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1.
Holocene climate variations from Zhuyeze terminal lake records in East Asian monsoon margin in arid northern China 总被引：4，自引：0，他引：4
Zhuyeze palaeolake is a terminal lake situated in the arid northern China in the East Asian monsoon margin. In order to examine the Holocene palaeoclimatic change in the East Asian monsoon margin, Qingtu Lake section (QTL) from Zhuyeze palaeolake is sampled in high resolution. Palaeoclimatic proxies such as grain size, carbonate, TOC, C/N and δ13C of organic matter, were analyzed; eleven 14C samples and six optically stimulated luminescence (OSL) samples were dated to provide chronological control. We also investigated the geomorphic features of lake shorelines in this area. The results show that the climate was warm and dry in early-Holocene (9.5-7.0 cal ka BP), cool and humid in mid-Holocene (7.0-4.8 cal ka BP), and increasingly drier in late-Holocene (since 4.8 cal ka BP). Comparisons of our records with other records in adjacent areas, as well as with the records in the Asian monsoon areas, suggested that changes in effective moisture was synchronous in East Asian monsoon marginal zone (i.e. the pattern of dry early-Holocene, humid mid-Holocene, and aridity-increasing late-Holocene), and that the moisture optimum during the Holocene was out-of-phase between Asian monsoon margin and Asian monsoonal dominated region, possibly due to the high temperature at that time. 相似文献
2.
Basin-wide Holocene environmental changes in the marginal area of the Asian monsoon,northwest China 总被引：1，自引：0，他引：1
In arid regions, because of spatial variability, using single climate records is difficult to reconstruct the past climate
change for the drainage basins. Holocene environmental records were collected from the upper, middle and lower regions of
the Shiyang River drainage basin in the marginal area of the Asian monsoon (northwest China). The main objective of this paper
was to compare the records from the terminal lake and the middle and upper reaches of the basin to study the basin-wide environmental
changes. During the early Holocene the vegetation was sparse, and the effective moisture was relatively low in the basin.
The Holocene Climatic Optimum started between 7.0 and 8.0 cal ka BP, during which the lake level reached the highest level
in the terminal lake; the vegetation density and the effective moisture reached the highest level during the Holocene in the
drainage basin. From 4.7 cal ka BP the terminal lake began to shrink, while the vegetation density decreased dramatically.
In the middle and upper regions of the drainage, the effective moisture began to decrease since 3.5 cal ka BP, and the arid
tendency was earlier in the terminal lake than it was in the middle and upper regions of the drainage basin. During the early
Holocene the relatively arid environment was affected by the gradually intensifying East Asian monsoon and the dry westerly
winds. The mid-Holocene Optimum benefited from the intensive East Asian monsoon and the humid westerly winds. Then, the East
Asian monsoon retreated since the late-Holocene. In the basin the arid tendency may be related to the retracting of the East
Asian monsoon. However, the intensifying acidification after 1.5 cal ka BP may be correlated to the increasing dryness of
the westerly winds. 相似文献
3.
通过对花海古湖泊沉积剖面8.42~0.405 m沉积物样品的矿物和化学元素测定,分析了沉积物中盐类矿物含量及化学元素K/Na比值的变化情况,结合已有的年代地层结果,重建了花海古湖泊10.47~5.5 cal ka BP湖水盐度变化. 结果表明：花海湖泊全新世湖相沉积阶段中,除个别层位以硫酸盐类矿物沉积为主外,早全新世(10.47~8.87 cal ka BP)和中全新世(8.87~5.5 cal ka BP)均以碳酸盐盐类矿物沉积为主,并且早全新世时期K/Na高于中全新世时期,揭示了早全新世时期湖水盐度高于中全新世时期. 这一结果与该湖泊沉积过程所揭示的湖泊水位变化、粒度等揭示的有效湿度变化具有一致性,表明花海湖泊早、中全新世湖水盐度的高低可以指示其湖泊水位的变化,并间接反映了有效湿度的变化. 结合花海湖泊晚全新世湖泊萎缩、气候干旱的特点,该区域早、中、晚全新世气候干湿变化变化模式可以概况为早全新世降水增强、气候呈现由干向湿的转变,中全新世有效湿度最大,晚全新世气候干旱. 这种全新世气候干湿变化模式有别于西风区,亦与季风区不完全相同,呈现出了一种季风-西风过渡带全新世气候干湿变化的模式. 相似文献
4.
