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1.
A REVIEW OF THE PALEOHYDROLOGICAL AND GEOMORPHOLOGICAL CHARACTER OF LAKE NAM CO|SOUTHCENTRAL TIBET 
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下载免费PDF全文 《第四纪研究》2009,29(4):655-664
Department of Earth Sciences,Freie Universität Berlin,Malteserstraße 74－100,12249 Berlin,Germany)
The endorheic Lake Nam Co,south Eastern Tibetan Plateau,was selected to investigate the interrelation between drainage basin processes,especially postglacial glacier decay,and lake level fluctuations. Landforms of the drainage basin are highly influenced by tectonics,superimposed by fluvial and periglacial processes,and locally by glacial and eolian processes. Thus,geomorphological features and hydrological characteristics were compiled for the lakebasin to provide an overview of the landscape character. Data show that during the Last Glacial Maximum melt water from the mountains accumulated fluvial deposits in the foreland. Concurrently,an increase of the lake level occurred which is presently shown by a cliff line all around Nam Co with its base approximately 29m above the present lake level. The Holocene decrease of the lake level is traced by beach ridges. As Nam Co is an endorheic lake postglacial water loss has to be primarily explained by evaporation and moisture conditions. However,more detailed conclusions on quantitative and chronological patterns of both factors,meltwater input and evaporation output,still remain to be drawn. 相似文献
The endorheic Lake Nam Co,south Eastern Tibetan Plateau,was selected to investigate the interrelation between drainage basin processes,especially postglacial glacier decay,and lake level fluctuations. Landforms of the drainage basin are highly influenced by tectonics,superimposed by fluvial and periglacial processes,and locally by glacial and eolian processes. Thus,geomorphological features and hydrological characteristics were compiled for the lakebasin to provide an overview of the landscape character. Data show that during the Last Glacial Maximum melt water from the mountains accumulated fluvial deposits in the foreland. Concurrently,an increase of the lake level occurred which is presently shown by a cliff line all around Nam Co with its base approximately 29m above the present lake level. The Holocene decrease of the lake level is traced by beach ridges. As Nam Co is an endorheic lake postglacial water loss has to be primarily explained by evaporation and moisture conditions. However,more detailed conclusions on quantitative and chronological patterns of both factors,meltwater input and evaporation output,still remain to be drawn. 相似文献
2.
ZHU Dagang MENG Xiangang ZHAO Xitao SHAO Zhaogang XU Zufeng YANG Chaobin MA Zhibang WU Zhonghai WU Zhenhan WANG Jianping Institute of Geomechanics Chinese Academy of Geological Sciences Beijing Institute of Geology Geophysics Chinese Academy of Sciences Beijing Jiangxi Institute of Geological Survey Nanchang Jiangxi Tibet Bureau of Land Resources Lhas Tibet 《《地质学报》英文版》2004,78(4):982-992
Nam Co is the largest (1920 km2 in area) and highest (4718 m above sea level) lake in Tibet. According to the discovery of lake terraces and highstand lacustrine deposits at several places in Nam Co and its adjacent areas, the authors confirm the existence of an ancient large lake in the southeastern part of the northern Tibetan Plateau. On the basis of the U-series, 14C and ESR dating, coupled with the levelling survey of lake deposits and geomorphology, the evolutionary process of the ancient large lake in the southeastern part of the northern Tibetan Plateau may fall into three stages: (1) the ancient large lake stage at 115-40 ka BP, when the ancient lake level was 140-26 m above the level of present Nam Co; (2) the outflow lake stage at 40-30 ka BP, when the ancient level was 26-19 m above the present lake level; and (3) the Nam Co stage since 30 ka BP, when the ancient lake level was < 19 m above the present lake level. During the ancient large lake stage, a large number of modern large, medium-siz 相似文献
3.
