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251.
252.
利用新疆测震台网在南天山地区架设的固定和流动台站记录的近8 a的观测资料,通过近震走时层析成像技术获得地壳三维速度结构,并利用三维速度结构对该区域的近震事件进行重定位。重定位后走时残差均方根由1.29 s减小为0.64 s,震源位置的不确定性约为0.1 km。三维速度结构显示,区域内速度结构表现出明显的横向和纵向不均匀性,5 km深度处,阿图什背斜和柯坪断裂以北表现为高速异常,以南表现为低速异常,波速比整体上以高值为主;15 km和20 km深度处,研究区P波速度主要以高速异常为主;25~30 km深度处,研究区内P波高速异常转变为以近NE向低速异常为主,波速比也以近NE向低值异常为主。区域内地震活动性与地壳速度结构具有较强的对应性,震源主要集中在P波高低速交界处的高速区域,同时波速比也偏向高波速比一侧。震源位置集中区的下方存在低速条带,该条带可为应变能的积累和释放提供有利的环境基础。 相似文献
253.
关于西部大开发的哲学思考 总被引:1,自引:0,他引:1
本文运用哲学思维从八个方面探讨了西部大开发面临的重大认识和决策问题,旨在西部人民中唤起艰苦奋斗的创业精神,要把西部大开发的立足点建立在主要依靠中国人自己的基础上。 相似文献
254.
利用1961-2010年天山山区44个气象站和10个水文站的观测资料,结合数字高程模型(DEM)1 km×1 km网格数据,采用了自然正交分解(EOF)、多元回归分析、最大熵谱值分析等方法,对天山山区面雨量进行了计算,建立了区域面雨量时间序列,研究其时空分布特征及变化规律.天山山区的面雨量基本上呈现北多南少,西多东少的特征,多年平均面雨量1098.7×108 m3,且在1987年发生突变.冬季降水在年际变化和年代际变化特征上都呈现出明显的增加趋势.. 相似文献
255.
256.
Crustal structure of the Paleozoic Kunlun orogeny from an active-source seismic profile between Moba and Guide in East Tibet, China 总被引:13,自引:0,他引:13
Zhongjie Zhang Simon Klemperer Zhiming Bai Yun Chen Jiwen Teng 《Gondwana Research》2011,19(4):994-1007
We herein present a new seismic refraction/wide-angle reflection profile that crosses the Songpan–Ganzi terrane, the Animaqing suture zone and the eastern Kunlun mountains (comprised of the South Kunlun and Middle Kunlun blocks separated by the Middle Kunlun fault). The profile is 380 km long and extends from Moba to Guide in eastern Tibet. The crustal thickness is about 62 km under the Songpan–Ganzi terrane, 62–64 km under the South Kunlun, and 60 km under the Middle Kunlun block. The Songpan–Ganzi flysch seems to be present up to a depth of 15 km south of the Animaqing suture zone, and up to a depth of 10 km in the Middle Kunlun block, with thicknesses elsewhere that depend on assumptions about the likely lithologies. The profile exhibits clear lateral variations both in the upper and lower crust, which are indicative of different crustal blocks juxtaposed by the Kunlun fault system. Whether or not the Songpan–Ganzi flysch was originally deposited on oceanic crust, at the longitude of our profile (100°E) it is now underlain by continental crust, and the presence of continental crust beneath the Songpan–Ganzi terrane and of a continental arc under the South Kunlun block suggest Paleozoic continent–continent arc collision in the eastern Kunlun Mountains. Comparison of crustal velocity columns from all wide-angle seismic profiles across the eastern Kunlun mountains indicates a remarkable west-to-east change in the Moho topography across the Kunlun fault system (15–20 km Moho step at 95°E, but only 2–5 km along our profile at 100°E). Lower-crustal thickness of the Kunlun terranes is rather uniform, about 35 km, from 80°–95°E, which suggests that similar thrust-thickening processes have played a role where the Qaidam Basin abuts the Kunlun fault, but thins to 20–25 km at 100°E, east of the Qaidam Basin. The increased crustal thickness from 93° to 98°E compared to that at 100°E may be due to the differences in the thickness of the crust of the two plates before their collision, and/or largely achieved by thickening of the lower crust, perhaps indicating a crustal flow mechanism operating more strongly in the western region. 相似文献
257.
