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1.
吉兰泰盐湖沉积物孢粉记录的季风边缘区全新世气候演化 总被引：1，自引：1，他引：1
全新世气候具有不稳定性,且存在着区域差异,在季风边缘区尤为显著.因此,本研究选取季风边缘区吉兰泰盐湖沉积物的孢粉记录并结合AMS14C测年结果,对该地区全新世的古植被演化及古气候变化历史进行了重建.结果表明,在全新世阶段,该地区植被类型未发生变化,以干旱的荒漠植被为主.早全新世(10.5 8.5 cal ka BP),以蒿属孢粉为主,伴随出现少量藜科、禾本科及麻黄属孢粉,蒿藜比(A/C比值)相对稳定(4.11左右),指示全新世早期气候逐步转湿的过程,在8.5 cal ka BP,蒿属孢粉数量下降且被藜科孢粉取代,指示一次明显气候干旱事件;中全新世(8.5 3.5 cal ka BP),蒿属孢粉含量增加及藜科孢粉含量降低,A/C比值在7.1 cal ka BP左右达到峰值,指示该地区中全新世气候最为湿润;晚全新世(3.5 cal ka BP至今),藜科孢粉含量增加且超过早全新世,A/C比值低至3.66,区域呈现明显的干旱化趋势.此外,结合吉兰泰盐湖沉积物矿物组成结果,发现中全新世湖泊沉积物中,钙芒硝大量出现,一定程度上指示降水量增多所带来的淡水注入,与孢粉指标指示该阶段湿润的结果一致.通过区域对比,发现吉兰泰地区在全新世时期的气候演化模式与东亚季风区具有较好的一致性,表明该地区受到东亚夏季风的影响较大,尤其是在中全新世,东亚夏季风增强,带来较多的降水,气候湿润. 相似文献
2.
选择位于新疆东北部的封闭湖泊-巴里坤湖作为研究对象,采用常规14C测年建立了该湖一剖面约9400 cal a BP以来的时间序列,对该剖面沉积自生碳酸盐碳（δ13Ccar）、氧同位素（δ18Ocar）、有机碳（TOC）等多代用指标进行了连续小波变换、奇异谱分析.结果表明,全新世以来巴里坤湖地区的气候变化模式具有明显的阶段性变化：9400～8000 cal a BP期间气温偏低且较干旱;8000～6000 cal a BP期间气候环境温凉湿润;6000～2700 cal a BP期间,气候环境在总体上较为暖干,在向全新世晚期演变过程中呈现出降温、增湿的趋势;2700～800 cal a BP期间气温降低,湿润状况有所改善;800 cal a BP以来气候环境偏干.巴里坤湖全新世气候变化过程与周边区域古气候记录具有较好地一致性.研究发现,全新世以来研究区的气候环境不仅可能受到了北大西洋地区气候变化的影响,同样可能与来自热带低纬过程的海-气相互作用有关,特别是自全新世中期以来,逐渐增强的El Nio/La Nia-South Oscillation（ENSO）活动对研究区的气候环境变化可能具有一定的影响.研究还发现,在全新世期间,新疆东北部地区的气候演变可能并非简单地遵循某种单一的气候变化模式,不同气候系统（如西风、季风）在该地区的强弱对比状况可能对此地区气候环境变化模式有重要影响. 相似文献
3.
河西走廊花海古湖泊全新世白云石的发现及其环境意义 总被引：4，自引：3，他引：1
通过对河西走廊花海古湖泊沉积物的X衍射分析发现,全新世期间有明显的白云石沉积.岩性、沉积过程、石膏以及Fe3+含量的变化表明,花海湖全新世白云石沉积环境以还原环境为主,即还原环境利于白云石的形成,为白云石的成因研究提供了新的证据.白云石作为碳酸盐矿物,可以反映湖水盐度,但并非直接指示了湖水的咸化.随着湖水盐度的进一步增加,在硫酸盐型湖泊中,白云石含量随盐度的增加而相应减少,表明利用白云石分析湖水盐度时需要结合其他矿物进行分析.结合石膏含量的变化,花海湖全新世时期白云石含量的变化可以揭示该区域湖水盐度的变化.在10.478.87 cal ka B.P.早全新世时期,湖水的盐度较高,气候由干向湿转变;8.87 cal ka B.P.时期,有大量石膏沉积,显示了湖水盐度的进一步升高,气候干旱;随后湖水相对淡化,气候湿润;5.50 cal ka B.P.至今,沉积出现间断,气候逐渐干旱. 相似文献
4.
