唐山地区晚更新世以来的孢粉组合特征及其与邻区的对比     

李玉嵩  陈建强  赵硕  王海英  李欣 《地球学报》2011,32(2):178-188

通过对唐山市复兴路十中旧址钻孔更新统上部和全新统部分的60 m岩芯的沉积物及92件孢粉样品的分析, 建立了4个组合带, 总结了唐山地区晚更新世以来的植被演替和气候变化: (1)孢粉带Ⅰ, 以针阔混交林-草原为主, 气候温暖湿润; (2)孢粉带Ⅱ, 以疏林草原为主, 气候寒冷干旱, 为晚更新世以来环境最为恶劣的时期; (3)孢粉带Ⅲa, 植被为针阔混交林-草原, 气候温暖湿润; (4)孢粉带Ⅲb, 发育暗针叶林-草原, 气候寒冷湿润; (5)孢粉带Ⅲc, 植被为疏林草原, 气候寒冷略干; (6)孢粉带Ⅳ, 发育针阔混交森林, 气候温暖湿润, 为晚更新世以来水热条件最佳的时期。通过与邻区及全球冰芯、深海沉积研究成果的对比分析, 探讨了华北平原晚更新世以来的气候变化特点: MIS3的温湿条件显著优于MIS2和MIS4, 达到间冰期气候, 与MIS5相似, 局部地区甚至超过MIS1; MIS2不是一个持续干冷的过程, 而是一个由湿冷逐渐转向干冷的过程。此成果对探讨华北平原第四纪地层划分、对比和气候演化提供了科学依据。  相似文献   

甘肃省临夏盆地更新世早期湖泊沉积孢粉记录的古气候演化          下载免费PDF全文

董铭  方小敏  史正涛  明庆忠  苏怀 《第四纪研究》2011,31(1):104-111

根据孢粉组合特征,将临夏盆地早更新统东山组(2.50-1.76Ma)的孢粉划分为3个孢粉带(含6个亚带),即3个植被、气候阶段,第一阶段(2.50-1.91Ma,带Ⅰ),植被类型是以柏科、榆属和禾本科为优势种的温带森林,气候表现为温凉稍干,并有逐渐干旱化的趋势.第二阶段(1.91-1.80Ma,带Ⅱ)是以云杉属、榆属和...  相似文献   

Spatial variation patterns of subtidal seaweed assemblages along a subtropical oceanic archipelago: Thermal gradient vs herbivore pressure     

Carlos Sangil  Marta Sansón 《Estuarine, Coastal and Shelf Science》2011,94(4):322-333

The structure and composition of subtidal rocky seaweed assemblages were studied at 69 sites on the Canary Islands (northeastern Atlantic). This group of islands are situated at the southern boundary of the warm temperate region and adjacent to the cold waters from the northwest African coastal upwelling, which creates a difference of almost 2 °C in surface seawater temperature from the eastern to the western islands. This thermal variation allows an examination of the transition between the warm temperate and the tropical regions along this longitudinal gradient together with the hypothesised Fucales-dominated assemblages towards the eastern islands in contrast to the Dictyotales-dominated assemblages towards the western ones. Environmental and biological parameters were considered in order to investigate which were the main factors explaining spatial variation along the gradient in a multi-scaled approach. Although seventy-nine macroalgae were identified, 87.63% of the total mean cover was due to six taxa (Lobophora variegata, nongeniculate corallines, Canistrocarpus cervicornis, Jania adhaerens, Cystoseira abies-marina and Pseudolithoderma adriaticum). At a large scale, sea urchin density explained the highest variation in seaweed assemblages (26.94%), and its pattern of distribution across the islands. The expected pattern of distribution according to the upwelling distance only occurred in restricted areas of the Canarian Archipelago in absence of herbivore pressure and habitat degradation. Spatial variations within islands (medium scale) were mainly related to wave exposure, while at a small scale these were mostly due to the degree of sedimentation.  相似文献   

