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1.
Glaciers and rock glaciers’ distribution at 28° SL,Dry Andes of Argentina,and some considerations about their hydrological significance 总被引：1，自引：0，他引：1
The area studied includes a little-known portion on the Dry Andes of the San Juan Frontal Cordillera, Argentina, where the
hydrological significance of glaciers and rock glaciers was earlier never studied. The surveyed sector includes Cerro El Potro
(5,870 m ASL) and nearby mountain chains (28°S). The predominant landforms in these areas were shaped in a periglacial environment
superimposed on an earlier glacial landscape. These regions comprise abundant rock glaciers, a noteworthy rock glacier zone
in the world, of which little is known in South America. This work employs geomorphological mapping to analyze the distribution
of active rock glaciers in relation to altitude, aspect and slope using optical remote sensing techniques with GIS. Statistical
estimation techniques were used based on a Digital Elevation Model (DEM) and aerial photos and Spot images interpretation.
The specific density of rock glaciers’ estimation in the surveyed area (Argentine border) is 1.56% with corresponds to 38
rock glaciers with an area of 5.86 km2 and 0.12 km3 of water equivalent. Furthermore, the analytical results show that elevations >4,270 m ASL, a southeast-facing aspect, and
slope between 2° and 40° favor the existence of rock glaciers, Finally, a comparison with glacier water equivalent, which
covers an area of ~16 km2 and 0.9 km3 of water equivalent, shows that glaciers are the main stores of water at 28°S (Cerro El Potro Glacier). However, the importance
of rock glaciers as water reserves in this portion of Argentina should not be underestimated. 相似文献
2.
川西螺髻山冰川侵蚀地貌研究 总被引：2，自引：4，他引：2
定量分析发现影响该地区冰斗形态的因素有海洋性较强的气候,朝向北(极向),朝向东和较大的地形起伏四种。槽谷的横剖面可以公式化为Y=a·X~b,槽谷形态不对称由冰川差异侵蚀和冻融差异所致。发现两种冰川侵蚀裂痕,即挤压剪切裂痕和拉张剪切裂痕。 相似文献
3.
LESZEK LINDNER LESZEK MARKS 《Boreas: An International Journal of Quaternary Research》1985,14(2):139-153
A proposal for the classification of accumulations formed at the foot of mountain slopes and glacier snouts is presented for South Spitsbergen. Simple (talus cones) and complex (protalus ramparts, protalus rock glaciers, moraine rock glaciers) landforms are distinguished. The homogeneity of the features deposited at the foot of mountain slopes on a bedrock as well as on a glacial ice is noted, although the latter are more easily destructed due to melting of the buried ice. A significance of the ice core (interstitial or glacial ice) for a development of protalus rock glaciers and moraine rock glaciers is emphasized. 相似文献
4.
PER HOLMLUND JENS-OVE NÄSLUND 《Boreas: An International Journal of Quaternary Research》1994,23(2):139-148
The glacial landscape beneath the Maudheimvidda ice sheet in East Antarctica was most probably formed during a more temperate phase of Antarctic glaciation than the present. Overdeepened glacial cirques and U-shaped valleys are found in the Heimefrontfjella and Vestfjella mountain ranges. These glacial landforms, located beneath the ice sheet, have been mapped with radio-echo sounders. The present ice sheet covering these landforms is cold and frozen to its bed, and has a negligible erosive effect on the substrate. Ice sheet thickening during the Quaternary glacial periods is not believed to have caused any significant increase in erosion at the investigated sites. Instead, the glacial morphology was most likely formed by smaller, temperate glaciers when the Antarctic climate was warmer than at present. Datings of foraminifera and ash layers from the Transantarc-tic Mountains indicate that the present cold ice sheet was formed 2.5 Ma years ago. Other studies imply that a cold Antarctic ice sheet has lasted even longer. The glacial landforms in Maudheimvidda may thus be of a pre-Quaternary age. 相似文献
5.
