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211.
准噶尔盆地的类型和构造演化 总被引:35,自引:1,他引:34
准噶尔盆地的早二叠世属于裂谷还是前陆盆地 ,存在意见分歧 ;晚二叠世—老第三纪盆地的性质也不确定。文中通过对盆地构造几何学、沉降史、热史及火山岩的综合分析研究 ,对盆地类型和构造演化获得了一些新的认识 :( 1)准噶尔盆地在早二叠世为裂谷 ,晚二叠世为热冷却伸展坳陷 ,三叠纪—老第三纪为克拉通内盆地 ,新第三纪至今 ,由于印度板块与亚洲大陆碰撞才形成陆内前陆盆地。 ( 2 )对石炭纪—早二叠世的岩浆活动结合区域构造资料的研究表明 ,准噶尔地区古生代的板块运动和造山作用具软碰撞特点 ,早二叠世的裂谷盆地是在软碰撞背景下造山带伸展塌陷的产物。 ( 3)地幔热对流作用可能是软碰撞造山后伸展塌陷的主要深部动力学机制。 相似文献
212.
冻土区块石护坡路基调温效果试验研究 总被引:2,自引:0,他引:2
块石护坡调温路基是多年冻土区铁路设计中所采取的一种积极保护冻土的措施,该调温过程包括暖季的热屏蔽作用和冷季的对流降温两个方面。根据现场观测资料,对两种不同粒径的块石层下地温热状况给予了初步分析。结果表明,暖季小块石层(粒径为50~80 mm)的热屏蔽作用要优于大块石层(粒径为400~500 mm),而冷季大块石层的对流降温作用要强于小块石层;综合一个暖冷季循环周期来看,大块石层的调温效果要好于小块石层。块石护坡路基下0 ℃等温线大部分已基本接近原天然地表。初步认为,此种发展趋势有利于路基的稳定。 相似文献
213.
Isopycnal analyses were performed on the Global Ocean Data Assimilation System(GODAS) to determine the oceanic processes leading to so-called second-year cooling of the La Nina event. In 2010–12, a horseshoe-like pattern was seen,connecting negative temperature anomalies off and on the Equator, with a dominant influence from the South Pacific. During the 2010 La Nina event, warm waters piled up at subsurface depths in the western tropical Pacific. Beginning in early 2011,these warm subsurface anomalies propagated along the Equator toward the eastern basin, acting to reverse the sign of sea surface temperature(SST) anomalies(SSTAs) there and initiate a warm SSTA. However, throughout early 2011, pronounced negative anomalies persisted off the Equator in the subsurface depths of the South Pacific. As isopycnal surfaces outcropped in the central equatorial Pacific, negative anomalies from the subsurface spread upward along with mean circulation pathways, naturally initializing a cold SSTA. In the summer, a cold SSTA reappeared in the central basin, which subsequently strengthened due to the off-equatorial effects mostly in the South Pacific. These SSTAs acted to initiate local coupled air–sea interactions, generating atmospheric–oceanic anomalies that developed and evolved with the second-year cooling in the fall of 2011. However, the cooling tendency in mid-2012 did not develop into another La Nina event, since the cold anomalies in the South Pacific were not strong enough. An analysis of the 2007–09 La Nina event revealed similar processes to the2010–12 La Nina event. 相似文献
214.
青藏高原东南缘地处印度与欧亚板块碰撞侧向逃逸的特殊构造部位,地势起伏相对较缓,形成三江并流的独特地貌格局.然而,对于东南缘大尺度地形地貌形成机制与水系演化的认识仍存在很大的分歧.本文获得的澜沧江流域芒康地区5个基岩样品磷灰石U-Th/He年龄表明该地区在早-中中新世(23~15Ma)经历了一次区域性冷却事件,且冷却速率在5Ma期间从40℃/Ma降低到28℃/Ma以下.目前可获得的青藏高原东缘-东南缘的低温年代学数据表明:尽管川西-藏东-滇北一带具有相似地貌特征,但高海拔、低起伏地貌面的形成是穿时性的,不能将它作为一个区域上连续的等时面来计算和探讨一个统一的区域抬升启动时间;三江地区地形属于非稳态的过渡型地形,尤其芒康-左贡地区剥蚀速率的差异比较清晰地展示了澜沧江流域地形演化处于非稳态期.此外,河流下切是塑造澜沧江流域的地形地貌主要驱动力之一:干流的侵蚀速率远远高于支流的侵蚀速率;河流下切强烈的地区(如德钦)对应的侵蚀速率及地形起伏度都较大,芒康地区微弱的地形起伏度取决于较低的侵蚀速率.第三纪以来的印度-欧亚板块碰撞导致青藏高原崛起的同时,也对周边尤其藏东南三江地区的地形地貌塑造及气候变化产生重大的影响. 相似文献
215.
For the purpose of enhancing air convection and controlling solar radiation, a new crushed-rock slope embankment design combined with a sun-shade measure is proposed. A newly designed embankment was constructed in the Tuotuohe section of the Qinghai-Tibet Railway and a field-testing experiment was carried out to determine its convection and temperature characteristics. The results show that distinct air convection occurred in the crushed-rock layer of the new embankment, especially in cold seasons, which was enhanced when it flowed upwards along the slope. This preliminarily indicated that the new design of the embankment slope was good for reinforcing air convection in the crushed-rock layer. The frequent fluctuations of the convection speed and the environmental wind speed were in good agreement, suggesting that the convection in the crushed rock primarily came from the ambient wind. It was also preliminarily determined that the new embankment had a better cooling effect and sun-shade effect for decreasing the temperature of the embankment slope compared with a traditional crushed-rock slope embankment, and the mean temperature difference between them was up to 1.7 °C. The mean annual temperature at the bottom boundary of the crushed-rock layer was obviously lower than that at the top boundary, and heat flux calculation showed that the shallow soil beneath the embankment slope was weakly releasing heat, all of which indicated that the new embankment slope design was beneficial to the thermal stability of the embankment. This study is helpful in providing some references for improved engineering design and maintenance of roadbeds in permafrost regions. 相似文献
216.
LIU Lei FEI Jianfang LIN Xiaopei SONG Xiangzhou HUANG Xiaogang Cheng Xiaoping 《Acta Meteorologica Sinica》2011,25(5):625-638
The high-resolution Weather Research and Forecasting (WRF) model is coupled to the Princeton Ocean Model (POM) to investigate
the effect of air-sea interaction during Typhoon Kaemi that formed in the Northwest Pacific at 0000 UTC 19 July 2006. The
coupled model can reasonably reproduce the major features of ocean response to the moving tropical cyclone (TC) forcing, including
the deepening of ocean mixed layer (ML), cooling of sea surface temperature (SST), and decaying of typhoon. 相似文献
217.
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219.
A. C. Edge R. J. Wilman R. M. Johnstone C. S. Crawford A. C. Fabian S. W. Allen 《Monthly notices of the Royal Astronomical Society》2002,337(1):49-62
We present a large sample of H - and K -band spectra of 32 optically line-luminous central cluster galaxies. We find significant rovibrational H2 emission in 23 of these galaxies as well as H recombination and/or [Fe ii ] emission in another five. This represents a fourfold increase in the number of molecular line detections known. A number of the detections are of extended emission (5–20 kpc). In several objects we find significant [Si vi ] emission that appears to correlate with the strength of high ionization lines in the optical (e.g. [O iii ]). This comprehensive sample builds on previous work and confirms that warm (1000–2500 K) molecular hydrogen is present wherever there is ionized material in the cores of cooling flows and in most cases it also coincides with CO molecular line emission. 相似文献
220.