Steepness and spectrum of nonlinear deformed shallow water wave     

Narcisse Zahibo  Irina Didenkulova  Andrey Kurkin  Efim Pelinovsky   《Ocean Engineering》2008,35(1):47-52

  相似文献   

Ecosystem structure and resilience—A comparison between the Norwegian and the Barents Sea     

Natalia A. Yaragina  Andrey V. Dolgov   《Deep Sea Research Part II: Topical Studies in Oceanography》2009,56(21-22):2141

Abundance and biomass of the most important fish species inhabited the Barents and Norwegian Sea ecosystems have shown considerable fluctuations over the last decades. These fluctuations connected with fishing pressure resulted in the trophic structure alterations of the ecosystems. Resilience and other theoretical concepts (top-down, wasp-waste and bottom-up control, trophic cascades) were viewed to examine different response of the Norwegian and Barents Sea ecosystems on disturbing forces. Differences in the trophic structure and functioning of Barents and Norwegian Sea ecosystems as well as factors that might influence the resilience of the marine ecosystems, including climatic fluctuation, variations in prey and predator species abundance, alterations in their regular migrations, and fishing exploitation were also considered. The trophic chain lengths in the deep Norwegian Sea are shorter, and energy transfer occurs mainly through the pelagic fish/invertebrates communities. The shallow Barents Sea is characterized by longer trophic chains, providing more energy flow into their benthic assemblages. The trophic mechanisms observed in the Norwegian Sea food webs dominated by the top-down control, i.e. the past removal of Norwegian Spring spawning followed by zooplankton development and intrusion of blue whiting and mackerel into the area. The wasp-waist response is shown to be the most pronounced effect in the Barents Sea, related to the position of capelin in the ecosystem; large fluctuations in the capelin abundance have been strengthened by intensive fishery. Closer links between ecological and fisheries sciences are needed to elaborate and test various food webs and multispecies models available.  相似文献   

Early Neoproterozoic Granite-Gneisses of the Junggar Alataw (Southeastern Kazakhstan): Age, Petrogenesis and Tectonic Implications     

Nadezhda KANYGINA  Andrey TRETYAKOV  Dmitriy ALEXEIEV  Kirill DEGTYAREV  Anfisa SKOBLENKO  Natalia SOLOSHENKO  Boris ERMOLAEV 《《地质学报》英文版》2024,98(1):67-82

The combined petrographic, petrological, geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the Precambrian tectonic evolution of the Aktau–Yili terrane. It is one of the largest Precambrian crustal blocks in the western Central Asian orogenic belt. The U-Pb single-grain zircon ages indicate that granite-gneisses formed from the same source and crystallised in the early Neoproterozoic ca. 930–920 Ma. The chemical composition of gneisses corresponds to A2-type granites. The whole-rock Nd isotopic characteristics (εNd(t) = ?4.9 to ?1.0 and TNd(DM-2st) = 1.9 to 1.7 Ga) indicate the involvement of Paleoproterozoic crustal rocks in magma generation. Early Neoproterozoic ca. 930–920 Ma A-type granitoids in the Aktau–Yili terrane of South and Central Kazakhstan might reflect within-plate magmatism adjacent to the collisional belt or a local extension setting in back-arc areas of the continental arc.  相似文献   

Submarine landslides at the eastern Sunda margin: observations and tsunami impact assessment     

Brune  Sascha  Ladage  Stefan  Babeyko  Andrey Y.  Müller  Christian  Kopp  Heidrun  Sobolev  Stephan V. 《Natural Hazards》2010,54(2):547-562

Our analysis of new bathymetric data reveals six submarine landslides at the eastern Sunda margin between central Java and Sumba Island, Indonesia. Their volumes range between 1 km3 in the Java fore-arc basin up to 20 km3 at the trench off Sumba and Sumbawa. We estimate the potential hazard of each event by modeling the corresponding tsunami and its run-up on nearby coasts. Four slides are situated remarkably close to the epicenter of the 1977 tsunamigenic Sumba M _w  = 8.3 earthquake. However, comparison of documented tsunami run-up heights and arrival times with our modeling results neither allows us to confirm nor can we falsify the hypothesis that the earthquake triggered these submarine landslides.  相似文献   

