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青藏高原湖泊遥感信息提取及湖面动态变化趋势研究 总被引：5，自引：0，他引：5
青藏高原湖泊星罗棋布,是我国盐湖主要分布区.本文以RS和GIS技术为基础,从Landsat的MSS、TM、ETM三期遥感影像中,提取了青藏高原的所有湖泊信息,建立了我国盐湖空间数据库.用ArcGIS对盐湖空间数据进行统计和空间分析,从时间和空间上分析青藏高原从70年代到2000年左右湖泊湖面动态变化情况.同时,在青海和... 相似文献
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青藏高原复杂地表能量通量研究 总被引：4，自引：0，他引：4
“全球能量水循环之亚洲季风青藏高原试验研究”（GAME/Tibet）和“全球协调加强观测计划（CEOP）亚澳季风之青藏高原试验研究”（CAMP/Tibet）的加强期观测和长期观测已经进行了9年多,并且已取得了大量的珍贵资料。首先介绍了GAME/Tibet 和CAMP/Tibet 试验的情况,并利用观测资料给出了局地能量分布（日变化和月际变化）特征。复杂地表区域能量通量研究是青藏高原地气相互作用研究中的重中之重。卫星遥感的应用成为解决这一问题，即实现GAME/Tibet和CAMP/Tibet试验主要初衷的必不可少的手段。利用卫星遥感观测（Landsat 7 ETM）资料结合地面观测的方法,计算得到了相关地区非均匀地表区域上的地表温度、地表反射率、标准化差值植被指数(NDVI)、校准的调整土壤植被指数（MSAVI）、植被覆盖度和叶面指数(LAI)及能量平衡各分量（净辐射通量、土壤热通量、感热和潜热通量）的分布图像，所得结果基本可信。为了得到整个青藏高原复杂地表的热通量分布，中国科学院青藏高原研究所正在与其他研究单位一起建立青藏高原地表和大气过程监测系统（MORP）。最后介绍了该监测计划和已建立的3个综合观测研究站及如何利用建立的台站把站点观测的热通量推广到整个青藏高原的途径。 相似文献
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The Tibetan block originated during the late Palaeozoic-early Mesozoic by separation from Gondwanic India and the opening of Neo-Tethys. The event, which was responsible for reactivating the Tibetan basement, closed Palaeo-Tethys, lying to the north of it, and created the Kun Lun fold system as a consequence of the collision of the north-moving Tibetan block with the Tarim—Tsaidam block.During the late Cretaceous, South Tibet developed into an Andean-type foldbelt (Nyenchen Thangla) by subduction of Neo-Tethyan lithosphere beneath Tibet which had begun in the late Triassic. Mesozoic sedimentary sequences in Tibet are the response to an extensional regime behind an active margin. A Neo-Tethys island arc system at this margin was crushed during the early Eocene with the development of the Transhimalayan ophiolite and plutonic belts. Final collision during mid-Eocene times between the Himalayan microcontinent, a fragment of India and reworked Tibet in the Mid-Eocene produced the Indus—Tsangpo suture zone. A large part of the microcontinent, with an unconsumed segment of Neo-Tethys oceanic crust attached to it, presumably underthrust Tibet prior to the Himalayan orogeny. This feature is responsible for the double thickness of Tibetan crust and its young volcanism. 相似文献
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西藏高原和喜马拉雅的隆升历史是新生代以来众多地质事件的边界条件。因此,它对于我们理解新生代全球气候变冷以及亚洲环境变化等许多地质过程都具有深远的意义。尽管各种替代指标已经被广泛应用于研究高原隆升历史,然而,不同方法所得出的高原隆升历史并不一致。这主要归咎于一些替代指标本身存在多解性和不确定性,从而严重阻碍了获取正确的高原隆升历史。在对这些替代指标进行详细的阐述之后,对其指示的高原隆升历史进行重新评估,并结合在高原腹地开展的工作,提出了原西藏高原的隆升模式,即拉萨地体和羌塘地体在始新世就已经达到现在的海拔高度,而此时青藏高原北部还是低地,南部和西部可能还处在海洋环境。在中新世时,高原向北、向东和向南生长并在第四纪时形成现在的高原特征。 相似文献
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西藏的缝合带一直是西藏高原基础地质研究中最热门的科学问题之一.立足于西藏高原4条主要缝合带的物质组成、缝合结构以及形成时代等资料,根据时空结构分析认为古特提斯演化与转换构造有关,雅鲁藏布江洋盆扩张与羌塘-三江地区的印支运动具有耦合的时空变换关系;重点讨论了以班公湖-怒江带为中心的古-新特提斯转换扩张性质,构造体制上属左行走滑拉分,形成了西藏高原上颇具特色的与走滑拉分方向平行的伸展构造类型杂岩系,其重要意义不亚于高原周缘逆冲-拆离系构成的杂岩系和美国西部的盆-岭变质核杂岩;探讨了西藏东、西部地区不同地质结构的科学问题,提出了冈底斯岩浆弧拓展加宽受雅鲁藏布洋双重俯冲的制约. 相似文献
