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971.
972.
环太湖地区汛期降水量与太湖水位的关系 总被引:2,自引:1,他引:1
本文利用环太湖地区站点的月降水资料,用曲面拟合方法作客观分 析,与太湖水位进行相关性研究。用环太湖地区的当月降水量建立下个月太湖水位 的预报方程。 相似文献
973.
层序地层体制中的陆相储层发育规律 总被引:46,自引:0,他引:46
沉积基准面旋回变化控制着陆相层序地层的形成与演化 ,并为预测陆相储层的发育与展布提供了一个参照格架。在纵向上 ,基准面旋回通过控制物源区的扩大与收缩、河流地貌的改造与变迁、沉积物的供给型式等 ,控制着储层形成条件与发育规律。基准面低位期是形成各类储集砂体和岩性圈闭的有利时期 ;在平面展布上 ,储层沉积作用受到古构造和古地理格局的制约 ,盆地内局部高地影响着水系的具体分布格局 ,古山口、侵蚀沟谷、古河道等决定着物源的搬运通道 ,古断层、古斜坡和坡折带等决定着沉积物卸载场所。因此 ,沟谷、河道等负向地貌单元与古断层、坡折带等地势梯度变化带相匹配的地理空间 ,是储集岩分布的有利所场。 相似文献
974.
Prediction and prevention of the impacts of sea level rise on the Yangtze River Delta and its adjacent areas 总被引:4,自引:0,他引:4
The Yangtze River Delta region is characterized by high density of population and rapidly developing economy. There are low lying coastal plain and deltaic plain in this region. Thus, the study area could be highly vulnerable to accelerated sea level rise caused by global warming. This paper deals with the scenarios of the relative sea level rise in the early half period of the 21st century in the study area. The authors suggested that relative sea level would rise 25 50 cm by the year 2050 in the study area, of which the magnitude of relative sea level rise in the Yangtze River Delta would double the perspective worldwide average. The impacts of sea level rise include: (i) exacerbation of coastline recession in several sections and vertical erosion of tidal flat, and increase in length of eroding coastline; (ii) decrease in area of tidal flat and coastal wetland due to erosion and inundation; (iii) increase in frequency and intensity of storm surge, which would threaten the coastal protection works; (iv) reduction of drainage capacity due to backwater effect in the Lixiahe lowland and the eastern lowland of Taihu Lake region, and exacerbation of flood and waterlogging disasters; and (v) increase in salt water intrusion into the Yangtze Estuary. Comprehensive evaluation of sea level rise impacts shows that the Yangtze River Delta and eastern lowland of Taihu Lake region, especially Shanghai Municipality, belong in the district in the extreme risk category and the next is the northern bank of Hangzhou Bay, the third is the abandoned Yellow River delta, and the district at low risk includes the central part of north Jiangsu coastal plain and Lixiahe lowland. 相似文献
975.
云南程海现代沉积物环境记录研究 总被引:9,自引:0,他引:9
本文通过对程海沉积物C、H、N等元素含量及其比值的综合分析,辨识了程海沉积物有机质H/C及C/N值的环境指示意义,发现它们增可作为程海水位波动及区域气候干湿变迁的替代性指标。研究结果表明:程海的水位和区域气候干湿主为化明显以历了两个不同的阶段,但整体上程海水位一直呈下降趋势,反映区域气候整体上向干旱化方向发展。 相似文献
976.
中朝地台南部下、中寒武统 (风台组—张夏组 )可划分 9个三级层序。除底部的 DS-A层序外 ,其余 8个层序均可与中朝地台大部分地区进行对比。下部的 3个层序 (DS- A~ DS-2 )属 型层序 ,其余为 型层序。研究表明 ,本区的沉积层序除受早古生代全球海平面变化控制之外 ,秦岭板块的俯冲对中朝地台南部层序地层的发育也具有一定的影响 相似文献
977.
978.
