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1.
Benxing Zheng 《GeoJournal》1988,17(4):525-543
The uplift of the Himalaya and Qinghai-Xizang plateau began at the end of Pliocene to the beginning of Early Pleistocene, changing the atmospheric circulation in Asia, enhancing the South Asian monsoon and enormously effecting the climatic conditions and glacial development.According to the evidence of glacial deposits, geomorphology, paleobiology, paleopedology, etc., at least four glaciations can be recognized. The uplift of the Himalayas was earlier than that of other mountains, so that the glaciation occurred in Early Pleistocene, forming small piedmont glaciers on the N slope, whilst at the same time there were wide short valley glaciers on the S slope. During the Middle Pleistocene, the height of Himalaya was about 4000 m a s l, the monsoon was strong, and much water vapour reached the interior of the plateau, the most favourable period for glacial development. Great piedmont glaciers and small ice caps formed on the mountains N of Himalayas and great valley glaciers occurred on the S slope, but no great ice sheet covered the plateau.During the early Late Pleistocene, the Himalayas had risen to over 5000 m asl, forming a barrier against the incursion of the Indian monsoon, so that the precipitation decreased sharply on the plateau N of Himalayas, thus diminishing the extent of the glaciation. But on the high mountains of the S part of Xizang and on several high mountains of the S slope of the Great Himalaya, the precipitation increased and the extent of glaciation reached a maximum. Since Last Glaciation, the precipitation of the alpine zone has decreased more sharply, the climate has become drier and colder, becoming unfavourable for glacial development.During the Holocene, three stages may be distinguished, i.e. the recession in Early Holocene (10,000-8000 BP); the disappearance of most glaciers in the Hypsithermal period in Middle Holocene, (8000-3000 BP); and the neoglacial fluctuations in Late Holocene (3000 BP up to present). The glaciers of the Neoglaciation advanced several hundred meters or even 3–5 km farther than existing glaciers. 相似文献
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Geomorphological mapping revealed five terminal moraines in the central Verkhoyansk Mountains. The youngest terminal moraine (I) was formed at least 50 ka ago according to new IRSL (infrared optically stimulated luminescence) dates. Older terminal moraines in the western foreland of the mountains are much more extensive in size. Although the smallest of these older moraines, moraine II, has not been dated, moraine III is 80 to 90 ka, moraine IV is 100 to 120 ka, and the outermost moraine V was deposited around 135 ka. This glaciation history is comparable to that of the Barents and Kara ice sheet and partly to that of the Polar Ural Mountains regarding the timing of the glaciations. However, no glaciation occurred during the global last glacial maximum (MIS 2). Based on cirque orientation and different glacier extent on the eastern and western flanks of the Verkhoyansk Mountains, local glaciations are mainly controlled by moisture transport from the west across the Eurasian continent. Thus glaciations in the Verkhoyansk Mountains not only express local climate changes but also are strongly influenced by the extent of the Eurasian ice sheets. 相似文献
4.
V. I. Astakhov 《Doklady Earth Sciences》2017,476(2):1200-1202
This is an overview of the latest data on the age of topographically expressed glacigenic formations of the Polar Urals obtained by international geological teams by modern dating techniques including optical luminescence, radiocarbon and cosmogenic beryllium in exposed boulders. The new dates combined with the results of geological mapping and remote sensing data is a basis for rejecting the concept of the Quaternary Uralian ice caps in favor of small alpine glaciers which developed south of the Kara ice sheet. 相似文献
5.
