共查询到20条相似文献，搜索用时 15 毫秒
1.
Kenneth Hewitt 《Quaternary Science Reviews》2009,28(11-12):1055-1069
The Nanga Parbat–Haramosh Massif has some of the greatest relief on Earth and highest measured rates of uplift, denudation, and river incision in bedrock. Many studies have sought to understand how its morphology relates to geotectonic evolution and glaciations. However, few catastrophic rock slope failures had been recognised and many of their impacts had been attributed to other processes. Recently more than 150 of these landslides have been found within a 100-km radius of Nanga Parbat (8125 m). New discoveries are reported east, north and west of Nanga Parbat along the Indus streams. Most generated long-run-out rock avalanches that dammed the Indus or its tributaries, some impounding large lakes. They initiated episodes of intermontane sedimentation followed by trenching and removal of sediment. Valley-floor features record a complex interplay of impoundment and sedimentation episodes, superimposition of streams in pre-landslide valley floors, and exhumation of buried features. These findings depart from existing reconstructions of Quaternary events. A number of the rock-avalanche deposits were previously misinterpreted as tills or moraine and their associated lacustrine deposits attributed to glacial lakes. Features up to 1000 m above the Indus, formerly seen as tectonically raised terraces, are depositional features emplaced by landslides, or erosion terraces recording the trenching of valley fill in landslide-interrupted river reaches. Unquestionably, tectonics and glaciation have been important but decisive and misread formative events of the Holocene involve a post-glacial, landslide-fragmented fluvial system. The latter has kept valley developments in a chronic state of disequilibrium with respect to climatic and geotectonic controls. Accepted glacial chronologies are put in doubt, particularly the extent and timing of the last major glaciation. The pace and role processes in the Holocene have been seriously underestimated. 相似文献
2.
M. Kuhle 《GeoJournal》1997,42(2-3):87-257
The results presented on the glacio-geomorphological reconstruction of a maximum Ice Age (LGM = Last Glacial Maximum) glaciation in High-Asia concern five test-areas in and around Tibet (Figure 1, Nos. 14, 6, 17, 2, 9, 18, 16). For the E-Pamir plateau and its mountains a covering ice cap is proved; a snow-line (ELA)-depression of 820–1250 m in relation to the present relief has been calculated. The Ice Age snow-line ran at 3750–3950 m asl. In the Nanga Parbat-massif a glacial (LGM) ice-stream network with a snow-line altitude (ELA) at c. 3400– 3600 m has been reconstructed. This corresponds to an ELA-depression of at least 1200 m. The lowest ice margin site of the connected 1800–1900 m-thick Indus glacier flowed down to c. 800 m asl. From N-Tibet the author introduces further observations of ground moraines and erratics from a high plateau area he had already investigated in 1981. They provide evidence of a complete inland ice sheet in Tibet. From the S edge of Tibet six large outlet glacier systems i.e. lowest High Glacial ice margin sites of the Himalaya ice-stream network are reconstructed. This is a continuation of the investigations in 1977, 1978, 1982, 1984, 1988 and 1989 between Kangchendzönga in the E and Nanda Devi in the W. In this place probably the lowest glacial glacier end of the Himalaya-S-slope was found at c. 460 m asl at the Dumre settlement, S of the Manaslu. C14-datings from the Tsangpo valley on the S edge of Central Tibet classify the reconstructed Tibetan ice as being from the Last Glacial Maximum (LGM) between older than 48580 ± 4660–2930 and 9820 ± 350 YBP. From this empirical findings and inductive results on the Ice Age Tibetan glaciation are derived deductive conclusions on the interaction of the relief and the snow-line altitude with concern to the ice cover. Modelling by means of those snow-line depressions and estimations of the precipitation provide ideas about surface heights, ice thicknesses and flow behaviour of the ice sheet. The hypothesis of a global triggering of the ice age by the uplift of the subtropical Tibet up to above the snow-line motivates the investigations presented here. 相似文献
3.
