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Holocene climatic change reconstructed from trace elements of an aeolian deposit in the southeastern Mu Us Desert, northern China 预览
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作者 Bing Liu HeLing Jin +2 位作者 LiangYing Sun WenPing Xue ZhenYu Liu 《寒旱区科学:英文版》 CSCD 2019年第2期126-138,共13页
In semi-arid and arid desert regions of northern China, aeolian deposits document the framework variation of an Asian monsoon during the late Quaternary. However, there is still a lack of detailed data pertaining to H... In semi-arid and arid desert regions of northern China, aeolian deposits document the framework variation of an Asian monsoon during the late Quaternary. However, there is still a lack of detailed data pertaining to Holocene Asian monsoonal variation especial in the modern Asian summer monsoonal boundary belt. In this study, we reconstructed Holocene millennial- scale climatic changes in the Mu Us Desert, northern China, through systematic analysis of the variation of trace elements (324 samples) in different lithological units of the palaeosol-aeolian sand deposit, in combination with 14C and OSL chronology. Statistical results, correlation and clustering analysis indicate that the high content of 11 trace elements (V, Y, Cr, Nb, P, Mn, Cu, Zr, As, Ni and Rb, represented by P) and lower Sr content corresponding to periods of palaeosol development, marked increase of vegetation, weathering degree, and enhanced Asian summer monsoonal strength. In contrast, their opposed variation are coincident with accumulated aeolian sand layers, implying weaker summer monsoons and less geochemical weathering and degraded vegetation. These associations can be considered as signaling regional humid and dry changes of the Holocene environment. Accordingly, relatively arid conditions dominated the region before 7.2 ka, and there was an optimal humid climate in 7.2?4.6 ka. Afterwards, the climate became obviously dry, accompanied with several cycles of relatively wet and dry, such as relatively wet intervals around 4.1?3.7 ka, 3.5?3.3 ka and 2.5 ka. In addition, six millennial-scale dry events were recorded, and these events were consistent with weaker Asian summer monsoonal intervals in low latitudes, declined palaeosol development and precipitation in middle latitudes, as well as increased winter monsoon and periodic ice-rafting events in high latitudes of the Northern Hemisphere, within limits of accuracy of existing dating ages. This possibly suggests a noteworthy synchronism between millennial-scale climatic changes in this reg 展开更多
关键词 HOLOCENE climatic change Mu Us DESERT Aeolian DEPOSIT trace element synchronism
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乌海盆地岗德尔山西麓断裂晚更新世-全新世活动性
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作者 徐东卓 尹海权 +1 位作者 李胜虎 朱传宝 《昆明理工大学学报:自然科学版》 CAS 北大核心 2019年第3期26-32,40共8页
岗德尔山西麓断裂是桌子山断裂带的重要组成部分,同时也是乌海盆地的控盆边界断裂.关于该断裂晚第四纪以来活动性的研究成果很少.通过实地地质地貌调查、构造剖面分析以及OSL测年,综合分析研究该断裂晚第四纪活动性.综上所得,岗德尔山... 岗德尔山西麓断裂是桌子山断裂带的重要组成部分,同时也是乌海盆地的控盆边界断裂.关于该断裂晚第四纪以来活动性的研究成果很少.通过实地地质地貌调查、构造剖面分析以及OSL测年,综合分析研究该断裂晚第四纪活动性.综上所得,岗德尔山西麓断裂为晚更新世晚期至全新世有过明显活动的断裂.自观音庙至岗德尔山陵园,断裂整体走向近SN,倾向W,倾角80°左右,被切断的沉积层顶部或断裂上覆地层底部的OSL年龄样品测试结果分布在83.5~7.8 ka之间,最新活动时间集中在晚更新世晚期至全新世之间;自岗德尔山陵园至黄河村,断裂整体走向NNE,倾向NWW-NW,倾角60°~80°,被切断的沉积层顶部或断裂上覆地层底部的OSL年龄样品测试结果分布在86.9~2.7 ka间,最新活动时间集中在晚更新世晚期至全新世之间.根据岗德尔山西麓断裂野外调查所得的几何学特征,显示该断裂是一条由多条近平行的高角度断层组成的正断层系,整体表现出以拉张为主的运动特征. 展开更多
关键词 乌海盆地 岗德尔山西麓断裂 晚更新世晚期 全新世 活动性
喀喇昆仑断裂北段晚第四纪活动特征及其构造意义 预览