青藏高原现代最大冰原区第四纪冰川作用 总被引：2，自引：1，他引：1
普若岗日冰原是青藏高原最大的冰原,总面积达400km2.野外观察表明,从现代冰舌前端开始向山外有5套终碛垄和侧碛垄系列,分别称之为冰碛垄Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ.根据地貌位置、地层关系、相对风化程度、风的改造程度和覆盖在有冰川漂砾的戈壁上的沙子的电子自旋共振(ESR)年代,并与中国西部山地第四纪冰川数值年代比较,这些冰碛垄分别形成于现代冰川、小冰期、新冰期、末次冰期晚阶段和早阶段.冰碛垄V中的花岗岩漂砾散布于距山前6km以内的山麓平原,说明在第四纪晚期冰原西坡的古冰川虽到达山麓平原,但未能与邻近山地古冰川相连形成统一大冰盖. 相似文献
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VALERY I. ASTAKHOV JOHN INGE SVENDSEN ALEXEI MATIOUCHKOV JAN MANGERUD OLGA MASLENIKOVA JAN TVERANGRE 《Boreas: An International Journal of Quaternary Research》1999,28(1):23-45
Glacial landforms in northern Russia, from the Timan Ridge in the west to the east of the Urals, have been mapped by aerial photographs and satellite images supported by field observations. An east-west trending belt of fresh hummock-and-lake glaciokarst landscapes has been traced to the north of 67°N. The southern boundary of these landscapes is called the Markhida Line, which is interpreted as a nearly synchronous limit of the last ice sheet that affected this region. The hummocky landscapes are subdivided into three types according to the stage of postglacial modification: Markhida, Harbei and Halmer. The Halmer landscape on the Uralian piedmont in the east is the freshest, whereas the westernmost Markhida landscape is more eroded. The west-east gradient in morphology is considered to be a result of the time-transgressive melting of stagnant glacier ice and of the underlying permafrost. The pattern of ice-pushed ridges and other directional features reflects a dominant ice flow direction from the Kara Sea shelf. Traces of ice movement from the central Barents Sea are only discernible in the Pechora River left bank area west of 50°E. In the Polar Urals the horseshoe-shaped end moraines at altitudes of up to 560 m a.s.l. reflect ice movement up-valley from the Kara Ice Sheet, indicating the absence of a contemporaneous ice dome in the mountains. The Markhida moraines, superimposed onto the Eemian strata, represent the maximum ice sheet extent in the western part of the Pechora Basin during the Weichselian. The Markhida Line truncates the huge arcs of the Laya-Adzva and Rogovaya ice-pushed ridges protruding to the south. The latter moraines therefore reflect an older ice advance, probably also of Weichselian age. Still farther south, fluvially dissected morainic plateaus without lakes are of pre-Eemian age, because they plunge northwards under marine Eemian sediments. Shorelines of the large ice-dammed Lake Komi, identified between 90 and 110 m a.s.l. in the areas south of the Markhida Line, are radiocarbon dated to be older than 45 ka. The shorelines, incised into the Laya-Adzva moraines, morphologically interfinger with the Markhida moraines, indicating that the last ice advance onto the Russian mainland reached the Markhida Line during the Middle or Early Weichselian, before 45 ka ago. 相似文献
8.
Tasmania is important for understanding Quaternary climatic change because it is one of only three areas that experienced extensive mid‐latitude Southern Hemisphere glaciation and it lies in a dominantly oceanic environment at a great distance from Northern Hemisphere ice sheet feedbacks. We applied exposure dating using 36Cl to an extensive sequence of moraines from the last glacial at Mt. Field, Tasmania. Glaciers advanced at 41–44 ka during Marine oxygen Isotope Stage (MIS) 3 and at 18 ka during MIS 2. Both advances occurred in response to an ELA lowering greater than 1100 m below the present‐day mean summer freezing level, and a possible temperature reduction of 7–8°C. Deglaciation was rapid and complete by ca. 16 ka. The overall story emerging from studies of former Tasmanian glaciers is that the MIS 2 glaciation was of limited extent and that some glaciers were more extensive during earlier parts of the last glacial cycle. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
9.