S. Meiners 《GeoJournal》2005,62(3-4):49-90
The most recent glacial history of the Bar Valley on the Batura south side of the great Karakorum main ridge shows a marked
retreat of the Kukuar and Baltar glaciers since 1915 by 8 km. This tendency is continuing. A great lateral moraine (GLM),
which shows the latest, historical maximum postglacial stage, is accompanied by a higher level, which reflects a neoglacial
glacier level whose ice margins no longer exist. An earth-pyramid moraine rising high above the glacier, as also occurs on
the northern declivities of the Batura, does not mark a specific level, but bears witness to a valley-filling glacier, for
which further indicators can be found along the valley flank. In the gorge-like narrow trough valley, the flanks of which
are covered by steep debris cones originating from the postglacial, numerous former glacial characteristics contrast with
the current glaciation of the far retreated Kukuar and Baltar glaciers. Moraine material found at the valley outlet at Chalt
and also on the Talmutz pass demonstrates complete ice filling of the Bar valley, also supported by the Daintar glacier. From
a glacial geomorphological perspective, this confirms a late to high glacial connection of the Bar glacier to a Hunza glacier,
as postulated by Kuhle (2005). 相似文献
4.
S. Meiners 《GeoJournal》2005,63(1-4):49-90
The most recent glacial history of the Bar Valley on the Batura south side of the great Karakorum main ridge shows a marked retreat of the Kukuar and Baltar glaciers since 1915 by 8 km. This tendency is continuing. A great lateral moraine (GLM), which shows the latest, historical maximum postglacial stage, is accompanied by a higher level, which reflects a neoglacial glacier level whose ice margins no longer exist. An earth-pyramid moraine rising high above the glacier, as also occurs on the northern declivities of the Batura, does not mark a specific level, but bears witness to a valley-filling glacier, for which further indicators can be found along the valley flank. In the gorge-like narrow trough valley, the flanks of which are covered by steep debris cones originating from the postglacial, numerous former glacial characteristics contrast with the current glaciation of the far retreated Kukuar and Baltar glaciers. Moraine material found at the valley outlet at Chalt and also on the Talmutz pass demonstrates complete ice filling of the Bar valley, also supported by the Daintar glacier. From a glacial geomorphological perspectives, this confirms a late to high glacial connection of the Bar glacier to a Hunza glacier, as postulated by Kuhle (2005). 相似文献
5.
Catastrophic flooding of parts of the frontal plains of the Pakistan Himalayas has occured throughout the historical past. The largest recorded flood (1841) originated from an earthquaketriggered landslip from the flanks of Nanga Parbat, which blocked the Indus river for six months. The earthquake probably occurred on the Liachar thrust, which has been responsible for uplifting the amphibolite facies Nanga Parbat gneisses to the Earth's surface in the last 10 million years. These movements raise serious problems for hydroelectric engineering project in this and other active mountain belts. 相似文献
6.
Daoming Xu 《GeoJournal》1991,25(2-3):233-242
Three kinds of moraines can be found in the Muztagh valley on the N slope of Mount K2, Karakorum: an old calco-cement moraine
lying at the altitude of 5000 m asl, a hilly moraine lying at the altitude of 4200–4800 m asl and a new lateral moraine, lying
on both sides of the present river valley. According to the moraines’ geomorphology, they are referred to the Middle Pleistocene
Glaciation, the Late Pleistocene Glaciation and the Post-Glacial Period respectively.
The lowest level of glacial cirques at 4200–4000 m asl, corresponding to the largest Glaciation, belongs to the Middle Pleistocene
(Riss). The ancient cirques at this altitude in the Shaksgam and Yargand valleys are poorly preserved while at the piedmont
of the West Kunlun mountains they are represented in better shape. This means that these ancient cirques had been submerged
and almost removed by the main ice flow of the valleys. Old cirques, however, are well shaped (or reshaped) where associated
with younger cirques at 4600 m als; they could be considered as the product of the Last Glaciation (Würm). Thus, the equilibrium
line altitude (ELA) decreased to 1600 m during the Riss Glaciation and to 1000 m during the Würm Glaciation.
On the basis of the ELA decrease and existence of complex morainic deposits found at the piedmont of the West Kunlun mountains
at about 2200 m asl, the author adheres to the opinion that Riss Glaciation had developed an ice cover (ice sheet), with the
central ice area located in Karakorum and reaching up to the high peaks of the Kunlun mountains, and down to the piedmont
region. During the Last Glaciation an immense ice cap covered the upper parts of the Shaksgam and Yarkant valleys. The paper
also deals with the relations between glaciations and tectonic uplift, indicating that topographic and climatic conditions
were favourable for the large-scale ice development in the Middle and Late Pleistocene. The uplift may have reached 600–800
m during the Postglacial period. The uplift rates are often reflected by the glaciostatic in the Postglacial Age. 相似文献
7.
