Sedimentary Characteristics and Models of Paleo-salt Lake During Paleocene and Eocene in the Jiangling Depression of Central China

正1 Sedimentary Characteristics of Paleo-salt Lake In early sedimentary stages of Shashi formation,because of drought climate and the concentration of lake,a set of salt strata of hundreds of meters is developed in the tension     

淮北煤田芦岭井田二叠纪含煤岩系原生沉积构造序列与沉积环境

通过对保留在沉积物中与水动力条件有密切联系的原生沉积构造的观察和研究,分析了淮北煤田芦岭井田二叠纪含煤岩系属于以河流作用为主的建设性三角洲沉积环境,阐明了根据原生沉积构造序列解释沉积环境的基本方法.     

珠江口盆地西部珠三坳陷珠江组沉积演化

为了加强珠三坳陷珠江组的油气勘探理论,笔者从层序格架、岩芯特征、有孔虫分布、岩石类型及岩性组合等方面,分析珠三坳陷及周缘珠江组三个层序的沉积特征及沉积演化规律:从S50--S60～S40--S41层序,岩芯特征呈现规律性变化,砂岩粒度减小、分选性增强,水动力条件从强-较强-弱转变;有孔虫丰度变化从零星中低值--连续中高值--连续中值,水深从浅-深-较深,神狐隆起从局部出露到完全沉没。古珠江三角洲及海南隆起—粤桂隆起物源三角洲是S50-S60及S41-S50层序的重点沉积体系。从S50-S60～S40-S41层序,古珠江三角洲规模从"大--中--小"依次演变,海南隆起—粤桂隆起物源三角洲呈"大-大-小/无"变化,浅海迅速扩张,仅半深海分布较稳定。     

珠江口枯季盐通量数值模拟研究

采用数学模型手段对珠江河口的盐通量进行了计算和分析.该平面二维水流盐度模型范围包括珠江三角洲河网与八大口门在内,计算结果与实测值符合良好,较好地反映了模拟区域盐度场的时空分布特点.结果显示:珠江河口枯季大潮时的总盐通量为1 954×104t,小潮时总盐通量为512×104t,仅为大潮时的26.2％;无论是在大潮还是小潮期间,大虎和官冲的盐通量所占比例最大,说明盐水入侵主要是通过虎门与崖门这两个通道进入;盐通量沿程明显减少,这是盐度、水通量等沿程变化的综合作用.不同类型水体的盐度等值线在枯季大小潮期间的分布     

干旱区典型绿洲热场分布规律研究——以渭干河-库车河三角洲绿洲为例

 全球气候变暖给整个地球的生态环境带来巨大的影响,在全球气候变暖背景下,绿洲热场的变化严重影响绿洲的生态稳定性,利用遥感卫星影像来监测热场分布规律具有很强的现实意义。采用Landsat7 ETM+热红外波段定量反演晴空状态下干旱区典型绿洲地表真实温度,运用影像叠加分析、直方图比对、缓冲区分析、空间自相关分析及剖面线分析方法,分析其热场分布规律。结果表明,绿洲热场分布具有显著的正的空间自相关特性,Moran’s I值为0.5489,z检验值为48.44,同时呈现出显著的局部空间集聚现象; 就全局而言,热场分布规律为水体温度<耕地温度<林草地温度<城镇温度<裸地温度<盐碱地温度,均温分别为21.65 ℃、27.86 ℃、35.59 ℃、36.52 ℃、40.06 ℃、42.07 ℃; 就局部而言,盐碱地温度低于周边裸地温度,盐碱地平均温度比周边300 m、900 m、1 500 m缓冲区裸地的均温分别低0.59 ℃、0.44 ℃、0.26 ℃。水体、城镇、盐碱地、裸地的温度波动较小,热力景观单一,热场分布均匀,而耕地和林草地的温度梯度大,热力景观复杂多样,热场分布极不均匀。绿洲荒漠交错带的面积较大,它可以降低荒漠对绿洲的热力侵蚀,对保护绿洲有重要作用。     