东昆仑山北缘山前构造带的特征及其对油气
成藏的意义 总被引:1,自引:0,他引:1
东昆仑山北缘山前构造带位于柴达木盆地南部,中新生代以来受东昆仑山和阿尔金断裂双重构造作用的影响,其油气成藏赋存规律尚不十分清楚。结合前人的资料,根据最新的地震资料解释成果,对研究区主要断裂的构造特征、活动性质、时代及其对油气成藏的控制作用进行了研究,认为东昆仑山北缘断裂与东昆仑山隆升、阿尔金断裂活动相关,中新世早期和早更新世末期为2期主要的活动期次,控制了该区生烃凹陷、油气成藏和后期的次生油藏。因此,研究东昆仑山北缘山前构造带的演化规律对寻找同类型油气藏具有重要意义。 相似文献
258.
The characteristics of the Bolokenu-Aqikekuduk (Bo-A) fault, a right-lateral strike-slip fault
that runs for more than 700 km long and obliquely cuts North Tianshan Mountains, are evaluated here
based on remote sensing data, and through an analysis of the results from field investigations as well
as climate-geomorphic events.
The fault is composed of a western segment with a NW strike and an eastern segment with a NWW
strike. The western segment is nearly 250 km long, extending northwestward into Kazakhstan with
a right-lateral strike-slip rate of 5 mm/a. This domain consists of 4e5 rupture sections, with 3e4 deformation
belts, caused by ancient or historical earthquakes, and suggesting the potential for the occurrence
of further strong earthquakes (with M z 7.5) in future.
The eastern segment of the fault shows a right-lateral strike-slip rate of 1e1.4 mm/a, with the development
of 3e4 deformation belts caused by ancient or historical earthquakes, and with a potential for
future strong earthquake with M z 7.0. A typical strain partitioning style in the compression area has developed between the intermontane Bo-
A fault and the piedmont thrust structures of Northern Tianshan Mountains, under the effect of oblique
compression, as indicated by the piedmont thrust structure and the strike-slip fault in the mountains. 相似文献
259.
北京山区地质复杂,工程频繁,边坡灾害发育以崩塌和滑坡为主.边坡灾害以岩质边坡和人工边坡为主,破坏模式为剥落、落石、崩塌和滑坡.从地质构造、地层岩性,气候条件和人类活动4个方面分析边坡灾害的影响因素,提出对应的防范措施. 相似文献
260.
Noah P. Molotch Peter D. Blanken Mark W. Williams Andrew A. Turnipseed Russell K. Monson Steven A. Margulis 《水文研究》2007,21(12):1567-1575
Direct measurements of winter water loss due to sublimation were made in a sub‐alpine forest in the Rocky Mountains of Colorado. Above‐and below‐canopy eddy covariance systems indicated substantial losses of winter‐season snow accumulation in the form of snowpack (0·41 mm d?1) and intercepted snow (0·71 mm d?1) sublimation. The partitioning between these over and under story components of water loss was highly dependent on atmospheric conditions and near‐surface conditions at and below the snow/atmosphere interface. High above‐canopy sensible heat fluxes lead to strong temperature gradients between vegetation and the snow‐surface, driving substantial specific humidity gradients at the snow surface and high sublimation rates. Intercepted snowfall resulted in rapid response of above‐canopy latent heat fluxes, high within‐canopy sublimation rates (maximum = 3·7 mm d?1), and diminished sub‐canopy snowpack sublimation. These results indicate that sublimation losses from the sub‐canopy snowpack are strongly dependent on the partitioning of sensible and latent heat fluxes in the canopy. This compels comprehensive studies of snow sublimation in forested regions that integrate sub‐canopy and over‐story processes. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献