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作者 赵一霖 刘健 +1 位作者 姜科庆 祝明伟 《地球学报》 EI CAS CSCD 北大核心 2019年第4期601-613,共13页
右旋走滑的喀喇昆仑断裂(KKF)作为青藏高原的西部边界,在印度板块与欧亚板块碰撞引起的陆内变形过程中扮演了重要的角色。近年来KKF北段全新世以来的活动特征存在争议。通过遥感解译和野外观测,在喀喇昆仑断裂(KKF)的北段——新疆卡拉... 右旋走滑的喀喇昆仑断裂(KKF)作为青藏高原的西部边界,在印度板块与欧亚板块碰撞引起的陆内变形过程中扮演了重要的角色。近年来KKF北段全新世以来的活动特征存在争议。通过遥感解译和野外观测,在喀喇昆仑断裂(KKF)的北段——新疆卡拉苏地区,对KKF及其两条分支断裂的几何学、运动学进行了研究,获得了现今发育的冰水扇被右旋错断和冰水扇上分布羽列式T张破裂等指示KKF右旋走滑的证据。采集了KKF控制的浅冰水湖相沉积中贝壳的AMS14C样品,获得年龄分别为(5.20±0.03)ka、(5.61±0.03)ka和(9.95±0.04)ka。表明KKF北段晚全新世以来仍在活动,其右旋走滑速率约为3.7mm/a,累计垂向滑移速率约为1.7mm/a。据前人在KKF中部的研究成果,推测KKF北段在卡拉苏地区由南东往北西右旋走滑速率有增大的趋势。 展开更多
关键词 全新世 喀喇昆仑断裂 活动断裂 走滑速率 浅冰湖沉积
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10,000 years of climate control over carbon accumulation in an Iberian bog(southwestern Europe) 预览
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作者 Xabier Pontevedra-Pombal Daniel Castro +7 位作者 Martín Souto Isabel Fraga William H. Blake Maarten Blaauw José A. López-Sáez Sebastián Pérez-Díaz Marcos Valcárcel Eduardo García-Rodeja 《地学前缘:英文版》 CAS CSCD 2019年第4期1521-1533,共13页
The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs,which are particularly sensitive to projected climate cha nge.In this context,the rate of carbon(C)accumulation in Chao de Veiga Mol.... The northwest region of the Iberian Peninsula is home to a unique ecosystem of bogs,which are particularly sensitive to projected climate cha nge.In this context,the rate of carbon(C)accumulation in Chao de Veiga Mol.an intact raised bog,was analysed.Changes in the accumulation rate over the past10 millennia were determined in a peat core of 847 cm in depth,with a high mean rate of peat growth(11 yr cm^-1,0.09 cm yr^-1).An age-depth model was generated from 22 14C dates and fallout radionuclides.Chronological,stratigraphical and physico-chemical data confirmed the existence of a single cycle of peat formation throughout the Holocene and the formation of ombrotrophic peat 9500 years ago.The total mean C content was 50.2%,and over 10 millennia 583 kg C m^-2 accumulated at a mean rate of 35.3 g C m^-2 yr^-1,with a long-term(apparent)rate of carbon accumulation in the catotelm of59.9 g C m^-2 yr^-1.These values are much higher than reported for other Iberian peatlands and are amongst the highest documented for peatlands in the northern hemisphere.The dynamics of C accumulation and other measured parameters reveals important variations throughout the Holocene.They could be associated with the main climatic events described in the northern hemisphere and are highly consistent with models established for northern latitudes.The Chao de Veiga Mol raised bog is unique and of great potential value for carrying out high resolution palaeoenvironmental studies,especially in relation to regional and Iocal modulations in southern Europe. 展开更多
关键词 PEATLAND GEOCHEMISTRY HOLOCENE Climate change Palaeoenvironmental reconstruction
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伶仃洋ZK19孔全新统有机物δ^13C和C/N值特征及东亚季风演变记录 预览
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作者 陶慧 王建华 +2 位作者 陈慧娴 瓦西拉里 吴加学 《中山大学学报:自然科学版》 CAS CSCD 北大核心 2019年第3期1-12,共12页
为了深入探讨珠江河口区全新世东亚季风演变历史,对珠江口伶仃洋海区ZK19孔全新统开展年代学、有机碳同位素等地球化学多指标的研究。年代测试结果分析显示:钻孔早、晚全新世沉积完整,缺失高海平面期的中全新世沉积,研究认为该地层缺失... 为了深入探讨珠江河口区全新世东亚季风演变历史,对珠江口伶仃洋海区ZK19孔全新统开展年代学、有机碳同位素等地球化学多指标的研究。年代测试结果分析显示:钻孔早、晚全新世沉积完整,缺失高海平面期的中全新世沉积,研究认为该地层缺失是因水下侵蚀导致。钻孔δ^13C和C/N值分析结果表明,早全新世沉积物中偏负的δ^13C值和逐渐增大的C/N值,指示早全新世东亚强夏季风不断增强,不断增强的降水使钻孔区含较多的陆源有机质;而晚全新世逐渐偏正的δ^13C值和变小的C/N值表明,东亚夏季风不断减弱,降水量逐渐减小,陆源有机质输入逐渐减少,但这些指标在1.5calkaBP开始受人类活动影响,近500年来影响较显著。早、晚全新世东亚夏季风变化趋势主要与岁差相关的北半球日照量相关,而在东亚夏季风整体变化趋势下,还存在千年-百年尺度的气候波动周期,与太阳活动强度和周期的相对应。 展开更多
