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1.
河流沉积与地貌对构造与气候的变化极为敏感,可记录区域构造活动、气候变化和环境演变等多方面的丰富信息。由于独特的构造背景与气候条件,帕隆藏布不仅成为雅鲁藏布水系水量最大的支流,而且其流域在藏东南地区占有重要的地位。帕隆藏布流域内地表过程活跃且河流地貌演化过程快速,是揭示青藏高原东南部构造地貌演化的重要载体。通过对该河流地貌的形态学和沉积学分析发现,帕隆藏布河流形态具有明显的线状特征,其干流近似直线展布,而主要支流呈羽状分布,两者多呈直角交汇,表明河流形态明显受到嘉黎断裂带的构造形迹控制。进一步利用光释光和14C定年方法,对帕隆藏布的晚第四纪河流地貌演化,尤其是干流和东久河支流的晚第四纪河流阶地进行研究后发现,末次冰期以来的气候变化导致帕隆藏布的晚第四纪河流地貌呈现出典型的分段式特征,根据海拔高度主要可划分为3段：1）海拔2 600 m以下的河谷地貌呈V形峡谷,河谷比降大,阶地沉积年龄均在9.0～2.0 kaBP间,沉积属性以河流相和坡积相为主,表明是全新世以来气候变暖条件下形成的;2）海拔2 600～3 300 m的中游段河谷呈冰蚀围谷盆地、U形槽谷等,河谷比降小,河岸谷坡坡度小,主谷两岸冰碛垄发育,存留了古冰缘地貌遗迹,阶地沉积属性以古湖相、冰水相及河流相为主,测年结果在29.8～10.9 kaBP和50.9～39.8 kaBP间,显示其曾经为末次冰期和冰消期冰缘湖泊体系,后被现今的帕隆藏布所贯通;3）海拔3 300 m以上河流地貌为典型的冰川U形槽谷,谷底平坦,发育现代冰湖,仅发育Ⅰ级阶地并上面覆有冰碛物堆积体,有末次冰期的冰缘地貌遗迹,但主要受周围海洋性冰川作用,呈现现代冰缘地貌特征。整体上看,帕隆藏布的现今河流地貌上、下游两端年轻,主要形成于全新世期间;中游的河流地貌出现较早,残留了末次冰期和冰消期的冰缘地貌特征,并保留了广泛的古冰湖相沉积物。因此,帕隆藏布现今的河流形态主要出现在末次冰期以来。 相似文献
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神农架是中国第四纪地质环境演变的热点地区之一。本文通过对第四纪冰川地貌、冰碛残迹及二者关系研究,提供了本区第四纪古冰川发育的多方面证据。神农架地区在第四纪时期曾发生三期冰期和两期冰缘期,即松柏冰期、木鱼坪冰期、龙潭冰期、松香坪冰缘期、神农架冰缘期。本文首次系统地建立了本区第四纪气候地层系列. 相似文献
4.
冰缘地貌与沉积是冰冻圈环境变化的载体,对其开展深入研究对了解青藏高原地表过程与过去气候变化,具有重要意义。基于青藏高原（格尔木-亚东）冰缘地貌和沉积野外记录和实验分析,获得以下认识：格尔木在LGM时多年冻土至少下限到达海拔2 900 m,年均气温降至< -4 ℃,比现在至少低9 ℃,气候寒冷干燥;冰消期和全新世存在极端干冷的气候事件,可能存在地面温度< -10 ℃的冬季迅速降温气候期。楚玛尔、那曲谷露和纳木错的冰楔假型分别记录了末次冰期冷期多年冻土扩张,亚东古砂楔记录了早全新世冷事件。西藏羊八井泥炭沉积剖面孢粉和测年揭示,该区自新仙女木事件以来经历了严寒（12.8~9.8 ka）、暖湿（9.8~5.0 ka）、干冷（5.0 ka至今）的气候阶段。青藏高原（格尔木-亚东）广泛发育的冻融褶皱、成层坡积、风沙沉积等,是古环境重建的重要佐证,具有刻画冷暖-干湿的意义。 相似文献
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冰缘风沙地貌与沉积研究进展 总被引：1，自引：0，他引：1