在西藏纳木错沿岸,发育了6级湖岸阶地及拔湖48～139.2m的高位湖相沉积.根据湖相沉积的U系法测年和孢粉分析结果,本文探讨了纳木错及邻区末次间冰期(MIS5)以来的古植被、古气候与湖面变化.研究表明,纳木错与邻区的湖面变化可以划分为116～37kaB.P.间的古大湖--"羌塘东湖"期、37～30kaB.P.间的"古纳木错"外流湖-残余古大湖期和30kaB.P.以来的纳木错-藏北湖群期等3大阶段.在MIS5的古大湖阶段,包括纳木错、色林错等藏北高原东南部的众多大、中型湖泊,是互相连通的一个大湖,其范围可能超过了现代的藏北内、外流(怒江)水系的分水岭.在MIS5e末的最高湖面时期,湖面面积可达78800km2,它或许还与藏北高原西南部和中南部的其他古大湖相连,成为面积巨大的网格状深水大湖--"羌塘湖".通过纳木错湖面变化曲线与西昆仑古里雅、格陵兰、南极等冰芯和深海岩芯的氧同位素变化曲线的对比可以发现,全球MIS5的气温要高于末次冰期间冰阶(MIS3),此时藏北高原为气候温和轻爽与湖面最高的大湖期;在末次冰期的两个冰阶(MIS4和MIS2)中,湖面明显下降,邻近的念青唐古拉山发育了小型山谷冰川;而在间冰阶MIS3中,其气候波动的幅度,要比世界其他地区更加明显,湖面波动也较大,特别是36～35kaB.P.间,气温和湿度都较今略高或较高,但不及MIS1中的全新世气候最宜时期的暖湿程度.总之,MIS5和MIS3是亚洲夏季风强烈时期,但前者的强烈程度应大于后者. 相似文献
4.
西藏纳木错盆地116ka以来沉积演化与青藏高原隆升 总被引：6，自引：0，他引：6
根据湖相或湖滨相沉积的铀系等时线年龄测定结果,116kaB.P.以来,在西藏纳木错沿岸,发育了拔湖48m以下的6级湖岸阶地和拔湖48m以上,最高至139.2m的高位湖相沉积.可划分出3个沉积相组合,其演化可划分为4个阶段:①116~72kaB.P.,为深湖环境,古湖面拔湖高于现今纳木错140~48m;②72~37kaB.P.,为半深湖环境,拔湖为48~26m;③37~30kaB.P.,为浅湖环境,拔湖26~19m;④30kaB.P.以来,湖水逐渐变浅,拔湖<19m.纳木错盆地沉积与青藏高原隆升响应关系,揭示出高原自116kaB.P.以来先后经历了稳定期、持续逐步较快隆升期(116~37kaB.P.)、急剧强烈阶段性隆升期(37~30kaB.P.)和较稳定期(30kaB.P.以来).青藏高原的隆升是一个多阶段、不等速和非均变的复杂过程. 相似文献
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西藏纳木错晚更新世以来湖面变化和湖相沉积中粘土矿物显示的环境信息 总被引：13，自引：1，他引：12
通过对西藏海拔最高、面积最大湖泊-纳木错周缘湖相沉积、湖岸堤的野外调查和湖岸阶地的水准测量,发现在纳木错沿岸拔湖48m以下,发育有6级湖岸阶地,拔湖48~139.2m发育有高位湖相沉积。湖相沉积物的同位素测年结果表明,纳木错湖泊发育与藏北高原东南部古大湖演化可划分为3个阶段:①116~37kaB.P.间的古大湖期;②37~30kaB.P.间的外流湖期;③30kaB.P.以来的纳木错期。根据纳木错晚更新世以来湖相沉积中粘土矿物的X光衍射分析结果,以及采用比值法、高岭石法和衍射峰法的研究,探讨了粘土矿物所显示的环境变化信息。粘土矿物成分变化表明,该区已具备了寒温带干旱、半干旱区的气候环境特征。为研究青藏高原的湖泊演化、气候变化、古地理变迁及其隆升过程等提供了新资料。 相似文献
7.
