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1.
东北地区向海湖泊沉积物正构烷烃单体碳同位素特征及其古环境意义 总被引：1，自引：0，他引：1
以松嫩平原西部向海1 420cm湖泊沉积物剖面为研究对象,根据AMS 14C年代信息建立末次冰消期以来的年代序列;结合沉积物类型、有机质丰度,重点对样品中正构烷烃及长链正构烷烃碳同位素等分子有机地球化学特征进行研究;通过综合对比各气候指标,重建该地区末次冰消期以来的古植被、古气候变化。结果表明:向海湖泊沉积物中正构烷烃的分布特征表明其主要来源于低等菌藻类生物和高等植物;正构烷烃的高碳数部分呈现明显的奇碳优势,高碳数部分主峰碳主要为nC31,指示有机质主要来源于陆生高等植物,且草本高等植物输入丰富;长链正构烷烃(nC27、nC29、nC31)稳定碳同位素整体呈偏正的趋势,并利用二元模式估算出湖区主要高等植被类型以C3植物占绝对优势,末次冰消期到全新世大暖期C4植物相对生物量增加;末次冰消期以来,研究区气候环境变化较不稳定,可分为5个阶段,分别为气候冷干的末次冰消期,气候冷湿的早全新世,气候暖干的中全新世大暖期前期,气候温暖湿润的中全新世大暖期后期以及气候温凉变干的晚全新世。 相似文献
2.
研究剖面位于洛川源北部的富县县城东郊。剖面由第一层古土壤(S_1)、马兰黄土(L_1)和全新世古土壤(S_0)组成。孢粉分析结果表明,黄土地层中孢粉非常丰富,为恢复古植被与古气候提供了可靠依据。S_1的植被是以榛、菊、蒿为主的疏林草原,有亚热带树种出现,反映了末次冰期的温湿气候。L_1时主要为菊、蒿干草原,气候冷干,其间有四次乔木增多期,反映了末次间冰期中有四次间冰阶的相对温湿气候波动。近代耕土中为以松、藜、中华卷柏为主的森林草原,反映了全新世某个时期比较温凉干旱的气候。 相似文献
3.
榆林长城沿线处于环境变化敏感带,其风沙滩区沉积剖面的磁化率和粒度分析结果显示,该区全新世早期11 500~10 000 a BP随着全球气候的逐渐转暖,磁化率、黏粒和粉沙含量逐渐增高;全新世中期的10 000~4 500 a BP气候相对比较湿润,植被覆盖度增大,风沙活动减弱,地表沉积物当中粉沙和黏土成分含量显著增大,风化成壤作用增强,地表发育沙质弱古土壤;全新世中期后段的4 500~3 000 a BP期间,气候以比较温和湿润为主,但在4 200~4 000 a BP出现一个气候干旱事件,风沙活动强烈;近3 000 a以来,气候显著干旱化,波动频繁,地表风沙沉积物显著变粗,表现出有5次沙漠扩张。该区生态环境演化、人文历史变迁基本上是自然因素与人为活动综合作用的结果,以自然演化为主,近代人为因素对环境变化起着加强和放大作用。 相似文献
4.
基于研究区施工的39个第四系浅层钻孔资料,通过系统采集粒度、孢粉、自然重砂、14C等样品,对研究区晚更新世以来地层结构、沉积类型及沉积相等进行了详细研究。结果表明,黑土湖组沉积早于10154BP,临沂组以1500~3500BP为主要沉积时期。晚更新世—全新世以来气候经历了温凉偏干、温暖湿润、趋于温凉3个阶段。粒度分析表明,于泉组为河床河漫滩沉积;第四纪沉积物主要来源为北侧胶北基岩隆起区,搬运距离短。对研究区第四纪沉积物按成因类型进行沉积相划分与对比,初步建立了沉积模式。 相似文献
5.
1、夏朝的玉龙 据杨伯达,在内蒙昭乌达盟夏家店文化下层,在内蒙昭乌达盟夏家店文化下层(距今4100～3500年,相当于夏朝)出土了如图1的玉猪龙二件.由于距红山文化时代久远,因此,不排除前代流传下来的可能性.但山西襄汾陶寺文化(距今4500～3900年)出土的彩绘纹陶盘,说明中原已从仰韶2500文化(距今7000～4500年)彩绘人格化鱼演化为鱼头、鳄嘴、角状耳、蛇身的龙. 相似文献
6.
