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921.
The Late Cretaceous (mainly Campanian and Maastrichtian) non-marine vertebrate faunas of Europe contain archosaurian reptiles which belong to groups otherwise known mainly or only from the southern ('Gondwanan') continents. They include titanosaurid sauropods, abelisaurid theropods, and trematochampsid crocodilians. The occurrence of these forms together with others of 'Asiamerican' affinities gives the Late Cretaceous vertebrate faunas of Europe a peculiar composition, which makes them clearly different from the well-known faunas from western North America and Central Asia. The Gondwanan dinosaurs and crocodilians from Europe provide evidence of faunal interchange across the Tethys Sea during the Cretaceous, possibly via the Alboran plate, or the Apulian plate, which may have functioned as 'stepping-stones', especially during periods of low sea level.  相似文献   
922.
The elemental solubilities of three coal fly ash samples and two coastal marine-aerosol samples in seawater are different. The coal fly ash samples were collected from the electrostatic precipitators on coal-fired power plants. The air particulates were collected by a high-volume air sampler located near the Washington coast. Samples were neutron-activated then contacted with seawater for several hours. The elements that were partially solubilized from both fly ash and aerosols included As, Sb, Se, Br and Cr. Zinc and Co were more soluble in aerosols then fly ash.  相似文献   
923.
924.
Petrogenetic model for the origin of carbonatites   总被引:1,自引:0,他引:1  
The petrological significance and distribution of igneous carbonatites is discussed. Particular attention is paid to the relationship that exists between carbonatites and volcanism in East Africa. Using a simple model of a carbonatite-nephelinite-ijolite volcanic complex it was discovered that all the peralkaline and carbonatitic rocks found in such a complex could be derived from a single primary nephelinitic magma. The origin of such a primary magma, and the subsequent evolution carbonatitic sub-magmas, is examined.  相似文献   
925.
Resolution of the iron sites in the Mössbauer spectra of Ca-Fe pyroxenoids is only partial, two doublets being apparent in each case, whereas there are up to nine cation sites in each structure. Thus the inner and outer doublets represent, respectively: two sites and two sites in Ca0.5Fe0.5SiO3 (ferrobustamite); five sites and two sites in Ca0.15Fe0.85SiO3 (pyroxferroite); and five sites and four sites in FeSiO3 (ferrosolite III). Disorder of iron and calcium which exists in the two calcium-bearing pyroxenoids is not readily apparent in the spectra.Publication authorized by the Director, U. S. Geological Survey.  相似文献   
926.
Nonlocal fluxes and Stokes drift effects in the K-profile parameterization   总被引:2,自引:0,他引:2  
 The K-profile parameterization of upper-ocean mixing is tested and extended using observations and large eddy simulations of upper-ocean response to a westerly windburst. A nonlocal momentum flux term is added, and the amplitude of the nonlocal scalar flux is recalibrated. Parameterizations of Stokes drift effects are added following recent work by McWilliams and Sullivan (2001). These changes allow the parameterization to produce both realistic gradients of momentum and scalars in the nocturnal boundary layer and enhanced mixing during stable conditions. The revised parameterization is expected to produce improved representations of lateral advection and sea-surface temperature in large-scale models. Received: 31 August 2001 / Accepted: 15 December 2001  相似文献   
927.
928.
Ocean Dynamics - Generally, ports in the North American Great Lakes are not supported with navigational guidance (water level, water temperature, currents, ice) by NOAA’s Great Lakes...  相似文献   
929.
He  Zhengkang  Chung  Eric T.  Chen  Jie  Chen  Zhangxin 《Computational Geosciences》2021,25(5):1681-1708
Computational Geosciences - In this paper, we propose offline and online adaptive enrichment algorithms for the generalized multiscale approximation of a mixed finite element method with velocity...  相似文献   
930.
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