Y. J. Ding 《GeoJournal》1991,25(2-3):243-248
Many of the present glaciers were perfectly developed on the northern slope of the Karakorum mountains. Different explanations
of the material foundation of the glaciers’ development are given owing to limitation of the data measured. This paper analyses
the changes of precipitation with altitude and the relation between precipitation and glacier distribution. The study shows
that precipitation increases rapidly with altitude from the valley floor at about 4000 m asl, which results in higher precipitation
in the firn area. Annual accumulation at equilibrium line comes up to 800 to 900 mm in the head of the Yarkant valley and
1500 to 2000 mm around Qogir area. 相似文献
8.
OBSERVATIONS ON THE QUATERNARY GEOLOGY OF THE LADAKH RANGE, NORTHWEST INDIAN HIMALAYA 相似文献
9.
Toby N. Tonkin Nicholas G. Midgley David J. Graham Jillian C. Labadz 《Boreas: An International Journal of Quaternary Research》2017,46(2):199-211
Despite a long history of glaciological research, the palaeo‐environmental significance of moraine systems in the Kebnekaise Mountains, Sweden, has remained uncertain. These landforms offer the potential to elucidate glacier response prior to the period of direct monitoring and provide an insight into the ice‐marginal processes operating at polythermal valley glaciers. This study set out to test existing interpretations of Scandinavian ice‐marginal moraines, which invoke ice stagnation, pushing, stacking/dumping and push‐deformation as important moraine forming processes. Moraines at Isfallsglaciären were investigated using ground‐penetrating radar to document the internal structural characteristics of the landform assemblage. Radar surveys revealed a range of substrate composition and reflectors, indicating a debris‐ice interface and bounding surfaces within the moraine. The moraine is demonstrated to contain both ice‐rich and debris‐rich zones, reflecting a complex depositional history and a polygenetic origin. As a consequence of glacier overriding, the morphology of these landforms provides a misleading indicator of glacial history. Traditional geochronological methods are unlikely to be effective on this type of landform as the fresh surface may post‐date the formation of the landform following reoccupation of the moraine rampart by the glacier. This research highlights that the interpretation of geochronological data sets from similar moraine systems should be undertaken with caution. 相似文献
10.
Mihaela Trelea‐Newton Nicholas R. Golledge 《Boreas: An International Journal of Quaternary Research》2012,41(4):614-628
Geomorphological mapping of locally nourished glaciers was conducted in four glens in the southeastern Monadhliath Mountains, Scotland. Three glaciers are interpreted to be of Younger Dryas age based on geomorphological similarity to features in other Scottish upland areas known to have been glaciated during the Younger Dryas, and on comparison to adjacent ice‐free areas in the lower glens where landform‐sediment assemblages typically reflect peri/paraglacial readjustment during the stadial. Here we reconstruct Younger Dryas glacier termini based on moraine alignments and associated geomorphological and sedimentological evidence. An adjacent wide plateau area at high altitude may have permitted extensive ice accumulation, but no unequivocal geomorphological signature is evident. To establish upper glacier limits, a series of ice profiles are modelled. The results yield a range of realistic glacier configurations bracketed between two distinct scenarios: a valley glaciation with the glaciers' upper limit on the plateau edge, and a low‐domed icecap centred on the plateau with ice flowing radially into the lower glens. Reconstructed equilibrium‐line altitudes are 795 m a.s.l. for the valley‐glacier scenario and 894 m a.s.l. for the icecap scenario. Calculated mean ablation‐season temperatures at the ELA are 1.2°C and 0.4°C for the valley‐glacier and the icecap scenario, respectively, from which we infer mean annual precipitation rates between 323 and 520 mm a?1. Palaeoclimate results indicate a stadial climate in central Scotland 65–79% more arid than at present, comparable to that of western Norway for the stadial and to the present‐day Canadian Arctic. 相似文献
11.
波堆藏布谷地冰碛丘陵形成机制及其环境意义 总被引：6，自引：4，他引：2
波堆藏布谷地中分布着大面积的冰碛丘陵, 通过考察发现其个体大小、外形、分布规模及内部砾石组成等方面都与高纬大冰盖外围形成的冰碛丘陵有很大的区别. 以冰川沉积学理论为基础, 从沉积动力学的角度讨论中低纬度波堆藏布谷地中冰碛丘陵的形成机制. 结果表明: 气候变化造成冰川的大面积死冰加之宽阔的河谷、海洋性冰川的特性促使波堆藏布谷中形成如此大面积的冰碛丘陵; 同时,大规模的冰碛丘陵表明气候转暖(抑或变干)的过程是突变的. 相似文献
12.
