Preliminary analysis of grain-size populations with environmentally sensitive terrigenous components in marginal sea setting

Terrigenous components were separated from the bulk sediment of Core A7 from the Okinawa Trough and Core A37 from the Ryukru Trench and grain-size distributions of these sub-samples were analyzed.Based upon and analysis of the grain-size data of the two sedimentary sequences,grain-size populations are identified to be sensitive to sedimentary environmental changes.The modal values and size ranges of the two main grain-size populations in Core A7 are evidently different from those of Core A37,indicating the spatial variability of sediment sources and transport processes between the two places.The downcore variations in the content of the environmentally sensitive sgrain-size populations reveal that during the accumulation of sedimentary material the environment remained relatively stable at the site where Core A7 was collected,except for the apparent events for the formation of two turbidite layers and a volcanic ash layer.However,the sedimentary sequence of Core A37 shows six sedimentary cycles,indicating a highly variable sedimentary environment at this location.     

长江下游巢湖湖泊沉积物的粒度特征与沉积环境

在巢湖取得3个有代表性的沉积物柱样,用激光粒度仪对其进行粒度分析,并用137Cs法测定了沉积速率.结果表明,沉积物的粒度特征随着湖区的水动力条件的波动而发生有规律的变化.近百年来湖区的沉积环境基本上比较稳定,C1、C2和C3三个研究区的沉积速率分别为0.29cm/a,0.35cm/a和0.24cm/a.根据粒度和沉积速率特征,两百多年来,巢湖存在两个洪水期和两个平水期,这些变化与巢湖自然环境和人类活动有着密切关系.     

沉积相的定量判别

本文提出了沉积相定量判别的一种新方法。选用多总体判别方法,在参数上不仅选择了粒度参数M_z,σ_1,Sk_1和K_G,还选用了与沉积相关系密切、在薄片中很易获取的成份参数,包括成份成熟度、杂基含量和胶结物的含量。利用多总体判别分析法建立起的粒度判别函数和成份判别函数不仅适用于两沉积相之间,也适用于多沉积相之间的判别,其正判率分别达76％和87％,高于Sahu判别式的正判率。这对于复杂沉积体系中沉积相(环境)的定量研究有一定参考价值。     

黄河下游原阳段沉积物粒度特征与沉积环境分析

为探究现代黄河下游沉积环境演化,在原阳段钻取了两个钻孔岩芯(YHX-1、YHX-2),通过对钻孔沉积物粒度测试与分析,运用沉积物粒度参数、频率曲线与概率累积曲线,结合沉积物岩性及周边钻孔年代信息,划分研究区钻孔地质年代,揭示研究区沉积水动力条件及环境演化历史。结果表明：YHX-1分为7个沉积段,YHX-2钻孔为11个阶段,中更新世时期,两根钻孔以中细砂为主,沉积相以河床亚相为主;晚更新世时期,钻孔经历短暂河漫滩微相,进入漫长的河床相沉积;全新世早期,YHX-1钻孔由湖泊沼泽沉积转变为河漫滩沉积,YHX-2钻孔为河漫滩沉积;全新世晚期,黄河改道流入当今河道,两根钻孔河床沉积相对比分析表明,改道后黄河主河道经历由北向南的变迁过程。     

High—resolution records of Holocene from the Shuangchi Maar Lake in Hainan Island

The results of sedimentary characteristics,grain-size,clay mineral,C/N and pollen analysis reveal the evolution history of the Shuangchi Maar Lake of Hainan Island as well as the short-term climate variations in tropical areas.It is testified that the Maar sediment system was sensitive in recording the rapid climate changes in the Holocene.These multidisciplinary results demonstrate that the thermal maximum in the Holocene climate lasted from 7200 to 2700 aBP,with serveral abrupt ephemeral vibrations occurring between 7250-6120aBP and at around 4460,3850 and 2700 aBP.In the late Holocent,particularly at -2700 aBP,a distinct environmental change indicating an important climate transition in the tropical eastern Asia was recorded,probably responding to the enhancement of ENSO phenomena in the Pacific Ocean.In addition,the high-resolution algae record clearly indicates periodical climate fluctuations at 500 a cyclicity during the last 2500 years.     