5.
《Quaternary Research》2014,81(3):500-507
We analyzed climate proxies from loessic-soil sections of the southern Chinese Loess Plateau. The early Holocene paleosol, S0, is 3.2 m thick and contains six sub-soil units. Co-eval soils from the central Loess Plateau are thinner (~ 1 m). Consequently higher-resolution stratigraphic analyses can be made on our new sections and provide more insight into Holocene temporal variation of the East Asian monsoon. Both summer and winter monsoon evolution signals are recorded in the same sections, enabling the study of phase relationships between the signals. Our analyses consist of (i) measurements of magnetic properties sensitive to the production of fine-grained magnetic minerals which reflect precipitation intensity and summer monsoon strength; and (ii) grain-size analyses which reflect winter monsoon strength. Our results indicate that the Holocene precipitation maximum occurred in the mid-Holocene, ~ 7.8–3.5 cal ka BP, with an arid interval at 6.3–5.3 cal ka BP. The winter monsoon intensity declined to a minimum during 5.0–3.4 cal ka BP. These results suggest that the East Asian summer and winter monsoons were out of phase during the Holocene, possibly due to their different sensitivities to ice and snow coverage at high latitudes and to sea-surface temperature at low latitudes. 相似文献
6.
我国西北夏季风边界千年尺度变化的证据--来自盐池和猪野泽盐类矿物分析结果 总被引：1，自引：0，他引：1
我国夏季风西北缘是响应长尺度气候变化最为敏感的区域之一, 但夏季风边界变化与千年尺度气候变化之间的关系尚不明确, 相关研究仍缺乏足够证据。夏季风西北缘湖泊沉积物中盐类矿物种类与含量的时空变化, 有助于推测气候变化特征。盐池和猪野泽分别位于祁连山北麓的河西走廊中段和东段, 是研究长时间尺度亚洲夏季风影响区西北边界变化的关键区域。研究全新世千年尺度下, 夏季风西北边界的变化对夏季风西北缘气候变化过程的影响, 对明确季风边缘区千年尺度季风变化机制, 预测未来长尺度气候变化有重要意义。因此, 本文选择盐池古湖泊盐池剖面(YC), 猪野泽青土湖01、02剖面(QTH01、QTH02)等三个剖面, 开展全新世千年尺度下, 亚洲季风西北边界地区湖泊沉积物盐类矿物时空变化对比研究。结果显示:QTH01、QTH02剖面盐类矿物以碳酸盐为主, 硫酸盐类矿物仅零星出现, 而YC剖面硫酸盐类矿物含量相对较高, 同时出现了氯化物型矿物, 全新世气候特征整体较猪野泽更为干旱。末次冰期和早全新世, 三个剖面受季风输送水汽影响明显, 碳酸盐类矿物能较好沉积, 季风边界在这一时期向北扩张, 推进到祁连山中段地区;中全新世QTH01、QTH02剖面受夏季风影响减弱, 湖泊退缩, 碳酸盐类矿物含量达到峰值, YC剖面则表现出极端干旱的气候特征, 硫酸盐类矿物因“盐效应”含量下降, 此时夏季风西北部水汽输送边界位于石羊河流域和盐池流域之间;晚全新世盐池和猪野泽均以风成沉积为主, 气候干旱, 碳酸盐类矿物难以保存, 硫酸盐和氯化物矿物含量出现高值, 说明夏季风西北边界进一步向南迁移。综上所述, 盐类矿物含量变化能良好反应夏季风西北缘全新世气候变化特征, 同时证明, 在全新世千年尺度上, 夏季风西北边界在盐池流域和石羊河流域之间存在变化。 相似文献
7.
