论冰碛石的形态特征及其与泥石流石的区别   总被引：1，自引：1，他引：0  

周尚哲 《冰川冻土》2021,43(3):683-689

长期以来流行的球度和圆度概念不足以刻画冰碛石及其他成因砾石的细微特征,需要在其基础上进一步挖掘有判别价值的标志性特征.针对冰碛石与泥石流石辨识的疑难问题,提出外接圆特征、粗糙度特征、圆度-体积特征以及混杂堆积砾石形态构成特征等几个概念.通过这些特征研究,结合真实的冰川擦痕、颤痕等标志,可更加准确地进行冰川沉积物与其他成...  相似文献   

风景区泥石流防治特点与技术   总被引：2，自引：0，他引：2  

崔鹏  陈晓清  柳素清  唐邦兴 《地学前缘》2007,14(6):172-180

中国大部分风景区位于山区,泥石流时有活动,破坏景观资源,危害生态环境,危及游人安全,而风景区泥石流往往暴发频次低,多含有漂木。分析了风景区泥石流防治的需求和特点,提出了风景区泥石流防治以保护自然景观和生态环境为主、灾害治理工程与自然景观相协调的基本目标。通过泥石流形成区源头治理、新型结构(梳齿坝、滤水坝、预制组合结构)和林内分散拦淤等措施,实现风景区的泥石流的治理目标,形成了以减灾工程与自然景观相协调和工程减灾与生态减灾功能相结合的风景区泥石流治理技术。采用这些技术对世界自然遗产九寨沟的14条灾害性泥石流进行治理,有效地控制了泥石流的发生和成灾,达到了保护景观资源、生态环境、游客与居民安全的目的。  相似文献   

大型矿床和成矿区(带)在混沌边缘   总被引：26，自引：8，他引：18  

於崇文 《地学前缘》1999,6(2):195-230

笔者将复杂性科学和矿床地质学相结合提出了一种新的金属成矿理论———“金属成矿动力系统的复杂性与自组织临界性”,并应用这一理论研究扬子古陆周缘四大成矿区（带）的矿床成因与成矿规律,发现“大型矿床和成矿区（带）在混沌边缘”。文章在概述“金属成矿动力系统的复杂性与自组织临界性”的理论纲要与噪声、混沌和混沌边缘基本概念的基础上,提出地质成矿系统在混沌边缘的四条判定准则：Ⅰ．自组织临界性的标志———广义地质学（地质学、地球物理学、地球化学）场（温度、流速、浓度、压力等场）的场量之时空幂律分布———及其基本属性：（１）长程时空关联与连通性及时空分形结构;（２）崩塌动力学;（３）“元胞自动机”的动力学机制;（４）自组织临界性涌现于“混沌边缘”,并具有最大的复杂性、演化性和创新性。Ⅱ．地质成矿过程向时间混沌及地质成矿系统向时空混沌的演化。Ⅲ．岩浆和热液“孤子”、“孤波”与“相干结构”以及其它弱混沌“拟序结构”。Ⅳ．超临界地质流体参与地质成矿作用。笔者进一步提出金属成矿动力系统的复杂性与自组织临界性的三大基础理论：（１）地质成矿过程的非线性动力学———应用非线性动力学理论研究矿床和矿集区形成的动力学机制;（２）“地质成矿作用?  相似文献   

砂质碎屑流和底流改造——部分传统浊积岩成因新解   总被引：4，自引：0，他引：4  

秦建华 《四川地质学报》1999,(4)

以鲍马层序为代表的古典浊积岩,在地质学界曾广泛流行。近年来的研究表明,真正的浊积岩是很少发生的。由于浊流和碎屑流具有不同的流变学特点,人们对部分传统浊积岩提出了砂质碎屑流和底流改造成因及其鉴别标志,并对传统海底浊积扇模式在进行重新研究的基础上提出了海底碎屑流模式。  相似文献   

铁路泥石流预报警报体系   总被引：8，自引：5，他引：3  

王韦  许唯临  谭炳炎  魏鸿 《山地学报》1999,17(2):183-187

简要介绍了铁路泥石流预报警报体系的构成和功能。在归纳分析资料采集内容和途径的基础上,总结并完善了评估泥石流沟严重程度的判识模型,泥石流暴发可能性的预报模型和铁路建筑是否成灾的警报模型,并用实测资料对其进行了验证。  相似文献   