他念他翁山中段地处青藏高原东南部和云贵高原过渡地带,海拔4 200 m以上保存着确切的第四纪冰川遗迹.对其进行深入研究,不仅可以重建横断山脉冰川作用的演化历史,还能够为青藏高原的隆升机制提供重要依据.采用野外地貌调查与电子自旋共振测年（ESR）相结合的方法,查明他念他翁山第四纪冰川发育的地貌特点,并初步对研究区的冰期系列进行划分.结果显示,他念他翁山中段古冰川类型主要为山麓冰川、山谷冰川和冰斗冰川.晚第四纪以来至少经历了4次冰川作用,分别为倒数第二次冰期（MIS 6）,年代为（192±51）~（207±45）ka;末次冰期中期（MIS 3）,年代为（55±8）~（54±9）ka;末次冰盛期（MIS 2）,年代为（25±1）~（38±6）ka,以及全新世新冰期/小冰期（MIS 1）. 相似文献
10.
综合青藏高原第四纪冰川早期记录的研究进展和典型盆地地层、沉积、古生物、古环境研究的系统成果,扎达盆地香孜组上部冻融层的出现代表了区域的古海拔达到了高原冰缘的高度,即3 500 m以上.这一段地层的时代可能从2.3 Ma前后开始.并与贡巴砾石层下部冰水沉积层的时代基本一致.卓奥友冰期和希夏邦马冰期的时代与扎达盆地沉积结束后,直接覆盖其上的终碛垄和冰碛垄的时代大致相当,展现了这一时期喜马拉雅山脉的山岳冰川进一步发育,也说明喜马拉雅山脉作为青藏高原海拔最高的地区开始冰冻圈的环境很可能在早更新世早中期.川西地区的早更新世的冰川沉积说明东喜马拉雅构造结附近地区这一时期已经抬升至冰冻圈高度,但是,海拨高度与气候环境与喜马拉雅山脉应有不同.具体的时代仍需要深入工作.青藏高原普遍开始冰冻罔记录是在中更新世早期.伴随着全球冰期的到来,这一时期的冰川作用在青藏高原最为发育和广泛.这些暗示着青藏高原在中更新世早期整体性地较快速抬升进入冰冻圈,即海拔3 500 m以上.详细的过程仍有待深入研究. 相似文献
11.
Timothy Kusky Liang Guo Shibao Xiang Xiaoyu Guo Xingyong Xu 《Journal of Asian Earth Sciences》2011,40(1):403-416
Accurately determining how far south Quaternary glaciers existed in eastern China has important implications for understanding global Quaternary climate. In this study, we provide evidence for a colder paleoclimate in the late Pleistocene of the Laoshan range on the eastern Shandong Peninsula at 36°05′–36°19′N latitude, through documentation of erosional and depositional landforms that were possibly formed by glaciation. We integrate field observations documenting and mapping the existence of typical glacial cirques, glacial horns, moraines, arêtes, tarn lakes, and other paleoglacial features in Mt. Laoshan, with a detailed digital elevation model (DEM) created in an ArcGIS environment, merged with Landsat ETM + imagery to document the spatial relations of these features. Other features that may or may not be glacial in origin include large boulder fields (that could be moraines or debris avalanches), and potholes (that could have formed beneath glaciers or in river systems). Additionally, some features previously interpreted as glacial features are here re-interpreted as weathering-related phenomena. Although some of these features alone provide only weak to moderate evidence for glaciation, together the suite of indicators provides strong evidence for sea-level glaciation at 36°N in the late Pleistocene of eastern China. We further integrate the evidence of glaciation with the late Pleistocene paleogeography and climate, and suggest that the glaciers formed as a result of orographic effects from moist monsoonal breezes crossing a paleolake developed in North China then rising over Mt. Laoshan and dropping their moisture there, with a wide desert formed on the leeward side of the mountains. 相似文献
12.
滇西北山地末次冰期冰川发育及其基本特征 总被引：1，自引：0，他引：1
对滇西北海拔4 000~4 500 m 山地的第四纪冰川发育和平衡线高度进行了研究. 结果表明: 古冰川发育主要依托海拔4 000~4 300 m的夷平面,早中期发育小型的冰帽以及流入四周谷地的山谷冰川,晚期主要发育规模较小的冰斗冰川. 冰川主要发育期为末次冰期,古冰川平衡线、山体最高峰以及夷平面的高度显示,冰川发育所依托的夷平面在末次冰期时超过古平衡线,二者差值为50~400 m,为冰川发生提供了良好的地形与地势条件. 冰川规模演化表明,滇西北地区多处山地MIS 3中期的冰川规模大于末次冰盛期（LGM）,可能与MIS 3中期较强南亚季风带来较丰富的降水有关. 古气候研究资料以及研究区的冰期系列表明,滇西北海拔4 000~4 500 m山地末次冰期的冰川作用是构造和气候相耦合的结果. 相似文献
13.
