21st century climate change for the hydrology of Washington State   总被引：5，自引：2，他引：3  

Marketa M. Elsner  Lan Cuo  Nathalie Voisin  Jeffrey S. Deems  Alan F. Hamlet  Julie A. Vano  Kristian E. B. Mickelson  Se-Yeun Lee  Dennis P. Lettenmaier 《Climatic change》2010,102(1-2):225-260

Pacific Northwest (PNW) hydrology is particularly sensitive to changes in climate because snowmelt dominates seasonal runoff, and temperature changes impact the rain/snow balance. Based on results from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4), we updated previous studies of implications of climate change on PNW hydrology. PNW 21st century hydrology was simulated using 20 Global Climate Models (GCMs) and 2 greenhouse gas emissions scenarios over Washington and the greater Columbia River watershed, with additional focus on the Yakima River watershed and the Puget Sound which are particularly sensitive to climate change. We evaluated projected changes in snow water equivalent (SWE), soil moisture, runoff, and streamflow for A1B and B1 emissions scenarios for the 2020s, 2040s, and 2080s. April 1 SWE is projected to decrease by approximately 38–46% by the 2040s (compared with the mean over water years 1917–2006), based on composite scenarios of B1 and A1B, respectively, which represent average effects of all climate models. In three relatively warm transient watersheds west of the Cascade crest, April 1 SWE is projected to almost completely disappear by the 2080s. By the 2080s, seasonal streamflow timing will shift significantly in both snowmelt dominant and rain–snow mixed watersheds. Annual runoff across the State is projected to increase by 2–3% by the 2040s; these changes are mainly driven by projected increases in winter precipitation.  相似文献   

Stress interaction between seismic and volcanic activity at Mt Etna     

Nathalie Feuillet  Massimo Cocco  Carla Musumeci  Concetta Nostro 《Geophysical Journal International》2006,164(3):697-718

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The 1708 Manosque earthquake (France): A reading of its archaeological traces as a contribution to estimate the effects on buildings     

Georgia Poursoulis  Agnès Levret  Nathalie Lambert  Alain Rideaud  Bruno Helly 《Journal of Seismology》2006,10(4):511-526

Archaeological techniques and methodology are used to identify seismic traces and disorders in ancient buildings. Clear evidence could be identified as direct seismic consequences or as communities’ technical answers for repair or reinforcement of buildings in order to reduce their vulnerability. This methodology is called “archaeological reading of buildings.” It is based on the identification of different construction phases, modifications and past events (human actions or natural phenomena) suffered by buildings during their life. The data read from the buildings are successively observed, identified, described, and recorded, following the principal of archaeological stratigraphy, in order to explain the buildings history. The seismic pathologies are identified according to detailed engineering knowledge of the behaviour of buildings during seismic motion. In this case study, our approach is applied to the historical city of Manosque, located in a seismic area along the “Moyenne–Durance” active fault. As a result of historical researches (Quenet G, Baumont D, Scotti O, Levret A, Ann Geophys, 47(2/3):583–595, 2004), many historical documents gave evidence about this earthquake’s effects. Among these documents, was an exceptional one: the record of a survey made in Manosque by bricklayers a few days after the 14th August 1708 shock. This gave us specific information concerning the seismic damage caused in the town of Manosque and was the starting point to validate the method. In the present paper, the archaeological reading of buildings method is illustrated by two specific cases: the Charité building in Manosque and the Sainte-Agathe chapel in Saint-Maime village. The buildings suffered various modifications during many centuries. This complicates the application of the method, however the observations made from the buildings correlate well with the indications deduced from written sources, validating our approach. The study highlights the necessity to cross correlate different field data in the frame of a multidisciplinary approach in order to obtain valuable results concerning details of seismic damage, its approximate dating by architectural chronology and the communities’ reaction in terms of repairs and reinforcement techniques.  相似文献