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991.
Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides
Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named
Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic
sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from
these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua
(an active submarine volcano off the southeastern tip of Epi) lavas. 相似文献
992.
993.
Based on the analysis of new data of a total of 60 000 km, the authors propose a new spreading model of the tectonic evolution of the South China Sea Basin and suggest that magnetic anomalies in the Basin are the magnetic anomalies of a new type in marginal basins, that the tectonic development of the Basin can be divided into three seafloor spreading phases and that the southward migration of spreading ridge is related to the asymmetric spreading. 相似文献
994.
Based on the shear effect of internal wave currents in stratified fluid, the necessary condition for the possible existence of an internal wave and the sufficient condition under which there will be no internal wave are deduced starting from the continuity equation of incompressible fluid. The above two conditions are verified by the measured results from vertical current meter arraies at some observation stations in the Bohai Sea and the South Huanghai Sea. In the treatment of measured results, first of all, the tidal period components are separated from the measured currents by Fourier-analysis method, and then the internal wave currents of tidal period from the tidal period components in the light of some considerations. The analytical results of observed currents are well consistent with theoretical analysis. Furthermore, one can also deduce some features of internal waves therefrom. Consequently, it is concluded that the observation from a vertical current meter array is an important means to verif 相似文献
995.
AN ECOSYSTEM MODEL ANALYSIS OF THE EFFECT OF MINE TAILINGS ON THE EUPHOTIC ZONE OF A PELAGIC ECOSYSTEM 总被引:1,自引:0,他引:1
A computer analysis was performed on experimental results obtained when mine tailings were added to seawater. The Mixed Upper-Layer Ecotrophie Simulation (MULES) model was tested by changing the extinction coefficient and the abundance of heterotrophic zooflagellates. Increasing the extinction coefficient resulted in a delay of phytoplankton growth, an increase in zooplankton standing stock and better growth of autotrophic flagellates compared with diatoms. Zooflagellates in the ecosystem influence the growth of zooplankton; secondary production by zooplankton was markedly depressed at low levels of zooflagellates. These results are believed to be of general significance for the diagnosis of suspended sediment effects on planktonic ecosystems. 相似文献
996.
997.
We establish the equations of finite element approximation for three-dimensional ocean current and calculate the Kuroshio current in the eastern sea area off Taiwan Province. The interpolation error of finite element approximation is given as Eq. (3. 14). 相似文献
998.
R.S.S. Wu 《Marine environmental research》1982,6(3):215-225
As a result of taxonomic uncertainty, generic and higher taxonomic ranks (family, order, class or phylum) are often treated as units in calculating diversity indices, instead of species. In this paper, the errors introduced by such practices are examined for various diversity indices (Shannon - Wiener Index, Maximum Information Index, Evenness, Margalef's Species Richness Index and Hurlbert's Probability of Interspecific Encounter). The use of higher taxonomic ranks may invalidate comparison of diversity indices. In a single study, substantial error and erroneous conclusion may arise, even if consistent practices are adopted. 相似文献
999.
Seismic reflection profiling demonstrates the importance of mass movement in the north-central California Borderland. Bulk
properties of surficial hemipelagic sediments in the Santa Barbara, Santa Cruz, and San Nicolas basins show that different
types of mass-transported sediments have different properties, although their general sedimentologic characteristics are very
similar. Slump deposits have moderate water contents (48% wet weight basis), high plasticity indices (46%), and moderate activities
(1.6). For debris flows these values are low: 28%, 5%, and 0.3, respectively, and for other types (liquefied flow, mudflows,
and turbidities) the values are high: 54 to 63%, 49 to 58%, and 1.2 to 1.5, respectively. 相似文献
1000.
A new approach to high-order Boussinesq-type equations with ambient currents is presented. The current velocity is assumed to be uniform over depth and of the same magnitude as the shallow water wave celerity. The wave velocity field is expressed in terms of the horizontal and vertical wave velocity components at an arbitrary water depth level. Linear operators are introduced to improve the accuracy of the kinematic condition at the sea bottom. The dynamic and kinematic conditions at the free surface are expressed in terms of wave velocity variables defined directly on the free surface. The new equations provide high accuracy of linear properties as well as nonlinear properties from shallow to deep water, and extend the applicable range of relative water depth in the case of opposing currents. 相似文献