Holocene alluvial environments at Barking,Lower Thames Valley (London,UK)     

C.P. Green  C.R. Batchelor  P.J. Austin  A.D. Brown  N.G. Cameron  D.S. Young 《Proceedings of the Geologists' Association. Geologists' Association》2014

Deposit modelling based on archived borehole logs supplemented by a small number of dedicated boreholes is used to reconstruct the main boundary surfaces and the thickness of the main sediment units within the succession of Holocene alluvial deposits underlying the floodplain in the Barking Reach of the Lower Thames Valley. The basis of the modelling exercise is discussed and the models are used to assess the significance of floodplain relief in determining patterns of sedimentation. This evidence is combined with the results of biostratigraphical and geochronological investigations to reconstruct the environmental conditions associated with each successive stage of floodplain aggradation. The two main factors affecting the history and spatial pattern of Holocene sedimentation are shown to be the regional behaviour of relative sea level and the pattern of relief on the surface of the sub-alluvial, Late Devensian Shepperton Gravel. As is generally the case in the Lower Thames Valley, three main stratigraphic units are recognised, the Lower Alluvium, a peat bed broadly equivalent to the Tilbury III peat of Devoy (1979) and an Upper Alluvium. There is no evidence to suggest that the floodplain was substantially re-shaped by erosion during the Holocene. Instead, the relief inherited from the Shepperton Gravel surface was gradually buried either by the accumulation of peat or by deposition of fine-grained sediment from suspension in standing or slow-moving water. The palaeoenvironmental record from Barking confirms important details of the Holocene record observed elsewhere in the Lower Thames Valley, including the presence of Taxus in the valley-floor fen carr woodland between about 5000 and 4000 cal BP, and the subsequent growth of Ulmus on the peat surface.  相似文献   

贵州雷公坪山地沼泽泥炭年代学和沉积速率研究     

张辉  李松  司云云  刘蕊  罗璇  何严华 《贵州地质》2021,38(4):382-386

通过对贵州东南部雷公坪泥炭进行年代学和有机碳同位素测定,雷公坪泥炭剖面底部150 cm处年龄为13 360±40 a BP,在中部70 cm处年龄为4 570±30 a BP,顶部10 cm处年龄为420±30 a BP,建立了雷公坪泥炭沉积的年代学序列,计算出泥炭层堆积速率由上至下分别为2381 cm·ka-1、1446 cm·ka-1、910 cm·ka-1。获得泥炭层泥炭有机碳同位素δ13C分别为-275‰、-288‰、-285‰,结合其他区域气候记录推断,说明研究区泥炭发育于相对温暖湿润的气候环境。  相似文献   

长白山圆池泥炭沼泽演变及环境信息记录   总被引：1，自引：0，他引：1  

张彦  史彩奎  王健  马小凡  吕宪国  王国平 《湿地科学》2012,10(3):271-277

通过分析长白山圆池泥炭剖面总有机碳含量、总正构烷烃含量、奇偶优势指数、(C23+C25)含量和2C31/(C27+C29)比值,讨论了泥炭发育不同时期植物输入情况,同时结合210Pb测年建立的年代序列来探讨该区的气候变化规律.研究结果显示,约1400年前,气候干冷,圆池尚没有出现沼泽化;1400年开始,气候稍暖,少量植物输入,圆池开始沼泽化;约从1860年至今,气候逐步转暖,大量植物输入,圆池沼泽化速度加快.  相似文献   

大兴安岭地区森林沼泽生态系统火生态效应研究   总被引：1，自引：0，他引：1  

杨永兴  杨玉娟  庞志平  杨永海 《海洋与湖沼》1995,26(6):610-618

于１９９０年５月－１９９３年１０月，为查清火灾对森林沼泽生态系统，采取野外面上考察与定位观测，野外实验与室内分析化验，定性分析与定量分析相结合的方法，在阿木尔林业局长缨林场、红旗林场选取观测点进行森林沼泽生态系统火生态效应的对比观测与实验。  相似文献   

New Holocene tephras and a proxy climate record from a blanket mire in northern Skye,Scotland     

P. G. Langdon  K. E. Barber 《第四纪科学杂志》2001,16(8):753-759

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Scale‐dependency of hydraulic conductivity: an example from Thorne Moor,a raised mire in South Yorkshire,UK     

