松辽盆地泉四段扶余油层地层层序新认识

松辽盆地泉四段扶余油层发育浅水湖泊三角洲相和浅水湖泊相，沉积构造环境属于闭塞浅水坳陷湖盆，其层序特征类似于稳定克拉通盆地层序，也类似于缓坡被动大陆边缘型盆地层序，气候是控制陆相坳陷盆地层序形成的主要因素，三级层序内总体应表现为水进体系域-高位体系域构成1个完整的层序，而低位体系域不发育。通过岩心、录井、地震等资料研究分析，认为泉四段扶余油层是1个三级层序，发育水进体系域和顶部薄层强制水退边缘体系域；泉四段与泉三段地层分界是其层序的底界；泉四段顶界地震反射层T2也是层序边界，是泉四段三级层序的顶界。精确识别和建立地层层序格架对石油勘探开发具有重要的指导意义。     

地震多属性在少井区和无井区沉积体系分析中的应用——以渤中西环BZ3-1区块沙河街组为例

钻井和地震资料的丰富程度决定了储层预测研究精度。在多井区,利用地震属性及单井沉积相来确定平面沉积相,研究精度高;而在少井、无井区的海域,如何利用地震资料进行沉积储层研究,至今没有一个成熟的方法。渤海湾盆地渤中凹陷西环BZ3-1区钻井较少,完整钻遇到沙河街组的井则更少,以该区的沙河街组为例,基于地震多属性分析技术,结合古地貌分析,半定量确定研究区的沉积体系分布特征。通过三维可视化技术和切片技术的高精度三维沉积体系分析表明,由于三级层序发育于二级层序的不同体系域,会导致三级层序的体系域沉积体发育特征的不同。沙三段SQsl3层序发育于二级层序的低位体系域(LST),其低位体系域的扇体规模要远远大于高位体系域(HST)的扇体;SQs3m层序发育于二级层序的水进体系域(HST),其低位体系域三角洲朵体规模与高位体系域的三角洲朵体相当;SQs3u层序发育于二级层序的高位体系域,其高位体系域三角洲朵体规模远远大于低位体系域的三角洲朵体。     

中国东部沿海平原第四系层序类型

据渤海湾西岸、长江三角洲地区钻孔资料,确定在构造沉降背景下形成的中国东部沿海平原第四系见两类层序。超过0.10Ma周期的大洪泛事件,分别发生在约2.60、0.8、0.5(?)和0.15Ma前后,相当于层序地层的水进体系域,在天津北部平原系华北盆地北边缘山体周期性隆升,在长江一线是附近低山丘陵周期性隆升的表现,反映沿海平原环境变化对西部构造-气候旋回的响应。MIS5以来沿海出现受全球海面变化控制的3期10ka级海侵,结合海域研究可以确定MIS1期间出现完整的海侵-海退层序,沿海平原10ka开始的全新世沉积为高位体系域,7～10ka基底泥炭作为最大海进面,在下切河谷内可见14C测年早于10ka的泥炭。     

北康-曾母盆地中中新世以来层序地层样式特征探讨

开展地震资料解释,分析上超、下超、顶超等地震反射终止关系、不整合面以及沉积趋势,识别出北康-曾母盆地中中新世以来14个三级层序界面。在层序界面内部,通过层序地层内幕结构刻画和原形剖面恢复,并结合地层堆砌方式,在北康-曾母盆地中中新世以来的层序地层内,划分了海进、高位正常海退、强制海退和低位正常海退4种成因单元。通过进一步研究该4种成因单元内地层结构和相分布关系,提出北康-曾母盆地中中新世以来的3种层序地层样式,即陆架边缘富砂型三角洲进积楔、退积型生物礁和陆架边缘富砂-富泥型退积楔,其中,沉积物源供应量充足且可容空间减小时,发育富砂的三角洲进积楔,陆架边缘-斜坡-盆地区域发育含砂深水扇;而可容空间增量远大于沉积物供应量时,发育退积型生物礁和富砂-富泥退积楔,斜坡-盆地区域含砂深水扇欠发育。     