头社盆地位于中国台湾省中部,东亚季风区的最前沿,对东亚季风的响应十分敏感,研究其中晚全新世以来古植被、重建古气候序列,探讨其气候与东亚夏季风的关系具有重要的科学意义。文章对头社盆地泥炭—湖泊沉积的AMS14C测年、体积磁化率测试的基础上,基于孢粉记录,重建晚全新世来植被变化,恢复古气候。结果表明全新世中晚期以来分六个阶段：6.2~6.0 cal ka BP,气候凉干,植被类型是亚热带常绿阔叶林;6.0~4.0 cal ka BP,气候转暖湿,植被类型为含较多热带成分的亚热带常绿阔叶林;4.0~2.2 cal ka BP,气候相对凉干,植被类型转为亚热带常绿阔叶林;2.2~1.9 cal ka BP,气候又变暖湿;1.9~1.7 cal ka BP,气候快速冷干事件,森林退化;1.7~1.3 cal ka BP,气候重转温暖湿润,植被类型为接近现代的沼泽草原。整体上6.2~2.2 cal ka BP的气候变化是由温暖湿润向温凉干燥转变的趋势,这是全新世中晚期以来的太阳辐射量减少所导致的,太阳辐射量的减少导致热带辐合南移,进而导致东亚夏季风减弱,而2.2 cal ka BP之后气候波动较大,可能是在东亚夏季风减弱的背景下,ENSO活动加强与人类活动的干扰下耦合的结果。 相似文献
8.
Environmental processes derived from peatland geochemistry since the last deglaciation in Dajiuhu,Shennongjia, central China 
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下载免费PDF全文 Yuanping Li Chunmei Ma Bin Zhou Anning Cui Cheng Zhu Run Huang Chaogui Zheng 《Boreas: An International Journal of Quaternary Research》2016,45(3):423-438
The Dajiuhu mire deposit is a sensitive archive of palaeoenvironmental evolution in the East Asian monsoon region. The aim of this study of the elemental geochemistry of a sediment core from Dajiuhu was to improve our understanding of the geochemical behaviour of elements in peat deposits, as well as the environmental and climatic history of the East Asian monsoon region since the Late Pleistocene. We conducted a principal components analysis (PCA) on inorganic geochemical data obtained by ICP‐MS and XRFS from a sediment core spanning the last 16 ka. In addition, spectral analysis was applied to the PC1 score profile to test periodicities. The PCA results suggest that variations in elemental concentrations in the Dajiuhu core are controlled by three main factors: input of inorganic mineral matter, effect of biological processes and a combination of changes in redox conditions and biological processes. Interpretation of the data suggests that monsoon precipitation increased, albeit with significant volatility, during the last deglaciation (16.0–11.3 cal. ka BP). The early Holocene (11.3–9.4 cal. ka BP) was a humid period, and was followed by monsoon deterioration in the early stages of the middle Holocene. A warm and wet climate dominated between 7.0 and 4.2 cal. ka BP, correlating with the Holocene Climatic Optimum. After a two‐step decrease in monsoon precipitation, beginning at 4.2 cal. ka BP, the climate became more arid until 0.9 cal. ka BP, after which humidity once again increased. The spectral analysis revealed statistically significant periodicities of approximately 1480, 360, 316, 204 and 188 years, indicating solar forcing for the East Asian monsoon evolution over millennial to centennial time scales and a link between the East Asian monsoon and North Atlantic climate. 相似文献
9.