A review of the stratigraphy and geological setting of the Palaeoproterozoic Magondi Supergroup,Zimbabwe – Type locality for the Lomagundi carbon isotope excursion     

Sharad Master  Andrey Bekker  Axel Hofmann 《Precambrian Research》2010

The Palaeoproterozoic Magondi Supergroup lies unconformably on the Archaean granitoid-greenstone terrain of the Zimbabwe Craton and experienced deformation and metamorphism at 2.06–1.96 Ga to form the Magondi Mobile Belt. The Magondi Supergroup comprises three lithostratigraphic units. Volcano-sedimentary rift deposits (Deweras Group) are unconformably overlain by passive margin, back-arc, and foreland basin sedimentary successions, including shallow-marine sedimentary rocks (Lomagundi Group) in the east, and deeper-water shelf to continental slope deposits in the west (Piriwiri Group). Based on the upward-coarsening trend and presence of volcanic rocks at the top of the Piriwiri and Lomagundi groups, the Piriwiri Group is considered to be a distal, deeper-water time-equivalent of the Lomagundi Group. The Magondi Supergroup experienced low-grade metamorphism in the southeastern zone, but the grade increases to upper greenschist and amphibolite facies grade to the north along strike and, more dramatically, across strike to the west, reaching upper amphibolite to granulite facies in the Piriwiri Group.  相似文献   

Source components of the Gran Canaria (Canary Islands) shield stage magmas: evidence from olivine composition and Sr–Nd–Pb isotopes     

Andrey A. Gurenko  Kaj A. Hoernle  Alexander V. Sobolev  Folkmar Hauff  Hans-Ulrich Schmincke 《Contributions to Mineralogy and Petrology》2010,159(5):689-702

The Canary Island primitive basaltic magmas are thought to be derived from an HIMU-type upwelling mantle containing isotopically depleted (NMORB)-type component having interacted with an enriched (EM)-type component, the origin of which is still a subject of debate. We studied the relationships between Ni, Mn and Ca concentrations in olivine phenocrysts (85.6–90.0 mol.% Fo, 1,722–3,915 ppm Ni, 1,085–1,552 ppm Mn, 1,222–3,002 ppm Ca) from the most primitive subaerial and ODP Leg 157 high-silica (picritic to olivine basaltic) lavas with their bulk rock Sr–Nd–Pb isotope compositions (⁸⁷Sr/⁸⁶Sr = 0.70315–0.70331, ¹⁴³Nd/¹⁴⁴Nd = 0.51288–0.51292, ²⁰⁶Pb/²⁰⁴Pb = 19.55–19.93, ²⁰⁷Pb/²⁰⁴Pb = 15.60–15.63, ²⁰⁸Pb/²⁰⁴Pb = 39.31–39.69). Our data point toward the presence of both a peridotitic and a pyroxenitic component in the magma source. Using the model (Sobolev et al. in: Science 316:412–417, 2007) in which the reaction of Si-rich melts originated during partial melting of eclogite (a high pressure product of subducted oceanic crust) with ambient peridotitic mantle forms olivine-free reaction pyroxenite, we obtain an end member composition for peridotite with ⁸⁷Sr/⁸⁶Sr = 0.70337, ¹⁴³Nd/¹⁴⁴Nd = 0.51291, ²⁰⁶Pb/²⁰⁴Pb = 19.36, ²⁰⁷Pb/²⁰⁴Pb = 15.61 and ²⁰⁸Pb/²⁰⁴Pb = 39.07 (EM-type end member), and pyroxenite with ⁸⁷Sr/⁸⁶Sr = 0.70309, ¹⁴³Nd/¹⁴⁴Nd = 0.51289, ²⁰⁶Pb/²⁰⁴Pb = 20.03, ²⁰⁷Pb/²⁰⁴Pb = 15.62 and ²⁰⁸Pb/²⁰⁴Pb = 39.84 (HIMU-type end member). Mixing of melts from these end members in proportions ranging from 70% peridotite and 30% pyroxenite to 28% peridotite and 72% pyroxenite derived melt fractions can generate the compositions of the most primitive Gran Canaria shield stage lavas. Combining our results with those from the low-silica rocks from the western Canary Islands (Gurenko et al. EPSL 277:514–524, 2009), at least four distinct components are required. We propose that they are (1) HIMU-type pyroxenitic component (representing recycled ocean crust of intermediate age) from the plume center, (2) HIMU-type peridotitic component (ancient recycled ocean crust stirred into the ambient mantle) from the plume margin, (3) depleted, MORB-type pyroxenitic component (young recycled oceanic crust) in the upper mantle entrained by the plume, and (4) EM-type peridotitic component from the asthenosphere or lithosphere above the plume center.  相似文献   