J. Bromley  M. Robinson  J. A. Barker 《水文研究》2004,18(5):973-985

The hydraulic conductivity (K) of many low permeability materials is strongly scale‐dependent. In raised mires and other types of peat deposit the effects of features such as abandoned infilled ditches, root holes and localized woody material, cause K to be heterogeneous and scale‐dependent. Despite this, field measurements are routinely made using auger hole (slug) tests at the scale of only a few tens of centimetres. Such measurements are locally valid, but where the regional subsurface movement of water through peat bogs is simulated using groundwater models, typically at the scale of hundreds of metres, they give rise to a systematic underestimate of flows and an overprediction of water table elevations. Until now, techniques to obtain values at a scale sufficiently large to include the effects of localized features of higher permeability have not been applied routinely. Research at Thorne Moor, a large raised mire, demonstrates that the K of peat varies over several orders of magnitude when measured at different scales, using a variety of techniques. Laboratory and auger hole tests cannot be relied upon to provide results that represent the hydraulic conductivity of large expanses of peatland. This has significant implications for the management and long‐term restoration of peatlands where both regional and local control of water levels is crucial. For groundwater models to be used successfully to plan such schemes, it is essential to apply the K values relevant to the scale of the simulation. This paper describes and tests novel techniques, using ditches, for the derivation of K at large scales which overcome many of the problems that have been identified with conventional techniques and are capable of producing estimates that are appropriate to the application of physically based regional flow models. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

THE ECOLOGICAL FEATURES AND ECOLOGICAL CONSTRUCTIONS OF A MIRE IN CHINA     

黄锡畴 《中国地理科学(英文版)》1991,1(1):54-61

A mire as an ecosystem, usually is considered as an aquatic ecosystem,or a terrestrial ecosystem. The author thinks that mire is a special ecosystem between these two ecosystems, and proposes the new concept that a mire is a natural ecosystem with transitional nature of semi-water and semi-land formed by water and land interaction. The paper discusses the nature of the mire ecosystem, the exploitation and utilization and ecological construction of a mire.  相似文献   

Patterned fen development in northern Scotland: Hypothesis testing and comparison with ombrotrophic blanket peats     

Daniel J. Charman 《第四纪科学杂志》1995,10(4):327-342

Patterned fens are part of the diverse Holocene peatland landscape of the Flow Country, northern Scotland. Their present vegetation and morphology allies them with boreal systems in Scandinavia and North America. However, previous work has shown that their mode of formation is rather different and has suggested a developmental model in which the poor fens have formed only recently and have arisen as a result of local hydrological change. These ideas are tested here by morphological, stratigraphical and macrofossil studies on three additional patterned fens covering a wider geographical and ecological range. Two sites corroborate the hypotheses of the earlier study, and one site which refutes the earlier findings can be shown to be dependent on different topographic controls. A comparison of two patterned fens with an ombrotrophic mire site in the same area shows that hydroseral processes dominate the early development of individual components of the mire complex. The time of initiation of patterned fens coincides with increasing surface wetness on the ombrotrophic mire. This may be due to climatic change and/or the coalescence of the constituent parts of the present integrated blanket mire system. The hydrological changes arising from this led to the emergence of the springs that currently supply the patterned fens with their water and elevated nutrient levels. The study supports the idea that landscape-scale research and conservation are essential for the understanding and hydrological integrity of blanket mire landscapes such as the Flow Country.  相似文献   

中国1∶400万沼泽图的编制研究     

王化群 《湿地科学》2004,(1)

中国 1∶4 0 0万沼泽图是我国第一幅大范围的沼泽图件。本图及其附图以地图图像的形式 ,形象地、系统地总结和反映了我国有关单位近 4 0年来在沼泽方面的研究成果 ,表现了我国及主要典型区的沼泽及诏泽化土地的类型、特征、形成及其分布规律。重点反映适合我国沼泽特点并具有新观点的分类体系和分区体系。全国沼泽分类体系被分为四级 :类 (第一级 )、亚类 (第二级 )、型 (第三级 )、组 (第四级 )。全国沼泽化土地的分类系统也相应分为四级。主图表示沼泽和沼泽化土地的前三级类型 ,在作为插图 (2幅 )和附图 (4幅 )的典型区沼泽图 (1∶2 0万～ 1∶15 0万 )上侧重表示第四级类型。另一幅插图为《中国沼泽分区图》(1∶2 5 0 0万 ) ,全国被分为 8个沼泽区和 4 0个沼泽亚区。中国 1∶4 0 0万沼泽图采用综合图型 ,范围法与符号法 (分级定位符号 )相结合的表现方法 ,室内制图资料综合分析利用与野外验正和缩编相结合的编绘方法。  相似文献   

含煤岩系沉积学研究的几点思考   总被引：7，自引：1，他引：7  

张鹏飞 《沉积学报》2003,21(1):125-128,136

根据沉积学和煤地质学的理论和方法 ,对聚煤作用、聚煤中心、煤层在地层格架中的分布、煤的前身--泥炭和成煤基地--沼泽地 ,以及煤和煤系中的矿物组分--高岭石进行了介绍、分析、论述 ,并再次提出华北晚古生代海侵问题。  相似文献