甘肃通渭县黄土堆积区全新世环境变迁 总被引：5，自引：2，他引：3
通过对甘肃通渭县四家庙全新世黄土剖面的粒度和磁化率分析。并依据前人研究成果对年均气温和年均降水量的相应恢复，揭示了该区全新世期间气候演化的特点和规律。分析认为，研究区全新世以来的环境变化是不稳定的，无论古土壤发育期还是黄土堆积期，气候都具有频繁的次级波动。尤其在全新世中期。两层古土壤间的黄土夹层，反映该区在全新世大暖期经历过一次历时千年之久的气候显著恶化事件。 相似文献
7.
末次冰期后,在全新世大暖期及区域沉降的影响下,渤海湾沿岸普遍发育海侵现象,位于莱州湾南岸的潍北平原区在经历全新世最大海泛面后,海水退却过程中留下了数条古海岸线,形成了多处贝壳堤、牡蛎礁等海岸带遗迹。研究区内新发现常家村、后柳家2处牡蛎礁,其14C年龄分别为（5130±30）a B.P.和（6030±30） a B.P.;通过对区内全新世海陆交互相沉积关系及海相地层分布规律的研究,结合已有测年数据与近现代遥感影像数据,对潍北平原区全新世以来的海陆变迁进行了总结,恢复了自6000 a B.P.至公元1989年间的6条海岸线。 相似文献
8.
本文通过钱塘江深切谷的论述对末次冰期深切谷的恢复主要依据下列证据进行：（1）谷底为侵蚀不整合面，为末次冰期海平面下降，河流侵蚀切割所致；（2）谷内为异常厚的河流沉积物所充填，是冰后期海平面上升时形成，其中河漫滩沉积年代约14000～7500a以前；（3）深切谷之上被海相地层覆盖。超浅层生物气田分布在深切谷内，当今河流及全新世晚期河口湾与末次冰期深切谷既有区别又有继承性，其流域是浅层生物气藏分布的有利地段。 相似文献
9.
上新世晚期以来,随着青藏高原的强烈隆升柴达木盆地急剧下沉,其第四系最大厚度达2800m,沉积连续,地层保存完好,地质事件记录完整。水6孔位于柴达木盆地中心,孔深910.10m。根据水6孔孢粉、古地磁和同位素年龄系统成果,区分出冷热交替的22个孢粉带,并估计了年代。水6孔的气候地层序列不仅在古气候的冷热变动上,而且在年代上都可与赤道太平洋 V28—238井的δ~(18)O 气侯记录阶段和中国洛川黄土—古土壤序列详细对比,说明距今0.8Ma 以来柴达木盆地的古气侯冷热变动具有全球意义。 相似文献
10.
泥炭作为一种环境信息载体,在全球变化的研究中具有重要的作用。东北地区的哈尼泥炭地位于全球气候变化的敏感区域,研究意义更加显著。运用碱提取溶液吸光度法对东北哈尼泥炭腐殖化度进行了测定,结合14C测年数据,与泥炭纤维素δ18O时间序列相比较,较好地恢复了全新世哈尼地区的古气候状况,指出了哈尼地区的全新世气候演变的5个阶段:①11.5~9.8 kaBP气候温暖阶段;②9.8~9.0 kaBP气候急剧降温寒冷阶段;③9.0~4.8 kaBP气候温暖阶段;④4.8~1.8 kaBP气候冷暖交替波动阶段;⑤1.8~0 kaBP气候寒冷阶段。 相似文献
11.
ＴＨＥＨＯＬＯＣＥＮＥＳＥＤＩＭＥＮＴＡＬＣＨＡＲＡＣＴＥＲＩＳＴＩＣＡＮＤＰＡＬＥＯＣＬＩＭＡＴＩＣＥＶＯＬＵＴＩＯＮＯＦＥＢＩＮＵＲＬＡＫＥ，ＸＩＮＪＩＡＮＧ吴敬禄，王苏民，吴艳宏ＴＨＥＨＯＬＯＣＥＮＥＳＥＤＩＭＥＮＴＡＬＣＨＡＲＡＣＴＥＲＩＳＴ... 相似文献
12.
