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71.
72.
Yves Lafoy Francois Missegue Dominique Cluzel Raymond Le Suave 《Marine Geophysical Researches》1996,18(2-4):337-356
The ZoNéCo 1 and 2 cruises of Ifremer's Research Vessel L'Atalante, collected new swath bathymetry and geophysical data over the southern and northern segments of the basins and ridges forming the Loyalty system. Between the two surveyed areas, previous studies found evidence for the resistance of the Loyalty Ridge to subduction beneath the New Hebrides trench near 22°S–169°E. On the subducted plate, except for seismicity related to the downbending of the Australian plate, recorded shallow seismicity is sparse within the Loyalty system (Ridge and Basin) where reliable focal mechanism solutions are almost absent.Swath bathymetry, seismic reflection and magnetic data acquired during the ZoNéCo 1 and 2 cruises revealed a transverse asymmetric morphology in the Loyalty system, and an along-strike horst and graben structure on the discontinuous Loyalty Ridge. South of 23°50S and at 20°S, the two WSW-ENE-trending fault systems, respectively, sinistral and dextral, that crosscut the southern and northern segments of the Loyalty system, are interpreted as due to the early effects of collision with the New Hebrides Arc. A NNW-SSE trend, evident along the whole Loyalty system and on the island of New Caledonia, is interpreted as an inherited structural trend that may have been reactivated through flexure of the Australian lithospheric plate at the subduction zone.Overall then, the morphology, structure and evolution of the southern and northern segments of the Loyalty system probably result from the combined effects of the Australian plate lithospheric bulge, the active Loyalty-New Hebrides collision and the overthrust of the New Caledonian ophiolite. 相似文献
73.
本文给出了一种从SASS测量的后向散射强度手数据中反演出大尺度海洋风场的新方法。计算结果与Peteherych等利用SASS表面风分析的结果比较在风向上是吻合的,在风速上本文所得结果更宇海面赵实风速。上述结果说明本文所采用的多解排除对两波束散射计探测海面风场的反演是成功的。 相似文献
74.
Alessandro Buccolieri Giovanni Buccolieri Nicola Cardellicchio Angelo Dell'Atti Antonella Di Leo Antonella Maci 《Marine Chemistry》2006,99(1-4):227
Al, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Ti and Zn concentrations have been determined in surface sediment samples collected in the Taranto Gulf (Ionian Sea, Southern Italy) in order to evaluate their levels and spatial distribution in this important area of the Mediterranean Sea. For various metals, the geoaccumulation index has been calculated as a criterion to assess if their concentrations represent contamination levels or can be considered as background levels. The results show that metals concentrations in sediments can be considered near the background levels found in the Mediterranean Sea.Analytical results have been elaborated by using a Geographical Information System (GIS) software to show metals accumulation areas. Using multivariate statistical analysis, we evaluate the possibility to distinguish the sampling stations, in relation to their geographical position. Results have showed metals distribution in the Taranto Gulf is principally influenced by industrial and urban wastes, located mostly in the northern coastal area of the Ionian Sea. Rivers in the Basilicata region and prevailing anticlockwise marine currents are further factors influencing metal accumulation in sediments. 相似文献
75.
Sauter Daniel Mendel Véronique Rommevaux-Jestin Céline Patriat Philippe Munschy Marc 《Marine Geophysical Researches》1997,19(6):553-567
The analysis of multibeam bathymetric data of the Southwest Indian Ridge(SWIR) domain between the triple junction traces from 68° E to theRodrigues Triple Junction (RTJ; 70° E) reveals the evolution of thisridge since magnetic anomaly 4 (8 Ma). Image processing has been used toshow that the horizontal component of strain due to a network of normal stepfaults increases dramatically between 69°30 E and the RTJ. Thisarea close to the RTJ is characterized by a deep graben at the foot of thetriple junction trace on the African plate and by a narrow fault-boundedridge that joins an offset of the trace on the Antarctic plate. In thatarea, spreading is primarily amagmatic and dominated by tectonic extensionprocesses. To the west of 69°30 E, some lobate bathymetricfeatures atop of a large topographic high suggest volcanic constructions.Between 68°10 E and 69°25 E the southern flank of theSWIR domain is wider than the northern one and is characterized by a series of 7 en echelon bathymetric highs similar in size,shape and orientation to the one centred at 69°30E near the present-day triple junction. Their en echelon organization along the triple junction trace on the Antarctic plate and the typical lack of conjugated parts on the northern flank show that these bathymetric highs have been shifted to the south by successive northward relocalisations of the SWIR rifting zone. This evolution results in the asymmetric spreading of the SWIR in the survey area. The off-axis bathymetric highs connect to the offsets of the triple junction trace on the Antarctic plate when the Southeast Indian Ridges lightly lengthenstoward the northwest and the triple junction is relocated to the north. We propose that the SWIR lengthens toward the northeast with two propagation modes: 1) a continuous and progressive propagation with distributed deformation in preexisting crust of the Central Indian Ridge, 2) a discontinuous propagation with focusing of the deformation in a rift zone when the triple junction migrates rapidly to the north. The modes of propagation of the SWIR are related to different localisation and distribution of strain which are in turn controlled by changes of the triple junction configurations due to propagation, recession or a symmetric spreading on the Central and Southeast Indian Ridges. 相似文献
76.
77.
78.
西太平洋暖池区气象学特征分析 总被引:1,自引:0,他引:1
本文根据TOGA-COARE强化观测资料及卫星资料分析讨论了西太平洋暖池区11-2月间海面气象要素的平均特征。分析发现海面气压平均日变化似乎同中纬度区明显不同。文中还分析讨论了在西太暖池区西风爆发、赤道浅涡、信风逆温及ITCE和南太平洋辐合带SPCZ的变化特征。 相似文献
79.
本文介绍并叙述了AEL-1型风向、风速仪的设计原理,仪器各部分的电路设计,工作过程及系统软件。该仪器适用于气象台站、工矿企业、海上浮标及科研单位等部门。 相似文献
80.
山西能源重化工基地建设关系到全国四个现代化的实现,被列为国家重点建设工程,制定了《山西能源重化工基地综合规划》。本文分析了80年代山西省经济建设的成就与问题。提出了“整体创新,综合开发”,把山西能源重化工基地建设成内陆经济开放区的战略大思路,为此,90年代应完成11项大型经济战略工程,同时展望了经济发展改革前景。 相似文献