Discovery and significance of deep-water gravity-flow deposits of the late Barremian of Early Cretaceous in Lower Congo Basin          下载免费PDF全文

Yu Ye  Wang Li  Yin Tai-Ju  Zhang Xing-Qiang  Huang Yan-Ran  Cao Tao-Tao 《古地理学报》1999,22(4):620-634

Taking the middle Pointe Indienne Formation of the Lower Cretaceous Barremian in the Lower Congo Basin as an example,based on the theory of deep-water sedimentology,combined with the latest research progress of gravity-flow,and with the help of the latest drilling core data and its analyzing test results in the study area,the lithology,sedimentary structure types and petrological characteristics were investigated. It is found that gravity-flow deposits were widely developed in the middle Pointe Indienne Formation of the study area. The deposition process and the conceptual model of sand-body development for the deep-water gravity-flow have also been summarized. The gravity-flow deposits are mainly composed of midium-fine grained sandstone where the flute cast,load cast,flame structure,ball and pillow structure are occurred at the bottom and the normal graded bedding,parallel bedding,climbing ripple bedding,convolute bedding,water escape structure and floating mud gravel are occurred in the internal part. The gravity flow sandstones whose transportation mechanism are dominated by suspension transport are mainly feldspathic detrital quartz sandstones which are poorly sorted,sub angular and sub rounded. Grainsize accumulation probability curve are characterized by both “one-segment” which suggests total suspension population and “two-segment” which suggests high suspension population. Five fluid types of gravity-flows including,slump,sandy debris flow,muddy debris flow and turbidity can be identified,and six styles of facies combination in vertical direction have been recognized. The gravity-flow sand-body in the study area can form large-scale oil and gas reservoir due to the better lateral continuity and the thicker vertical stack thickness.  相似文献   

Estimate of Ablation Rate of Glacier Ice under a Supraglacial Debris Layer     

Masayoshi Nakawo  & Birbal Rana 《Geografiska Annaler: Series A, Physical Geography》1999,81(4):695-701

The ablation rate under a debris layer is very difficult to measure directly at debris-covered glaciers, because the surface is highly heterogeneous, and the ablation rate varies tremendously from place to place. Heat budget considerations with a debris layer on top of glacier ice suggested that 'thermal resistance' of the debris layer could be estimated from surface temperature and the heat fluxes at the debris surface, and the ablation rate of the underlying glacier ice from the thermal resistance and meteorological data. The method was tested at the Lirung Glacier in Langtang Valley, Nepal Himalayas, using the thermal band of LANDSAT satellite for estimating surface temperature distribution of the debris top surface. The amount of melt water thus estimated was compatible with the observed discharge data from the glacier basin for periods of the monsoon season in 1985 and the pre-monsoon to the monsoon season in 1996. The investigation also revealed that the amount of discharge was much larger than the amount of precipitation over the basin, and it was suggested that the melt water from the debris-covered glacier contributes significantly to the river flow as a result of the shrinkage of the glacier.  相似文献   

Quaternary Moraines vs Catastrophic Rock Avalanches in the Karakoram Himalaya, Northern Pakistan     

Kenneth Hewitt 《Quaternary Research》1999,51(3):220

A history and conception of glacial events for the central Karakoram Himalaya, proposed some 80 years ago by Giotto Dainelli, are largely accepted today. However, certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches. In the Skardu and Shigar intermontane basins of Baltistan, at least 15 rock avalanche events were previously mapped as moraine or till. Criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix, clast shape, facies characteristics, the large scale unity of emplacement, and morphological relations to valley topography. The deposits of three events, at Katzarah, Satpura, and the north end of Shigar Valley, have been reconstructed in detail. Thick supraglacial debris does not result in similar deposits. Extensive valley fills, river terraces, large sediment fans, and lacustrine sediments formerly attributed to late-glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development. Existing reconstructions of glaciations are left in doubt, especially late-glacial events in the central Karakoram, as are the roles assigned to Karakoram, main Indus Valley, and western Himalayan ice.  相似文献   

The Saharan debris flow: an insight into the mechanics of long runout submarine debris flows   总被引：6，自引：0，他引：6  