关键词 珠江口 伶仃洋 全新世 Δ^13C C/N 东亚季风
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海南岛三亚湾全新世以来沉积特征与古环境演变 预览
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作者 孙倩文 黄康有 +3 位作者 谢德豪 周斯 王萌 郑卓 《中山大学学报:自然科学版》 CAS CSCD 北大核心 2019年第3期13-21,共9页
根据海南岛三亚湾SY01钻孔AMS14C测年建立沉积物年代框架,结合粒度、烧失量、色度和有孔虫等分析研究了三亚湾地区的海平面变化、沉积相和古环境演变过程。结果表明,SY01钻孔的沉积物呈现5个变化阶段:含砾粉砂层-含粗砂粉砂层-含中砂粉... 根据海南岛三亚湾SY01钻孔AMS14C测年建立沉积物年代框架,结合粒度、烧失量、色度和有孔虫等分析研究了三亚湾地区的海平面变化、沉积相和古环境演变过程。结果表明,SY01钻孔的沉积物呈现5个变化阶段:含砾粉砂层-含粗砂粉砂层-含中砂粉砂层-含细砂粉砂层-粉砂层;有孔虫和介形虫的分析结果显示出其主要出现在8.1~3.7calkaBP期间,且含量最丰富的层位在5.2~4.7calkaBP;烧失量的分析结果表明有机质和碳酸盐在5.2~4.7calkaBP期间的含量相对较高,揭示该时期陆地或海洋生物较为繁盛;色度值的结果也反映该阶段处于还原状态的沉积环境。因此,综合各个环境代用指标,研究区域的沉积过程划分为5个阶段:洪积相内侧-洪积相远端-滨岸相-海湾相-潟湖相;三亚湾地区从~9calkaBP开始沉积,全新世海侵高海平面期为~5calkaBP,之后进入晚全新世海退阶段,河流泥沙输送形成了三亚湾砂质海岸。 展开更多
关键词 三亚湾 全新世 沉积相 海平面变化
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珠江三角洲中部全新世以来的微体动物群记录与古环境重建 预览
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作者 吴月琴 刘春莲 +3 位作者 杨小强 黄毅 殷鉴 张恺 《海洋地质与第四纪地质》 CAS CSCD 北大核心 2019年第2期31-43,共13页
通过分析珠江三角洲中部钻孔沉积物的微体动物群(有孔虫和介形类)组成和分布特征,结合测年、岩性、沉积物粒度和软体动物群数据,重建了珠江三角洲中部全新世以来的古环境演化。受末次冰期影响,珠江三角洲地区暴露地表遭受风化剥蚀,普遍... 通过分析珠江三角洲中部钻孔沉积物的微体动物群(有孔虫和介形类)组成和分布特征,结合测年、岩性、沉积物粒度和软体动物群数据,重建了珠江三角洲中部全新世以来的古环境演化。受末次冰期影响,珠江三角洲地区暴露地表遭受风化剥蚀,普遍发育杂色黏土。随着冰后期气候回暖,海平面快速回升,海水经多个口门自南向北侵入珠江三角洲地区。南部较早接受海侵,约9010cal.aBP海水入侵至中部地区,研究区开始发育河口湾环境,并持续至4510cal.aBP。期间,钻孔记录的微体动物群组成和丰度特征反映了2次短周期的水体条件波动,最大水深发生于约7000~5630cal.aBP,微体动物群的丰度达到最高值。约4510cal.aBP以来为持续海退期,河流作用逐渐增强,发育三角洲平原环境。 展开更多
关键词 有孔虫 介形类 全新世 古环境 珠江三角洲
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全新世中期郑州地区古代农业的时空演变及其影响因素
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作者 王灿 吕厚远 +10 位作者 顾万发 吴乃琴 张健平 左昕昕 李丰江 汪道京 董亚杰 汪松枝 刘彦锋 鲍颖建 胡亚毅 《第四纪研究》 CAS CSCD 北大核心 2019年第1期108-122,共15页
郑州地区地处中原腹地,是我国旱作农业起源和稻作农业早期传播的重要区域之一,在华夏文明形成与发展过程中具有非常重要的地位。然而,由于区域性系统植物考古研究较少,目前全新世中期郑州地区古代农业的时空演变过程及其影响因素仍不清... 郑州地区地处中原腹地,是我国旱作农业起源和稻作农业早期传播的重要区域之一,在华夏文明形成与发展过程中具有非常重要的地位。然而,由于区域性系统植物考古研究较少,目前全新世中期郑州地区古代农业的时空演变过程及其影响因素仍不清晰。文章在郑州地区选择位于不同地貌部位、不同等级规模的13处裴李岗-仰韶文化遗址进行系统采样,通过植硅体分析和AMS 14C测年,揭示出郑州地区在裴李岗文化和仰韶文化中晚期均属于以黍为主的稻-旱混作的农业模式,其形成得益于全新世适宜期暖湿气候下的稻作北传。裴李岗时期,黍粟旱作分布在浅山丘陵区的黄土台塬沟谷地带,稻-旱混作仅存在于冲积平原,农业模式的选择主要受地形和水文因素影响;仰韶中晚期,粟和稻的比例显著提高,稻作不再局限于冲积平原和大型聚落,在台塬沟谷和中小聚落也有分布,标志着农耕技术的进步和作物结构的优化,这意味着农业生产开始打破自然条件限制,为郑州地区农业社会的建立和文明化进程奠定了基础。 展开更多
关键词 郑州地区 全新世 植硅体 旱作农业 稻作农业 裴李岗文化 仰韶文化
全新世以来长白山区孤山屯泥炭地炭屑记录与古火演化历史
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作者 蒙萌 介冬梅 +5 位作者 李楠楠 刘宝健 牛洪昊 李德晖 刘颖 张桂华 《微体古生物学报》 CSCD 北大核心 2019年第1期70-78,共9页
长白山拥有亚洲目前保存较为完好的温带山地森林生态系统,由于近年来无火事件发生而积累了大量可燃物,火灾隐患逐年增加,重建古火历史找出火事件发生规律有助于现代火灾的有效防控。本文以长白山区孤山屯泥炭剖面的68个样品为研究载体,... 长白山拥有亚洲目前保存较为完好的温带山地森林生态系统,由于近年来无火事件发生而积累了大量可燃物,火灾隐患逐年增加,重建古火历史找出火事件发生规律有助于现代火灾的有效防控。本文以长白山区孤山屯泥炭剖面的68个样品为研究载体,选取炭屑作为主要指标反演了长白山全新世以来的火事件演化历史;并结合前人利用孢粉、植硅体等代用指标重建的古环境、古气候特征,分析了火事件的成因机制。在11 686-10 883 cal aBP、7 336-2 624 cal aBP、2 624-1 189 cal aBP,炭屑浓度较高,古火事件发生频繁,强度较大;在10 883-7 336 cal aBP、1 189 cal aBP至今,炭屑浓度较低,古火事件发生频率较小,强度相对较弱。气候和植被对于火事件的影响贯穿了整个全新世时期,火事件多发生在寒冷干燥气候时期且以区域性火事件为主;近千年以来,人类活动与火山喷发对火事件的影响显著,局域性火事件比例逐渐增多。 展开更多
关键词 炭屑 火事件 古环境 孤山屯泥炭地 全新世 长白山
The East Asian Monsoon since the Last Glacial Maximum:Evidence from geological records in northern China
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作者 Shiling YANG Xinxin DONG Jule XIAO 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第8期1181-1192,共12页