通过2007-2011年纳木错站人工积雪观测资料,对西藏纳木错流域MODIS两种积雪产品(MOD10A1和MOD10A2)进行了精度验证,分析了纳木错流域积雪累积和消融的空间差异,以及流域积雪覆盖率的时空变化;利用纳木错站人工积雪观测资料及自动气象站资料,分析了纳木错流域积雪要素(积雪深度、雪水当量、积雪密度)的时间变化及其与气候参数(气温、降水量、风速等)的关系.结果表明：纳木错流域MOD10A2数据的积雪识别精度(67.1%)高于MOD10A1(42.2%),总识别精度(73.0%)略低于MOD10A1数据(78.4%).纳木错流域积雪累积和消融存在空间差异,积雪在流域南部的念青唐古拉山脉最先累积,之后为流域东部,最后为流域西部;积雪消融的空间变化则相反.由此导致流域积雪日数南部最大、东部次之、西部及西北部最小.纳木错流域各积雪要素的年内变化存在双峰值特征,峰值分别出现在10-11月和1月,积雪在10-11月受降水和气温共同作用,12月至次年3月主要受气温影响.纳木错流域的平均积雪覆盖率为21.9%,受湖泊效应影响区域(主要为东部地区)达到50.6%,而其他区域仅为18.3%.同时,受湖泊效应影响,纳木错平均积雪深度、积雪水当量均显著大于周边地区. 相似文献
8.
The Permo-Carboniferous Talchir Formation in the southeastern part of the Talchir basin is represented by about 260 m thick clastic succession resting on the Precambrian basement rocks of the Eastern Ghats Group. The succession is tentatively subdivided into four lithostratigraphic units, namely A-I, A-II, B and C from base to top. Unit A-I comprises mud-matrixed, very poorly sorted diamictites and interbedded thin sandstone and mudstone yielding dropstones. They reveal deposition in a proglacial lake environment in which ice rafting and suspension sedimentation, as well as meltwater-underflow processes, produced variety of facies. The succession of unit A-II is dominated by pebble to boulder conglomerates and sandstones. They were deposited mostly from various kinds of high-energy sediment gravity flows, both subaerial and subaqueous, and formed steep-faced fan-delta on the margin of the basin. Unit B demonstrates turbidite sedimentation in lake-margin slope and base-of-slope environments, in which a sublacustrine channel-fan system developed. The lake-margin slope was dissected by channels which were accompanied by overbank and levee deposits. Sediments delivered from the mouth of a channel were deposited at the base-of-slope, forming a fan lobe which prograded onto the lake basin floor. Unit C dominantly consists of mudstone with intercalations of siltstone and sandstone and forms a large-scale coarsening-upward deltaic sequence eventually covered by the fluvial deposits of the Karharbari Formation.Following the glacially influenced sedimentation, the Talchir succession shows a vertical facies progression suggesting gradual deepening of the lake basin and eventual filling up of it due to rapid delta progradation. Such a succession represents deglacial control on basin evolution during the Talchir time. In the initial stage of glacial recession, collapse of a glacier and failure of montane glacial lakes frequently occurred and gave rise to generation of a highly sediment-laden debris flow and a catastrophic flood, which brought abundant coarse clastics into the lake and built a fan-delta on the basin margin. The continued recession and disappearance of glacier resulted in abundant supply of ice-melt water into the graben as well as eustatic sea-level rise, being the cause of the rise in lake-level. Subsequent rapid delta progradation and eventual filling-up of the lake basin suggest rapid lake-level fall after deepening of lake basin. It was possibly caused by the regional uplift due to post-glacial isostatic rebound. Rapid draining of lake water through the graben gave rise to the establishment of an axial drainage system which rapidly filled the lake basin in form of an axially fed delta. 相似文献
9.
渭河盆地和三门峡盆地内发育的河湖相三门组沉积,记录了上新世-更新世的盆地沉积历史,对认识区域古环境及盆地演化特征具有重要意义.通过两个盆地三门组地层的沉积相分析和物源重建,发现2.8~2.6 Ma盆地环境发生了明显变化,2.8~2.6 Ma渭河盆地由深湖转为浅湖沉积,水位下降,而三门峡盆地由河流相转为滨浅湖,水位上升.结合前人古地貌重建和区域应力反演结果,认为上新世渭河盆地和三门峡盆地相互独立,早更新世两个盆地才连通,湖水由渭河盆地注入三门峡盆地,形成统一的三门古湖.对比区域构造事件和物源分析结果,认为青藏高原的快速隆升导致秦岭的抬升,可能是盆地及其水系演化的触发动力. 相似文献
10.