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During seven expeditions new data were obtained on the maximum extent of glaciation in Tibet and the surrounding mountains. Evidence was found of moraines at altitudes as low as 980 m on the S flank of the Himalayas and 2300 m on the N slope of the Tibetan Plateau, in the Qilian Shan. On the N slopes of the Karakoram, Aghil and Kuen Lun moraines occur as far down as 1900 m. In S Tibet radiographic analyses of erratics document former ice thicknesses of at least 1200 m. Glacial polishing and knobs in the Himalayas, Karakoram etc. are proof of glaciers as thick as 1200–2000 m. On the basis of this evidence, a 1100–1600 m lower equilibrium line altitude (ELA) was reconstructed for the Ice Age, which would mean 2.4 million km2 of ice covering almost all of Tibet, since the ELA was far below the average altitude of Tibet. On Mt. Everest and K2 radiation was measured up to 6650 m, yielding values of 1200–1300 W/m2. Because of the subtropical latitude and the high altitude solar radiation in Tibet is 4 times greater than the energy intercepted between 60 and 70° N or S. With an area of 2.4 million km2 and an albedo of 90% the Tibetan ice sheet caused the same heat loss to the earth as a 9.6 million km2 sized ice sheet at 60–70° N. Because of its proximity to the present-day ELA, Tibet must have undergone large-scale glaciation earlier than other areas. Being subject to intensive radiation, the Tibetan ice must have performed an amplifying function during the onset of the Ice Age. At the maximum stage of the last ice age the cooling effect of the newly formed, about 26 million km2 sized ice sheets of the higher latitudes was about 3 times that of the Tibetan ice. Nevertheless, without the initial impulse of the Tibetan ice such an extensive glaciation would never have occurred. The end of the Ice Age was triggered by the return to preglacial radiation conditions of the Nordic lowland ice. Whilst the rise of the ELA by several hundred metres can only have reduced the steep marginal outlet glaciers, it diminished the area of the lowland ice considerably. 相似文献
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据西藏自治区大地构造演化特征,从整个青藏高原构造单元分布特点考虑,本文将西藏自治区地层区划结合构造单元和含煤地层一并考虑,将其划分为三个构造-地层大区:羌塘-三江构造-地层大区、班公湖-双湖-怒江构造-地层大区、冈底斯-喜马拉雅构造-地层大区。从区域地层、沉积构造及其古生物化石组合等特点综合分析,得出西藏赋煤区聚煤作用具有时代多、分布广、煤层层数多、厚度薄和稳定性差的总体特点。区内含煤地层包括下石炭统、上二叠统、上三叠统、中侏罗统、下白垩统和古近系等。最主要煤系是下石炭统马查拉煤系、上二叠统妥坝煤系、上三叠统土门煤系、下白垩统多尼煤系。 相似文献
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青藏高原西部叶城-狮泉河地区岩石圈各向异性研究 总被引：4，自引：0，他引：4
对青藏高原西部新疆叶城—西藏狮泉河地区宽频地震探测记录到的剪切波进行了各向异性分析,计算结果给出了该地区上地幔各向异性的特征:西昆仑地区各向异性大都沿北东方向分布,总体方向变化不大,各向异性整体走向与青藏高原和塔里木盆地北缘各向异性空间分布一致。由此得出:印度板块向北推进的构造运动是形成本区岩石圈剪切波各向异性的主要原因,青藏高原各地体的各向异性在较大的东西向范围内保持稳定,各地体岩石圈固有的各向异性方向为北东向;作为羌塘地体和拉萨地体的分界线,班公怒江断裂带是主要的地表分界位置,在深部,无论西部剖面还是中部剖面,印度板块岩石圈的各向异性在该断裂带上均没有变化。 相似文献