冰缘风沙地貌与沉积是在冰缘寒冷干旱气候环境中,伴有冰川或冻融作用影响,主要由风沙作用形成的荒漠地貌.现代冰缘荒漠主要分布于南、北半球的高纬度地区及中低纬度的高海拔地区,部分温带沙漠也有古冰缘荒漠沉积分布.冰缘沙丘的规模一般较小,沙丘沉积富含腐殖质及冰粒,并兼具冻融和积雪层理构造等,砂的化学及物理成熟度较低.冰缘风沙沉积往往与邻近的其它沉积相伴生,如黄土、冰川、湖泊、海洋甚至火山碎屑,因而可参与区域气候、环境,尤其是古环流的恢复与重建,也可为研究温带荒漠在冰期时的演化提供参考.目前在冰缘沙漠研究中已经取得了一些可喜的成绩,但在确定冰缘荒漠的原因过程方面还没有形成系统的理论,更多工作有待进行.青藏高原腹地的普若岗日冰缘沙丘与戈壁,是我国典型的冰缘荒漠地貌与沉积,研究其地貌与环境过程,对丰富我国沙漠学研究内容和了解晚第四纪高原腹地气候、环境变化具有重要意义. 相似文献
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贺兰山西侧紫泥湖地区晚更新世以来冰缘地貌过程与环境变化 总被引：3，自引：0，他引：3
紫泥湖地区座落在贺兰山西边４５ｋｍ处，海拔高度约１２００ｍ，区域地形呈现向北“Ｖ”字形开口的箕状洼地，其上生长旱生植被群落，沿自南而北流的沟谷阶地下发育了冻融 褶皱、冰楔和砂楔等冰缘地貌类型和过程，研究结果表明区域年平均气温末次冰期早期（５５－３５ｋｂＢＰ）较氏１０．５－１２．５℃，末次冰期盛期（２０－１５ｋｂＢＰ）今低１２．５－１３．７ 相似文献
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内蒙古额济纳旗地貌特征及其构造、气候事件 总被引：3，自引：0，他引：3
根据遥感卫星影像解译及野外地质实地调查,将内蒙古额济纳旗地区的地貌单元划分为中低山区、冲—洪积平原、湖积盆地及风成地貌。根据不同地貌单元组成的沉积物年龄测定和分析,初步认为上新世—早更新世的构造抬升形成苏泊淖尔级湖积阶地;早更新世末(750±60kaBP),发生一次明显的构造抬升活动,形成东、西居延海间的台地;另一次明显的构造抬升记录发生在中更世末—晚更新世初,即149±60kaBP之后,形成黑城冲湖积台地;苏泊淖尔级阶地形成于全新世早、中期,属气候干旱湖泊萎缩形成的气候阶地,阶地沉积物中保存的古风成砂丘,表明晚更新世末—全新世早期气候一度恶化。天鹅湖湖积阶地的形成表明5000a之后一段时间,气候相对适宜;全新世中后期,气候波动强烈,1200aBP出现一次丰水期。 相似文献
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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
9.
内蒙古伊盟盐海子Ya02孔氧碳同位素记录的第四纪末次冰期及全新世气候特征 总被引：2，自引：0，他引：2
从内蒙古伊盟盐海子Ya02孔氧碳同位素资料中可以看到,东亚季风气候在22000aBP时由第四纪末次冰期气候开始转入末次间冰期气候,东亚季风带第四纪末次冰期时的气候环境是湿冷的淡化期,而末次冰期的气候环境是热干的成盐期.其次,末次冰期以来,气候由湿冷变为热干,5400aBP时气候达到热干的大暖期的最热点,之后又逐级降至现代暖趋冷的气候特征,东亚季风气候带的末次间冰期开始界线在22000aBP左右,δ^18O资料告诉我们内蒙古高原第四纪末次冰期曾有过冰川或冰盖地貌景观,在22000aBP以后才消融进入第四纪末次间冰期. 相似文献
10.