Qianggong Zhang Shichang Kang Feiyue Wang Chaoliu Li Yanwei Xu 《Aquatic Geochemistry》2008,14(4):321-336
The major cations and anions from lake water samples and its sources, including glacier snow, precipitation, stream, and swamp
water in the Nam Co basin, central Tibetan Plateau, were studied. The concentrations of the major ions varied significantly
in the five environmental matrices. Generally, the mean concentrations of most ions are in the order of lake water > swamp
water > stream water > precipitation > snow. Rock weathering is the dominant process controlling the chemical compositions
of the stream and swamp waters, with carbonate weathering being the primary source of the dissolved ions. The Nam Co lake
water is characterized by high Na+ concentration and extremely low Ca2+ concentration relative to other ions, resulting from evapoconcentration and chemical precipitation within the lake. Comparison
with the water chemistry of other lakes over the Tibetan Plateau indicated that Nam Co is located in a transition area between
non-saline lakes and highly saline lakes. The relatively low concentration of total dissolved solids is possibly due to the
abundant inflow of glacial meltwater and relatively high annual precipitation. 相似文献
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西藏纳木错及邻区全新世气候与环境变化的地质记录 总被引：20，自引：1，他引：19
综合分析了全新世期间内的多种与气候和环境变化密切相关的地质记录,结果表明该区全新世期间的气候变化可划分为3个阶段:1)约11.8～8.4kaBP期间,处于微温期和升温期,气候相对温和稍湿.2)8.4～4.0kaBP期间,为全新世气候最适宜时期或大暖期.该期间的平均气温可能比现今高约5℃,降水量比今多100～200mm.3)4.0kaBP以来,气候整体较为干冷.纳木错湖面发生持续下降,其最大下降幅度可达11.4m.冰川进退和湖面波动表明,该期间内的气候波动过程分别与新冰期和小冰期相对应,其中又各包含了3次明显的冷期,其中新冰期期间的最低年平均气温可达-6℃左右.约1970年以来,区域气候向暖湿方向转化,造成念青唐古拉山西布冰川后退约120～200m,纳木错湖面上涨了约2m. 相似文献
13.
Astrid Lyså Eiliv Larsen Jan‐Pieter Buylaert Ola Fredin Maria A. Jensen Denis Kuznetsov Andrew S. Murray Dmitry A. Subetto Aurelien van Welden 《Boreas: An International Journal of Quaternary Research》2014,43(4):759-779
The Late Pleistocene stratigraphy from the Severnaya Dvina‐Vychegda region of northwestern Russia is revised based on investigations of new localities, revisiting earlier localities, introduction of about 110 new OSL dates and burial depth corrections of earlier published OSL dates, in addition to six new radiocarbon dates. Most of the OSL samples studied here are from fluvial and subaquaeous sediments, which we found to be well bleached. Six chronostratigraphical units and their sedimentary environment are described, with the oldest unit consisting of pre‐Eemian glacial beds. For the first time, Early Weichselian sediments are documented from the region and a fluvial environment with some vegetation and permafrost conditions is suggested to have persisted from the end of the Eemian until at least about 92 ka ago. The period in which a Middle Weichselian White Sea Lake could have existed is constrained to 67?62 ka, but as the lake level never reached the thresholds of the drainage basin, the lake probably existed only for a short interval within this time‐span. Blocking and reversal of fluvial drainage started again around 21?20 ka ago when the Fennoscandian Ice Sheet advanced into the area, reaching its maximum 17?15 ka ago. At that time, an ice‐dammed lake reached its maximum water level, which was around 135 m above present sea level. Drainage of the lake started shortly after 15 ka ago, and the lake was emptied within 700 years. Severe periglacial conditions, with permafrost and aeolian activity, prevailed in the area until about 10.7 ka. 相似文献
14.