Jakob Heyman Arjen P. Stroeven Helena Alexanderson Clas Hättestrand Jon Harbor Yingkui Li Marc W. Caffee Liping Zhou Daniel Veres Feng Liu Martin Machiedo 《第四纪科学杂志》2009,24(7):710-727
Key locations within an extensive area of the northeastern Tibetan Plateau, centred on Bayan Har Shan, have been mapped to distinguish glacial from non‐glacial deposits. Prior work suggests palaeo‐glaciers ranging from valley glaciers and local ice caps in the highest mountains to a regional or even plateau‐scale ice sheet. New field data show that glacial deposits are abundant in high mountain areas in association with large‐scale glacial landforms. In addition, glacial deposits are present in several locations outside areas with distinct glacial erosional landforms, indicating that the most extensive palaeo‐glaciers had little geomorphological impact on the landscape towards their margins. The glacial geological record does indicate extensive maximum glaciation, with local ice caps covering entire elevated mountain areas. However, absence of glacial traces in intervening lower‐lying plateau areas suggests that local ice caps did not merge to form a regional ice sheet on the northeastern Tibetan Plateau around Bayan Har Shan. No evidence exists for past ice sheet glaciation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
6.
黑沟源于东天山最大现代冰川作用中心博格达峰的南坡. 在第四纪冰期与间冰期旋回中,该流域的冰川均发生过多次规模较大的进退,在谷中留下了较为完整的冰川沉积序列. 这些冰川地形包含有重要的古气候变化信息,对其研究可重建黑沟流域的冰川演化史. 应用OSL对该流域的冰川沉积物进行定年,测定结果表明冰水沉积物（沙质透镜体）比冰碛物更适宜应用单片再生剂量（SAR）测年技术进行测定. 基于测得的年龄并结合地貌地层学原理可初步得出：晚第四纪期间,黑沟流域共发生了5次规模较大的冰川作用,分别为全新世期间的小冰期（16世纪以来冷期的冰进）与新冰期（距今3~4 ka的冰进）,末次冰期晚冰阶（MIS 2）与早冰阶（MIS 4）以及倒数第二次冰期（MIS 6）. 相似文献
7.
迭山西北部位于青藏高原的东缘, 属西秦岭山脉的西段. 在海拔3 700 m以上保存有类型较为齐全的冰蚀地形(冰斗、刃脊、U形谷、悬谷、粒雪盆、鲸背岩与基岩磨光面等)与冰碛地形(侧碛垄与终碛垄). 采用野外考察、遥感影像解译与填图等方法对该区的冰川地貌分布及其特征进行了探讨. 基于研究区冰川地形分布与特征, 结合青藏高原现代的抬升速率、邻近山地冰川地形的年代学资料以及其他古环境研究成果进行综合分析得出: 该区的古冰川发育于末次冰期, 末次冰期最盛期是其最主要的形成期. 冰川最盛时面积约38 km2, 为具有暖底性质的冰帽冰川. 相似文献
8.
在西藏阿里阿伊拉日居山脉南北两麓及切割山脉的各沟谷中,分布着4套早更新世以来的冰川沉积物。根据这些冰川沉积物的地层层序和冰川沉积物的电子自旋共振(ESR)年龄测定结果,将阿伊拉日居山脉南北两麓所发生的4次早更新世以来的冰川作用,分别命名为札达冰期(1161-952 ka BP)、阿伊拉日居冰期(762-730 ka BP)、学朗冰期(336-211 ka BP)和弄穷冰期(105-15 ka BP),并与青藏高原及其他地区冰期进行了对比。各次冰期的冰川性质分别为大型山岳冰川、冰帽、山麓冰川和中小型山谷冰川。全新世时期,现代冰川有过冰川推进。近期冰川则发生了明显的后退。 相似文献
9.
四川康定折多山末次冰盛期古冰川重建及其气候意义 总被引：1，自引：0，他引：1
折多山位于青藏高原东缘,地势上处于由高原面向高山峡谷的过渡区,古冰川遗迹保留较好。对折多山冰川地貌进行深入研究,对揭示青藏高原东缘地形演化与古气候变化的耦合机制具有重要意义。在野外考察的基础上,结合Google Earth遥感影像、《中国第二次冰川编目》和DEM等资料,对折多山冰川地貌及其特征参数进行了识别、提取和计算。研究共识别出189条古冰川,覆盖面积为497 km2。基于研究区已有年代学资料,本区冰川地貌主要为末次冰盛期（LGM）以来冰川作用遗存。恢复研究区LGM冰川平衡线高度（ELA）,在西坡和东坡分别为4 380 m和4 110 m,相差270 m,揭示出分水岭东侧更有利于冰川发育。广泛发育的冰蚀湖、冰蚀基岩面、羊背石等,以及深切的冰川槽谷（U形谷）指示海洋性冰川作用特征;冰川作用正差、冰川朝向、冰蚀地貌的差异,揭示积累区地形条件和水汽来源对研究区冰川发育具有重要的影响。 相似文献
10.