Murchison's first sighting of the Permian, at Vyazniki in 1841     

Michael J. Benton  Andrey G. Sennikov 《Proceedings of the Geologists' Association. Geologists' Association》2010,121(3):313-318

Roderick Impey Murchison named the Permian Period in 1841 based on his work on Lower Permian marine sediments around the city of Perm’, on the west flank of the Ural Mountains. However, he had observed post-Carboniferous red beds earlier, around the town of Vyazniki, west of Moscow, lying above the classic Carboniferous limestones of the Moscow Basin. Murchison's notebooks and papers show that he and colleagues equivocated about the exact age of these red beds, whether latest Permian or early Triassic, but he always favoured the former view. So, his initial observation of the Vyazniki redbeds provided a marker for the top of the Permian and base of the Triassic in the European Russian platform.  相似文献   

Libration celestial mechanics experiment     

O. N. Andreev  S. A. Antonenko  V. M. Gotlib  G. V. Zakharkin  V. M. Linkin  A. N. Lipatov  V. S. Makarov  B. K. Khairulin  L. I. Khlyustova 《Solar System Research》2010,44(5):438-443

The exploration of planet moons and minor bodies (Avduevskii et al., 1996) is a basic task for comprehending the nature of the processes occurring in our Solar System. Knowing the current state of the moons, we can better describe their past and look into the future. This knowledge is important, first of all, for understanding the origin of the Solar System. Interest in the Martian moon Phobos has been displayed during recent decades. The interest is caused by some questions to which there have been no answers up until now (Sagdeev et al., 1988; 1989). For example, there is a question regarding the origin of the moon: whether it is an asteroid captured by Mars’ gravitational field or it is an accumulated body in the Martian orbit. In connection with this, it is interesting to conduct studies aimed at answering this question. If Phobos appears to be an asteroid, then investigations regarding the chemical and isotopic compositions of the moon as the primary matter of the Solar System as well as its evolution are of great interest.  相似文献   

Origin of REE-rich ferrocarbonatites in southern Siberia (Russia): implications based on melt and fluid inclusions     

Ilya R. Prokopyev  Alexander S. Borisenko  Andrey A. Borovikov  Galina G. Pavlova 《Mineralogy and Petrology》2016,110(6):845-859

  相似文献   

Trophic structure of the Barents Sea fish assemblage with special reference to the cod stock recoverability   总被引：1，自引：0，他引：1  

Andrey V. Dolgov   《Progress in Oceanography》2009,81(1-4):165

The species composition and trophic structure of the Barents Sea fish assemblage is analysed based on data from research survey trawls and diet analyses of various species. Atlantic cod was the dominant fish species encountered, accounting for more than 55% by abundance or biomass. Only five fish species (long rough dab, thorny skate, Greenland halibut, deepwater redfish and saithe) were sufficiently abundant to be considered as possible food competitors with cod in the Barents Sea. However, possible trophic competition is not high, due to low spatial and temporal overlap between cod and these other species. Analyses of fish assemblages and trophic structures of the Barents Sea and other areas (North Sea, Western Greenland, Newfoundland-Labrador shelf) suggest that Barents Sea cod is the only cod stock for which the ability to recover may not be restricted by trophic relations among fishes, due to a lack of other abundant predatory species and low potential for competition caused by spatial-temporal changes.  相似文献