GEE  MASSON  WATTS  & ALLEN 《Sedimentology》1999,46(2):317-335

New 3·5 kHz profiles and a series of piston cores from the north-west African margin provide evidence that the Saharan debris flow travelled for more than 400 km on a highly fluid, low-friction layer of poorly sorted sediment. Data suggest that the Saharan debris flow is a two-phase event, consisting of a basal, volcaniclastic debris flow phase overlain by a pelagic debris flow phase. Both phases were emplaced on the lower continental rise by a single large debris flow at around 60 ka. The volcaniclastic flow left a thin deposit less than 5 m thick. This contrasts with the much thicker (over 25 m) deposit left by the pelagic debris flow phase. We suggest that pelagic sediment, sourced and mobilized as debris flow from the African continental margin, loaded and destabilized volcaniclastic material in the vicinity of the western Canaries. When subjected to this loading, the volcaniclastic material appears to have formed a highly fluid sandy debris flow, capable of transporting with it the huge volumes of pelagic debris, and contributing to a runout distance extending over 400 km downslope of the Canary Islands on slopes that decrease to as little as 0·05°. It is likely that the pelagic debris formed a thick impermeable slab above the volcanic debris, thus maintaining high pore pressures generated by loading and giving rise to low apparent friction conditions. The distribution of the two debris phases indicates that the volcaniclastic debris flow stopped within a few tens of kilometres after escaping from beneath the pelagic debris flow, probably because of dissipation of excess pore pressure when the seal of pelagic material was removed.  相似文献   

Typical debris accumulation forms and formations in High Asia – A glacial-history-based concept of the origin of Postglacial debris accumulation landscapes in subtropical high mountains with selected examples from the Hindu Kush, the Karakoram and the Himalayas     

Lasafam Iturrizaga 《GeoJournal》1999,47(1-2):277-339

An abridged version of a geomorphological inventory and typology of Postglacial debris accumulations in High Asia is presented, with selected examples from the Hindu Kush, the Karakoram and the Himalayas. The debris accumulations were surveyed in the course of four research expeditions lasting a total of ten months in selected valley systems of High Asia (the eastern Hindu Kush, the northwestern Karakoram, the Nanga Parbat massif (Pakistan), the Ladakh and Zanskar ranges, the Nun Kun massif, the Kumaon and Garhwal Himalayas with the Kamet, Trisul and Nanda Devi massifs (India) and in the central Himalayas with the Kanjiroba, Annapurna, Manaslu and Makalu massifs (Nepal)). The study areas being widely scattered, a supraregional comparison of the debris accumulations proved possible. The debris accumulations are considered in centre-to-periphery sequences from the mountain interior to the mountain fringes, and in vertical sequences, i.e. altitudinal zones, taking into account their topographical relationship to adjoining elements of the landscape. Supraregional and climate-specific types of debris accumulation are distinguished and it is recognized that the debris accumulations of the Karakoram and the Himalayas resemble each other more closely with increasing elevation. The core of the study is the dominant role played by past glaciation in the formation of Postglacial debris accumulations in the high mountains of Asia. This glacial-history-oriented concept of debris accumulation stands in sharp contrast to previous opinions about the genesis of the debris accumulation landscape in the extreme high mountains of Asia. The study shows that at many places morainic deposits mask extensive portions of the valley sides up to several hundred metres above the valley floor. These moraines are the main debris sources and exert a strong influence on, or even suppress, the purely slope-related formation of debris accumulations. Resedimentation of morainic material in combination with additional talus delivery leads to numerous characteristic composite types of debris accumulations, which are here termed transitional glacial debris accumulations. Various stages in the transition from moraine to slope-related debris accumulations were observed, making it necessary to consider the evolutional element in the development of debris accumulations by taking into account both genetic series of debris accumulations and formations of debris accumulations. A significant proportion of debris accumulations are also due to collapse processes which result from pressure release at the valley sides after deglaciation and occur in the course of glacial trough valleys being transformed into more stable fluvial V-shaped valleys. The residual morainic landscape has left debris accumulations that are basically similar in study areas of different climate – i.e. in the Hindu Kush and the Karakoram on the one hand, and the Himalayas on the other. The age classification of the debris accumulations was based on the location of the slope-derived debris accumulations in relation to the corresponding stages of glaciation. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献