Rock glaciers and block fields,review and new data 总被引：1，自引：0，他引：1
Sidney E. White 《Quaternary Research》1976,6(1):77-97
Tongue-shaped and lobate rock glaciers are recognized in most alpine regions today. For the tongue-shaped, two situations emerge: those with buried glacier ice (debris-covered glaciers) called ice-cored rock glaciers, and those with interstitial ice known as ice-cemented rock glaciers. Those with ice cores are revealed by depressions between rock glacier and headwall cliff (where a former glacier melted), longitudinal marginal and central meandering furrows, and collapse pits. Ice-cemented rock glaciers ordinarily do not possess these features. As applied to 18 rock glaciers in the Colorado Front Range, 11 of 12 east of the Continental Divide are ice-cored, 6 west of the Divide are ice-cemented. The majority of lobate rock glaciers in the Colorado Front Range are on the south sides of valleys, and, except for talus, are the most voluminous form of mass wasting. All those active and above treeline have characteristics common to all rock glaciers. In addition, they originate from talus, contain interstitial ice, move outward from valley walls at 1–6 cm/yr, and transport more debris as a process of erosion than heretofore realized. Block fields and block slopes, in polar and alpine regions, are thin accumulations of angular to subrounded blocks, on bedrock, weathered rock, or transported debris. They extend along slopes parallel to the contour. Block streams are similar but extend downslope normal to the contour and into valleys. They are made of interlocked blocks without interstitial detritus, but many have finer material deeper inside. The fabric of surface blocks indicates that motion most likely occurred during a periglacial time when interstitial debris, now washed or piped out, permitted movement of the whole deposit. 相似文献
11.
龙门山古冰川作用 总被引：1，自引：1，他引：0
汶川地震中央区域龙门山主山九顶山海拔4 984 m,山脊北坡有三处成排分布不少规模较小的冰斗-冰川谷地形,恢复当时雪线高度在4 100 m高度。根据其形态保存程度、古今雪线高度差等情况判断,应当是2阶段冰川作用遗存。据气温和降水资料,现在九顶山雪线高度在5 000 m,刚好超出九顶山顶部。故而九顶山3 800 m以上目前处于冰缘环境,石冰川、石环、融冻泥流等冰缘现象比较突出。九顶山不存在更老的冰川作用及其地貌遗存,是青藏高原以东5 000 m上下的高山只是在末次冰期时抬升跨越冰期雪线而发育冰川这一新观点的又一证据,也是青藏高原第四纪晚期剧烈抬升的又一证据。 相似文献
12.
Chronology of cirque glaciation,Colorado front range 总被引：2，自引：0，他引：2
James B. Benedict 《Quaternary Research》1973,3(4):584-599
Moraines and rock glaciers in Front Range cirques record at least four, and possibly five, intervals of Holocene glacier expansion. The earliest and most extensive was the Satanta Peak advance, which deposited multiple terminal moraines near present timberline shortly before 9915 ± 165 BP. By 9200 ± 135 BP, timberline had risen to at least its modern elevation; by 8460 ± 140 BP, patterned ground on Satanta Peak moraines had become inactive. Although a minor ice advance may have occurred just prior to 7900 ± 130 BP, there is no evidence that glaciers or perennial snowbanks survived in the Front Range during the “Altithermal” maximum (ca. 6000–7500 BP), or during a subsequent interval of alpine soil formation (ca. 5000–6000 BP).Glaciers were larger during the Triple Lakes advance (3000–5000 BP) than at any other time during Neoglaciation. Minimum ages of 4485 ± 100 BP, 3865 ± 100 BP, and ca. 3150 BP apply to a threefold sequence of Triple Lakes deposits in Arapaho Cirque. After an important interval of soil formation and cavernous weathering, glaciers and rock glaciers of the Audubon advance (950–1850 BP) reoccupied many cirques, and perennial snowbanks blanketed much of the area above present timberline; although the general Audubon snow cover had begun to melt from valley floors by 1505 ± 95 BP, expanded snowbanks lingered on tundra ridge crests until 1050–1150 BP, and glaciers persisted is sheltered cirques until at least 955 ± 95 BP. Following a minor interval of ice retreat, glaciers of the Arapaho Peak advance (100–300 BP) deposited multiple moraines in favorably oriented cirques.Interpretation of Holocene glacial deposits in the Southern and Central Rocky Mountains has been hampered by (1) a heavy reliance upon relative-dating criteria, many of which are influenced by factors other than age; (2) the assumption that glacial advances in high-altitude cirques can be correlated directly with alluvial deposition in far-distant lowlands; and (3) the assumption that glacial advances have necessarily been synchronous throughout the Rocky Mountain region and the world. Although Holocene glacier fluctuations in the Front Range are believed to reflect changes in regional climate, the Front Range chronology does not have particularly close analogs in other parts of North America. Better-dated local sequences are needed before the hypothesis of global synchroneity can be adequately evaluated; until synchroneity has been proven, long-distance correlations and worldwide cycles of recurring glaciation will remain unconvincing. 相似文献
13.