The impact of global warming on the climate of northern China has been investigated intensively, and the behavior of the East Asian monsoon during previous intervals of climatic warming may provide insight into future... The impact of global warming on the climate of northern China has been investigated intensively, and the behavior of the East Asian monsoon during previous intervals of climatic warming may provide insight into future changes. In this study, we use paleovegetation records from loess and lake sediments in the marginal zone of the East Asian summer monsoon(EASM) to reconstruct the EASM during the interval of warming from the Last Glacial Maximum(LGM) to the Holocene. The results show that during the LGM, desert steppe or dry steppe dominated much of northern China;in addition, the southeastern margin of the deserts east of the Helan Mountains had a distribution similar to that of the present-day, or was located slightly further south, due to the cold and dry climate caused by a strengthened East Asian winter monsoon(EAWM) and weakened EASM. During the last deglaciation, with the strengthening of the EASM and concomitant weakening of the EAWM, northern China gradually became humid. However, this trend was interrupted by abrupt cooling during the Heinrich 1(H1) and Younger Dryas(YD) events. The EASM intensified substantially during the Holocene, and the monsoon rain belt migrated at least 300 km northwestwards, which led to the substantial shrinking of the desert area in the central and eastern part of northern China, and to the large expansion of plants favored by warm and humid conditions. Paleoclimatic records from the marginal zone of the EASM all show that the EASM reached its peak in the mid-Holocene, and past global climatic warming significantly strengthened the EASM, thereby greatly improving the ecological environment in northern China. Thus, northern China is expected to become wetter as global warming continues. Finally, high resolution Holocene vegetation records are sparse compared with the numerous records on the orbital timescale, and there is a need for more studies of Holocene climatic variability on the centennial-to-decadal scale. 展开更多
关键词 East Asian monsoon Last GLACIAL Maximum HOLOCENE PALEOVEGETATION Global WARMING
广东西樵剖面主量元素记录的全新世气候突变
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作者 司月君 牛东风 +4 位作者 李保生 王丰年 郭亿华 舒培仙 琚琛琪 《第四纪研究》 CAS CSCD 北大核心 2019年第3期629-641,共13页
以广东佛山市西樵山(22°56'15"N,112°57'16"E)全新统厚153 cm的河湖相及红土为研究对象,在11个AMS-14C测年数据和沉积物主量元素分析的基础上探讨全新世以来该剖面的化学风化特征及古环境意义,对具有明确... 以广东佛山市西樵山(22°56'15"N,112°57'16"E)全新统厚153 cm的河湖相及红土为研究对象,在11个AMS-14C测年数据和沉积物主量元素分析的基础上探讨全新世以来该剖面的化学风化特征及古环境意义,对具有明确指示化学风化意义的脱硅富铝铁化指标Al2O3/SiO2和(Al2O3+TFeO)/SiO2进行分析,结合孢粉指示的古生态,确定了气候旋回与化学风化旋回之间的关系,为南亚热带地区全新世环境演变提供了地球化学证据。研究结果表明,西樵山全新统共记录了13次弱风化-冬季风事件,其中发生于2000 cal.a B.P.(xc1)、2900 cal.a B.P.(xc3)、4100 cal.a B.P.(xc4)、5300 cal.a B.P.(xc5)、7800 cal.a B.P.(xc10)、9300 cal.a B.P.(xc11)、9500 cal.a B.P.(xc12)和9700 cal.a B.P.(xc13)的事件可对应北大西洋深海沉积Bond事件1~8,前6次事件与南海陆坡北部的17940孔10 ka B.P.以来的6个弱季风事件相应,且这13个冷事件几乎都可与太阳黑子活动最小值阶段相对应。这意味着西樵山剖面全新世突变事件除受北半球高纬冰量变化的影响外,可能还在相当程度上受到太阳活动的强迫。 展开更多
关键词 广东西樵山 全新世 主量元素 气候突变
重庆金佛洞石笋δ13C记录的全新世千年尺度气候振荡
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作者 王宝艳 杨勋林 +2 位作者 孙喜利 史志超 刘睿恺 《地球与环境》 CAS CSCD 北大核心 2019年第1期1-9,共9页