RUILIN WEN JULE XIAO ZHIGANG CHANG DAYOU ZHAI QINGHAI XU YUECONG LI SHIGERU ITOH 《Boreas: An International Journal of Quaternary Research》2010,39(2):262-272
Wen, R. L., Xiao, J. L., Chang, Z. G., Zhai, D. Y., Xu, Q. H., Li, Y. C. & Itoh, S. 2009: Holocene precipitation and temperature variations in the East Asian monsoonal margin from pollen data from Hulun Lake in northeastern Inner Mongolia, China. Boreas, 10.1111/j.1502‐3885.2009.00125.x. ISSN 0300‐9483. Quantitative palaeoclimatic reconstruction with the weighted averaging partial least squares method was applied to the pollen profile from Hulun Lake in northeastern Inner Mongolia. The data provide a detailed history of variations in precipitation and temperature over the northeastern margin of the East Asian summer monsoon during the Holocene. A warm and dry climate prevailed over the lake region until c. 8000 cal. BP. During the period c. 8000–4400 cal. BP, precipitation increased markedly and temperature gradually declined. The interval between c. 4400 and 3350 cal. BP was marked by extremely dry and relatively cold conditions. Precipitation recovered from c. 3350 to 1000 cal. BP, with temperatures rising c. 3350–2050 cal. BP and dropping c. 2050–1000 cal. BP. During the last 500 years, the climate of the lake region displayed a general trend of warming and wetting. While Holocene temperature variations in the mid‐high latitude monsoonal margin were controlled by changes in summer solar radiation in the Northern Hemisphere, they could also be related to the strength of the East Asian summer monsoon. The lack of precipitation during the early Holocene could be attributed to the weakened summer monsoon resulting from the existence of remnant ice sheets in the Northern Hemisphere. Changes in the monsoonal precipitation during the middle to late Holocene would have been associated with the ocean–atmosphere interacting processes occurring in the western tropical Pacific. 相似文献
10.
河北坝上地区位于东亚季风边缘区和农牧交错带,季风强弱的变化深刻影响着该地区人类文明的发展.为了重建河北坝上地区中-晚全新世以来的气候演化过程,剖析气候变化与人类文明发展的关系,以坝上地区安固里淖湖为研究对象,通过对该湖沉积剖面植硅体的分析,并结合孢粉组合特征,恢复了安固里淖地区5 000 cal.a BP以来的气候演变历史.结果显示,在千年尺度上该区域气候总体呈冷干趋势,但在5 030~3 070 cal.a BP时期气候相对湿润,千年尺度上气候的变化主要受控于北半球太阳辐射量的变化.在百年尺度上安固里淖地区经历了7次冷干事件,分别发生于4 500 cal.a BP、4 100~3 800 cal.a BP、3 500 cal.a BP、3 000 cal.a BP、2 100 cal.a BP、1 100 cal.a BP和800~270 cal.a BP左右,这7次冷干事件对应于东亚季风减弱阶段,主要受到了北半球高纬气候和太阳活动的共同影响.该区人类文明的演化敏感响应于气候变化,气候温湿期以农业文明为主,气候冷干期以草原文明为主. 相似文献
11.
猪野泽记录的季风边缘区全新世中期 气候环境演化历史* 总被引：4，自引：16，他引：4
通过季风边缘区石羊河古终端湖猪野泽QTL剖面年代学及沉积物粒度、碳酸盐、有机碳、碳氮比和有机质稳定同位素等多项气候代用指标的综合分析,建立了季风边缘区9~3cal.kaB.P. 的古气候演化序列。结果表明,9cal.kaB.P. 到7.8cal.kaB.P. 期间,流域的水分条件和温度逐渐上升,植被状况好转,此时气候逐渐转暖湿;而在7.8~7.5cal.kaB.P. 出现了显著的百年尺度的干旱事件,沉积物主要以砂质沉积为主,此时湖泊生产力显著下降;全新世期间最为暖湿的气候适宜期出现在7.5~5.0cal.kaB.P.;约5.0cal.kaB.P. 以来,该区域出现了较为明显的干旱化趋势。另外,对猪野泽地区的白碱湖的湖泊地貌学和年代学研究表明该区域在7.5~5.0cal.kaB.P. 出现了3次高湖面,并且湖岸堤时序变化指示了全新世后半期湖泊逐渐退缩的过程进而指示该区域出现了显著的干旱化趋势。 相似文献
12.