《Journal of South American Earth Sciences》1999,12(3):333-341
Remnants of an old aggradational landscape, Cerro Cuadrado Proglacial, are preserved on top of the high mesetas Pampa Alta and La Meseta on both sides of the upper Santa Cruz river valley, South Patagonia.A first dissection of the mesetas, attributable to extended river erosion, predates the expansion of glacier lobes down the piedmontane area. The glacial advance is represented by the moraines of Pampa Alta Glaciation displayed on the top of Meseta Pampa Alta. Glacifluvial outlets contribute to the proglacial plain, Pampa Alta Proglacial, which is widespread to the southeast.Strong and persistent fluvial erosion followed the retreat of the ice masses leading to the formation of several terrace levels in the main upper valley, La Australasia Terraces and San Fernando Terraces, and a step, Cordón Alto, that truncates the Meseta Pampa Alta. These foreland features and the relief covered by the basalts at Cerro Fraile in the cordillera, are probably a consequence of a diastrophic phase that affected both areas during this stage.Late Pliocene basaltic lavas draining into the main and tributary valleys overran this landscape. The evidence indicates that during the eruption of the basalts the glaciation was active in the cordillera and that coeval fluvial and lacustrine aggradation took place in the extra-andean valleys.During the Middle Pleistocene subsequent lava flows covered the high pampas and partially occupied the fluvial valleys again. After this last volcanic episode the glaciers reached their maximum expansion to the east. 相似文献
14.
Discovery and Significance of Quaternary Glacial Vestiges in the Hexigten Area of the Southern Da Hinggan Mountains, Inner Mongolia 总被引：4，自引：0，他引：4
SUN Hongyan TIAN Mingzhong WU Fadong ZHANG Jianping China University of Geosciences Beijing E-mail: shywch@.com 《《地质学报》英文版》2005,79(4):564-569
1 Introduction Hexigten is situated at the eastern part of the Inner Mongolian Plateau, south of the Da Hinggan Mountains and northwest of Chifeng City, Inner Mongolia, China. It is also at the junction of the Da Hinggan Mountians, Inner Mongolian Plateau and Yanshan Mountains. It is about 650 km north of Beijing. The geographic coordinates are 116?30'?118?20'E and 42?20'?44?10'N (Fig. 1). The elevation range is from 1100 m to 1700 m, and the highest peak (2029 m) of the Da Hinggan… 相似文献
15.
《Boreas: An International Journal of Quaternary Research》2018,47(2):379-389
This is a synthesis of the glacial history of the northern Urals undertaken using published works and the results of geological surveys as well as recent geochronometric and remote sensing data. The conclusions differ from the classical model that considers the Urals as an important source of glacial ice and partly from the modern reconstructions. The principal supporting evidence for the conventional model – Uralian erratics found on the adjacent plains – is ambiguous because Uralian clasts were also delivered by a thick external ice sheet overriding the mountains during the Middle Pleistocene. Alternative evidence presented in this paper indicates that in the late Quaternary the Ural mountains produced only valley glaciers that partly coalesced in the western piedmont to form large piedmont lobes. The last maximum glaciation occurred in the Early Valdaian time at c. 70–90 ka when glacial ice from the Kara shelf invaded the lowlands and some montane valleys but an icecap over the mountains was not formed. The moraines of the alpine glaciation are preserved only beyond the limits of the Kara ice sheet and therefore cannot be younger than MIS 4. More limited glaciation during MIS 2 generated small alpine moraines around the cirques of the western Urals (Mangerud et al. 2008: Quaternary Science Reviews 27, 1047). The largest moraines of Transuralia were probably produced by the outlet glaciers of a Middle Pleistocene ice sheet that formed on the western plains and discharged across the Polar Urals. The resultant scheme of limited mountain glaciation is possibly also applicable as a model for older glacial cycles. 相似文献
16.