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藏北双湖-安多地区侏罗纪菊石新资料及地层述评 总被引：2，自引：0，他引：2
近期采集的菊石鉴定表明藏北安多地区布曲组、“夏里组”和“索瓦组”的时代为中巴通期至中卡洛维期。特别要指出的是 ,从藏北地区沉积演化和古生物地理区系的角度来看 ,该地不具备存在晚侏罗世提塘期“斯匹提页岩动物群”的地质背景 ,所以藏北地区近年来多次报道的晚侏罗世提塘期的“斯匹提页岩菊石动物群”值得怀疑 ,有关化石的鉴定是不可靠的 ;还应该指出的是 ,雁石坪地区侏罗纪岩石单位也不适宜在安多地区运用。双湖地区菊石层序指明该地富含油页岩的缺氧性沉积 ,即“海螂蛤页岩相”的时代为早侏罗世晚普林斯巴赫至早图阿尔期 ,它们是早侏罗世晚期全球性缺氧事件在东特提斯北缘的响应。 相似文献
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The Tibetan Plateau, largely derived from the accretion of several Gondwana microplates to the southern margin of Asia since the late Palaeozoic, is the highest and largest topographic relief on Earth. Although the first order geodynamic processes responsible for its pre-Cenozoic evolution are quite well-known, many issues are still debated, among which is the timing of collision of each terrane with the southern margin of Asia. Even more uncertain is the pre-Palaeozoic history of these terranes, due to the lack of basement exposures. As a contribution to understanding the pre-Cenozoic evolution of the Tibetan Plateau, this paper focuses on the Aghil Range, a remote and poorly investigated area close to the Karakorum Fault between Kunlun and Karakorum (Xinjiang, China) in western Tibet. The tectono-metamorphic and magmatic evolution of the Aghil Range is investigated using a multidisciplinary approach that combines field mapping, petrology and geochronology (UPb on titanite, zircon, monazite and xenotime using SHRIMP-RG). We demonstrate that the Aghil Range preserves a coherent slice of Neoproterozoic crystalline basement with a late Palaeozoic sedimentary cover deposited on a passive continental margin during the Gondwana break-up. This represents the westernmost exposure of Precambrian crystalline basement known so far in the Tibetan Plateau. Furthermore, petrological and geochronological results allow reconstructing the Mesozoic poly-metamorphic evolution of this sector of the Tibetan Plateau, which records the evidence of Middle Jurassic (ca. 170 Ma) and Late Cretaceous (66 Ma) collisional events, as well as of the Late Jurassic (ca. 150 Ma) early subduction of an accretionary complex developed on its southern margin. Evidence of Late Cretaceous subduction-related magmatism preceding the last collisional event is also recorded. These results allow tentative correlation of the different terranes of Central Tibet with those of the Pamir-Karakorum Range on both sides of the Karakorum fault. 相似文献
13.
MAGNETOSTRATIGRAPHIC DATING:IMPLICATIONS FOR TERTIARY EVOLUTION OF THE HOH XIL BASIN, NORTHERN TIBET 总被引：1，自引：0，他引：1
MAGNETOSTRATIGRAPHIC DATING:IMPLICATIONS FOR TERTIARY EVOLUTION OF THE HOH XIL BASIN, NORTHERN TIBET1 BGMRQ (BureauofGeologyandMineralResourcesofQinghai) .RegionalgeologyofQinghai(inChinesewithEnglishab stract) [M] .Beijing :ChinaGeolPress,1991.