巴丹吉林沙漠全新世的高湖面与泛湖期 总被引：3，自引：0，他引：3
《中国科学:地球科学》2016,(8)
巴丹吉林沙漠腹地及东南部湖泊众多,除分布110个常年积水湖泊外,还存在若干季节性湖泊和干涸湖盆.通过对巴丹吉林沙漠湖泊群的实地考察、湖泊遗迹测量及14C和OSL定年,获得了全新世泛湖期存在的地貌学、沉积学和生物遗迹证据,揭示了巴丹吉林沙漠全新世早、中期湖盆面积扩大、区域气候相对湿润的特点.测年结果表明,巴丹吉林沙漠泛湖期开始于10cal ka BP,此前为泥炭发育期或湖沼期(11~10cal ka BP),大致在8.6~6.6cal ka BP,湖泊群达到全新世最大高湖面,并于晚全新世(约3.5cal ka至今)普遍出现退缩乃至干涸.根据植物钙质根管的形成时代及其所揭示的降水量阈值研究,巴丹吉林沙漠东南部在7.7~5.3cal ka BP期间古降水量可能达到200mm a~(-1).水量平衡计算表明,百年至千年尺度相对暖湿的区域气候条件,特别是南部和东南部深层地下水来水量增多,是巴丹吉林沙漠全新世湖泊群维持和史前文化发展的关键因素. 相似文献
5.
中国东部山地泥炭高分辨率腐殖化度记录的晚冰期以来气候变化 总被引：4，自引：0，他引：4
对中国东部中纬度季风区内的两处山地泥炭——神农架大九湖泥炭和天目山千亩田泥炭腐殖化度进行了研究,并对两剖面的孢粉记录、有机质含量、TOC和Rb／Sr对比分析,结果表明在东亚季风区山间盆地,气候越干冷时泥炭的分解就越强烈,以吸光度表征的腐殖化度就越高;相反,当气候较温暖潮湿时泥炭主要处于还原状态,分解较慢,腐殖化度较低．大九湖剖面的腐殖化度记录了晚冰期（约16．0～11．4cal ka BP）中的新仙女木（YD）（约11．4～12．6cal ka BP）冷干事件、博令．阿勒罗德暖湿期（B．A暖期,约12．6～15．2cal ka BP）、最老仙女木冷干事件（OD,约15．2～16．0cal ka BP）、早全新世的湿润期（约11．4—9．4cal ka BP）、8．2cal ka BP前后的冷干事件和约7．0～4．2cal ka BP之间的全新世最佳适宜期．神农架大九湖和天目山千亩田近5000a以来的泥炭腐殖化度记录有着很好的一致性,表明相近纬度不同经度的山地泥炭对东亚季风降水变化的响应是同步的．近5000a来的气候变化在两个山地泥剖面中几乎同步记录有3大阶段：4．9～3．5cal ka BP,季风降水整体处于高值,但波动剧烈,其中,在约4．2cal ka BP前后,季风降水急剧下降,在3．7cal ka BP前后达到最干旱的峰值后又快速回升：3．5～0．9cal ka BP,季风降水强度整体较弱,但也存在明显的次级干湿波动;0．9cal ka BP以来,吸光度值逐渐降低,表明季风降水增多．与中国东部季风区其他高分辨率沉积记录对比,文中亚高山泥炭记录的约1．6万年以来的气候变化响应了北半球夏季太阳辐射的统一驱动． 相似文献
6.