太白山第四纪冰碛物特征与冰期 总被引：3，自引：0，他引：3
在晚更新世早期(Q_3~1)和晚期(Q_8~3),太白山主峰八仙台先后发生过两次冰川作用,即三爷海冰期和太白冰期。其中太白冰期又可划分为早太白和晚太白两个副冰期。经人工剖面证实的三道不同时期的侧碛垄分别与上述冰期相对应。各种冰蚀地貌都受到该区构造的控制和影响。 相似文献
17.
《Boreas: An International Journal of Quaternary Research》2018,47(4):1050-1071
The aim of this research is to improve our current understanding of the deglaciation stages in the southeastern Pyrenees and integrate it into reconstructions of the long‐term deglaciation in the Iberian mountains since the Last Glaciation. First, we examine the existing chronological data for deglaciation in Iberian mountain ranges, mainly focusing on the Pyrenees and the results derived from cosmic ray exposure dating methods. Then, we recalculate the age of 17 samples from four different areas in the SE Pyrenees (Arànser, La Llosa and Duran valleys and Malniu‐Guils complex) based on the 36Cl isotope and applying a new age calculator. In addition, we date eight new samples from the Malniu‐Guils complex to provide a more accurate chronology for this site. The results do not clarify the timing of the maximum glacier extent, but support an extensive glacial advance followed by multiple small advances and retreats during the Last Glacial Maximum (LGM). Geomorphological and chronological data show evidence of massive deglaciation at the end of the LGM around 18 ka, and deglaciation was practically complete during the Bølling‐Allerød interstadial. There is no geomorphological evidence of glacial advances in the cirques during the Younger Dryas. Instead, cirque walls were covered with rock glaciers during the Bølling‐Allerød interstadial. The fronts of these rock glaciers stabilized at the end of this period, while their roots remained active until well into the Holocene. 相似文献
18.
The Quaternary glacial landforms, such as cirques, glacial troughs, rockdrumlins and lateral moraines are discovered in the area of the middle-lower reaches of the Yangtze river. The isograms of gravels in the moraines reveal that the a-axes of the gravels are mostly parallel to the trends of the valleys. The inclinations of the a-axes of the gravels are 18°–23°. The tendency of the ab-pianes is varied. The inclinations of ab-planes are 15°–20°. The fine grains in the moraines are of bimodal form in the size-frequency curves. The surface of the quartz grains of the moraines possess typical characteristics of glacial sands. Based on the feature of glacial landforms and the data of analysis of the experiment in the laboratory, authors divide the climatic period of Quaternary in this area into four glacial stages. 相似文献
19.
贡嘎山第四纪冰川遗迹及冰期划分 总被引：22，自引：1，他引：22
在对贡嘎山现代冰川和古冰川考察研究的基础上，结合定位观测分析，对该区第四纪冰川遗迹进行了深入讨论，划分出三次冰期，即中更新世早期的倒数第三次冰期，中更新世晚期的倒数第二次冰期和晚更新世的末次冰期，以及全新世的新冰期和小冰期。提出在早更新世时，由于山体未达到当时冰川发育的雪线高度，所以未发育冰川；中更新世早期的冰期冰川为半覆盖式冰川类型，规模不大；中更新世晚期的冰期冰川是本区最大冰川作用时期，形成网状山麓冰川，东坡冰川曾达磨西台地；晚更新世冰期冰川以山谷冰川为主，以后规模逐次缩小。 相似文献
20.
The extent of a large mountain icefield that existed in the western Grampians during the Loch Lomond stade has been mapped. The main types of evidence used in establishing the limits comprise moraines, thick drift, fluvioglacial landforms, erratics, ice-smoothed bedrock, striae, friction cracks and relict periglacial forms. Trimlines on 198 spurs, and various forms of glacial and periglacial evidence on 73 cols and in c . 200 cirques, enable the upper limits and morphology of the icefield to be reconstructed. Abundant striae and friction cracks in many areas enable ice-flow directions and the surface form of the icefield to be inferred in some detail. The icefield had ice-shed altitudes of c . 750 m, a maximum width of 80 km and an area over 2,000 km2 . At least 60 nunataks stood above the icefield, and on its western side outlet glaciers reached the sea and flowed for as much as 28 km along major tidal water lochs. 相似文献