2 CowardWP ,KiddWSF ,Pang,Y ,etal.Thestructureof1985TibetGeotraverse ,LhasatoGolmud.In:Sino BritishComprehensiveGeologicalExpeditionTeamoftheQinghai TibetPlateau.ThegeologicalevolutionoftheQin… 相似文献
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《International Geology Review》2012,54(16):2008-2015
Growing geologic evidence documents incremental Mesozoic and early Cenozoic shortening and thickening of the Tibetan crust prior to the onset of the main Cenozoic orogenic event. The Tibetan crust shows spatial and temporal variability in thickness, style, and timing of thickening, and in plateau-forming processes. The Songpan–Ganzi area of northeastern Tibet provides evidence for shortening and thickening of the crust in Late Triassic time. An oil exploratory well (HC-1) of 7012.4 m located in the area shows at least six tectonic repetitions, resulting in more than ～46% thickening of the Triassic sequence. It indicates that the true thickness of the Songpan–Ganzi Triassic flysch is not 10–15 km as previously assumed, but not more than 3–5 km. Based on this evidence, combined with prior tectonostratigraphic studies, we propose that substantial crustal shortening and thickening, leading to initial plateau formation in the northeastern Tibetan Plateau, had already occurred during the Late Triassic. 相似文献
15.
青藏高原晚新生代的扩展和隆升对周边环境演变产生重大影响,确定扩展和隆升的起始年代是一个重要的科学问题。近年来在六盘山、积石山和祁连山及其相邻盆地的研究表明,青藏高原东北缘晚新生代(5~10MaB.P. 或约8MaB.P. )发生了准同期、影响深远的构造变形,导致了沉积盆地的消亡和山脉的隆起。青藏高原北缘的阿尔金山和东缘的岷山、龙门山及川滇高原也在该时段发生了构造活动的加速和构造隆升。所有这些准同期的事件反映了约8MaB.P. 前后青藏高原向周边的扩展,扩展的方式是通过一系列逆冲断裂、褶皱变形、左旋走滑及其伴随的山脉隆起和盆地消亡而实现的。该时期青藏高原的扩展导致了周边的环境变化,奠定了今日环境的格局。 相似文献
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在前人研究成果的基础上,划分出青藏高原及邻区上新世残留盆地共95个,探讨了青藏高原及邻区上新世构造岩相古地理演化。青藏高原上新世总体构造地貌格局主要受控于印度板块与欧亚板块沿雅鲁藏布江缝合带的碰撞及持续挤压,影响着青藏高原广大范围内的构造抬升。东北部昆仑山、祁连山地区是两大构造隆起蚀源区,两大山系夹持的柴达木盆地是高原东北部最大的陆内盆地,祁连山以北和以东地区则以盆山相间的格局接受周围山系的剥蚀物质,直到晚上新世(青藏运动"A"幕)高原东北部进一步强烈隆升,山间盆地抬升成为剥蚀区。新疆塔里木和青藏高原东部羌塘、可可西里地区主体表现为大面积的构造压陷湖盆-冲泛平原沉积区。高原东南部为一系列走滑拉分断裂运动形成的拉分盆地,上新世早期堆积洪冲积相砾岩,中期为湖泊、三角洲沉积,晚期随着山体的进一步抬升,盆地又接受冲洪积扇相砾岩堆积,并被河流侵蚀剥露。高原南部上新世多分布一些近南北向盆地,是响应高原隆升到一定程度垮塌而成的断陷盆地,同东南部拉分盆地类似,上新世沉积相也由早至晚分为3个阶段。恒河地区上新世由于喜马拉雅山的快速抬升,沉积以粗碎屑为主,形成狭长的西瓦利克群堆积。上新世青藏高原总体地势继承了中新世西高东低、南高北低的地貌特征,但地势高差明显较中新世增大。 相似文献
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It seems to be progressively recognized that the stress of the India-Asia convergent front can be transferred rapidly through the southern and central Tibetan lithosphere to the northern Tibet, hence leading to the crustal thickening deformation there during or immediately after the onset of the India-Asia collision(ca.55 Ma).This study focuses on the late Cenozoic deformation and tectonic uplift of the northern Tibet and Tian Shan area.Detailed compilations of a variety of proxy data from sediments and bedrocks suggest that the northern Tibet and Tian Shan area underwent one stage of approximately synchronous widespread contractile deformation since 25–20 Ma, which seemed to decrease at circa 18 Ma as revealed by low-temperature thermochronological data.The latest Oligocene-early Miocene was also significant basin-forming episodes when many intermontane subbasins began to receive syntectonic sedimentation in the northeastern Tibet.Subsequently, the other phase of compressional deformation began to encroach more widely into the northern Tibet and Tian Shan area in episodic steps or continuously from 16–12 Ma to present. 相似文献
18.