鄂西七姊妹山泥炭藓湿地沉积物粒度特征及其环境意义探讨

以鄂西七姊妹山泥炭藓湿地QZMS钻孔沉积物为研究对象,通过AMS14C测年、岩性特征与沉积物粒度综合分析,探讨了鄂西南山地13 000 cal. a BP以来的沉积环境变迁.研究结果显示：QZMS钻孔沉积物粒度组成主要以细粉砂和中粉砂为主,频率分布曲线均为单峰分布,由下至上,峰度由宽到窄,偏度从近于对称到正偏,揭示了搬运动力和沉积环境的演变过程;综合分析结果表明研究区沉积环境演化可分为4个阶段：1) 12.9～11.6 cal. ka BP,气候波动频率高,但幅度较小,水动力条件相对较弱;2) 11.6～10.2 cal. ka BP为晚更新世向全新世的过渡阶段,水动力条件持续较弱,环境相对稳定;3) 10.2～7.7 cal. ka BP早全新世,气候变得暖湿,水动力条件较前一阶段有所增强,泥炭藓湿地开始形成;4) 7.7～2.0 cal. ka BP气候暖湿,水动力条件达到最强,峰度和偏度波动频率低,但幅度增大,为沼泽湿地环境.研究表明七姊妹山泥炭藓湿地沉积物的粒度粗细与区域内水文条件和物源的变化密切相关,借助粒度组成和参数特征,可反演该区域的沉积环境演变,揭示泥炭藓湿地发育形成的过程,为该地区泥炭藓湿地的保护和气候环境变化研究提供科学参考.     

昌福山矿区童子岩组三段上亚段沉积特征及聚煤环境分析

通过对昌福山矿区主要含煤地层的沉积特征,即鲕粒、结核、层理、岩矿、古生物及煤质等分析,总结出昌福山矿区童子岩组第三段上亚段地层的沉积环境为:3号煤层为河控三角洲相沉积;5号煤层为下三角洲平原型沉积;7号煤层为海湾潮坪型沉积;9号煤层为独立障壁岛泻湖沉积。研究成果对区内煤岩层对比具有重要意义。     

Recent 2000-year geological records of mud in the inner shelf of the East China Sea and their climatic implications

AMS^14C dating and grain-size analysis for Core DD2, located at the north of the Yangtze River-derived mud off the Zhejiang-Fujian coasts in the inner shelf of the East China Sea, provide us a high-resolution grain-size distribution curve varying with depth and time. Data in the upper mud layer of Core DD2 indicate that there are at least 9 abrupt grain-size increasing in recent 2000 years, with each corresponding very well with the low-temperature events in Chinese history, which might result from the periodical strengthening of the East Asian Winter Monsoon (EAWM), including the first-revealed maximum temperature lowering event at around 990 a BP. At the same time, the finer grain size section in Core DD2 agrees well with the Sui-Tang Warming Period (600--1000 a AD) defined previously by Zhu Kezhen, during which the climate had a warm, cold and warm fluctuation, with a dominated cooling period of 750-850 a AD. The Little Ice Age (LIA) can also be identified in the core. It starts around 1450 a AD and was followed by a subsequent cooling events at 1510, 1670 and 1840 a AD. Timing of these cold events revealed here still needs to be further verified owing to some current uncertainty of dating we used in this study.     

Sedimentation processes and sedimentary characteristics of tidal bores along the north bank of the Qiantang Estuary

A tidal bore is a unique Earth surface process, characterized by its highly destructive energy, predictable periodicities and magni-tudes, and the production of characteristic sedimentary features. Tidal bores and associated rapid flood flows are highly turbulent flows of the upper-flow regime with a velocity over several meters per second. Reynolds (Re) and Froude (Fr) numbers, respectively, are larger than 104 and 1.0, making them significantly different from regular tidal flows but analogous to turbidity currents. Until now, understanding of tidal-bore depositional processes and products has been limited because of the difficulty and hazards involved with gauging tidal bores directly. The Qiantang bore is known as the largest breaking bore in the world. Field surveys were carried out in May 2010, along the north bank of the Qiantang Estuary to observe the occurrence of peak bores, including regular observations of current, water level and turbidity at the main channel. Several short cores were sampled on the intertidal flats to study the characteristic sedimentary features of tidal bores. Hydrodynamic and sedimentological studies show that the processes of sediment resuspension, transport and deposition are controlled primarily by the tidal bores, and the subsequent abruptly accelerated and decelerated flood flows, which only account for one tenth of each semidiurnal tidal cycle in the estuary. Tidal-bore deposits are generally poorly sorted because of rapid sedimentation after highly mixed suspension by intense turbulence. This behavior is characteristic of the absence of tractive-current depositional components in a C-M diagram. It also goes along with well-developed massive bedding, graded bedding, basal erosion structures, convolute bedding and dewatering structures. Together, these sedimentary features can constitute fingerprinting of turbidites, widely distributed in the deep-water environment. However, a tidal bore is triggered by intensely deformed tidal waves propagating into a shallow-water environment, which returns to regular tidal flows rapidly after the passage of the bore head. The tidal-bore deposits are usually bounded by the intertidal-flat deposits with typical tidal beddings at the top and on both flanks. The difference between tidal-bore deposits (TBD) and tidal sandy/muddy deposits (TSD/TMD) is evident not only in sedimentary structures, but also in the grain-size composition. They can be clearly distinguished in grain-size bivariate plots, typically the plot of mean grain size vs. standard deviation (or sorting). Some trend variations generally exist in mean grain size with TBD>TSD>TMD, sorting with TMD>TBD>TSD (larger value indicating poorer sorting), and both skewness and kurtosis with TSD>TBD>TMD. These findings will undoubtedly shed new light on our understanding of tidal-bore sedimentology, ancient tidal-bore sedimentary facies and environments, and related oil-and-gas field prospecting.     