通过对现代乌伦古湖附近出露的古湖相沉积剖面的AMS~(14)C测年,粒度、总有机碳、总有机氮以及碳酸盐等环境代用指标的分析及其与全新世钻孔沉积记录的对比研究,结果发现:乌伦古湖在MIS-3晚期的33600-22500 cal a BP以及冰后期至早中全新世的16500-6500 cal a BP期间,维持着湖相沉积环境,湖面约比现在湖面高40 m.33600-22500 cal a BP的MIS-3晚期,气候相对温暖,乌伦古湖呈现高湖面特征,湖泊沉积物来源以流水搬运为主;22500-16500 cal a BP的末次冰期冰盛期,气候寒冷干燥,湖泊沉积物来源以风力搬运为主;16500-6500 cal a BP的冰后期以及早、中全新世期间,气候回暖,湖泊沉积物主要来源于河流径流作用.6500-5500 cal a BP,受高温干旱事件的影响,湖面收缩、水位剧降,除沉积中心外的其它钻孔位置出现沉积中断.5500 cal a BP后气候转冷变湿,湖泊重新恢复到现在的状态.乌伦古湖MIS-3晚期以来的古湖相沉积环境变化及其反映的古气候万年尺度上的干湿变化与周边区域气候环境变化记录有很好的一致性,响应了区域环境变化和全球气候突变事件.季风和西风的强度消长变化及其引起的环流条件改变以及温度变化引起的蒸发效应可能是区域气候环境变化的主要原因.这一古湖相沉积记录的研究可为MIS-3晚期以来北疆地区的古湖泊演化以及长时间尺度上西风和季风环流相互关系及其影响区的气候环境演化提供地质证据. 相似文献
7.
赛里木湖孢粉记录的亚洲内陆西风区全新世植被与气候变化 总被引：1，自引：0，他引：1
通过对西风区新疆赛里木湖沉积岩芯的精确定年和孢粉、炭屑分析,重建了该地区全新世以来的植被和气候环境演化历史.结果表明,~9.6cal.kaBP前的早全新世,研究区以荒漠植被为主,A/C比值和第一主成分样品得分所指示的有效湿度明显偏低,第二主成分样品得分所指示的气温回升,气候干旱.9.6~5.5cal.kaBP的中全新世湖区为典型的荒漠草原/草原植被,区域有效湿度明显增加,气温较高,为温暖时期.其中6.5~5.5cal.kaBP期间,研究区植被由荒漠草原/草原迅速转变为荒漠,有效湿度明显降低,同时温度升至最高,可能是一次千年尺度的高温干旱事件.5.5cal.kaBP以来的中-晚全新世,研究区呈现出典型的草原/草甸景观,有效湿度相对较高,温度大幅降低,气候温凉湿润,相对较为适宜.赛里木湖孢粉、炭屑记录的温度和湿度变化与区域其他湖泊记录对比的一致性表明,太阳辐射是造成区域温度变化的主要驱动因素,同时温度变化影响了区域的有效湿度变化.该地区早全新世气候干旱,中-晚全新世气候相对湿润的气候环境演化特征与季风影响区有着明显的差异.早全新世干旱是中纬度西风减弱和上风向蒸发减少的环流背景下局地温度高蒸发强烈的结果. 相似文献
8.