C. D. Woodroffe D. M. Kennedy D. Hopley C. E. Rasmussen S. G. Smithers 《Marine Geology》2000,170(3-4):331-346
The platform and fringing reefs of Torres Strait are morphologically similar to reefs of the northern Great Barrier Reef to the south, except that several are elongated in the direction of the strong tidal currents between the Coral Sea and the Gulf of Carpentaria. Surface and subsurface investigations and radiocarbon dating on Yam, Warraber and Hammond Islands reveal that the initiation and mode of Holocene reef growth reflect antecedent topography and sea-level history. On the granitic Yam Island, fringing reefs have established in some places over a Pleistocene limestone at about 6 m depth around 7000 years BP. Emergent Holocene microatolls of Porites sp. indicate that the reefs have prograded seawards while sea level has fallen gradually from at least 0.8 m above present about 5800 years BP. On the Warraber Island reef platform drilling near the centre indicated a Pleistocene limestone foundation at a depth of about 6 m over which reefs established around 6700 years BP. Reef growth lagged behind that on Yam Island. Microatolls on the mature reef flat indicate that the reef reached sea level around 5300 years BP when the sea was around 0.8–1.0 m above present. On the reef flat on the western side of Hammond Island bedrock was encountered at 7–8 m depth, overlain by terrigenous mud. A progradational reef sequence of only 1–2 m thickness has built seaward over these muds, as sea level has fallen over the past 5800 years. Reef-flat progradation on these reefs is interpreted to have occurred by a series of stepwise buildouts marked by lines of microatolls parallel to the reef crest, marking individual coalescing coral heads. Detrital infill has occurred between these. This pattern of reef progradation is consistent with the radiocarbon dating results from these reefs, and with seismic investigations on the Torres Reefs. 相似文献
979.
Catherine Schuur Duncan John A. Goff James A. AustinJr. Craig S. Fulthorpe 《Marine Geology》2000,170(3-4):395-421
Seafloor geomorphology and surficial stratigraphy of the New Jersey middle continental shelf provide a detailed record of sea-level change during the last advance and retreat of the Laurentide ice sheet (120 kyr B.P. to Present). A NW–SE-oriented corridor on the middle shelf between water depths of 40 m (the mid-shelf “paleo-shore”) and 100 m (the Franklin “paleo-shore”) encompasses 500 line-km of 2D Huntec boomer profiles (500–3500 Hz), an embedded 4.6 km2 3D volume, and a 490 km2 swath bathymetry map. We use these data to develop a relative stratigraphy. Core samples from published studies also provide some chronological and sedimentological constraints on the upper <5 m of the stratigraphic succession.The following stratigraphic units and surfaces occur (from bottom to top): (1) “R”, a high-amplitude reflection that separates sediment >46.5 kyr old (by AMS 14C dating) from overlying sediment wedges; (2) the outer shelf wedge, a marine unit up to 50 m thick that onlaps “R”; (3) “Channels”, a reflection sub-parallel to the seafloor that incises “R”, and appears as a dendritic system of channels in map view; (4) “Channels” fill, the upper portion of which is sampled and known to represent deepening-upward marine sediments 12.3 kyr in age; (5) the “T” horizon, a seismically discontinuous surface that caps “Channels” fill; (6) oblique ridge deposits, coarse-grained shelly units comprised of km-scale, shallow shelf bedforms; and (7) ribbon-floored swales, bathymetric depressions parallel to modern shelf currents that truncate the oblique ridges and cut into surficial deposits.We interpret this succession of features in light of a global eustatic sea-level curve and the consequent migration of the coastline across the middle shelf during the last 120 kyr. The morphology of the New Jersey middle shelf shows a discrete sequence of stratigraphic elements, and reflects the pulsed episodicity of the last sea-level cycle. “R” is a complicated marine/non-marine erosional surface formed during the last regression, while the outer shelf wedge represents a shelf wedge emplaced during a minor glacial retreat before maximum Wisconsin lowstand (i.e., marine oxygen isotope stage 3.1). “Channels” is a widespread fluvial subarial erosion surface formed at the late Wisconsin glacial maximum 22 kyr B.P. The shoreline migrated back across the mid-shelf corridor non-uniformly during the period represented by “Channels” fill. Oblique ridges are relict features on the New Jersey middle shelf, while the ribbon-floored swales represent modern shelf erosion. There is no systematic relationship between modern seafloor morphology and the very shallowly buried stratigraphic succession. 相似文献
980.
垃圾卫生填埋场渗滤液水头是填埋设计和场地管理的一个重要参数,一般很难获得。本文将Oweis等人提出的数学模型和解析解编制成一个计算机程序,仅需几个容易获得的计算参数就可以计算出垃圾填埋场渗滤液水位的年、月变化。 相似文献