青藏高原气候系统变化及其对东亚区域的影响与机制研究进展 总被引：1，自引：0，他引：1
青藏高原地区特殊的大气圈、水圈、冰冻圈、生物圈等多圈层相互作用过程及其变化,不仅对青藏高原及其周边地区的气候格局和变化有重要影响,而且对东亚、北半球乃至全球的环流形势和异常产生深远影响。为此,全球变化研究重大科学研究计划于2010年9月启动了"青藏高原气候系统变化及其对东亚区域的影响与机制研究"项目,旨在开展青藏高原环境、地表过程、生态系统对全球变化的响应及其对周边地区人类生存环境影响的综合交叉研究,以揭示青藏高原气候系统变化及其对东亚区域的影响机制,提出前瞻性的应对气候变化与异常的策略,减少其导致的区域自然灾害的损失。项目实施近3年来,开展了青藏高原首次"星—机—地"综合立体协同观测试验和大规模地气相互作用综合观测试验。在遥感结合地面观测估算青藏高原地表特征参数和能量通量方法,高原地区上对流层和下平流层结构,高原季风与东亚季风和南亚季风之间的内在联系,中国及青藏高原地区太阳辐射和风速的年代际变化趋势,青藏高原春季感热源减弱及其对亚洲夏季风和中国东部降水的影响,以及极高海拔地区土地覆被格局等方面取得了一些突出进展。 相似文献
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Tibetan Plateau, with its unique characteristics and its impact on the global environment, ecology and climate, is an important research region of the international scientific community. The development of international cooperation in the field of Tibetan Plateau was reviewed and the quantitative statistics and data in accordance with the SCI papers of international cooperation in the field of Tibetan Plateau were analyzed during the 35 years of 1980-2014. The experience of international cooperative research in the field of Tibetan Plateau from starting stage to rapid development to tend to mature stage of development was summarized. International cooperative research has become the main organization of research in the field of Tibetan Plateau. Tibet Plateau international collaboration changing from single academic discipline to multi academic disciplines was analized. Changes in major countries of international cooperation research and independent research in the field of Tibetan Plateau were compared and suggestions for strengthening international cooperative research in the field of Tibetan Plateau for China in the future were put forward. 相似文献
20.
青藏高原东部及其邻区力学耦合的岩石圈变形模式 总被引：1，自引：0，他引：1
根据青藏高原东部及其邻区布设的143个宽频带固定和流动地震台站的远震记录的SKS波分裂分析获得了各台站的快波偏振方向和快慢波之间的时间延迟。SKS分裂分析结果总体上反映了高原东部的上地幔物质流动方向,即高原内部表现为环绕喜马拉雅东构造结的顺时针旋转。在造山运动过程中有关岩石圈地壳和地幔力学耦合的造山变形方式,用从GPS和第四纪断裂滑动速率数据确定的地面变形场和由地震波各向异性数据推断的地幔变形场联合分析来定量求得。在青藏高原东部和云南、四川等地区新近快速增加的GPS和SKS波分裂观测数据,提供了对青藏高原岩石圈地幔实际变形方式的检验。这些新的数据不仅加强了高原内部力学耦合岩石圈的证据,而且也解释了高原外部相同的耦合特征。文中引入简单剪切变形和纯剪切变形的概念,用于解释高原内外不同的耦合变形特征。青藏高原和周围区域力学耦合岩石圈的垂直连贯变形有两个方面的大陆动力学含义:第一,岩石圈垂直强度剖面被一个重要的条件所约束,即要求与重力势能变化相关的应力能够从地壳传递到地幔;第二,青藏高原各向异性的空间变化反映了一个岩石圈变形的大尺度模式,以及从高原内部的简单剪切变形向高原外部的纯剪切变形的过渡带。文中提出的力学耦合岩石圈变形模型与当前已有的多种造山运动变形模型具有不同的变形含义,因此,地幔变形在青藏高原隆升过程中起主要作用。 相似文献