Evidence of lacustrine sedimentation in the Upper Permian Bijori Formation, Satpura Gondwana basin: Palaeogeographic and tectonic implications 总被引：1，自引：0，他引：1
The Upper Permian Bijori Formation of the Satpura Gondwana basin comprising fineto coarse-grained sandstone, carbonaceous
shale/mudstone and thin coal bands was previously interpreted as the deposits of meandering rivers. The present study documents
abundance of wave ripples, hummocky and swaley cross-stratification and combined flow bedforms in the Bijori Formation, suggesting
that a significant part of the formation was deposited in a wave-agitated environment. Evidence of near-emergent depositional
conditions provided by repeated occurrence of rootlet beds and hydromorphic paleosols, local flooding surfaces denoting rapid
fluctuation of water level, occurrences of temnospondyl vertebrate fossils, and absence of tidal signatures and marine fossils
suggest a lacustrine rather than marine depositional regime. Five facies associations recognised within the Bijori Formation
are inferred to represent fluvial channels and associated floodplains (FA1), lake shorelines (FA2), subaqueous distributary
channels and associated levees (FA3), waveand storm-affected delta front (FA4), and open lacustrine/lower shoreface (FA5)
deposits. The planoconcave fluvial channel-fill sandbodies with unidirectional cross-beds are clearly distinguishable from
the delta front bars that show a convexo-plan or bi-convex sandbody geometry and dominance of wave and combined flow bedforms.
Some of the distributary channels record interaction of fluvial and wave-dominated basinal processes. Major distributary sandbodies
show a north to northwest flow direction while wave-affected delta front sandbodies show very complex flow patterns reflecting
interaction between fluvial discharge and wave processes. Wave ripple crest trends show that the lake shoreline had an overall
east-northeast to west-southwest orientation. The lack of documented contemporaneous lacustrine or marine sediments in the
Satpura Gondwana basin posed a major problem of basin-scale palaeogeographic reconstruction. The existence of Bijori lake
solves the problem and the lake is inferred to have acted as repository for the contemporaneous alluvial drainage. Development
of the large Bijori lake body implies generation of accommodation space exceeding the rate of sediment supplied and thus represents
locus of high tectonic subsidence. Transition of fluvial sediments with red mudstone and calcareous soil profile in the lower
part of the succession to carbonaceous shale and coal-bearing lacustrine sediments in the upper part, denote a change from
a warm semi-arid climate with seasonal rainfall to a more humid one. 相似文献
15.
关于间歇性涨缩湖盆沉积作用的几点认识(主要以柴达木盆地早第三纪沉积为例) 总被引：2，自引：1，他引：2
以柴达木盆地第三系为例,介绍了形成间歇性涨缩湖盆的构造、地形和气候条件。论述了盆地的沉积作用和沉积体系,着重指出陡坡以交互进积作用和洪积-潮积体系为特征,次陡坡以过速加积作用和非常规三角洲为特征,也简述了缓坡正常侧向加积作用及常规三角洲体系。笔者认为,陡坡洪积-湖积体系中的砂砾岩和次陡坡非常规三角洲相砂岩体是油气勘探的主要目标。 相似文献
16.
The rift succession of the Araripe Basin can be subdivided into four depositional sequences, bounded by regional unconformities, which record different palaeogeographic and palaeoenvironmental contexts. Sequence I, equivalent to the Brejo Santo Formation, is composed of fluvial sheetflood and floodplain facies association, while Sequence II, correspondent to the lower portion of the Missão Velha Formation, is characterised by braided fluvial channel belt deposits. The fluvial deposits of Sequences I and II show palaeocurrents toward SE. The Sequence III, correspondent to the upper portion of Missão Velha Formation, is composed of fluvial sheetflood deposits, which are overlain by braided fluvial channel deposits displaying a palaeocurrent pattern predominantly toward SW to NW. Sequence IV, equivalent to the Abaiara Formation, is composed of fluvio–deltaic–lacustrine strata with polimodal paleocurrent pattern. The type of depositional systems, the palaeocurrent pattern and the comparison with general tectono-stratigraphic rift models led to the identification of different evolutionary stages of the Araripe Basin. Sequences I, II and III represent the record of a larger basin associated to an early rift stage. However, the difference of the fluvial palaeocurrent between sequences II and III marks a regional rearrangement of the drainage system related to tectonic activity that compartmentalised the large endorheic basin, defining more localised drainage basins separated by internal highs. Sequence IV is associated with the renewal of the landscape and implantation of half-graben systems. The high dispersion of palaeocurrents trends indicate that sedimentary influx occurs from different sectors of the half-grabens. 相似文献
17.