基于重庆市金佛洞石笋J119铀系测年数据和碳同位素数据重建了全新世9.6~1.6 ka B.P.时段的古气候演化序列。分析结果显示:在早全新世的9.6~7.4 ka B.P.期间,J119δ13C记录呈现出偏负趋势,表明此时段内季风逐渐加强,气候开始变暖湿;中全... 基于重庆市金佛洞石笋J119铀系测年数据和碳同位素数据重建了全新世9.6~1.6 ka B.P.时段的古气候演化序列。分析结果显示:在早全新世的9.6~7.4 ka B.P.期间,J119δ13C记录呈现出偏负趋势,表明此时段内季风逐渐加强,气候开始变暖湿;中全新世的7.4~4.2 ka B.P.期间,J119δ13C值整体偏负,与全新世大暖期相对应;在4.2 ka B.P.附近δ13C记录出现较大幅度的迅速偏正,并持续到约2.5 ka B.P.,随后石笋δ13C值出现偏负趋势,表明在4.2 ka B.P.以后气候持续处于干冷状态直到2.5 ka B.P.才有所转暖。在全新世期间,重庆金佛洞石笋清晰地记录了7次千年尺度气候震荡事件,分别发生在大约2.7 ka B.P.、4.2 ka B.P.、5.5 ka B.P.、8.3 ka B.P.、9.4 ka B.P.附近,与大西洋染赤铁矿记录的冷事件2、3、4、5、6相对应。除此之外,J119δ13C记录显示在7.0~6.7 ka B.P.、7.8~7.3 ka B.P.时段也存在千年尺度震荡,这些突变事件与董哥洞石笋氧同位素记录的弱季风事件(2.7 ka B.P.、4.4 ka B.P.、5.5 ka B.P.、6.3 ka B.P.、7.2 ka B.P.、8.3 ka B.P.)也存在一定的对应关系。因此,本文研究表明金佛山石笋δ13C记录能够反映全新世千年尺度的气候事件,并可以与石笋δ18O记录进行相互对比和验证。 展开更多
关键词 全新世 石笋δ13C 千年尺度 气候震荡 金佛山
马四剖面揭示的共和盆地12ka以来的环境演变
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作者 胡梦珺 冯淑琴 李向锋 《地层学杂志》 CSCD 北大核心 2019年第1期101-108,共8页
以共和盆地东部风成沉积剖面(MS剖面)磁化率为依据,运用四次回归方程重建了剖面形成时的年均气温和降水量,确定近12 ka以来共和盆地年均温度–0.37℃~5.09℃,多年平均温度为2.5℃,降水量267.91~550.77 mm,多年平均降水量为418.62 mm。... 以共和盆地东部风成沉积剖面(MS剖面)磁化率为依据,运用四次回归方程重建了剖面形成时的年均气温和降水量,确定近12 ka以来共和盆地年均温度–0.37℃~5.09℃,多年平均温度为2.5℃,降水量267.91~550.77 mm,多年平均降水量为418.62 mm。对常量元素氧化物(SiO2、Al2O3和Fe2O3)含量进行分析,结果表明:1)古土壤层SiO2含量均低于风成砂层, Al2O3和Fe2O3含量均高于风成砂层;2)风成砂层SiO2含量S3>S5>S1,Al2O3和Fe2O3含量S5>S3>S1,揭示S3层形成时期冷干, S5层次之, S1层干旱程度较弱;土壤层SiO2含量S4>S2>S6, Al2O3和Fe2O3含量为S6>S2>S4,表明S6形成时期气候温湿, S2层次之, S4层温湿程度较低;3)分层氧化物变异系数大小表明S2和S6层形成时气候波动剧烈, S1和S3层形成时期气候较稳定。以常量元素氧化物含量、温度和降水为依据,结合14C测年,重建了近12 ka以来共和盆地环境演变过程:11.9 ka BP以前为凉干期,11.9~9.7 ka BP为温湿期, 9.7~8.0 ka BP为冷干期, 8.0~4.8 ka BP为暖湿期, 4.8~2.9 ka BP为凉干期, 2.9 ka BP以来为温润期。马四剖面记录的环境演变过程与青藏高原其他区域环境演变过程具有相似性,表明共和盆地环境演变与区域环境变化具有同步性。 展开更多
关键词 古气候 古土壤 磁化率 常量元素氧化物 环境演变 全新世 共和盆地 青海省
7.5-7.0 cal.ka B.P.气候事件在中国地区的表现及其动力机制
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作者 吴文祥 侯梅心 +1 位作者 郑洪波 葛全胜 《第四纪研究》 CAS CSCD 北大核心 2019年第2期267-281,共15页
识别全新世气候事件、阐明其区域环境表现特征、揭示其驱动机制是理解气候系统变化行为、预测未来气候变化以及弄清考古学文化转变动因的关键,具有重要的科学价值和现实意义。随着高分辨率全新世古气候重建的进展,7.5~7.0cal.kaB.P.事... 识别全新世气候事件、阐明其区域环境表现特征、揭示其驱动机制是理解气候系统变化行为、预测未来气候变化以及弄清考古学文化转变动因的关键,具有重要的科学价值和现实意义。随着高分辨率全新世古气候重建的进展,7.5~7.0cal.kaB.P.事件逐渐被揭示,但到目前为止仍缺乏针对该气候事件各种类型证据的系统收集、对比以及对其产生动力机制的分析。本文基于中国26条古气候记录,系统总结了这一气候事件在中国地区的环境表现。结果显示,7.5-7.0cal.kaB.P.气候事件在中国多个地区都有明显的反映,整体表现为温度下降、夏季风强度减弱。与全球其他地区的古气候记录对比显示7.5-7.0cal.kaB.P.气候事件可能具有全球性的特征;与驱动因子系列对比发现该气候事件发生在北半球夏季太阳辐射逐渐减少、太阳活动减弱、火山活动频发、劳伦泰德冰盖快速融化期间,表明这4种因素在7.5-7.0cal.kaB.P.气候事件发生过程中发挥了作用。未来需要更多测年准确、分辨率高的古气候记录定量-半定量刻画该气候事件的变化幅度、起止时间以及区域差异,同时结合古气候模拟揭示7.5-7.0cal.kaB.P.气候事件产生的动力机制。 展开更多
关键词 中国 全新世 7.5-7.0 cal.ka B.P.气候事件 夏季风强度 驱动机制
山东蒙山冰川遗迹的类型、特征和年代--答王乃昂教授、李吉均院士质疑 预览
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作者 王照波 王江月 《地质论评》 CAS CSCD 北大核心 2019年第3期603-622,共20页
鉴于王乃昂教授、李吉均院士等否定了蒙山拦马墙等冰川遗迹的冰川成因,本着学术的辩论是接近科学真相的有效途径,故撰写本文。重点就王乃昂教授在其论文中采用人工采样坑作为地震撞击坑的证据问题、冰川擦痕认知的局限性问题进行了阐述... 鉴于王乃昂教授、李吉均院士等否定了蒙山拦马墙等冰川遗迹的冰川成因,本着学术的辩论是接近科学真相的有效途径,故撰写本文。重点就王乃昂教授在其论文中采用人工采样坑作为地震撞击坑的证据问题、冰川擦痕认知的局限性问题进行了阐述。详细描述了蒙山存在的擦痕、颤痕、新月形裂纹、新月形裂口、新月形凿口、钉头鼠尾擦痕等类型丰富的冰川遗迹,并与四川海螺沟现代冰川槽谷各类擦痕、美国缅因州的颤痕等进行了对比。就争议较大的拦马墙巨石垄的组构特征、形成过程与形成时代进行了研究分析。在此基础上就冰川与洪水、泥石流之间的动力学差异进行了讨论。研究发现,脱离了"冰是固体"这一基本的认知范畴,必然导致泥石流论的泛滥。蒙山类型丰富、形迹清晰的冰川擦痕,为我国第四纪冰川遗迹的研究提供了实物样本。 展开更多
关键词 蒙山 擦痕 新月形裂纹 新月形裂口 新月形凿口 颤痕 侧碛垄 全新世
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Evolution of permafrost in China during the last 20 ka
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作者 Huijun JIN Xiaoying JIN +8 位作者 Ruixia HE Dongliang LUO Xiaoli CHANG Shaoling WANG Sergey S MARCHENKO Sizhong YANG Chaolu YI Shijie LI Stuart A HARRIS 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第8期1207-1223,共17页
