最佳小波包基的矿区植被及红边位置提取

小波包变换能同时对植被光谱信息的低频和高频分量进行分解,并能克服小波变换时间分辨率高而频率分辨率低的缺陷从而具有能够探测植被细微变化的优势。实验利用Hyperion高光谱影像对云南省普朗铜矿区植被像元的光谱进行最佳小波包基参量获取与植被信息识别,并在此基础上提出一种提取重金属污染下植被红边位置的最佳小波包基系数应用模型。研究结果表明基于最佳小波包基参量的植被信息识别及基于最佳小波包基系数的重金属污染探测具有可行性与一定优越性。     

流动单元研究在乌石A油田扇三角洲沉积体系复杂储层的应用

乌石A油田为近年来在南海西部盆地新发现的油田之一,主要发育近源扇三角洲沉积体系,通过评价井产能测试和测压取资料表现出研究区储层渗流特征复杂,产能与测井解释储层物性相关性差,常规方法无法准确表征储层渗流特征。针对海上油田资料较匮乏的特点,应用流动单元研究思路,以微观孔隙结构特征分类为基础划分流动单元,总结归纳各类流动单元的微观与宏观特点,提出以分选性、电性、孔隙度3参数在全区范围内划分流动单元以及评价其产能,评价结果与实测结果吻合度较高,目前来看此方法能准确评价此类复杂储层,有效指导该油田后期开发部署。     

The Roaches and Ashover Grits: sequence stratigraphic interpretation of a ‘turbidite-fronted delta’ system

A single Upper Carboniferous fluvio-deltaic cycle (Namurian, R₂b5) in the south part of the Pennine Basin of northern England has been reinterpreted using a sequence stratigraphic approach. In upward succession the deposits comprise basinal mudstones, localized thick density current deposits, delta slope deposits and delta-top sandstones, followed abruptly by basinal mudstones. Earlier interpretations linked these elements with a single, mainly regressive, cycle, referred to as a turbidite-fronted delta. Recent evidence for strong glacio-eustatic sea-level fluctuations in the Namurian suggests that it is unlikely that the previous simple model can explain the spatial arrangement of all the lithological units. This paper attempts to identify elements of the Exxon sequence stratigraphic model, in which changes of sea level are an essential part. The basinal mudstones represent deep-water deposition and imply a highstand of sea level. Thick density current deposits are now known to be localized close to the basinward limit of delta progradation, so cannot be seen as a ubiquitous component of the depositional system. They may form a detached fan, or a fan located at the foot of the delta slope. Slope siltstones include turbidite-like sandstones, but these are interbedded with tractional sandstones and Pelecypodichnus trace fossils, giving no clear indication of water depth. The delta-top sandstones, some coarse and pebbly, can in places be shown to consist of two parts separated by a significant erosion surface now regarded as a type 1 sequence boundary. The erosion surface is locally incised about 80 m into the delta deposits, forming a major palaeovalley. Giant cross-beds (foresets 20 m thick) forming part of the palaeovalley fill are restricted to the basinward end of this feature. A curve of relative sea level inferred for the R₂b5 interval suggests a fourth-order cycle in which two sharp rises are separated by a gradual fall. Possible minor (fifth-order) rises and falls may be superimposed. © 1997 John Wiley & Sons, Ltd.     

鼎湖山自然保护区大气气溶胶中的PAHs

多环芳烃（PAHs)是环境中分布广泛、危害人类健康的有机化合物，通过对鼎湖山自然保护区自然地理和大气气溶胶中苯并（a)芘分析认为，春季样品中大气气溶胶中PAHs主要来源于高等植物排放，夏季来源于珠江三角洲经济区化石燃烧排放。     

珠江三角洲城市地质问题及对策

珠江三角洲地区的城市地质问题主要有地表塌陷、地裂缝、泥石流、滑坡和崩塌以及软土沉陷等。其成因除最直接的自然因素所致外,还有人为不合理的生产和生活活动诱发而加剧城市地质问题的发生发展。根据珠江三角洲城市地质问题的现状,提出了城市地质问题的防治对策。     

黄河三角洲北部贝壳堤岛的近期演变

通过不同年代地形图、卫星影像的对比及野外实地测量等,综合分析了黄河三角洲北部开敞型和潮沟型两类贝壳堤岛近50年来的数量和面积变化及其演化特征。结果表明,该区两类贝壳堤岛自20世纪50年代以来在自然和人为因素的共同作用下发生了明显的变化,但其演化特征因岛屿成因的类型差异而各不相同。目前,该区贝壳堤岛群逐渐萎缩,人类活动已成为影响三角洲北部两类贝壳堤岛发育演变的主导因素,特别是潮沟型贝壳堤岛,基本上结束了自然演化的历史,呈现出新的演化特征。     