Sharp-crested moraines, up to 120 m high and 9 km beyond Little Ice Age glacier limits, record a late Pleistocene advance of alpine glaciers in the Finlay River area in northern British Columbia. The moraines are regional in extent and record climatic deterioration near the end of the last glaciation. Several lateral moraines are crosscut by meltwater channels that record downwasting of trunk valley ice of the northern Cordilleran ice sheet. Other lateral moraines merge with ice-stagnation deposits in trunk valleys. These relationships confirm the interaction of advancing alpine glaciers with the regionally decaying Cordilleran ice sheet and verify a late-glacial age for the moraines. Sediment cores were collected from eight lakes dammed by the moraines. Two tephras occur in basal sediments of five lakes, demonstrating that the moraines are the same age. Plant macrofossils from sediment cores provide a minimum limiting age of 10,550-10,250 cal yr BP (9230 ± 50 14C yr BP) for abandonment of the moraines. The advance that left the moraines may date to the Younger Dryas period. The Finlay moraines demonstrate that the timing and style of regional deglaciation was important in determining the magnitude of late-glacial glacier advances. 相似文献
14.
Henrik Rother Georg Stauch David Loibl Frank Lehmkuhl Stewart P. H. T. Freeman 《Boreas: An International Journal of Quaternary Research》2017,46(3):503-524
The Burhan Budai Shan in NE Tibet represents a key location for examining the variable influence of the mid‐latitude westerly and monsoonal circulations on late Quaternary glaciations in this sector of the Tibetan Plateau. Our study investigates the glacial history of mountains near Lake Donggi Cona (35°17′N, 98°33′E) using field mapping in combination with 10Be surface exposure dating and numerical reconstructions of former glacial equilibrium line altitudes (palaeo‐ELA). A set of 23 new exposure ages, collected from moraines in four glacial valleys, ranges from 45 to 190 ka, indicating ice expansion during the early and middle part of the last glacial cycle, and during the penultimate and possibly an earlier Mid‐Pleistocene glaciation. Ice advances reaching 12–15 km in length occurred at around 190–180 ka (≥MIS 6), between 140–100 ka (late MIS 6/MIS 5), and 90–65 ka (late MIS 5/early MIS 4), with a maximum ELA depression of 400–500 m below the estimated modern snowline. Exposure ages from the valley headwaters further indicate a small glaciation between c. 60–50 ka (late MIS 4/early MIS 3), which was essentially restricted to the cirque areas. Significantly, we find no evidence for any subsequent glaciation in the area during MIS 2 or the Holocene period. These results indicate a diminishing trend of glaciation in the region since at least MIS 4, and corroborate the case of a ‘missing LGM’ in the more interior parts of the northeastern Tibetan Plateau. The emerging pattern suggests that the most favourable conditions for glaciation during the Late Pleistocene correspond to periods of relatively moderate cooling combined with an intermediate or rising East Asian monsoon strength. 相似文献
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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
16.