河相层序地层研究进展述评 总被引：7，自引：0，他引：7
将河流平衡剖面看成是陆区基准面的观点已受到怀疑，有迹象表明地貌基准面有可能是陆区基准面。河相沉积记录不仅与基准面变化有关，也与源区和流域盆地的许多因素有关，而且河相地层对基准在的响应也比过去理解的复杂得多。上游区由不整合面办公室的河相层序一般难以与海相层序对比。已可相层序模式仍以基准面为支撑理论，层序界面常按财相向盆迁移、复合砂体、古流向偏转和无沉积非作用面等识别，内部仍为三分。目前对可相层序发育 相似文献
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19.
青藏高原湖泊蒸发估算方法的比较研究——以纳木错为例 总被引：1，自引：1，他引：0
基于青藏高原纳木错湖面2012-2014年日尺度气象观测数据,运用五类水面蒸发模型中的9种经验式估算湖面蒸发量,分别与涡动相关实测值对比分析,优化各公式的参数,进而评价、比较优化后各式的精度和适用性。优化后的Dalton系列估算式精度最高,但要求日尺度数据,且所需参数较多,因而其应用受限;组合模型精度近似Dalton系列公式,适合在气象资料较全时使用;温度-辐射模型和温度-日长模型的精度能达到较高要求,且所需参数少,因而经济简便,是利用常规气象资料估算湖泊蒸发的优良选择;温度模型估算式的精度较差。纳木错季风气候明显,需分季风期和非季风期分别对水面蒸发进行估算,两个时段经验估算式的参数有差异。还分析了纳木错湖面观测点与周边地区四个气象站（当雄、申扎、班戈和那曲）之间常规气象因子的相关关系。其中,太阳总辐射、气温和比湿等存在着较好的线性关系,因而可以在通过线性订正后用于湖泊蒸发估算,不会产生大的误差;但风速的相关性差。 相似文献
20.
The Kathmandu and Banepa Basins, Central Nepal, are located in a large syncline of the Lesser Himalayas. The Older Kathmandu Lake evolved during the Pliocene and early Pleistocene; the Younger Kathmandu Lake, which is the focus of this study, is infilled with late Quaternary sediments. Three formations, arranged in stratigraphical order, the Kalimati, Gokarna and Thoka Formations formed during the infilling stage of this lacustrine basin. Structural and textural sedimentological analyses, a chemical survey across the basin and mineralogical investigations of fine‐grained sediments form the basis of this palaeogeographical study. The basin under investigation was covered by a perennial freshwater lake before 30 000 yr BP. The lake was infilled with alluvial and fluvial sediments delivered mainly from the mountains north of the basin. A fairly low gradient was favourable for the formation of diatomaceous earths, carbonaceous mudstones and siltstones, which were laid down in the centre of the lake and in small ponds. Towards the basin edge, lacustrine sediments gave way to deltaic deposits spread across the delta plain. Crevasse splays and anastomosing rivers mainly delivered suspended load for the widespread siltstones and mudstones. The proximal parts of the alluvial–fluvial sedimentary wedge contain debris flows that interfinger with fine‐grained floodplain deposits. Three highstands of the water‐level (>30 000 yr BP, 28 000–19 000 yr BP, 11 000–4000 yr BP (?)) have been recognised in the sedimentary record of the younger Kathmandu Lake in the Late Quaternary. Second‐order water‐level fluctuations are assumed to be triggered by local processes (damming by tectonically induced landslides). First‐order water‐level fluctuations are the result of climatic changes. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献