珠江三角洲晚第四纪红树林的演化及其环境意义     

翁毅  张伟强 《台湾海峡》2011,30(2):264-268

广州番禺东涌剖面样品的AMS（磁谱仪）年龄及红树林孢粉分析结果表明,珠江三角洲存在晚更新世和全新世的红树林,红树林是海侵的标志之一.按照检出红树属花粉的9个剖面的分布以及5处埋藏红树林腐木的分布,可以描绘出全新世海侵的边界.根据东涌剖面的沉积旋回、样品年龄、红树林花粉含量曲线、半咸水-淡水硅藻及热性-温性硅藻含量曲线的综合分析,可将沉积环境的变迁分为4个阶段.第一阶段和第三阶段的海侵有利于红树林的发展,第二阶段不利于红树林的发展,第四阶段的晚全新世,红树林的生长频繁,显示人为因素的影响.  相似文献   

中全新世福建沿海地区海平面波动：基于NDQK5岩芯介形类化石记录     

贾宝岩  彭博  王继龙  于俊杰  周保春  赵泉鸿  李保华  王亚琼 《地质学报》2024,98(2):333-345

福建沿海地区第四系较为发育,是研究晚更新世以来相对海平面变化的理想区域。本文以福建宁德NDQK5岩芯中产出的高分辨率介形类化石为研究对象,结合加速器质谱法(accelerator mass spectrometry, AMS)14C和光释光测年技术建立岩芯年代框架,重建了中全新世期间福建沿海地区的相对海平面变化。结果显示,NDQK5岩芯中的介形类化石记录主要分布于4~17. 1 m段,对应年代约为8. 2~6. 9 ka BP。岩芯内共计识别出海相介形类23属26种,根据优势种以及特征种的相对丰度变化特征可将岩芯内的介形类动物群划分为3个组合：① 介形类组合A以Bicornucythere bisanensis和Sinocytheridea impressa为主,代表潮下带环境;② 介形类组合B以Sinocytheridea impressa和Neomonoceratina delicata为优势种,指示近岸内陆架的沉积环境;③ 介形类组合C以Sinocytheridea impressa和Loxoconcha ocellifera为主,代表潮间带的沉积环境。基于介形类组合的分布特征,本文推断福建沿海地区海平面约在8. 2~7. 4 ka BP期间持续上升,并在约7. 9~7. 4 ka BP区间达到最高;7. 4~7. 0 ka BP期间海平面下降,随后再次上升。因此,介形类化石记录指示福建沿海地区在全新世高海平面背景下依然存在相对海平面的次一级波动。同时,结合已有福建沿海地区海平面变化驱动机制的研究结果,本研究推断8. 2~7 ka BP期间福建沿海地区的海平面变化可能主要受控于冰盖融水;7 ka BP后该地区的海平面波动可能受控于“冰川- 水均衡调整”作用。  相似文献   

Tectonic Zonation and Tectonic Rock Assemblages of Melange in Bangong Lake Area   总被引：1，自引：0，他引：1  

ZHOU Tao  LI Dewei  FENG Minxuan 《《地质学报》英文版》2013,87(Z1):200-200

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滴哨沟湾地层沉积特征记录的毛乌素沙漠变迁   总被引：15，自引：12，他引：3  

靳鹤龄  董光荣  左昕昕 《中国沙漠》2008,28(6):1064-1072

毛乌素沙漠的盛衰变化明显地受到全球变化特别是东亚夏季风变化的影响。根据毛乌素沙漠东南缘萨拉乌苏河流域滴哨沟湾地层沉积物的物质组成、粒度参数等,结合孢粉研究结果,将沙漠演化过程划分为若干阶段：中更新世晚期沙漠萎缩期,气候温暖半干旱-半湿润,沙漠缩小,为森林草原或灌丛草原;中更新世晚期沙漠稳定期,气候在寒冷干旱-半干旱间波动频繁,自然景观在荒漠、荒漠草原与干草原间变化,并有河流和小湖存在;晚更新世早期沙漠固定期,气候温暖半湿润至半干旱,期间自然景观经历了森林草原、灌丛草原、草原、荒漠草原多种变化;晚更新世晚期沙漠扩张期,气候干旱寒冷,自然景观以荒漠和荒漠草原为主,同时也有草原乃至灌丛草原出现;全新世沙漠频繁变化期,气候变化频繁,沙漠出现多次盛衰变化,自然景观在荒漠、荒漠草原、草原、疏林草原间变化。  相似文献   