On the basis of lacustrine sedimentary profile of Ebinur Lake, sequences of evolution of paleoclimate and paleoenvironment
in Ebinur Lake area have been rebuilt by analysing the sedimentary stratigraphy, bio-stratigraphy and geochemistry as well
as the chronological records. The results show that, during the last 10 ka years, the general change trends of the paleoclimate
in E-binur Lake area can be divided into three stages: (1) 10. 2 – 8.3 ka B. P., a warm-cool dry climate stage; (2) 8.3–3.5
ka B. P., a warmer moist climate stage (specially, 7.3–6.4 ka B. P., a relatively stable humid temperate stage); (3) 3.5 ka
B. P. —present, adraught temperate climate stage, similar to the present climate. In addition, there existed clearly several
times of secondary undulations of dry-humid climate, i.e. 8.3 ka and 7.3 ka for dry climate 相似文献
13.
Information on the palaeoenvironment from Late Pleistocene to Holocene in northwestern Yannan Plateau has been deduced from a study of a 28.81m-long core taken from Napahai Lake.The results from Relative Brightness In-dex(RBI) as well as those from the lithological analyses of bulk sediments,total organic carbon and granulometric analy-ses have been used to reconstruct the environmental and climatic evolution of the area.The ages were provided by three ^14C datings.The record suggested a climate fluctuation between warm-dry and cool-wet from ca.57 to 32ka B.P.which led a shallowing and swamping of the lake.The water level again increased quickly at ca.32ka B.P.,reached itˊs peak during LGM(Last Glacial Maximum,ca.18-20kaB.P.)and remained relative high until ca.15kaB.P.The high wa-ter level at LGM is attributed to cold-wet conditions.The area experienced an abrupt and unstable climatic changes dur-ing the transition period form 15 to 10ka B.P.with a dominated littoral environment.Awarm-dry climate led to the contrac-tion of the lake during the Holocene and reed-swamps became dominant..After a minor wet-cool pulse during the Late Holocene,the modern climate became to be established. 相似文献
14.
ＲＥＳＰＯＮＳＥＯＦＲＩＶＥＲＴＥＲＲＡＣＥＳＴＯＨＯＬＯＣＥＮＥＣＬＩＭＡＴＩＣＣＨＡＮＧＥＳＩＮＨＥＸＩＣＯＲＲＩＤＯＲ,ＧＡＮＳＵ,ＣＨＩＮＡ①ＬｉＹｏｕｌｉ（李有利）ＹａｎｇＪｉｎｇｃｈｕｎ（杨景春）ＤｅｐａｒｔｍｅｎｔｏｆＧｅｏｇｒａｐｈｙ... 相似文献
15.
天水谢家湾全新世环境变迁及人地关系演化 总被引：2，自引：1，他引：1
在野外详细观测的基础上，对天水谢家湾全新世黄土剖面以2cm为间距进行了连续采样，并对所有样品作了磁化率和粒度分析，结果综合反映出研究区自全新世以来，经历了早期升温、中期基本暖湿、晚期趋于干冷的气候环境演化阶段，其中全新世中期在总体温湿的大背景下，存在频繁的气候波动。以此为基础，结合对渭河文化的历史研究资料，探讨了区内约1万年以来的人地关系演化历史，指出人地关系的和谐与统一，对人类社会发展具有重要意义。 相似文献
16.
Analysis of 13 spore-pollen assemblage zones reflecting environmental changes since the later middle Pleistocene showed the
seccession of paleovegetation and the paleogeographic changes in the Bohai Basin and circumjacent area. Paleoclimatic variations
here can obviously be divided into 5 cold and 5 warm periods: 2 cold and 1 warm periods in 200,000–100,000 a B.P.(late middle
Pleistocene) 3 cold and 3 warm periods in 100,000–12,000 a B.P.(late Pleistocene), and 1 warm period since 12,000 a B.P. Late
Pleistocene climate tended to become colder and colder. The coldest period was in the later stage of late Pleistocene, when
the study area was a periglacial zone. The mean annual temperature then was about 10°C lower than it is now. In the middle
stage of late Pleistocene, climate became warm; the mean annual temperature then was about 3–4°C higher than it is now.
By applying principles of climatic stratigraphy, the authors deduced through sporo-pollen analysis, that the boundary between
middle and late Pleistocene should be at 178–181 m, and that between Pleistocene and Holocene should be at 12.8 m. The results
of climatic stratigraphy are consistent with those of magnetic stratigraphy.