S. Meiners 《GeoJournal》2001,54(2-4):429-450
The post to late glacial valley reconstruction is focused on the Mani- Baska and Phuparash valleys on the Rakaposhi- Haramosh Muztagh in the south Karakoram. The recently glaciated valleys join the Indus valley near Sassi at 1500 m. The knowledge of the tributary valley reconstruction can be seen in the context of the scientific discussion about the extent of glaciation along the main Indus valley. Today, the recent avalanche fed glaciers come down from high lying catchment areas with an average altitude of 6700–6800 m and terminate at 2700 m. Snow line runs at 4700–4800 m in the steep flanks which is common in the Karakoram Mountains. The postglacial extent is marked by the great lateral moraine (GLM) and reached down not more than 2.5–5 km away from the recent glaciers with a calculated snow line depression of 300 m in maximum. It can be shown that the valleys were already glaciated during the lastest Late Glacial down to the valley outlet at 1500 m. The snow line was depressed 600–700 m during that period. A high glacial ice filling of the Haramosh valley and glacial erosion of the flat top of the Darchan ridge as an intermediate valley head is strongly probable. 相似文献
13.
《Journal of Asian Earth Sciences》2000,18(5):547-559
Analysis of fault-striations measured in the Kohistan part of the Indus Suture Zone (NW Himalaya, Pakistan) has been carried out to document dynamic evolution during the brittle stage of the collision of India and Asia. Processing of the data with a direct inversion method identified four stress fields which were chronologically ordered from field evidence as SSE–NNW compression, E–W compression, radial extension and SSW–NNE compression. The last corresponds to the present-day stress field defined from seismic activity. The earlier stress fields are related to times during the Miocene, when convergence-related stresses were disturbed by the formation of the nearby Nanga Parbat and Indus syntaxes. 相似文献
14.
希夏邦马峰东南富曲河谷的冰川沉积和冰川构造 总被引：2，自引：0，他引：2
在希夏邦马峰（海拔８０１２ｍ）东南富曲河谷，中更新世以来有三次冰期；即聂拉木、富曲和普罗冰期。它们均可再分为两个亚阶段。聂拉木南的高冰碛平台长３.５ｍ，宽１.５ｋｍ，厚２００ｍ。属于中更新世聂拉木冰期（聂聂雄拉冰期）的巨大山谷冰川沉积，中尼公路从高冰碛平台尾端通过，形成数公里长的冰碛剖面，呈现出美丽多姿的冰川成因类型沉积和冰川构造现象，包括冰下，冰上融出碛，冰内.冰下河道沉积，冰湖沉积，坠碛，流磺等。冰川运动时造成的冰川构造，如断层、滑动面-…等也很清楚，代表了海洋型（暖冰川）冰川沉积和冰川构造特征，是中国目前研究冰川构造最理想的场所。 相似文献
15.
西天山托木尔峰南麓大型山谷冰川冰舌区消融特征分析 总被引：4，自引：3，他引：1
基于对托木尔峰南麓托木尔型山谷冰川的野外考察和典型冰川的定位观测,对冰面被表碛广泛覆盖的所谓“托木尔型”冰川冰舌区表碛与冰面消融的关系进行了研究. 结果表明：表碛对冰面消融、冰川水文过程、冰川变化等均具有重要影响,当表碛厚度超过3 cm时,表碛对冰面消融就产生明显抑制作用,且随着厚度增加,冰面消融显明减弱. 科其喀尔冰川表面的观测表明,由末端向上,表碛厚度逐渐减薄. 受表碛影响,科其喀尔冰川区最大的消融量出现在海拔3 800~3 900 m之间、表碛物厚度小于10 cm的区域内;冰川消融强度由此向上随着海拔的升高而下降,向下随表碛厚度的增大而减弱. 冰面湖的发育是表碛覆盖冰川的又一主要特征,湖水对冰面的融蚀和快速排泄成为冰面产汇流的主要过程. 科其喀尔冰川研究表明,两三个冰面湖排泄形成的融蚀冰量就相当于冰川末端退缩造成的冰量损失. 因此,冰面湖等热喀斯特地形的形成、扩张融蚀、融穿排泄、形成湖区低地,这一周而复始的过程不仅是其主要消融方式之一,而且也强烈的影响着冰川水文及冰川变化. 托木尔峰南麓地区大型冰川变化主要以厚度减薄为主,而不是像大多数冰川显著的变化主要表现在末端和面积减少方面. 相似文献
16.