The formation and evolution of permafrost in China during the last 20 ka were reconstructed on the basis of large amount of paleo-permafrost remains and paleo-periglacial evidence, as well as paleo-glacial landforms, ... The formation and evolution of permafrost in China during the last 20 ka were reconstructed on the basis of large amount of paleo-permafrost remains and paleo-periglacial evidence, as well as paleo-glacial landforms, paleo-flora and paleofauna records. The results indicate that, during the local Last Glacial Maximum(LLGM) or local Last Permafrost Maximum(LLPMax), the extent of permafrost of China reached 5.3×106-5.4×106 km2, or thrice that of today, but permafrost shrank to only0.80×106-0.85×106 km2, or 50% that of present, during the local Holocene Megathermal Period(LHMP), or the local Last Permafrost Minimum(LLPMin). On the basis of the dating of periglacial remains and their distributive features, the extent of permafrost in China was delineated for the two periods of LLGM(LLPMax) and LHMP(LLPMin), and the evolution of permafrost in China was divided into seven periods as follows:(1) LLGM in Late Pleistocene(ca. 20000 to 13000-10800 a BP)with extensive evidence for the presence of intensive ice-wedge expansion for outlining its LLPMax extent;(2) A period of dramatically changing climate during the early Holocene(10800 to 8500-7000 a BP) when permafrost remained relatively stable but with a general trend of shrinking areal extent;(3) The LHMP in the Mid-Holocene(8500-7000 to 4000-3000 a BP)when permafrost degraded intensively and extensively, and shrank to the LLPMin;(4) Neoglaciation during the late Holocene(4000-3000 to 1000 a BP, when permafrost again expanded;(5) Medieval Warming Period(MWP) in the late Holocene(1000-500 a BP) when permafrost was in a relative decline;(6) Little Ice Age(LIA) in the late Holocene(500-100 a BP), when permafrost relatively expanded, and;(7) Recent warming(during the 20 th century), when permafrost continuously degraded and still is degrading. The paleo-climate, geography and paleopermafrost extents and other features were reconstructed for each of these seven periods. 展开更多
关键词 PERMAFROST EVOLUTION Cryogenic wedge structures LOCAL LAST GLACIAL Maximum(LLGM) LOCAL Holocene MEGATHERMAL Period(LHMP) China
Vegetation pattern of Northeast China during the special periods since the Last Glacial Maximum
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作者 Xiaoqiang LI Chao ZHAO Xinying ZHOU 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第8期1224-1240,共17页
Since the Last Glacial Maximum(LGM), the global climate has experienced several stages, such as cold and warming events, which provide an ideal model for evaluating climate change in the future. Based on the pollen re... Since the Last Glacial Maximum(LGM), the global climate has experienced several stages, such as cold and warming events, which provide an ideal model for evaluating climate change in the future. Based on the pollen records in Northeast(NE) China, the vegetation pattern during special periods since the LGM was reconstructed in this work. During the LGM(approximately 18,000 cal yr BP), the steppes expanded rapidly in NE China, and a cold-dry meadow-steppe developed on the Songnen Plain. The Liaohe Plain and the Hulun Buir Plateau were occupied by a steppe-desert, with forest-steppe vegetation grown in the central and southern plains;there were cold-dry coniferous forests and mixed conifer-broadleaf forests in mountainous areas. In the early Holocene(10,000–9,000 cal yr BP), Changbai mountain(CBM) forests thrived in the eastern hilly area and the Sanjiang Plain, while the central region was dominated by steppes, and warm-temperate broadleaf forests