13.8ka以来内蒙古吉兰泰盐湖的演化过程 总被引：2，自引：1，他引：1
通过系统分析吉兰泰盐湖JLT-2010孔蒸发盐类矿物、碳酸盐矿物、碎屑岩矿物等,结合AMS14C测年获得的年代序列,研究该湖13.8 ka以来的演化过程.结果表明:吉兰泰盐湖13.8-11.7 cal ka BP期间水体较淡;11.7-10.2 cal ka BP期间湖泊开始萎缩、咸化,进入咸水湖阶段;10.2-5.5 cal ka BP期间湖泊进入硫酸盐沉积阶段,其中9.0-8.2 cal ka BP经历了一个明显的淡化过程;5.5 cal ka BP以来,湖泊成盐作用进一步加强,由前期的硫酸盐沉积转变为氯化物沉积,其中3.7-2.0 cal ka BP达到全面氯化物沉积阶段,2.0-1.7 cal ka BP又经历了一个短暂而明显的淡化过程;目前,该盐湖已进入干盐湖发展阶段.总体而言,吉兰泰盐湖蒸发盐类矿物主要是在全新世增温的背景条件下逐步萎缩形成的,由于区域性干旱气候的持续影响,吉兰泰盐湖逐步萎缩、咸化,进而析盐. 相似文献
9.
作为全球主要的粉尘源区之一，亚洲中部干旱区全新世环境变化备受关注，但目前仍缺乏连续的风成沉积记录。本文利用蒙古西北部Tolbo湖岩芯（TB19-A,332 cm）沉积物，在AMS14C定年和粒度分析基础上，采用对数正态分布函数拟合及粒级-标准偏差相结合的方法分离出沉积物中风成组分以重建区域风沙活动历史。结果显示，Tolbo湖沉积物中值粒径为15～84μm和大于84μm的组分分别是区域尘暴和局地风沙活动的良好指标。蒙古西北部地区末次冰消期晚期（13.75 11.6 cal ka BP）,Tolbo湖流域内有较强的局地风沙活动，可能与YD寒冷事件有关。全新世以来，流域内局地风沙活动与蒙古西北部区域尘暴活动的变化具有一致性，具体表现为：早中全新世风沙活动总体较弱，其中9.7 8.6 cal ka BP和7 6 cal ka BP为区域尘暴较强时段；5 cal ka BP之后局地风沙活动与区域尘暴强度显著增加，直至0.7 cal ka BP两者均维持在较高水平；0.3 cal ka BP以来区域尘暴活动再次增强。蒙古西北部与中国北方公海、博斯腾湖记录的尘暴历史具有一致的变化趋势，反映了与西伯利... 相似文献
10.
全新世镜泊湖粒度特征记录的该地区古降水变化历史 总被引：3，自引：5，他引：3
在湖泊沉积与环境演变研究中,粒度参数通常用来反映湖泊水动力条件的变化,进而反映湖面波动状况以及湖区环境有效湿度的变化．镜泊湖JPH-1钻孔沉积物粒度分析表明:全新世以来镜泊湖沉积物粒度的变化呈现明显的粗细交替变化的规律性．结合14C测年,镜泊湖沉积物粒度特征有效地指示了历史时期镜泊湖水动力变化的情况．进而揭示了该地区古降水的变化历史．9300-8540cal aBP,是一个降水较少的偏干旱时期;8540-6350 cal aBP,降水颇丰的湿润时期; 6350-3120cal aBF,气候波动频繁,前期(6350-4800 cal aBP)由湿润向干旱过渡,后期(4800-3120cal aBP左右)又由于早转向湿润,31 20-1 580 cal aBP,降水较多,气候湿润;1 580 cal aBP至今,降水变化波动剧烈,这阶段粒度特征的变化除了与降水的自然变化有关外,还与人类活动的剧烈影响有关系．湖区周围人类活动破坏了原始植被,大量地表裸露,降水冲刷地表作用明显增大,陆源物质被携带人湖,粗颗粒含量显著增多． 相似文献
11.