内蒙古伊盟盐海子YaO2孔氧碳同位素记录的第四纪末次冰期及全新世气候特征 总被引：2，自引：0，他引：2
从内蒙古伊盟盐海YaO2孔氧碳同位素资料中可以看到:东亚季风气候在22 000aBP时由第四纪末次冰期气候开始转入末次间冰期气候。东亚季风带第四纪末次冰期时的气候环境是湿冷的淡化期。而末次间冰期的气候环境是热干的成盐期。其次,末次冰期以来,气候由湿冷转变为热干,5400aBP时气候达到热干的大暖期的最热点。之后又逐级降至现代暖趋冷的气候特征。东亚季风气候带的末次间冰期开始界线在22 000aBP左右。δ18O资料告诉我们内蒙古高原第四纪末次冰期曾有过冰川或冰盖地貌景现,在22000aBP以后才消融进入第四纪末次间冰期。 相似文献
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Impressive flood deposits are described resulting from a catastrophic lake outburst in the Upper Chandra valley in the Lahul Himalaya, northern India. Reconstructions of the former glacial lake, Glacial Lake Batal, and the discharges were undertaken using landforms and sediment data. The glacial dam burst released 1.496 km3 of water in 0.72 days, with peak discharges of between 21000 and 27000 m3 s−1 at Batal. Dating by OSL suggests the flood occurred ca. 36.9 ± 8.4 to 43.4 ± 10.3 ka ago. This cataclysmic flood was responsible for major resedimentation and landscape modification within the Chandra valley. 相似文献
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Markus Wagner 《GeoJournal》2005,62(3-4):91-113
In semi-arid orographic left tributaries of the Kali Gandaki at the northern and western flank of the Nilgiri Himal, glacio-geomorphological
and pedological investigations were carried out on prehistoric moraines. Geomorphological relief analysis was derived from
other literature and the own fieldwork of the author. The resulting glacial chronology was used as benchmark to explore the
limits of different pedological dating methods regarding the degree of soil development. These methods are based on iron fractionation,
total element contents and particle size distribution. In general the different glacial stages are mirrored correctly in the
relative graduation of soil development. The ratio of well crystallised pedogenic iron-oxides to the total iron content and
the ratio fine clay to total clay are most suitable, because they are almost independent from existing changes in the lithological
composition. The total element based weathering indices are less suitable, because they react highly sensitive to the geology
dependent shift to higher carbonate contents. Most of the grain size based weathering indices are inapplicable because of
the typically high textural variability within till deposits. 相似文献
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Iain M. Brown 《第四纪科学杂志》1993,8(3):235-250
The mode of deglaciation of the last Scottish ice sheet is assessed from evidence provided by geomorphological mapping and sedimentology. Ice-marginal deposits in the Dee valley have a distinctive morphological expression and a characteristically varied sedimentology that strongly resembles those from subpolar glaciers. The deposits tend to occur in certain topographic situations which can be accounted for by compression of ice near the margin and formation of an ice-cored supraglacial land system. A series of recessional stages of the ice-front can be mapped demonstrating that active retreat occurred. However, additional evidence shows there was probably a thin marginal zone of stagnant ice. Recessional stages are inferred to be stillstands that are considered to be topographically controlled rather than related to climate. Development of the supraglacial land system during deglaciation suggests that the ice sheet had a polythermal basal regime with a cold-based margin. This implies that deglaciation took place in northeast Scotland while the climate remained cold, probably due to a precipitation deficit, which agrees well with chronostratigraphic data. 相似文献
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Lasafam Iturrizaga 《GeoJournal》1999,47(1-2):277-339
An abridged version of a geomorphological inventory and typology of Postglacial debris accumulations in High Asia is presented,
with selected examples from the Hindu Kush, the Karakoram and the Himalayas. The debris accumulations were surveyed in the
course of four research expeditions lasting a total of ten months in selected valley systems of High Asia (the eastern Hindu
Kush, the northwestern Karakoram, the Nanga Parbat massif (Pakistan), the Ladakh and Zanskar ranges, the Nun Kun massif, the
Kumaon and Garhwal Himalayas with the Kamet, Trisul and Nanda Devi massifs (India) and in the central Himalayas with the Kanjiroba,
Annapurna, Manaslu and Makalu massifs (Nepal)). The study areas being widely scattered, a supraregional comparison of the
debris accumulations proved possible. The debris accumulations are considered in centre-to-periphery sequences from the mountain
interior to the mountain fringes, and in vertical sequences, i.e. altitudinal zones, taking into account their topographical
relationship to adjoining elements of the landscape. Supraregional and climate-specific types of debris accumulation are distinguished
and it is recognized that the debris accumulations of the Karakoram and the Himalayas resemble each other more closely with
increasing elevation.
The core of the study is the dominant role played by past glaciation in the formation of Postglacial debris accumulations
in the high mountains of Asia. This glacial-history-oriented concept of debris accumulation stands in sharp contrast to previous
opinions about the genesis of the debris accumulation landscape in the extreme high mountains of Asia. The study shows that
at many places morainic deposits mask extensive portions of the valley sides up to several hundred metres above the valley
floor. These moraines are the main debris sources and exert a strong influence on, or even suppress, the purely slope-related
formation of debris accumulations. Resedimentation of morainic material in combination with additional talus delivery leads
to numerous characteristic composite types of debris accumulations, which are here termed transitional glacial debris accumulations.