developed northward. During the Holocene warm period(approximately 6,000 cal yr BP), CBM forests and cold-temperate coniferous forests developed in the north, while spruce-fir forests developed in the eastern Xiao Hinggan Mountains and the Sanjiang Plain. The distribution centre of deciduous broadleaf forests migrated to the south of the Changbai Mountains and the Liaodong Peninsula. The isolated woodlands increased on the Songnen Plain and the meadow-steppes expanded to the Liaohe Plain. Therefore, the increase in temperature leads to the increase of monsoon precipitation in NE China, which is beneficial to the development of warm-temperate forest vegetation. The increase of summer monsoons and precipitation caused by climate warming may be the main reason for the improved plant load. 展开更多
关键词 Last GLACIAL Maximum HOLOCENE WARM period Vegetation pattern NORTHEAST China
Spatiotemporal evolution of C3/C4 vegetation and its controlling factors in southern China since the last glacial maximum
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作者 Linlin CUI Jianfang HU Xu WANG 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第8期1256-1268,共13页
To date, few research have been reported on the evolution of C3/C4 vegetation in southern China, and the main mechanism influencing the evolution of C3/C4 vegetation is unclear. That makes it difficult for researchers... To date, few research have been reported on the evolution of C3/C4 vegetation in southern China, and the main mechanism influencing the evolution of C3/C4 vegetation is unclear. That makes it difficult for researchers to understand the competition mechanism of C3 and C4 plants under different climate environments and its relationship with the climate factors. It is also not conducive for researchers to assess the influence of future climate change on regional C3/C4 vegetation. Exactly, C3/C4 vegetation change in the regional-scale will have a significant impact on the global carbon cycle and agricultural production.Therefore, it is especially important to reconstruct the evolutionary history of C3/C4 vegetation in southern China and clarify the influencing mechanism of climate change. In this study, we systematically analyzed stable carbon isotope(δ13 C) of the longchain n-alkanes in sediment samples from eight lakes and four peat profiles in southern China, to reconstruct the spatiotemporal evolution of C3/C4 vegetation in these regions since the Last Glacial Maximum(LGM) and to investigate the climate factors that affect the C4 plant abundance change in the research area. The integrated long-chain n-alkane(C27–C33) stable carbon isotope results of samples from Zhanjiang Huguangyan Maar Lake, Xingyun Lake, Lugu Lake and Dingnan peat showed that, from the LGM to the Early Holocene, C4 plant relative abundance exhibited a gradually increasing trend from 21% to 34%. In the Middle Holocene, the C4 plant abundance significantly declined and reached a lowest value of 10%. In space, the C4 plant abundance generally exhibited a gradually declining trend from south to north in the LGM and the Early Holocene, while it showed an opposite trend in the Holocene Climate Optimum(6.0 cal ka BP). It reflected that the main influencing factor on C4 plants spatial distribution was changing from temperature to precipitation. This study indicated that temperature was the dominant factor affecting C4 plant distribution in southern 展开更多
关键词 Stable carbon isotope LONG-CHAIN N-ALKANES C3/C4vegetation Last GLACIAL Maximum Holocene Climate Optimum period