A 4.96-m-long sediment core from the Hanon paleo-maar in Jeju Island, Korea was studied to investigate the paleoclimatic change and East Asian monsoon variations during the latest Pleistocene to early Holocene (23,000-9000 cal yr BP). High-resolution TOC content, magnetic susceptibility, and major element composition data indicate that Jeju Island experienced the coldest climate around 18,000 cal yr BP, which corresponds to the last glacial maximum (LGM). Further, these multi-proxy data show an abrupt shift in climatic regime from cold and arid to warm and humid conditions at around 14,000 cal yr BP, which represents the commencement of the last major deglaciation. After the last major deglaciation, the TOC content decreased from 13,300 to 12,000 cal yr BP and from 11,500 to 9800 cal yr BP, thereby reflecting the weakening of the summer monsoon. The LGM in Jeju Island occurred later in comparison with the Chinese Loess Plateau. Such a disparity in climatic change events between central China and Jeju Island appears to be caused by the asynchrony between the coldest temperature event and the minimum precipitation event in central China and by the buffering effect of the Pacific Ocean. 相似文献
13.
Holocene climate changes in the mid-high-latitude-monsoon margin reflected by the pollen record from Hulun Lake, northeastern Inner Mongolia 总被引：6，自引：0，他引：6
Pollen-assemblage data from a sediment core from Hulun Lake in northeastern Inner Mongolia describe the changes in the vegetation and climate of the East Asian monsoon margin during the Holocene. Dry steppe dominated the lake basin from ca. 11,000 to 8000 cal yr BP, suggesting a warm and dry climate. Grasses and birch forests expanded 8000 to 6400 cal yr BP, implying a remarkable increase in the monsoon precipitation. From 6400 to 4400 cal yr BP, the climate became cooler and drier. Chenopodiaceae dominated the interval from 4400 to 3350 cal yr BP, marking extremely dry condition. Artemisia recovered 3350-2050 cal yr BP, denoting an amelioration of climatic conditions. Both temperature and precipitation decreased 2050 to 1000 cal yr BP as indicated by decreased Artemisia and the development of pine forests. During the last 1000 yr, human activities might have had a significant influence on the environment of the lake region. We suggest that the East Asian summer monsoon did not become intensified until 8000 cal yr BP due to the existence of remnant ice sheets in the Northern Hemisphere. Changes in the monsoon precipitation on millennial to centennial scales would be related to ocean-atmosphere interactions in the tropical Pacific. 相似文献
14.
Yanbin Lu ChengBang An Zongli Wang Jiaju Zhao Haitao Wei Shichen Tao Wei Huang Minmin Ma 《Environmental Earth Sciences》2013,68(8):2163-2169
A sediment core from Lake Barkol located in the eastern Xinjiang autonomous region, northwest China, provided a high-resolution record of environmental change covering the last ~8.6 cal ka BP. Three major climate stages, 8.6–7.1, 7.1–2.0 and from 2.0 cal ka BP to the present, were divided by grain size and the authigenic carbonate stable isotope of the lake sediment. Climatic drought during the period 7.1–4.5 cal ka BP, deduced from Lake Barkol, prevailed in the mid-Holocene climate in northern Xinjiang and northwest Mongolia. In contrast, it was wet in central Xinjiang, northwest India and the Middle East during the same period. The climatic difference between northern and southern arid central Asia demonstrates the southward shifting of the Westerlies, which indicates the potential contribution of the Siberian high in the mid-Holocene. 相似文献
15.