废弃的黄河三角洲的地形特征及演化

根据2005年开展的海底地形调查资料并结合前人资料,对废弃的黄河口三角洲海区的海底地形特征及演化进行了分析。通过分析表明,近20年来,本区海岸处于侵蚀状态,蚀退速率约在50～80 m/a之间,海底地形处于冲涮状态,5m和10m等深线向岸方向移动600～900 m左右。     

Depositional evolution of a progradational to aggradational,mixed-influenced deltaic succession: Jurassic Tofte and Ile formations,southern Halten Terrace,offshore Norway

Predicting the hydrodynamics, morphology and evolution of ancient deltaic successions requires the evaluation of the three-dimensional depositional process regime based on sedimentary facies analysis. This has been applied to a core-based subsurface facies analysis of a mixed-energy, clastic coastal-deltaic succession in the Lower-to-Middle Jurassic of the Halten Terrace, offshore mid-Norway. Three genetically related successions with a total thickness of 100–300 m and a total duration of 12.5 Myr comprising eight facies associations record two initial progradational phases and a final aggradational phase. The progradational phases (I and II) consist of coarsening upward successions that pass from prodelta and offshore mudstones (FA1), through delta front and mouth bar sandstones (FA2) and into erosionally based fluvial- (FA3) and marine-influenced (FA4) channel fills. The two progradational phases are interpreted as fluvial- and wave-dominated, tide-influenced deltas. The aggradational phase (III) consists of distributary channel fills (FA3 and FA4), tide-dominated channels (FA5), intertidal to subtidal heterolithic fine-grained sandstones (FA6) and coals (FA7). The aggradational phase displays more complex facies relationships and a wider range of environments, including (1) mixed tide- and fluvial-dominated, wave-influenced deltas, (2) non-deltaic shorelines (tidal channels, tidal flats and vegetated swamps), and (3) lower shoreface deposits (FA8). The progradational to aggradational evolution of this coastal succession is represented by an overall upward decrease in grain size, decrease in fluvial influence and increase in tidal influence. This evolution is attributed to an allogenic increase in the rate of accommodation space generation relative to sediment supply due to tectonic activity of the rift basin. In addition, during progradation, there was also an autogenic increase in sediment storage on the coastal plain, resulting in a gradual autoretreat of the depositional system. This is manifested in the subsequent aggradation of the system, when coarse-grained sandstones were trapped in proximal locations, while only finer grained sediment reached the coastline, where it was readily reworked by tidal and wave processes.     

Seasonal variation of suspended-sediment transport through the southern Bohai Strait

Based on field observations made in winter 2006 and summer 2007 and on multiscene MODerate resolution Imaging Spectrometer (MODIS) imagery, the seasonal variation of suspended-sediment transport in the southern Bohai Strait and its possible mechanisms are examined. The field observations in two different seasons allow an exponential empirical model to be used to retrieve suspended-sediment concentration (SSC) from MODIS imagery. Both the field-survey data and the MODIS-derived SSC show that the sediment transport in the southern Bohai Strait has a significant seasonal variation due to the seasonally varying thermohaline structure of the water column and the hydrodynamics resulting from the seasonally alternating monsoons. The SSC in winter is approximately 3–10 times higher than in summer. Considering the seasonal variation of water flux (WF) and SSC, the annual sediment flux (SSF) through the southern Bohai Strait is estimated to be approximately 40.0 Mt yr⁻¹, about 4–8 times previous estimates, which did not take into account seasonal variation. Although the Huanghe (Yellow River) discharges a large amount of sediment in the summer, the SSF through the southern Bohai Strait in the winter (∼32.0 Mt) is about 4 times greater than it is in the summer. The strong seasonal variability of SSF through the southern Bohai Strait indicates that strong resuspension along the coast of the Huanghe delta in winter and enhanced longshore transport by coastal currents due to winter monsoon activity might be the major mechanisms of cross-strait transport of sediment in winter.     

The Sediment Source and Transport Trends around the Abandoned Yellow River Delta,China

Sediment source and transport trends are influenced by various hydrodynamic factors, and thus play important roles in sedimentary evolution and coastal stability. To examine sediment transport trends around the abandoned Yellow River delta promontory and its erosion mechanism, we employ empirical orthogonal function (EOF) analysis to study sedimentary characteristics and transport trends of the abandoned Yellow River delta in northern Jiangsu Province, China. The results showed that: (1) the main sediment source in the abandoned Yellow River delta is the submarine coastal slope and both sides of the abandoned Yellow River Delta; (2) the main hydrodynamics controlling sediment transport is the current that runs along the shore, coupled with waves, especially southward currents; (3) the sediment of the study area was redistributed under hydrodynamics; coarse sediments were eroded and broadly transported to the south. Therefore, it is concluded that the sediment sources and transport have important influence on coastal evolution: the sediment source area shows mass loss of deposits and erosion; deposits in the submarine coastal slope provide the source and were continuously eroded to provide materials to other places as a sediment source.