贵州中三叠世盘县动物群产出地层的稀土元素特征及其地质意义

对产出盘县动物群化石的贵州羊件剖面岩石样品中稀土元素含量(质量分数)变化规律进行了研究,结果表明：剖面大部分沉积时间是处于弱还原的沉积环境;样品中稀土元素含量的异常波动主要受当时的火山作用影响,其沉积物物源有2大类4亚类,分别来自拉斑玄武岩和沉积岩;沉积岩样品的轻稀土、中稀土、重稀土配分极为相似,表现为稳定的演化特征,指示出当时剖面所处位置的构造环境较为稳定。     

Age of long sediment cores from Lake Baikal

The new BDP-98 drill core of the Baikal Drilling Project is a key palaeoclimate record in continental Asia because globally sensitive sedimentary records of such length and continuity are very rare. Kashiwaya et al. have attempted signal processing of the BDP-98 average grain-size record, but in constructing their age model they excised a 100-metre interval from the 600-metre section, stating that it is "erroneous". On the basis of our lithological studies, we consider that this excision is unjustified.     

惠民凹陷西部沙三段三角洲和浊积扇砂体的粒度特征

本文分析了惠民凹陷沙三段三角洲和浊积扇砂体的475块样品,用福克公式计算了它们的粒度参数,并用计算机绘制了概率图、C-M图以及其它图件。综合岩性、沉积构造等资料,总结了三角洲和深水浊积扇亚环境的概率图特征,指出概率图的垂向变化也能反映沉积环境的变迁。根据岩芯观察,解释了三角洲和深水浊积扇 C-M图不同段的沉积环境意义,同时也研究了成岩作用对粒度特征的影响。研究表明,研究区内成岩作用并不显著,粒度资料基本反映了沉积物沉积时的水动力条件和沉积环境。强调指出了使用粒度资料时应综合岩性、电性、沉积构造等多种信息,才能对沉积环境进行正确分析、判断。     

浙江省内不同成土母质红土粒度特征比较

浙江省内7个典型红土剖面红土粒度测试表明：（1）浙江省内红土发育母质多样,沉积环境和母岩性状对红土粒度特征的控制意义较为显著,粒度组成能够有效区分不同成因的红土类型．（2）金华汤溪（TX）、浦江上山西南（SSSW）、安吉（AJ）、金华湖海塘（HHT）剖面红土以粉砂粒组占优势,粘粒含量次之,但TX、SSSW、AJ剖面砂含量很小,均值0．13％～1．18％;HHT剖面125～2000μm之间粗粒组分明显．前者显示风成特性,后者受风动力以外其他近源动力改造．风成特性加积型红土的存在对于认识第四纪期间风尘沉积物在长江以南地区的分布和季风演化信息具有重要意义．（3）基岩风化壳型红土的粒度组成因母岩性质而不同．相比较,众数峰值以砂岩红土最粗（30—63μm）,花岗岩红土次之（15—30μm）,玄武岩红土最细（4—6μm）．此外,花岗岩红土在125～2000μm之间有明显的中粗砂组分;玄武岩红土在0．2—1．0μm之间有明显的粘粒组分;砂岩红土除众数粒度峰外,在2—4μm以及0．2—1．0μm之间还存在多个分量．玄武岩红土比砂岩和花岗岩红土更均化．     

剥谱方法解析海洋沉积物粒径谱

建立了剥谱解析沉积物粒径谱方法，该方法用高斯函数表示每个组分的粒径谱，由总谱数据确定高斯函数参数．应用该方法对胶州湾沉积物粒径谱进行了分析．分析结果显示：胶州湾不同站点沉积物的细粒径组分比较相似．显示其来源一致性；粗粒径组分则随着采样站点的不同存在显著的差异．     

矩值法和图解法计算山区河流沉积物粒度参数的差异

在宜昌市山区小河莲沱溪采集一组以粗砂和极粗砂为优势粒度组成的沉积物样品,在筛析法进行粒度分析的基础上,用矩值法和图解法分别计算沉积物的粒度参数,并对两种方法所得的结果进行对比.两种计算方法得到的平均粒径和分选系数十分接近,基本上可以互相替代.峰态呈一定的相关性,但不可互相代替.偏态较为离散,不具有明显的相关性.分析发现...     