冰川厚度测量是冰储量估算的关键。基于2019年7月利用探地雷达在托来南山6号冰川主冰川的测厚结果,通过普通克里格法绘制了主冰川的冰厚分布图,计算出主冰川的平均厚度为（39.61±5.32） m,冰厚空间分布呈自边缘向中间逐渐增厚的特征,最大冰厚［（100.78±1.78） m］位于纵剖面海拔4 770 m附近的凹陷盆地,结合半物理公式估算出整条冰川的冰储量为（0.0504±0.0082） km3。冰床为典型槽谷地形,谷槽横剖面呈U形,且随海拔的升高谷槽宽度逐渐变小。现有的面积-体积公式并不适用于单条冰川的冰储量估算,但分类型拟合公式具有降低估算结果误差的潜力。 相似文献
17.
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
18.
On the basis of location levels of push marginal formations and maximal distribution heights of charted lateral moraine, the
surface form of the Late Valdai ice sheet in the region of Khibini and Lovozerskii massifs during cool stadial phases of the
Middle and Younger Dryas was reconstructed. It has been established that the glacier surface came to 700 m and 500 m, respectively,
and its inclination varied from 30 to 70 m per 10 km, which is well below that in marginal fields of ice sheets of Western
Greenland and East Antarctica. The maximal ice thickness in the Middle Dryas came to about 600 m, and in the Younger Dryas,
it was about 400 m. The inclination of the glacier surface increased during the cool stadial phase. On the whole, it coincides
well with the drift directions of detrital sediments by ice streams, established by the transfer direction of detrital sediments,
orientation of drumlins, ice scars, and other factors of ice activity. 相似文献
19.
《Russian Geology and Geophysics》2015,56(11):1509-1521
Analysis and summary of publications on southern East Sayan, eastern Tuva, and northern Mongolia have shown that the late Pleistocene glaciation covered a large area and had a complicated dynamics of glacier advance and retreat. Starting with MIS 5, the Todza Basin and, partly, the Oka Plateau, Azas Volcanic Plateau, Mondy Basin, and river valleys in southern East Sayan were periodically covered with ice. The thickness of ice in the eastern Todza Basin was 700 m, on the Azas Volcanic Plateau it reached 300–600 m, and in the valleys of southern East Sayan it is estimated as 700–800 m. The thickness of ice in the Mondy Basin was 300–350 m.Geological and geomorphological studies and isotope surface exposure dating (10Be method) of boulders from terminal moraine complexes have provided evidence for extensive MIS 2 glacier advance in the Mondy Basin and in the Sentsa, Jombolok, and Sailag river valleys (southern East Sayan). The average age of exposure for three groups of samples is 14, 16, and 22 ka. 相似文献
20.
Complex moraine-ridge sequences in front of seven outlet glaciers of the Jostedalsbreen ice-cap (Austerdalsbreen, Bergsetbreen, Fåbergstølsbreen, Lodalsbreen, Stegaholbreen, Tuftebreen, Bødalsbreen) are dated using families of lichenometric dating curves established previously at an eighth outlet (Nigardsbreen). Applicability of the Nigardsbreen curves at the regional level is tested using independent historical evidence: moraines deposited during the present century are dated to an accuracy of ± 9.4 yr (16.0%), and most of them are dated to an accuracy of ± 5.5 yr (9.4%). Results from the moraine sequences are combined to form a composite ‘Jostedalsbreen’ record. Median predicted dates for moraine ridges cluster around AD 1939 ± 2 yr, 1929 ± 3, 1908 ± 3, 1886 ± 5, 1875 ± 2, 1867 ± 4, 1855 ± 3, 1842 ± 5, 1822 ± 5, 1807 ± 4 and 1785 ± 5. At least four glaciers reached their ‘Little ice age’ maxima prior to AD 1780, two (Nigardsbreen and Bødalsbreen) at ca. 1750, one (Fåbergstølsbreen) at ca. 1705. Stegaholbreen attained its maximum ca. 1863. Since the ‘Little ice age’ maximum, and despite large differences in glacier size, frontal variations of the various outlets have exhibited a high degree of synchroneity, which suggests that the moraine sequences contain a sensitive record of high-frequency climatic variations over the last ca. 250 yr. During the early twentieth century, measured readvances of the order of 5–150 m over 1–10 yr led to moraine formation. Dendroclimatic evidence indicates that since the late eighteenth century, moraine ridges formed about 5 yr after summer temperature minima and correlate with runs of cool summers (temperature depression of 0.5–1.0°C below the AD 1700–1950 average). Almost simultaneous glacier advances appear to have been caused by reduced ablation. This near-immediate response to climatic variation, by glacier tongues that descend to relative low altitudes, is superimposed upon the longer-term dynamic response of the ice cap to climate. 相似文献