南沙群岛海域北康盆地生物礁高精度层序地层学及其新近纪生物礁层序演化模式

新近系生物礁油气储层是南海含油气盆地油气勘探两大主力目的层系之一,过去有关其高精度层序地层学和层序演化模式的研究不多.为此,通过对北康盆地2万余公里地震资料的精细解释和钻井资料的综合研究,获得了以下重要成果:1)识别划分出该盆地新近纪11条主要等时界面、7个三级层序和基本层序组.2)描述了生物礁低位体系域、海侵体系域和高位体系域地震反射结构特征.3)提出南海首个中中新世生物礁高精度层序演化模式,代表中中新世(16.3-10.4Ma BP)海宁期(T13-T2)生物礁的剖面形态,含由1个低位体系域层序单元+5个高位体系域层序单元构成的一个典型海进体系域和由1个早期高位体系域层序单元+1个晚期高位体系域层序单元构成的1个典型高位体系域;可见中中新世完整海进-海退旋回生物礁发生、发展和消亡的过程.通过与曾母盆地中新世生物礁解释剖面对比,指出该模式具有区域性古海洋学代表意义.4)通过对L礁、西琛一井和南海-地中海中新世古海洋演化研究,确定研究区中中新世分别发育5-8个海平面升降旋回,形成晚中新世"南中国海事件",具有冰川型海退性质,可与全球和南海北部特别是与"Missinian"事件对比;确定北康盆地乃至南海新近系生物礁形成至逐渐消亡,也是新构造运动与新近纪古海洋事件共同作用的结果.5)指出L礁气田发现有9.8Ma BP、13.8Ma BP、14.5Ma BP和15.5Ma BP等多个层序界面,分别系高孔渗层段;同期南海礁型油气圈闭层序界面当为优良储层;若其为油气充满,则油气"高产"或构成"高压气包".以上成果,将有助于对全球变化及南海古海洋区域响应过程与结果的理解,并对南海的油气勘探有启示作用.     

珠江口盆地珠三坳陷层序地层样式分析

珠江口盆地珠三坳陷是一个典型的箕状断陷盆地,其层序地层格架受到主干断裂特别是珠三南断裂的强烈控制。由于珠三南断裂活动的差异性,盆地东部、中部和西部表现为不同的格架样式。并据此划分出坳陷内的3种典型层序样式,分别是缓坡型、断控陡坡型和断阶型层序样式。文昌A凹陷与阳江低凸起过渡的斜坡区和文昌B凹陷与琼海低凸起过渡区为具有坡折的缓坡背景,发育缓坡坡折型层序样式,发育斜坡扇、盆底扇、低位楔。珠三南断裂等主干断裂下降盘发育断控陡坡带层序样式,在珠三南断裂中部地区,发育断阶型层序样式。     

南海纳土纳台地的演化及层序地层学

通过综合地层、测井及岩心资料，我们将南海纳土纳台寺中新世特隆布组碳酸盐岩划分出七个完整的沉积层序，每个层序包括低水位体系域，海侵体系域及凝缩层和高水位体系域。     

强制海退沉积作用及其地质意义

较为全面地回顾了强制海退概念的提出及对传统层序地层学发展的推动作用;结合国内外对强制海退沉积的最新研究进展,探讨了沉积层序体系域四分法的可行性和强制海退体系域的主要沉积特征。     

珠江口盆地中部珠海组—珠江组层序结构及沉积特征

南海北部珠江口盆地珠海组分为SQ32、SQ25.5两个三级层序,珠江组划分为SQ23.8、SQ21、SQ17.5和SQ16.5四个三级层序,其中前3个层序分为水进域、高位域,后3个层序分为低位域、水进域和高位域。珠江组初期的白云运动使珠海组的浅水陆架环境变更为珠江组的陆架-陆坡沉积环境,造就了古地貌的更迭、层序界面的形成和沉积相的突变。层序界面在陆架主要为粗粒沉积物形成的侵蚀界面、浅水暴露界面,而陆坡为下切水道、丘状扇体底部侵蚀界面和滑塌层。层序的更迭使古珠江三角洲物源供给强度呈现强-弱-强-弱的特点,即珠海组时期的三角洲为陆架三角洲,沉积规模大;之后珠江组物源变弱,珠江组各层序低位域形成陆架边缘三角洲,水进域、高位域演化为陆架三角洲。低位期的三角洲前缘带越过坡折带沉积,并与陆架外的峡谷水道相连,三角洲进积、加积的碎屑沉积物向上陆坡内的白云凹陷内沉积,形成深水扇。因此,相对海平面变化、构造升降和沉积物供给强度控制着层序结构和沉积体展布。     

神狐海域水合物钻探区第四纪米氏旋回高频层序地层划分

基于高分辨率2D地震资料,建立了珠江口盆地白云凹陷第四纪层序地层格架,将第四纪沉积充填序列划分为3个体系域,即低位体系域(LST)、海侵体系域(TST)、高位体系域(HST)。根据陆坡进积特征和地层叠加样式、垂向上侵蚀特征变化(其上见下切水道)、中频强振幅同相轴的空间可追踪性等地震反射特征,将高位体系域(HST)进一步划分为两个沉积旋回单元HST-I、HST-II。在等时地层格架的约束下,以神狐海域水合物钻探区well-I钻井作为研究对象,选择自然伽马曲线(GR)通过频谱分析进行米兰科维奇旋回特征的研究,识别出偏心率周期(95ka)、斜率周期(40ka)和岁差周期(22、19ka)。研究区第四纪沉积充填序列主要受偏心率周期(95ka)的控制,偏心率(95ka)对应于旋回厚度11.494m,以此周期和对应的旋回厚度计算出钻探区第四纪沉积速率为12.1cm/ka。通过构建滤波器对测井曲线进行滤波处理,发现95ka的偏心率控制的优势旋回个数在20个左右。对斜率周期(40ka)识别出的高频旋回采用Fischer图解法求取其可容纳空间变化曲线,检验了高精度层序地层划分的正确性。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.