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从末次冰盛期冰川规模探讨当时的气候环境 总被引：4，自引：2，他引：4
根据乌鲁木齐河源区末次冰盛期形成的保存完好的古冰川遗迹和现代气候条件下冰川特平衡与气候的关系。用冰川动力学方法估算出冰川达到末次冰盛期规模时的气候条件。依据末次冰盛期冰川面积，结合冰川平衡线高度和冰川体积综合分析，乌鲁木齐河源区末次冰盛期的夏季气温应比现代低４．８℃左右，降水约只有现代的３０％，但目前其它古气候方法的研究结果表明，末次冰盛期的夏季气温比现代低５．６℃左右，两者相差０．８℃，其原因可 相似文献
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末次冰盛期（LGM）时全球大范围降温,青藏高原冰川大规模扩张,重建LGM时期古冰川规模对认识高原冰川水资源演化及古气候条件有重要的科学意义。根据青藏高原东南巴松措流域及派山谷两地的冰川地貌及其10Be暴露年代数据,本文应用冰川纵剖面模型定量重建了两地冰川在LGM时期的范围、冰储量和平衡线高度（ELA）等参数,并通过冰川气候模型恢复了LGM时的气候条件。结果表明：巴松措流域LGM时期的冰川面积约为982.3 km2,是现代冰川面积的4.5倍,冰储量约为274.4 km3;派山谷无现代冰川分布,LGM时期的冰川面积达5.76 km2,冰储量约为0.51 km3;LGM时期两冰川的平衡线高度分别为4 460~4 547 m和3 569~3 694 m,与现代冰川相比分别降低了535 m和1 034~1 184 m。在降水减少60%的情况下,考虑LGM以来的构造剥蚀对平衡线高度变化的影响,LGM时期巴松措流域和派山谷冰川的夏季平均气温分别比现在低约2.96~4.89 ℃和5.09~6.99 ℃。 相似文献
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黄河上游阿尼玛卿山区冰川波动与气候变化 总被引：19，自引：13，他引：19
以黄河上游阿尼玛卿山的冰川为研究对象, 通过应用航空相片、卫星遥感影像、地形图和数字高程模型(DEM), 分析了末次冰盛期、小冰期、自1966年及2000年的冰川范围及变化情况. 结果表明, 末次冰盛期的冰川范围是现代冰川的3.1倍; 小冰期以来, 冰川已经开始退缩, 尤其在1966-2000年期间退缩有加速趋势. 介绍了一种提取冰川雪线高度的方法, 并根据现代气候数据, 探讨了研究时段雪线高度上的夏季平均气温变化趋势. 结果表明, 末次冰盛期时, 雪线下降了420 m左右, 相应的夏季平均气温比现代低1.9 ℃, 小冰期盛时夏季平均气温比现代低0.6 ℃. 相似文献
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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
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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
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黄河上游末次冰盛期古洪水事件的初步研究 总被引：8，自引：0，他引：8
洪水的发生规律是洪灾预报的前提，已有的人类洪水记录时间尺度，不足以认识和把握洪水的出现规律。因此，利用地质记录延长洪水序列，探讨地球特征气候期的洪水特点，就显得非常重要的必要。黄河上游兰州－银川段的洪水地质记录表明，在末次冰盛期的20－18ka，该区共发生了106次大洪水漫滩事件，其中有18次为多次洪峰叠加的复合型大洪水，洪水的发生频率达53次/ka。发生于末次冰盛期的大洪水可能属冰凌洪水，与末次冰盛期强烈的气候波动和不稳定有关。这些大洪水的频发与中国西部的末次冰盛期出现的高湖面相对应，既不符合一般的季风气候理论，也不同于我国东部广大地区末次冰盛期以冷干为主的气候特点，表明中国西部气候的独特性和复杂性。 相似文献
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回顾了课题组近年来有关末次冰盛期和中全新世气候模拟分析的研究进展,包括中国气候、东亚和全球季风以及相关的主要大气环流系统等变化。多模式试验数据的分析表明,末次冰盛期中国降温和年均有效降水变化与重建记录定性一致,但模拟幅度偏弱;中国冻土区扩张、永冻土区活动层变薄,中国西部冰川物质平衡线高度降低;东亚季风变化在不同模式间差异较大,中国季风区范围和季风降水减小,北半球陆地季风区南移、全球季风区缩小和降水强度减弱共同引起全球季风降水减少;全球降水和潜在蒸散发共同减小使得全球干湿变化总体很小;北半球西风带在高层北移、低层南移,热带宽度变化依赖于指标的选取,厄尔尼诺—南方涛动气候影响、热带太平洋沃克环流均减弱并东移。在中全新世,多模式模拟的中国年和冬季偏冷仍然与大部分重建记录显示的偏暖不同;东亚冬季风增强,东亚夏季降水变化存在空间不一致性;中国和全球尺度的季风区范围和季风降水均增加;东北多年冻土退化、青藏高原多年冻土向低海拔扩张,北半球永冻土区减小、季节性冻土扩张、冻土区北退、永冻土区活动层变厚;全球干旱区面积总体变化很小;夏季东亚西风急流显著减弱并北移,厄尔尼诺—南方涛动减弱,热带太平洋沃克环流... 相似文献
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青藏高原末次冰期最盛时的冰川与环境 总被引：40，自引：12，他引：40
在１６－３２ｋａＢｐ的末次冰期最盛时，青藏高原较现代降温７℃左右，降水为现代的０３－７０％。极地型冰川广泛分布，高原内部平衡线较下降值减至５００－３００ｍ以内，高原东部，南缘及西缘可能以亚极地型冰川为主，并有小部分温冰川，平衡线下降８００ｍ以至１００－１２００ｍ。初步统计，包括周围高山在内冰川面积在３５×１０＾４ｋｍ＾２左右，为现代冰川的７．５倍，冰储量相当于全海平面变化２４．２ｃｍ。其时，多年冻 相似文献
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SOIL CO_2 EMISSIONS ON THE GLACIER SHRINKING AREA IN HAILUOGOU GLACIERtheNational(G19980 40 80 0 )andCAS'sKeyProjectforBasicResearchonTibetanPlateau(KZ95 1 A1
2 0 4;KZ95T 0 2 ) 相似文献
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Studying the mass balance on the Xiao Dongkemadi Glacier and Hailuogou Glacier shows that the mass balance variation of continent type glacier in the interior of the plateau is in the same phase with that of the marine type glacier in the southeast margin of the plateau. However, the mass balance in the continent type glacier is always positive, and the marine type glacier is in large negative mass balance. The continent type glacier is slow to climate change and the marine glacier is sensitive to climate change. 相似文献