来自东亚夏季风北界内蒙古一个盐湖的岩心沉积物内发现粗粒沉积物 ,既可沉积在湖泊收缩期 ,也可以沉积在沙丘再次活动时期。这些沉积物有机磷含量低而碎屑组分高 ,说明它沉积在一种干旱的环境中 ;反之 ,有机质含量高而碎屑组分低的细粒沉积物则最终沉积在高湖面期 ,这是因为砂坪呈围迁状态及风成尘埃较好地保存于水体中。所揭示的三个湿期分别是 13.4～ 8kaBP、6 .4～ 5 .8kaBP和4.2～ 3.1kaBP ,第一期最湿 ,其次是第三期、第二期。上述干和湿期自始至终和早先发现的同一个干旱和半干旱转换带一致 ,但是 ,这和中国大陆东部、台湾岛、冲绳海槽和中国南海所揭示的湿润的全新世大暖期不一样 ,而且 ,全新世最冷期 (4～ 2kaBP)则对应内蒙古的一个湿期 (即 4.2～ 3.1kaBP) ,这些差别可能是由于高蒸发量远远地超过了较高的季风降水量 ,这是确定夏季风北界在该地区有效湿度的一个关键标志。 相似文献
16.
研究全新世典型气候突变事件的内部结构及区域特征,有助于明晰季风气候突变事件的成因机制。通过对贵州七星洞石笋14个高精度230Th定年和779个氧同位素数据的分析,重建了过去6 380～2 700 yr B.P.时段平均分辨率达4.7年的东亚夏季风演化序列。该石笋δ18O值整体上呈逐渐偏正的特征,指示中晚全新世以来东亚夏季风持续变弱的趋势。叠加在此长期季风减弱变化趋势上,最为显著的百年尺度振荡主要发生在4 548～3 715 yr B.P.时段,对应于4.2 kyr B.P.事件。该记录与同区域董哥洞石笋δ18O记录一致,均显示在此事件内部并非持续干旱,而是具有两次显著的季风强降雨期。相似的季风强降雨期在我国北方气候记录中也有体现。在更大的空间尺度上,这种4.2 kyr B.P.事件的内部结构特征与澳洲—印度尼西亚(澳—印)季风区的石笋记录结构相对应,但呈显著的反相位耦合关系,证实了亚洲与澳—印季风间的动力学联系。此外,该事件结构与ENSO记录的耦合暗示了4.2 kyr B.P.事件的发生可能与热带太平洋密切相关。 相似文献
17.
中纬度亚洲地区存在主要受季风环流影响的东南部湿润地区(简称季风区)和主要受西风环流控制的内陆干旱区(包括青藏高原北部高寒干旱区,简称西风区)。根据对近年来新发表的气候变化记录证据梳理总结,发现西风区在中—晚全新世气候湿润,与亚洲季风在早—中全新世强盛的格局显著不同。过去千年的西风区中世纪暖期干旱,而小冰期相对湿润,与此相对,万象洞石笋氧同位素记录则显示季风降水在中世纪暖期时整体处于高值,在小冰期处于低值段。在近百年,尤其是近50a,西北干旱区湿度增加,而季风影响范围内的西北东部和华北等地变得更干。不仅如此,在分属西风和季风影响区的青藏高原北部和南部,年代际—百年尺度上降水变化也表现出反相位关系。据此我们提出,亚洲中部西风带控制区在现代间冰期从数千年到年代际的各个时间尺度上均存在不同于季风区的湿度(降水)变化模式,称之为现代间冰期气候变化的西风模式。 相似文献
18.