全新世以来珠江三角洲海鸥沙形成过程的地貌动力学分析 预览
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作者 莫文渊 韦惺 吴超羽 《热带海洋学报》 CAS CSCD 北大核心 2019年第3期68-78,共11页
海鸥沙是珠江三角洲一个极富特色的沉积砂体。本文基于钻孔资料并结合长周期“动力-沉积-形态”模型,从沉积学和地貌动力学角度对全新世以来海鸥沙的形成演变过程进行了探讨。海欧沙在全新世的沉积层序自下而上分别为河流相、河口湾浅... 海鸥沙是珠江三角洲一个极富特色的沉积砂体。本文基于钻孔资料并结合长周期“动力-沉积-形态”模型,从沉积学和地貌动力学角度对全新世以来海鸥沙的形成演变过程进行了探讨。海欧沙在全新世的沉积层序自下而上分别为河流相、河口湾浅海相和三角洲相。全新世海侵盛期以来,虎门涨潮射流和东北—西南向涨落潮流是影响海鸥沙形成演变的主要动力。6000—2500a BP,受东北—西南向涨落潮流的影响,海鸥沙中北部地区一直处于冲刷无沉积状态,由虎门涨潮射流带来的泥沙主要在海鸥沙南部沉积,沉积速率约为0.67mm·a^-1;2500—1700a BP,随着番禺平原的发育,东北—西南向涨落潮流逐渐消弱,海鸥沙进入一个快速沉积期,平均沉积速率约为15mm·a^-1,沉积由两端向中间发展;1700—600a BP,随着沙湾水道的形成,海鸥沙中部迅速发展,至600a BP 左右,海鸥沙基本形成并出露水面。 展开更多
关键词 珠江三角洲 海鸥沙 全新世 演变 长周期模型
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Spatial patterns of vegetation and climate in the North China Plain during the Last Glacial Maximum and Holocene climatic optimum
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作者 Manyue LI Shengrui ZHANG +2 位作者 Qinghai XU Jule XIAO Ruilin WEN 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第8期1279-1287,共9页
Reconstructing the spatial patterns of regional climate and vegetation during specific intervals in the past is important for assessing the possible responses of the ecological environment under future global warming ... Reconstructing the spatial patterns of regional climate and vegetation during specific intervals in the past is important for assessing the possible responses of the ecological environment under future global warming scenarios. In this study, we reconstructed the history of regional vegetation and climate based on six radiocarbon-dated pollen records from the North China Plain. Combining the results with existing pollen records, we reconstruct the paleoenvironment of the North China Plain during the Last Glacial Maximum(LGM) and the Holocene Climatic Optimum(HCO). The results show that changes in the regional vegetation since the LGM were primarily determined by climatic conditions, the geomorphic landscape and by human activity.During the LGM, the climate was cold and dry;mixed broadleaf-coniferous forest and deciduous-evergreen broadleaf forest developed in the southern mountains, and cold-resistant coniferous forest and mixed broadleaf-coniferous forest were present in the northern mountains. The forest cover was relatively low, with mesophytic and hygrophilous meadow occupying the southern part of the plain, and temperate grassland and desert steppe were distributed in the north;Chenopodiaceae-dominated halophytes grew on the exposed continental shelf of the Bohai Sea and Yellow Sea. During the HCO, the climate was warm and wet;deciduous broadleaf forest and deciduous-evergreen broadleaf forest, with subtropical species, developed in the southern mountains, and deciduous broadleaf forest with thermophilic species was present in northern mountains. Although the degree of forest cover was greater than during the LGM, the vegetation of the plain area was still dominated by herbs, while halophytes had migrated inland due to sea level rise. In addition, the expansion of human activities, especially the intensification of cultivation,had a significant influence on the natural vegetation. Our results provide data and a scientific basis for paleoclimate modelling and regional carbon cycle assessment in north China, w 展开更多
关键词 North China Plain Last GLACIAL Maximum HOLOCENE Climatic OPTIMUM POLLEN VEGETATION PALEOENVIRONMENT
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