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Stephen C. Porter 《Quaternary Research》1980,14(1):1-32
A considerable portion of Northern Eurasia, and particularly its continental shelf, was glaciated by inland ice during late Weichsel time. This was first inferred from such evidence as glacial striae, submarine troughs, sea-bed diamictons, boulder trains on adjacent land, and patterns of glacioisostatic crustal movements. Subsequently, the inference was confirmed by data on the occurrence and geographic position of late Weichselian end moraines and proglacial lacustrine deposits.The south-facing outer moraines in the northeastern Russian Plain, northern West Siberia, and on Taimyr Peninsula are underlain by sediments containing wood and peat, the radiocarbon dating of which yielded ages of 22,000 to 45,000 yr B.P. The youngest late-glacial moraines are of Holocene age: the double Markhida moraine in the lower Pechora River basin, presumably associated with “degradational” surges of the Barents Ice Dome, is underlain by sediments with wood and peat dated at 9000 to 9900 yr B.P.: this suggests that deglaciation of the Arctic continental shelf of Eurasia was not completed until after 9000 yr B.P.The reconstructed ice-front lines lead to the conclusion that the late Weichselian ice sheet of Northern Eurasia (proposed name: the Eurasian Ice Sheet) extended without interruptions from southwestern Ireland to the northeastern end of Taimyr Peninsula, a distance of 6000 km: it covered an area of 8,370,000 km2, half of which lay on the present-day continental shelves and a quarter on lowlands that were depressed isostatically below sea level. Hence, the ice sheet was predominantly marine-based.A contour map of the ice sheet based both on the dependence of the heights of ice domes upon their radii and on factual data concerning the impact of bedrock topography upon ice relief has been constructed. The major features of the ice sheet were the British, Scandinavian, Barents, and Kara Ice Domes that had altitudes of 1.9 to 3.3 km and were separated from one another by ice saddles about 1.5 km high. At the late Weichselian glacial maximum, all the main ice-dispersion centers were on continental shelves and coastal lowlands, whereas mountain centers, such as the Polar Urals and Byrranga Range, played only a local role.The portions of the ice sheet that were grounded on continental shelves some 700 to 900 m below sea level were inherently unstable and could exist only in conjunction with confined and pinned floating ice shelves that covered the Arctic Ocean and the Greenland and Norwegian Seas.The Eurasian Ice Sheet impounded the Severnaya Dvina, Mezen, Pechora, Ob, Irtysh, and Yneisei Rivers, and caused the formation of ice-dammed lakes on the northern Russian Plain and in West Siberia. Until about 13,500 yr B.P. the proglacial system of lakes and spillways had a radial pattern; it included large West Siberian lakes, the Caspian and Black Seas, and ended in the Mediterranian Sea. Later, the system became marginal and discharged proglacial water mainly into the Norwegian Sea. 相似文献
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《Applied Geochemistry》2002,17(7):855-883
