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981.
982.
983.
大洋核杂岩和拆离断层是洋中脊中发育的重要构造,被广泛关注。拆离断层一般为长期活动的,低角度的,大断距的正断层,绝大多数形成于慢速和超慢速扩张洋中脊的内侧角上,其将地壳深部和上地幔的物质拆离到海底面形成大洋核杂岩。大洋核杂岩因其表面发育了窗棱构造,在多波束图像上更容易识别。大洋核杂岩所处的地壳年龄较年轻,为0~10Ma。洋中脊半扩张速率约为10mm/a,具有不对称扩张的特点,有拆离断层的一侧扩张速率更快。在大洋核杂岩取得的岩芯中代表性岩石为辉长岩,地震资料解释认为大洋核杂岩下具有一个大的辉长岩侵入体。发育大洋核杂岩和拆离断层的区域有升高的布格重力异常,高的P波速度和抬升的莫霍面。拆离断层起源于岩浆供给不足的区域,大多在大洋中脊洋脊段(segment)的末端,其演化会受到上地幔辉长岩体侵入的影响,通过旋转铰链的模式进行。总结了全球大洋核杂岩和拆离断层的分布情况,讨论了其岩石特征、地球物理场特征,探讨其成因机制和演化模式,并探讨了未来的研究方向。 相似文献
984.
A lot of well-preserved plants from the Linxi Formation are collected in the Soron area,Inner Mongolia,consisting of 34 species of 16 genera. They are Late Permian in age. The flora is characterized by a lot of Angaran plants,such as Paracalamites,Comia,Rhachiphyllum,Iniopteris,Rufloria,etc. Some Cathaysian elements,such as Lobatannularia lingulata,L. multifolia,Fascipteris Cathaysiantus,F. densata,Taeniopteris szei,Cladophlebis liulinensis and C. permica,are also mixed within the present flora. This indicates that the Soron of Inner Mongolia was located in the sector between the Angaran and Cathysian floristic provinces in Lopingian. It is beneficial for depicting the location and the evolution of the Solenker--Xar Moron suture zone in the phytogeographic view. The transmigration of tropical and subtropical Cathaysian plants to the north indicates that the Paleoasian Ocean was closed during the late Permian along the suture zone. 相似文献
985.
986.
A Dipole Pattern of Summer Precipitation over Mid-high Latitude Asia and Related Snow Cover Anomalies in the Preceding Spring
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A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China (MNC) region and the West Siberian Plain (WSP), is found to be clear and stable on both interdecadal and interannual scales during 1981- 2011. Spring snow cover anomalies over a small region within the WSP and the Heilongjiang River (HR) region are closely related to the variation of this dipole mode during the subsequent summer, and they can therefore be considered as forecasting factors. Our statistical results imply a potential process explaining the relationship between the spring snow anomalies and the summer rainfall dipole. Corresponding to the snow anomalies, Rossby waves propagate along a path from the WSP region, via the Mongolian Plateau, to the Stanovoy Range during summer. At the same time, Rossby-wave energy divergences and convergences along this path maintain and reinforce an anomalous cyclone and anticyclone pairing over the Asian continent, which is significantly linked to opposite summer precipitation anomalies between the MNC and WSP regions. Numerical experiments are need- ed to further confirm the above conjecture and demonstrate the detailed physical mechanisms linking the spring snow cover anomalies and summer precipitation dipole. 相似文献
987.
基于Jenkins(1989)建立的包含Stokes漂流、风输入和波耗散影响的修正Ekman模型,采用Paskyabi等(2012)使用的推广的Donelan等(1987)中的谱和波耗散函数,并利用Paskyabi等(2012)中修正方法给出的包含高频波的风输入函数,在粘性不依赖于水深及粘性随深度线性变化的条件下,研究了包含高频毛细重力波的随机表面波对Stokes漂流和Song(2009)导出的波浪修正定常Ekman流解的影响。结果表明高频表面波使Stokes漂流在海表面剪切加强,对定常Ekamn流解的影响通常不能忽略,但对Ekman流场的角度偏转影响很小。最后,将考虑高频表面波尾谱影响所估算的定常Ekman流解与已有观测结果以及经典Ekman解进行了比对分析。 相似文献
988.
破碎波对近海海岸地形以及海岸建筑物影响强烈,通过物理模型实验对孤立波、规则波作用下破碎带的床面形态以及孔隙水压力进行分析。破碎波冲击海床,破碎处床面上形成沙坝和沙坑,与规则波相比,孤立波破碎时对床面的冲刷更加剧烈,床面形成的沙坝和沙坑尺度更大,且土体内孔隙水压力幅值也较大。同时研究了波面变化对孔隙水压力的影响,发现波面变化历时曲线与孔隙水压力历时曲线相似,与孔隙水压力梯度历时曲线更为相似,说明波面变化更能反映海床内部孔隙水压力梯度的变化。通过探讨波浪与海床之间相互耦合作用,发现破碎带地形变化使得波浪出现不同破碎类型,分析得出卷破波比崩破波作用下孔隙水压力幅值大。 相似文献
989.
基于ROMS模型数值研究南海温跃层的季节变化 总被引:2,自引:0,他引:2
On the basis of the regional ocean modeling system (ROMS), the seasonal variations of the thermocline in the South China Sea (SCS) were numerically investigated. The simulated hydrodynamics are in accordance with previous studies: the circulation pattern in the SCS is cyclonic in winter and anticyclonic in summer, and such a change is mostly driven by the monsoon winds. The errors between the modeled temperature profiles and the observations obtained by cruises are quite small in the upper layers of the ocean, indicating that the ocean status is reasonably simulated. On the basis of the shapes of the vertical temperature profiles, five thermocline types (shallow thermocline, deep thermocline, hybrid thermocline, double thermocline, and multiple thermocline) are defined herein. In winter, when the northeasterly monsoon prevails, most shallow shelf seas in the northwest of the SCS are well mixed, and there is no obvious thermocline. The deep region generally has a deep thermocline, and the hybrid or double thermocline often occurs in the areas near the cold eddy in the south of the SCS. In summer, when the southwesterly monsoon prevails, the shelf sea area with a shallow thermocline greatly expands. The distribution of different thermocline types shows a relationship with ocean bathymetry: from shallow to deep waters, the thermocline types generally change from shallow or hybrid to deep thermocline, and the double or multiple thermocline usually occurs in the steep regions. The seasonal variations of the three major thermocline characteristics (the upper bound depth, thickness, and intensity) are also discussed. Since the SCS is also an area where tropical cyclones frequently occur, the response of thermocline to a typhoon process in a short time scale is also analyzed. 相似文献
990.
Design of a hydraulic power take-off system for the wave energy device with an inverse pendulum 总被引:1,自引:0,他引:1
This paper describes a dual-stroke acting hydraulic power take-off (PTO) system employed in the wave energy converter (WEC) with an inverse pendulum. The hydraulic PTO converts slow irregular reciprocating wave motions to relatively smooth, fast rotation of an electrical generator. The design of the hydraulic PTO system and its control are critical to maximize the generated power. A time domain simulation study and the laboratory experiment of the full-scale beach test are presented. The results of the simulation and laboratory experiments including their comparison at full-scale are also presented, which have validated the rationality of the design and the reliability of some key components of the prototype of the WEC with an inverse pendulum with the dual-stroke acting hydraulic PTO system. 相似文献