Late Quaternary glaciation in the Tianshan and implications for palaeoclimatic change: a review 总被引：1，自引：0，他引：1
XIANGKE XU AXEL KLEIDON LEE MILLER SHIQIN WANG LIQIANG WANG GUOCHENG DONG 《Boreas: An International Journal of Quaternary Research》2010,39(2):215-232
Xu, X., Kleidon, A., Miller, L., Wang, S., Wang, L. & Dong, G. 2009: Late Quaternary glaciation in the Tianshan and implications for palaeoclimatic change: a review. Boreas, 10.1111/j.1502‐3885.2009.00118.x. ISSN 0300‐9483. The Tianshan mountain range has been extensively and repeatedly glaciated during the late Quaternary. Multiple moraines in this region record the extent and timing of late Quaternary glacier fluctuations. The moraines and their ages are described in three sub‐regions: eastern, central and western Tianshan. Notable glacial advances occurred during marine oxygen isotope stages (MIS) 6, 4, 3, 2, the Neoglacial and the Little Ice Age (LIA) in these sub‐regions. Glaciers in western Tianshan advanced significantly also during MIS 5, but not in eastern and central Tianshan. The local last glacial maximum (llgm) of the three sub‐regions pre‐dated the Last Glacial Maximum (LGM) and occurred during MIS 4 in eastern and central Tianshan, but during MIS 3 in western Tianshan. The spatial and temporal distribution of the glaciers suggests that precipitation (as snow at high altitude) is the main factor controlling glacial advance in the Tianshan. The late Quaternary climate in the Tianshan has been generally cold–dry during glacial times and warm–humid during interglacial times. Between neighbouring glacial times, the climate has had a more arid tendency in eastern and central Tianshan. These palaeoclimatic conditions inferred from glacial landforms indicate important relationships between the mid‐latitude westerly, the Siberian High and the Asian monsoon. 相似文献
17.
The coastal cliffs of Cape Shpindler, Yugorski Peninsula, Arctic Russia, occupy a key position for recording overriding ice sheets during past glaciations in the Kara Sea area, either from the Kara Sea shelf or the uplands of Yugorski Peninsula/Polar Urals. This study on Late Quaternary glacial stratigraphy and glaciotectonic structures of the Cape Shpindler coastal cliffs records two glacier advances and two ice‐free periods older than the Holocene. During interglacial conditions, a sequence of marine to fluvial sediments was deposited. This was followed by a glacial event when ice moved southwards from an ice‐divide over Novaya Zemlya and overrode and disturbed the interglacial sediments. After a second period of fluvial deposition, under interstadial or interglacial conditions, the area was again subject to glacial overriding, with the ice moving northwards from an inland ice divide. The age‐control suggests that the older glacial event could possibly belong to marine oxygen isotope stage (MOIS) 8, Drenthe (300–250 ka), and that the underlying interglacial sediments might be Holsteinian (>300 ka). One implication of this is that relict glacier ice, buried in sediments and incorporated into the permafrost, may survive several interglacial and interstadial events. The younger glacial event recognised in the Cape Shpindler sequence is interpreted to be of Early‐to‐Middle Weichselian age. It is suggested to correlate to a regional glaciation around 90 or 60 ka. The Cape Shpindler record suggests more complex glacial dynamics during that glaciation than can be explained by a concentric ice sheet located in the Kara Sea, as suggested by recent geological and model studies. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
18.
Late Palaeozoic glaciation in Australia, discovered over a century ago, is now known to have covered a large part of the continent. In South Australia, tillite and outwash debris lie upon clearly striated pavements within glacial valleys, and show that ice sheets with valley tongues moved northward from sources now occupied by deep ocean south of the continent. These glaciers reached into the Cooper, Arckaringa, and Pedirka Basins at the end of the Carboniferous and laid down patches of till in the Early Permian, now preserved largely in the subsurface. In Tasmania, an ice sheet waxed in the latest Carboniferous from sources to the west of the island, and deposited till and “drop‐stones” into fossiliferous marine strata until well into the Late Permian. In Victoria, the ice cap laid down till on a striated floor, and here and there sequences of outwash, including boulder pavements. In New South Wales, continental glaciation expanded eastward to the sea early in the Permian, and left a record intercalated with volcanics and coal beds into the Late Permian. Bordering the Tamworth Trough of northern New South Wales, and occurring also in the highlands of New England, alpine glaciers left a record in the form of striated stones and dropstones, in very thick sequences of fluviatile, lacustrine, and marine clastic sediments. The mountains existed in Middle and early Late Carboniferous times, and were largely worn down to gentle relief when continental glaciers expanded northward in the Early Permian. A non‐glacial interval at the end of the Carboniferous therefore probably occurred in New South Wales. In Queensland, alpine glaciers occupied mountains at the western rim of the Bowen Basin at the end of the Carboniferous. Large blocks carried by icebergs from glaciers of unknown locations were dropped into Lower and Upper Permian strata of the Bowen Basin as well. In Western Australia Early Permian ice centres were located on the Yilgarn Block, east of the Perth Basin, on the Pilbara Block southwest of the Canning Basin, and on the Kimberley Block. Evidence for this glaciation consists mostly of ice‐rafted debris and fluvial‐glacial and glacial‐marine strata that reached as far north as the Bonaparte Gulf Basin. The rapid growth northward of continental glaciers in Australia near the end of the Carboniferous corresponds with a rapid shift of palaeolatitude as judged from Irving's palaeomagnetic studies. The ice sheet grew quickly upon upland areas when Gondwanaland moved to a near polar position and the unfrozen Palaeo‐Pacific lay near at hand to provide an abundant source of moisture. 相似文献
19.