Various stages in the transition from moraine to slope-related debris accumulations were observed, making it necessary to
consider the evolutional element in the development of debris accumulations by taking into account both genetic series of
debris accumulations and formations of debris accumulations. A significant proportion of debris accumulations are also due
to collapse processes which result from pressure release at the valley sides after deglaciation and occur in the course of
glacial trough valleys being transformed into more stable fluvial V-shaped valleys.
The residual morainic landscape has left debris accumulations that are basically similar in study areas of different climate
– i.e. in the Hindu Kush and the Karakoram on the one hand, and the Himalayas on the other. The age classification of the
debris accumulations was based on the location of the slope-derived debris accumulations in relation to the corresponding
stages of glaciation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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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
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The glacial geomorphology of the Waterville Plateau (ca. 55 km2) provides information on the dynamics of the Okanogan Lobe, southern sector of the Cordilleran Ice Sheet in north‐central Washington. The Okanogan Lobe had a profound influence on the landscape. It diverted meltwater and floodwater along the ice front contributing to the Channeled Scabland features during the late Wisconsin (Fraser Glaciation). The glacial imprint may record surge behaviour of the former Okanogan Lobe based on a comparison with other glacial landsystems. Conditions that may have promoted instability include regional topographic constraints, ice marginal lakes and dynamics of the subglacial hydrological system, which probably included a subglacial reservoir. The ice‐surface morphology and estimated driving stresses (17–26 kPa) implied from ice thickness and surface slope reconstructed in the terminal area also suggest fast basal flow characteristics. This work identifies the location of a fast flowing ice corridor and this probably affected the stability and mass balance of the south‐central portion of the Cordilleran Ice Sheet. Evidence for fast ice flow is lacking in the main Okanogan River Valley, probably because it was destroyed during deglaciation by various glacial and fluvial processes. The only signature of fast ice flow left is the imprint on the Waterville Plateau. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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This paper systematically reviews the glacial geomorphological evidence of the Loch Lomond Stadial (LLS; Younger Dryas) glaciation in Britain (12.9–11.7 ka). The geomorphology of sub‐regions within Scotland, England and Wales is assessed, providing the most comprehensive synthesis of this evidence to date. The contrasting nature of the evidence at the local scale is reviewed and conceptual themes common to multiple sub‐regions are examined. Advancements in glaciological theory, mapping technologies, numerical modelling and dating have been applied unevenly to localities across Britain, inhibiting a holistic understanding of the extent and dynamics of the LLS glaciation at a regional scale. The quantity and quality of evidence is highly uneven, leading to uncertainties regarding the extent of glaciation and inhibiting detailed analysis of ice dynamics and chronology. Robust dates are relatively scarce, making it difficult to confidently identify the limits of LLS glaciers and assess their synchroneity. Numerical models have allowed the glacier–climate relationships of the LLS to be assessed but have, thus far, been unable to incorporate local conditions which influenced glaciation. Recommendations for future research are made that will allow refined reconstructions of the LLS in Britain and contribute to a more comprehensive understanding of glacier–climate interactions during the Younger Dryas. 相似文献
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中国东部（105o E以东）第四纪冰川及其演化可为中国东部乃至东亚地区古气候环境重建提供基础信息及关键证据,正确认知冰川发育条件及正确运用冰川遗迹判别标准又是重建中国东部第四纪冰川及其演化的关键。中国东部中低山地第四纪期间冰川发育与否,即泛冰川论与有限冰川论的争议由来已久。近年来,山东与周边地区中低山及沿海丘陵带的“第四纪冰川”研究波澜再起。在系统地回顾中国东部第四纪冰川研究历史及新近出现争议的基础上,结合冰川发育条件、山地冰川地貌组合、判别原则与识别依据、中国东部数座中高山地存在无争议且形态清晰的冰川地形及其测年资料以及东亚古气候环境演化记录等得出：中国东部仅有台湾山地、长白山、贺兰山与太白山等数座主峰海拔超过2 500 m的中高山地保存有晚更新世以来的冰川作用地形。其余山地及海拔更低的丘陵带在第四纪期间任何一次冰川作用中均未达到与当时冰期气候相耦合的高度,不存在泛冰川作用。已报道的“冰川遗迹”皆为各种形似地质地貌现象的系统误判,其确切成因及环境意义有待深入探讨。 相似文献