This paper was published in Chinese inOceanologica et Limnologia Sinica.18 (3): 253–266, 1987. 相似文献
17.
Sporo-pollen Assemblage and Paleoclimate Events in Shelf Area of the Southern Yellow Sea Since 1.5 ka B.P. 总被引：1，自引：0，他引：1
Based on the authors‘ 1986 to 1994 sporo-pollen assemblage analysis in the southern Yellow Sea area, data from 3 main cores were studied in combination with ^14C, palaeomagnetic and thermoluminescence data. The evolution of the paleoclimate environments in the southern Yellow Sea since 15ka B.P. was revealed that, in deglaciation of the last glacial period, the climate of late glaciation transformed into that of postglaciation, accompanied by a series of violent climate fluctuations. These evolution events happened in a global climate background and related to the geographic changes in eastern China. We distinguished three short-term cooling events and two warming events. Among them, the sporo-pollen assemblage of subzone A1 showed some cold climate features indicating that a cooling event occurred at about 15 - 14ka. B .P. in early deglaciation. This subzone corresponds to the Oldest Dryas. In subzone A3 , many drought-enduring herbal pollens and some few pollens of cold-resistant Picea, Abies, etc. were found, which indicated that a cooling event, with cold and arid climate, occurred at about 12- 11ka. B.P. in late deglaciation. This subzone corresponds to the Younger Dryas. The sporo-pollen assemblage of zone B showed warm and arid climate features in postglaciation. Although the assemblage of subzone B2 indicated a cold and arid climate environment, the development of flora in subzone B2 climate was less cold than that in A3 . Subzone B2 indicated a cooling event which occurred at about 9ka B.P. in early Holocene. Subzone A2, with some distinct differences from subzone A1 and A3 , indicated a warming event which occurred at 14 - 13ka. B.P. and should correspond to a warming fluctuation. The sporo-pollen assemblage of zone C showed features of warm-moist flora and climate, and indicated a warming event which universally occurred along the coast of eastern China at 8 - 3ka B.P. in middle Holocene, and its duration was longer than that of any climate events mentioned above. This period was climatic optimum and belonged to an altithermal period in postglaciation. 相似文献
18.
PALYNOLOGICAL RECORD OF PALEOVEGETATIONCHANGE DURING HOLOCENE AT NORTH TUMDPLAIN IN INNER MONGOLIA,CHINA 总被引：3，自引：0，他引：3
I~are~orsruDVThemiddleinnerMongoliaissituatedintherearpartoftheeasternAsianmonsonzone,itissensitivetotheclimatechange,thereforeitsenvironmentchangeintheHOIOcenehasbeenPaidattentiontobythescholarsofpaleoclimateandpal~nvirorunent.Wedidhighr~lutionPOllenanalysisonapeatprofileinpluvialfan,whichwaslocated3kmtothenorthOfQaSq,theheadquarteroftheTumdBanner,InnerMongolia,withaltitudeof1000malerssealevel.Theaverageannualtemperaturewas5.6t,annualprecipitation300--450rum,theclimatewascontinentaland… 相似文献
19.
Although the mid-late Holocene cold and dry event about 4000 years ago(the 4 ka event) has been observed almost globally, it was most prominent in terrestrial climate proxies from the lower latitudes. Here we evaluate the oceanic response to this event in terms of a Holocene sea surface temperature(SST) record reconstructed using the K'37U index for Core B3 on the continental shelf of the East China Sea. The record reveals a large temperature drop of about 5℃ from the mid-Holocene(24.7℃ at 5.6 ka) to the 4 ka event(19.2℃ at 3.8 ka). This mid-late Holocene cooling period in Core B3 correlated with(i) decreases in the East Asia summer monsoon intensity and(ii) the transition period with increased El Nino/Southern Oscillation activities in the Equatorial Pacific. Our SST record provides oceanic evidence for a more global nature of the mid-late Holocene climate change, which was most likely caused by a southward migration of the Intertropical Converge Zone in response to the decreasing summer solar insolation in the Northern Hemisphere. However, the large SST drop around Core B3 indicates that the mid-late Holocene cooling was regionally amplified by the initiation/strengthening of eddy circulation/cold front which caused upwelling and resulted in additional SST decrease. Upwelling during the mid-late Holocene also enhanced with surface productivity in the East China Sea as reflected by higher alkenone content around Core B3. 相似文献