Glacierised areas present an ideal environment in which to study water-rock interaction, since chemical weathering rates are high and anthropogenic impacts are often minimal. Detailed investigations of meltwater quality variations have suggested the importance of these environments in estimates of terrestrial chemical erosion and global biogeochemical cycles. Most notably, the role of meltwaters in CO2 sequestration during episodes of deglaciation has attracted considerable attention, since this may impact on climate at glacial-interglacial timescales. However, there is still considerable uncertainty surrounding estimates of CO2 drawdown by meltwaters which remains to be resolved. Water flow through glaciers exerts an important control on ice mass dynamics, and influences the quantity and quality of water delivered to environments downstream of glacierised basins. Thus, the study of the configuration and dynamics of subglacial drainage systems is important not only to enhance scientific understanding, but also to allow effective water resource utilisation in glacierised headwater catchments. Bulk meltwater quality characteristics draining terrestrial ice masses also offer the potential to provide unique information on hydrological and hydrochemical processes operating in the inaccessible subglacial environment. Here, significant advances have been made in understanding the controls on chemical weathering reactions, based on the identification of key dissolved indicator species. This has allowed water quality variations to be exploited as a tool for both subglacial hydrochemical and hydrological investigations. As a result, this area of glaciology has received considerable attention in recent years, utilising an increasing range of dissolved ions, and integrating field and laboratory studies. However, uncertainty still surrounds certain areas of meltwater quality science, including the role of microorganisms in a system which to date has largely been viewed as abiotic. A better understanding of the processes and rates of chemical weathering in glacierised environments has the potential to enhance our understanding of the environment, and to facilitate the exploitation of water quality variations for both scientific and applied objectives. In this paper the development and current state of meltwater quality science as a tool for investigating subglacial hydrology and geochemistry is detailed, and problems and future directions identified. This will hopefully stimulate wider interest in an important area of aquatic chemistry with significant applied implications. 相似文献
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近期喀喇昆仑山叶尔羌河冰川阻塞湖突发洪水及冰川变化监测分析 总被引：3，自引：1，他引：2
喀喇昆仑山叶尔羌河冰川突发洪水在1987年暴发之后沉寂了近10a,但最近10a(1997—2006年)突发洪水又频繁发生.2002年8月13日发生的冰川湖突发洪水,下游卡群站洪峰流量达4670m3·s-1,洪量125×106m3,远超过1987年实测上游冰湖最大蓄水量.利用多景Landsat 7 ETM+影像对该次洪水进行了研究分析,在克勒青河谷的影像上发现了长6.02km,面积3.01km2的冰川阻塞湖.利用2002年8月最大冰川湖的数据结合实测地形图,估算出冰坝较1987年实测值升高了约35m.分析周边气候资料认为,近20a夏季气温下降和冬季降水增加导致流域内冰川前进,冰川湖规模扩大,是叶尔羌河冰川洪水频率和幅度增加的主要原因. 相似文献
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庐山冰期是否存在一直是国内外学术界争论的话题,至今也无法定夺。大量争论文献,特别是“冰斗”“U形谷”形态、“冰碛”的粒径、网纹红土的分布、孢粉的分析及古气候等研究较为支持施雅风、李吉均等前辈的观点,庐山不存在第四纪冰川。本文根据2008年冻雨灾害现象,进行大胆推测,是否是极端气候造成了庐山冰期？超级丰富的过冷却水加上极其苛刻的暖锋逆温层条件形成了极强极长时期的冻雨,冻雨是滴雨成冰减少了从雪到冰的这一漫长过程,庐山“冰川”是否是在短时间内形成？ 相似文献