Effects of the 'Prestige' oil spill on macroalgal assemblages: large-scale comparison     

Lobón CM  Fernández C  Arrontes J  Rico JM  Acuña JL  Anadón R  Monteoliva JA 《Marine pollution bulletin》2008,56(6):1192-1200

An assessment of the effects of the 'Prestige' oil spill on intertidal, macroalgal assemblages was carried out comparing abundance data obtained before and after the spill. Four zones in the North and Northwest coast of Spain were sampled, one of them located at the immediate vicinity of the spill, the zone most heavily oiled. Macroalgal assemblages had similar structure between years. Neither critical decrease in abundance of the dominant macroalgae, nor increase in opportunistic species were found. Some differences in abundance were observed, but they did not show any pattern, being more likely the result of the natural variability of the assemblage. Extensive, but not intense fuel deposition on the shores and a limited use of aggressive cleanup methods are suggested as possible causes for the lack of the effects in these assemblages after the 'Prestige' oil spill.  相似文献   

中国北方森林群落现代花粉与植被和气候的关系     

李月丛  许清海  张丽艳  王学丽  曹现勇  阳小兰 《地理学报(英文版)》2009,19(6):643-659

53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).  相似文献   

江苏宜兴骆驼墩、西溪遗址全新世软体动物   总被引：1，自引：1，他引：0  

黄宝玉  朱祥根  蔡华伟  林留根  田名利 《海洋科学》2005,29(8):84-94

江苏宜兴骆驼墩、西溪遗址化石丰富,除软体动物外,还有植物、孢粉、昆虫、脊椎动物等。作者研究的软体动物化石,计有8属17种,其中有一新种：Corbicula yixingensis Huang et Caisp．nov．,隶属于双壳类（Bivalvia）的殊蚌科（Unionidae）、蚬科（Corbiculidae）及腹足类（Gastropoda）的田螺科（Viviparidae）。可分成3个组合类群,一是Unio—Cuneopsis类群,本类群属种个体数量虽然少,但地质历程长,从第三纪晚期中新世至第四纪全新世均有,代表古老的类群。如：Cuneopsis spocki Leroy最早发现于内蒙古锡林郭勒盟二连第三纪晚期中新世通古尔期：Unio tschiliensis Sherany曾发现于河北张家口岔道口更新世早期,上述二种均未见现生种。二是Arconaia-Lamprotula类群。这个类群从第四纪早期至现代河、湖、池塘、水库中均有分布。其中Arconaia—laneceolata（Lea）见于江苏沭阳钱集西南更新世早期。Lamprotula（Sinolamprotula）leai（Gray）见于河南三门峡更新世早期。三是Corbicula-Bellamya类群。该类群时代长,分布广,适应性强,属种个体数量极多,其中Corbicula largillierti Heude从第三纪晚期至现代均有。化石种曾发现于内蒙古乌兰察布盟四子王旗第三纪晚期;山西垣曲,陕西大荔更新世早期：但在江苏金坛、江阴、宜兴的全新世时大量发育、繁衍、繁盛。以致现代长江流域太湖、洞庭湖、鄱阳湖及其相通的河流中也有,为中国广泛分布的特有种,本种似乎起源于中国内蒙古,而后向西、向南迁移。Bellamya quadrata（Benson）见于广西桂林南郊全新世,也有现生种。  相似文献