NOAA6361活动区现象分析

本文分析了ＮＯＡＡ６３６１活动区中的一些现象，发现该活动区在衰亡阶段经历了两次同极性黑子的复合过程，复合后的黑子本影间均有光桥存在，观测结果倾向于支持Ｐａｒｋｅｒ１９７９年提出的黑子多磁流管模型。１４日复合后的黑子本影还顺时针方向旋转了约７０度角，从半影纤维的同样顺时针旋转可以认为：该黑子的半影磁场并非是普遍认为的简单的本影磁场的发散部分。我们还观测到另外两个比较有趣的现象：①δ黑子中的ｐ极性黑子     

Climatic variations in the coastal zone — Comparison between the Po River delta (Adriatic Sea,Italy) and the Huanghe River delta (Bohai Sea,China)

The aim of this work is to research the influence of natural climatic changes on the evolution of the coastal zone in modern times and the possible implication of human activities on the configuration of the present coastline. Comparison of data of two very far and different areas, the Po River delta, Adriatic Sea and the Huanghe River delta, Bohai Sea, reveals the planetary diffusion of climatic fluctuations and their effects on coastal evolution. Contribution No. 820 from the Marine Geology Institute, C. N. R., Italy. Contribution No.2207 from the Institute of Oceanology, Academia Sinica. Project supported by the National Natural Science Foundation of China.     

Depositional model and stratigraphic architecture of rift climax Gilbert-type fan deltas (Gulf of Corinth, Greece)

Facies, depositional model and stratigraphic architecture of Pleistocene giant Gilbert-type fan deltas are presented, based on outcrop data from the Derveni–Akrata region along the southern coast of the Gulf of Corinth, Greece. The common tripartite consisting of topset, foreset and bottomset [Gilbert, G.K., 1885. The topographic features of lake shores: Washington, D.C., United States Geol. Survey, 5th Annual Report, 69–123.] has been identified, as well as the most distal environment consisting of turbidites, and is organised in a repetitive pattern of four main systems tracts showing a clear facies and volumetric partitioning.The first systems tract (ST1) is characterised by the lack of topset beds and the development of a by-pass surface instead, thick foresets and bottomset beds, and thick well-developed turbiditic systems. This systems tract (ST1) is organised in an overall progradational pattern. The second systems tract (ST2) is characterised by a thin topset and almost no foreset equivalent. This systems tract is not always well-preserved and is organised in an overall retrograding trend with a landward shift in the position of the offlap break. The offshore is characterised by massive sandy turbidites. The third systems tract (ST3) is characterised by small-scale deltas prograding above the staked topsets of the giant Gilbert-type fan delta. Those small Gilbert-type fan deltas are generally organised in a pure progradation evolving to an aggradational–progradational pattern. In the distal setting of those small Gilbert-type fan deltas, almost no deposits are preserved on the remaining topography of the previous Gilbert-type fan delta. The fourth systems tract (ST4) is characterised by continuous vertically aggrading topsets that laterally pass into aggrading and prograding foresets. Bottomsets and distal turbiditic systems are starved. This fourth systems tract (ST4) is organised in an overall aggrading trend.These giant Gilbert-type fan deltas correspond to the Middle Group of the Corinth Rift infill and their stratigraphic development was strongly influenced by evolving rift structure. They record the migration of the depocenter from the rift shoulder to the rift axis in four main sequences from ca. 1.5 to 0.7 Ma, related to the migration of fault activity. It is worth noting that the maximum paleobathymetry was recorded during the final stage of the progradation of the Middle Group, suggesting that the rift climax was diachronous at the scale of the entire basin. The rapid (< 1 Ma) structural and sedimentological evolution, the migration of fault activity as well as the youth of the Corinth Rift, are probably exceptional factors allowing the characterisation of such diachronism.