TIAN Fei WANG Yong ZHAO Zhili LI Yang DONG Jin LIU Jin LING Yuan YUAN Lupeng YE Mengni 《《地质学报》英文版》2020,94(4):1178-1186
A consensus on Holocene climate variability at the modern northern fringe of the East Asian summer monsoon (EASM) region remains elusive. Here, we present a pollen-based reconstruction of vegetation history and associated climate variations of a sediment core from Huangqihai Lake, central Inner Mongolia. During 10.7 to 8.8 cal kaBP, typical steppe with small patches of forest dominated the lake area, suggesting a moderately wet climate, followed by ameliorating climatic conditions until 8.0 cal kaBP as deduced by the expansion of forest. Typical steppe recovered the lake area between 8.0 and 7.2 cal kaBP, reflecting a deterioration of climatic conditions; in combination with other proxy records in the study region, we noticed that severe aridity was prevailed in the lake area between 8.0 and 7.6 cal kaBP. During 7.2 to 3.2 cal kaBP, abundant tree pollen indicated dominance of forest-steppe around the lake, marking regionally wet conditions. A notable absence of broadleaved trees after 5.2 cal kaBP reveals a slight drying trend, and climate deterioration from 4.5 to 4.1 cal kaBP might be linked to the 4.2 ka event. After 3.2 cal kaBP, a transition to steppe was associated with dry conditions in the region. Based on our pollen record and prior paleoclimatic reconstructions in the Huangqihai Lake region, there was a generally-accepted, stepwise shift to a wet climate during the early Holocene, an overall humid climate from 7.2 to 3.2 cal kaBP, and then severe drought for the rest of the Holocene. Moreover, regional comparisons among pollen records derived from lakes situated in the temperate steppe region suggested a roughly synchronous pattern of vegetation and climate changes during the Holocene and demonstrated an intensified EASM during the middle Holocene. 相似文献
19.
阿拉善高原位于现代西风环流与东亚季风环流过渡带,该地区分布的湖泊对全球性气候变化响应极为敏感,阿拉善高原广泛分布的古湖岸堤为较准确地重建晚第四纪湖泊水位变化提供了良好载体.近年对黑河、石羊河尾闾湖泊以及吉兰泰盐池、雅布赖盆地等地的古湖岸堤的沉积地层以及石英和钾长石释光测年研究,重建了不同区域较高分辨率的末次间冰期以来湖泊时空演化过程.发现早在300 ka以前阿拉善高原就已经形成了高水位湖泊,黑河尾闾额济纳盆地在MIS11或更早、 MIS9、 MIS7、 MIS5和MIS 1形成了高湖面湖泊,高湖面湖泊形成存在100 ka的周期.阿拉善高原在末次间冰期及全新世形成了稳定高湖面湖泊,但间冰期内部湖面波动具有空间差异性,东部区域湖泊高湖面出现在MIS 5e^5c和中全新世,西部湖泊高湖面出现在MIS 5a^5c和晚全新世.湖面变化的空间差异性很可能与冰期-间冰期旋回尺度及间冰期内部东亚夏季风与西风气候系统在阿拉善高原的相互作用密切相关. 相似文献
20.
MARTIN KLUG STEFFI SCHMIDT OLE BENNIKE OLIVER HEIRI MARTIN MELLES BERND WAGNER 《Boreas: An International Journal of Quaternary Research》2009,38(1):59-71
A 2.9 m long sedimentary record was studied from a small lake, here referred to as Duck Lake, located at 76°25'N, 18°45'W on Store Koldewey, an elongated island off the coast of Northeast Greenland. The sediments were investigated for their geophysical and biogeochemical characteristics, and for their fossil chironomid assemblages. Organic matter began to accumulate in the lake at 9.1 cal. kyr BP, which provides a minimum age for the deglaciation of the basin. Although the early to mid-Holocene is known as a thermal maximum in East Greenland, organic matter accumulation in the lake remained low during the early Holocene, likely due to late plant immigration and lack of nutrient availability. Organic matter accumulation increased during the middle and late Holocene, when temperatures in East Greenland gradually decreased. Enhanced soil formation probably led to higher nutrient availability and increased production in the lake. Chironomids are abundant throughout the record after 9.1 cal. kyr BP and seem to react sensitively to changes in temperature and nutrient availability. It is concluded that relative temperature reconstructions based on biogeochemical data have to be regarded critically, particularly in the period shortly after deglaciation when nutrient availability was low. Chironomids may be a suitable tool for climatic reconstructions even in those high arctic environments. However, a better understanding of the ecology of chironomids under these extreme conditions is needed. 相似文献