JIANG QingFeng JI JunFeng SHEN Ji Ryo MATSUMOTO TONG GuoBang QIAN Peng REN XueMei YAN DeZhi 《中国科学:地球科学(英文版)》2013,(3):339-353
Changes in the vegetation and climate of the westerly-dominated areas in Central Asia during the Holocene were interpreted using pollen-assemblages and charcoal data from a 300-cm-long sediment core of the Sayram Lake,northern Xinjiang.Accele-rator Mass Spectrometry(AMS) radiocarbon dating methods were applied to bulk organic matter of the samples.Artemisia spp./Chenopodiaceae ratios and results from principal component analysis were used to infer that the lake basin was dominated by desert vegetation before ca.9.6 cal.ka BP,which suggests a warm and dry climate in the early Holocene.Desert steppe/steppe expanded during 9.6-5.5 cal.ka BP,indicating a remarkable increase both in the precipitation and temperature during the mid-Holocene.Desert vegetation dominated between 6.5 and 5.5 cal.ka BP,marking an extreme warmer and drier interval.The steppe/meadow steppe recovered,and temperatures decreased from 5.5 cal.ka BP in the late Holocene,as indicated by the increased abundance of Artemisia and the development of meadows.Holocene temperatures and moisture variations in the Sayram Lake areas were similar to those of adjacent areas.This consistency implies that solar radiation was the main driving factor for regional temperature changes,and that the effect of temperature variations was significant on regional changes in humidity.The evolution of climate and environment in the Sayram Lake areas,which were characterized as dry in the early Holocene and relatively humid in the middle-late Holocene,are clearly different from those in monsoonal areas.Dry conditions in the early Holocene in the Sayram Lake areas were closely related to decreased water vapor advection.These conditions were a result of reduced westerly wind speeds and less evaporation upstream,which in turn were caused by seasonal changes in solar radiation superimposed by strong evaporation following warming and drying local climate. 相似文献
12.
High-resolution peat records for Holocene monsoon history in the eastern Tibetan Plateau 总被引：5，自引：1，他引：5
Holocene peat sediment has been attached impor-tance to reconstruct the Holocene climatic variations because it can provide much palaeoclimatic informa-tion with high resolution. Analysis on the plant mac-rofossil[1], pollen[2―4], isotope ratio[5―9], element con-tent[10,11], total organic carbon (TOC)[12], humifica-tion[13,14] and grayscale[12] for peat sediment has shown its superiorities as a recorder medium for reconstruct-ing the Holocene climate. Hong et al. have done great fruitful w… 相似文献
13.
Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field investigations on Badain Jaran Desert lake group, alongside measurements and dating performed on lake relic, prove that these lakes expanded while the climate was relatively wet during early and middle Holocene. The dating results suggest that the pan-lake period of the Badain Jaran Desert began at 10 cal kyr BP, before which the limnic peat period occurred(11–10 cal kyr BP). Many lakes reached their maximal water-level during 8.6–6.3 cal kyr BP and retreated or dried up in the late Holocene(about 3.5–0 cal kyr BP). During that period, the precipitation at Badain Jaran Desert may have reached 200 mm yr~(-1) for 7.7–5.3 cal kyr BP, inferred from both the age and precipitation rate of calcareous root tubes. The water balance calculation shows that wetter and warmer climate and the increase of underground water recharge were key factors in maintaining and developing the lake group at both centennial and millennial time scales. Furthermore, lake surface expansion and the increasing fresh water availability set the background for the prosperous prehistoric culture. 相似文献
14.
15.
A high-resolution climatic change since the Late Glacial Age inferred from multi-proxy of sediments in Qinghai Lake 总被引：12，自引：3，他引：9
Ryo Matsumoto 《中国科学D辑(英文版)》2005,48(6):742-751
The study of climatic changes since the Late Glacial Age has become one of the hotspots of the PAGES in recent years.Deep-sea cores from the high-latitude area show that the climate was very unstable during the transitional period from the Late Glacial Age to the Holocene[1,2],which has also been testified by the geological records from ocean sediments,ice cores and terrestrial sections in different latitudes of the earth[3—8].What’s more,climatic instability also ex-isted in the Holoce… 相似文献
16.