Interpreting grain-size trends associated with bedload transport on the intertidal flats at Dafeng, central Jiangsu coast

IN THE MARINE ENVIRONMENT, IT IS OFTEN DIFFICULT TO IDENTIFY THE NET SEDIMENT TRANSPORT PATHWAY BECAUSE OF THE COMPLICATED HYDRODYNAMICS AND SEDIMENT SOURCES. GAO AND COLLINS HAVE RE-EXAMINED A 1-D MODEL ORIGI- NALLY DERIVED BY MCLAREN AND BOWLES AND DEVE…     

长江河口及其水下三角洲的沉积特征和沉积环境

近两千年来,长江河口河道束狭淤浅,南岸边滩伸展,河槽成形,河道加深,形成现代河口的形态。长江河口的沉积物分布是和河口地形及水下三角洲的发育密切相关的。本文研究了沉积特征以及它与沉积环境、地貌和水文特征之间的关系。大量材料分析表明,沉积物的粒度大小和水动力条件相适应,分选系数、偏态和中值粒径之间有相关性。长江河口可分为四个沉积区:河口段上段沉积区;河口分汊河段沉积区;河口拦门沙沉积区;水下三角洲沉积区。     

A study on environmental changes based upon cladoceran assemblages from the core sediments in Chen Co,southern Tibet

A consecutive sediment core (CC2) was drilled in Chen Co (lake) of southern Tibet using a PISTON sampler in 1998 AD. Cladoceran remains including their species,amount richness and ecological features are analyzed for the top 117 cm sections of the core, upon which 5 cladoceran assemblages are distinguished. CL0 is an assemblage without any cladocera in the depth between 117-105 cm. CL1 assemblage (depths between I01-77 cm, ca.1407-1533 AD) possesses total 9 cladoceran species that appear in the core,and performs the greatest richness in the whole sequence.This assemblage reflected that there was plenty of exotic cold water and organic debrises inputing to the sedimentary site under the warmer conditions. The lake was wide and shallow that satisfied the big hydrophyte living. Cladoceran species and richnesses of CL2 assemblage (depths between 77-29cm, ca. 1533-1831AD) perform much more decreasing than those of CLI. There was only less Chydorus sphaericus which was acclimatized to wide environmental ranges. This implied that the sedimentary environment is so execrable that most of cladoceran lost their living abilities. Compared with CL1 assemblage, CL3 assemblage (depths between 29-10 cm, ca.1831--1941 AD) possesses nearly the same dominant species but lower richnesses. Especially, the cladoceran preferring organic debris also decrease in their amounts. This meant that the surface vegetation in the drainage basin was still poor though the environment turned to be better. Except the 2 zooplankton species, the other 7 species of cladoceran in this core are found in CL4 assemblage (depths between 10-0cm, ca. 1941-1998 AD), in which the eurythermal species had not performed their competition ability comparing withnarrow-temperatures adapted species. It implied that water temperatures were stable and much more influenced by air temperatures under the shallow-water conditions. The environmental features reflected by cladocera assemblages of CC2 core are fully supported by the evidences from ostracoda assemblages, diatom-salinity transfunction, environmental magnetism and relative proxies of the parallel CC1 core. Cladoceran assemblages in the lake sediments of Tibetan Plateau are sensitive to sedimentary environment and very significant to the studies of environmental changes.     

长江河口及其水下三角洲的沉积特征和沉积环境

近两千年来,长江河口河道束狭淤浅,南岸边滩伸展,河槽成形,河道加深,形成现代河口的形态。长江河口的沉积物分布是和河口地形及水下三角洲的发育密切相关的。本文研究了沉积特征以及它与沉积环境、地貌和水文特征之间的关系。大量材料分析表明,沉积物的粒度大小和水动力条件相适应,分选系数、偏态和中值粒径之间有相关性。长江河口可分为四个沉积区:河口段上段沉积区;河口分汉河段沉积区;河口拦门沙沉积区;水下三角洲沉积区。     

Study of CH4 and CO oxidation from electrochemical method

THE TWO FACTORS USED FOR EVALUATING THE QUALITY OF CATALYST ARE I) THE AMOUNT OF ACTIVE SITE PARTICIPATING IN THE REACTION, I.E. THE AREA OF REDOX PEAKS; AND II) THE REGENERATION FREQUENCY OF ACTIVE SITE IN THE REACTION, I.E. THE MATCH OF REDOX POTENTIALS. THE CONTRIBUTION OF EACH FACTOR HAS ITS OWN STRONG POINT IN DIFFERENT REACTIONS, WHILE CYCLIC VOLTAMMETRY (CV) IS A SUITA…