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61.
Late Quaternary systematic stream offsets caused by repeated large seismic events along the Kunlun fault, northern Tibet 总被引:8,自引:0,他引:8
The Kunlun fault is one of the largest strike-slip faults in northern Tibet, China. In this paper, we focus upon the Kusai Lake–Kunlun Pass segment of the fault to understand the geomorphic development of offset streams caused by repeated large seismic events, based on tectono-geomorphic analysis of high-resolution satellite remote sensing images combined with field studies. The results indicate that systematic left-lateral stream offsets appear at various scales across the fault zone: Lateral offsets of small gullies caused by the 2001 Mw 7.8 Kunlun earthquake vary typically from 3 m to 6 m, meanwhile streams with cumulative offsets of 10 m, 25–30 m, 50–70 m, 250–300 m and 750–1400 m have resulted from repeated large seismic events during the late Quaternary. An average slip rate of 10 ± 1 mm/year has been estimated from the lateral stream offsets and 14C ages of alluvial fan surfaces incised by the streams. A three-dimensional model showing tectono-geomorphic features along a left-lateral strike-slip fault is also presented. The Kusai Lake–Kunlun Pass segment provides an opportunity to understand the relationship between geomorphic features produced by individual large seismic events and long-term geomorphic development caused by repeated large seismic events along a major strike-slip fault. 相似文献
62.
With Empirical Orthogonal Function (EOF) and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai-Tibet Plateau during the period 1971-2004. Analysis indicates that the total cloud amount decreases from the southeast to the northwest of the plateau, and that the annual and seasonal variations in total cloud amount both show an apparent declining tendency over the past decades. Correlation analysis demonstrates that the total cloud amount is negative with sunshine duration and diurnal temperature range (DTR), and is positive with precipitation and the relative humidity, respectively. The negative correlation is consistent with the radiative effect of cloud, while the positive correlation between total cloud amount and precipitation is obscured because of the influence of topographic factors. Discussion implies that the decrease of total cloud amount is possibly due to the variation of atmospheric aerosol content and ozone concentration over the plateau, although it is difficult to quantify the driving force mechanism up to now. 相似文献
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Solar energy is clean and renewable energy that plays an important role in mitigating impacts of environmental problems and climate change. Solar radiation received on the earth’s surface determines the efficiency of power generation and the location and layout of photovoltaic arrays. In this paper, the average daily solar radiation of 77 stations in China from 1957 to 2016 was analyzed in terms of spatial and temporal characteristics. The results indicate that Xinjiang, the Qinghai-Tibet Platea... 相似文献
65.
海洋对全球变暖的响应及南海观测证据 总被引:1,自引:0,他引:1
回顾了世界各大洋和若干区域海洋的海平面、热含量、温盐结构及珊瑚变化等方面的主要成果,并对中国南海温盐结构的长期变化趋势进行了初步分析。结果表明,对全球增暖的响应,南海中层水盐度的长期变化表现出一定的淡化趋势。 相似文献
66.
CHEN Meixiang) ZUO Juncheng) LI Peiliang) DU Ling) and LI Lei)) Oceanography Department Ocean University of China Qingdao P. R. China ) Key Laboratory of Coastal Disaster Defence Ministry of Education Hohai University Nanjing P. R. China 《中国海洋大学学报(英文版)》2007,6(2):117-124
Based on a ship survey during January 1998, the characteristics of the flow, the thermohaline properties and the volume transport of the Arabian Sea are discussed. A strong westward flow exists between 10.5?N and 11?N, part of which turns to the south as the Somali current near the coast at about 10?N and the rest turns north. At the passage between the African continent and the So- cotra Island, the northern branch separates into two flows: the left one enters the passage and the right one flows eastward along the southern slope of the island. Off the island the flow separates once more, most of it meandering northeast and a small fraction flow- ing southeast. Volume transport calculation suggests that the tidal transport is one or two orders of magnitude smaller than the total transport in this region and it becomes more important near the coast. The average velocity of the flow in the upper layer (0-150 m) is about 20 cm s-1, with a maximum of 53 cm s-1 appearing east of the Socotra Island, and the subsurface layer (200-800 m) has an aver- age velocity of 8.6 cm s-1; the velocity becomes smaller at greater depths. The depth of the seasonal thermocline is about 100 m, above which there is a layer with well mixed temperature and dissolved oxygen. High-salinity and oxygen-rich water appears near the surface of the northern Arabian Sea; a salinity maximum and oxygen minimum at 100 m depth along 8?N testifies the subduction of surface water from the northern Arabian Sea. Waters from the Red Sea and the Persian Gulf also influence the salinity of the area. 相似文献
67.
An estimation of internal soliton forces on a pile in the ocean 总被引:2,自引:0,他引:2
DU Tao SUN Li ZHANG Yijun BAO Xianwen FANG Xinhua 《中国海洋大学学报(英文版)》2007,6(2):101-106
Internal soliton forces on oil-platform piles in the ocean are estimated with the Morison Formula. Different from sur- face wave forces, which change only in magnitude along a pile, internal soliton forces can be distributed over the entire pile in the water and they change not only in magnitude but also in direction with depth. Our calculations show that the maximum total force caused by a soliton with its associated current of 2.1 m s-1 is nearly equal to the maximum total force exerted by a surface wave with a wavelength of 300 m and a wave-height of 18 m. The total internal soliton force is large enough to affect the operations of marine oil platforms and other facilities. Therefore, the influence of internal solitons should not be neglected in the design of oil platforms. 相似文献
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70.
异常压力与油气分布 总被引:123,自引:2,他引:123
随着油气勘探活动的不断加深,国内外相继发现了许多异常高压油气田。据不完全统计,全世界已发现超压盆地180多个,其中160多个为富含油气盆地。异常高压油气田约占全球油气田30%左右,因此,对异常压力的研究,具有举足轻重的意义。本文介绍了异常地层压力的概念、特征及分类;详细论述了异常压力的成因,即烃类生成作用、欠压实作用、液态烃类的裂解作用、粘土矿物的后生成岩作用、构造作用、温度变化等;系统阐述了世界典型含油气盆地的超压形成机制、超压体系中油气初次运移机理以及超压与油气分布关系;并在此基础上,归纳总结出了五种超压油气藏成藏模式,即:(1)位于超压体系中的低渗超压油气藏;(2)位于超压层系中,以礁灰岩(或浊积砂岩)为储层的高压油气藏;(3)位于超压带上倾方向,以退覆三角洲平原和分流河道砂岩为储层的常压或过渡带超压油气藏;(4)位于超压带上、下部的超压油气藏;(5)位于远离超压体系的泄压区常压油气藏,本文对指导、加深新老油气区勘探具有实际应用价值。 相似文献