Climate variability recorded by n-alkanes of paleolake sediment in Qaidam Basin on the northeast Tibetan Plateau in late MIS3 总被引：1，自引：0，他引：1
PU Yang ZHANG HuCai LEI GuoLiang CHANG FengQin YANG MingSheng ZHANG WenXiang LEI YanBin YANG LunQing & PANG YouZhi State Key Laboratory of Lake Science Environment Nanjing Institute of Geography Limnology Chinese Academy of Sciences Nanjing China Graduate University of Chinese Academy of Sciences Beijing Key Laboratory of Boyang Lake MOE School of Environmental Chemical Engineering Nanchang University Nanchang 《中国科学:地球科学(英文版)》2010,(6)
Here we combine n-alkanes preserved in a shell bar section from Qarhan paleolake, Qaidam Basin with the other sedimentary proxies to elucidate the lake evolution process during the period 39.7 to 17.5 14C ka BP (calibrated age ranges from 43.5 to 22.4 cal. ka BP). In different stages, the n-alkane homologues exhibited different distribution modes indicative of variations in the surrounding vegetation and the hydrologic condition of the lake. The n-alkanes proxies (CPIh, ACLh, Paq) have the same trends as th... 相似文献
17.
Vietnam's Central Highlands in Pleiku feature numerous volcanic craters (i.e. maars) formed over 0.2 Ma ago that contain continuous high-resolution lacustrine sediment records extending from the Late Pleistocene through the Holocene. Their evolution and sedimentary proxies are potentially powerful archives for interpretation of East-Asian monsoon variability across Vietnam, as well as for local to regional changes in landcover. The focus of this study is to develop a reliable chronology for the Biển Hồ 25-m-long lake sediment sequence in Vietnam's Central Highlands. We present a combined sediment chronology extending back to 55 ka cal BP that is based on 137Cs surface sediment chronology, paleomagnetic dating, and 47 14C dates distributed evenly throughout the sequence. Based on sedimentary facies analysis and a smooth age-depth model based on 137Cs and 14C data, we infer a long-term stable rate of sedimentation in Biển Hồ lake without unconformities or erosional hiatuses, except for the uppermost section (ca. 100 years) where human activities increase the rate of sedimentation significantly. The Biển Hồ sequence thus provides a complete and uninterrupted record of the lake's depositional history. The present contribution is a geochronologic opening salvo for future contributions from Biển Hồ lake featuring multi-disciplinary evidence for longer-term paleoclimate and environmental changes. 相似文献
18.
Climate changes in East China since the Late-glacial inferred from high-resolution mountain peat humification records 总被引：1，自引：0，他引：1
High-resolution peat humification records were obtained from Dajiuhu of the Shennongjia Mountains and Qianmutian of the Tianmu Mountains to study climate changes in East China. The analyses of pollen, organic matters, TOC, and Rb/Sr indicate a high degree of peat humification and thus strong decomposition of organic matter when climate was dry. Conversely, when climate was humid, the degree of humification is low because peat was preserved in a waterlogged condition. Peat humification from Dajiuhu occurred not only during the Younger Dryas (about 11.4–12.6 cal ka BP), the Bølling-Allerød Warm Period (12.6–15.2 cal ka BP), and the Oldest Dryas (about 15.2–16.0 cal ka BP), but also during the early Holocene (about 11.4–9.4 cal ka BP), the 8.2 cal ka BP cold event, and the Holocene Optimum (about 7.0–4.2 cal ka BP). Both peat humification records since nearly 5 ka BP are consistent, showing that mountain peatland has synchronous responses to the East Asia monsoon-induced precipitation. The LOI data confirm the above observation. The monsoon precipitation since nearly 5 ka BP recorded in these two peat profiles can be divided into three phases. During 4.9–3.5 ka BP, precipitation amount was high but fluctuated greatly. During 3.5–0.9 ka BP, precipitation amount was low. During 0.9–0 ka BP, degree of humification reduced gradually, indicating the increase of monsoon precipitation. Contrast to other high-resolution records from East China monsoon region shows that the monsoon precipitation records of the two peat profiles since nearly 16 ka BP are controlled by a common forcing mechanism of summer solar radicalization in the Northern Hemisphere. 相似文献