SANDRA PASSCHIER CEES LABAN CHRIS S. MESDAG KENNETH F. RIJSDIJK 《Boreas: An International Journal of Quaternary Research》2010,39(3):633-647
Passchier, S., Laban, C., Mesdag, C.S. & Rijsdijk, K.F. 2010: Subglacial bed conditions during Late Pleistocene glaciations and their impact on ice dynamics in the southern North Sea. Boreas, Vol. 39, pp. 633–647. 10.1111/j.1502‐3885.2009.00138.x. ISSN 0300‐9483. Changes in subglacial bed conditions through multiple glaciations and their effect on ice dynamics are addressed through an analysis of glacigenic sequences in the Upper Pleistocene stratigraphy of the southern North Sea basin. During Elsterian (MIS 12) ice growth, till deposition was subdued when ice became stagnant over a permeable substrate of fluvial sediments, and meltwater infiltrated into the bed. Headward erosion during glacial retreat produced a dense network of glacial valleys up to several hundreds of metres deep. A Saalian (MIS 6) glacial advance phase resulted in the deposition of a sheet of stiff sandy tills and terminal moraines. Meltwater was at least partially evacuated through the till layer, resulting in the development of a rigid bed. During the later part of the Saalian glaciation, ice‐stream inception can be related to the development of a glacial lake to the north and west of the study area. The presence of meltwater channels incised into the floors of glacial troughs is indicative of high subglacial water pressures, which may have played a role in the onset of ice streaming. We speculate that streaming ice flow in the later part of the Saalian glaciation caused the relatively early deglaciation, as recorded in the Amsterdam Terminal borehole. These results suggest that changing subglacial bed conditions through glacial cycles could have a strong impact on ice dynamics and require consideration in ice‐sheet reconstructions. 相似文献
20.
在对唐古拉山口现代冰川和古冰川考察研究的基础上，结合定位观测资料和TL、^10B-^26Al-^21Ne及^14C测年数据，对区内第四纪冰川遗迹进行了深入讨论，划分出二次冰期(即中更新世晚期的倒数第二次冰期、晚更新世中一晚期的末次冰期)和二次全新世冰进(即新冰期和小冰期)。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。但在唐古拉山口地区，截止目前还未找到中更新世早期的倒数第三次冰期的冰川遗迹，由于高原隆升的滞后性和冰川发育的延滞效应及“亚洲干极”的耦合，推测仍只发育局部冰川作用。进一步研究表明，古今雪线由高原边缘向腹地升高，唐古拉山地区高出边缘1500m左右，生动表现了“亚洲干极”的作用；广泛分布的湖群说明羌塘地区是一个大江大河尚未伸入的内流地区，意味着青藏高原是个年青的高原。由于青藏高原的隆升，对高原腹地引起的干旱化过程和水分严重不足，使唐古拉山地区的冰川自倒数第二次冰期以来，冰川规模一次比一次明显地减小。 相似文献