大别山混杂岩带中的石榴石

本文利用X粉晶、电子探针和仪器中子活化等手段,对大别山混杂岩带中榴辉岩及伴生石榴石橄榄岩中的18个石榴石作了研究。研究表明,石榴石的成份为连续过渡变化,其晶胞参数与Ca~(2+)有正相关关系,其镁铝榴石端员组分为17～63%,与全岩的Mg/比值呈线性正相关关系。稀土元素球粒陨石标准化模式为重稀土富集型,正铕异常。稀土元素的总量较低,为9～29ppm。推测:榴辉岩和石榴石橄榄岩为同一来源的基性岩浆分异后,在地慢与地壳之间(壳幔边界层)发生深成变质作用而形成。     

西南印度洋中脊50°E基性超基性岩石地球化学特征及其成因初探

西南印度洋中脊是典型的慢速扩张洋中脊之一。对采自西南印度洋中脊50°E附近的7件玄武岩和蛇纹石化橄榄岩样品所作的分析表明,基性玄武岩类SiO2含量为43.72%～48.40%,TiO2含量较少,为1.14%～1.52%;MgO含量为5.96%～10.98%;TFe2O3含量为4.55%～5.2%;Mg#值为0.53～0.64,里特曼指数σ为2.34～20.10。微量元素Zr/Nb和Y/Nb比值为显示N-MORB的性质,但是其他微量元素的比值(Ba/Nb,Ba/Th,La/Nb,Nb/U,Nb/Pb)均不显示正常洋中脊玄武岩的特征,微量元素原始地幔标准化蛛网图显示强烈富集K和Pb,亏损Nb,稀土元素显示较为平缓的分配模式。超基性蛇纹石化橄榄岩的主量元素特征为SiO2为38.91～45.49;TiO2含量为0.02～0.28;MgO含量很高,为36.87～40.61,TFe2O3含量为2.82～3.91,Mg#值为0.92～0.94。微量元素中Ni,Cr的含量很高,原始地幔标准化蛛网图显示橄榄岩强烈富集K和Pb,Ba,Th,La,Ce,Ti中等程度富集,而亏损Nb,Sr。稀土元素总量较低,标准化曲线显示轻稀土元素富集模式。结合地球化学特征及前人研究资料分析认为,西南印度洋中脊的基性岩和超基性岩属同源性质,其原始地幔物质可能为部分正常洋中脊亏损地幔混染了陆壳或远洋沉积物的结果。     

华北东部青岛地区煌斑岩岩石地球化学特征与成因

华北东部青岛地区煌斑岩广泛发育,其岩石成因、构造环境等方面研究程度较低。本文通过研究其岩石学和地球化学特征,讨论岩浆的源区性质、形成的构造环境,进而推断研究区的地质演化过程。研究区内煌斑岩的SiO2含量(W(SiO2))为39.13%~51.26%,属于钾玄质碱性岩。样品的稀土元素整体表现出轻稀土元素富集、重稀土元素亏损的特征,Ce和Eu异常(分别用δCe和δEu表示)不显著。样品微量元素总体表现出大离子亲石元素(Ba、K、Pb)和轻稀土元素富集(LREE),而高场强元素(Nb、Ta和Ti)亏损的特征,具有典型的俯冲特征。源区为三叠纪时北向俯冲的扬子板块析出的熔体,交代上覆华北板块地幔橄榄岩而形成的地幔交代岩。白垩纪时,俯冲带岩石圈大范围坍塌,软流圈上涌形成伸展环境,地幔源区发生部分熔融,岩浆上升侵位形成煌斑岩。     

青岛仰口榴辉岩及其围岩的岩石地球化学特征和成因机制

青岛仰口地区保存了完整的从变辉长岩到榴辉岩的超高压变质岩石组合。地球化学特征表明,榴辉岩、变辉长岩和片麻岩属钙碱性系列,超基性岩属拉斑系列;CIPW标准矿物计算显示榴辉岩和变辉长岩中长石以钠长石为主,超基性岩主要标准矿物为橄榄石、紫苏辉石和锥辉石,片麻岩中出现标准矿物刚玉;榴辉岩、变辉长岩和片麻岩富集大离子亲石元素,亏损高场强元素,超基性岩的微量元素相对于N-MORB亏损;榴辉岩和变辉长岩轻稀土明显富集,配分型式与岛弧玄武岩相似,片麻岩具明显的Eu的负异常,配分型式与后造山A型花岗岩相似,超基性岩稀土总量较球粒陨石偏高,具强烈的Ce的负异常。微量元素比值及地球化学图解表明榴辉岩与变辉长岩的原岩为辉长岩,片麻岩的原岩为造山后A型花岗岩,原岩的岩浆源区位于下地壳,超基性岩的岩浆源区位于上地幔,原岩均形成于岛弧环境。     

山东荣成榴辉岩和石榴石橄榄岩的岩石学矿物化学及其成因

用电子探针分析了山东荣成榴辉岩和石榴石橄榄岩中的石榴石和单斜辉石的化学组成。利用石榴石成分—成因判别图解并结合矿物地质温度计估算结果,判断荣成榴辉岩和石榴石橄榄岩为地幔来源,部分榴辉岩经历了后期壳内角闪岩相退变质作用。最后讨论了它们的成因意义和动力学演化。     

山东荣成马草夼大理岩中的榴辉岩岩石地球化学特征及成因

山东荣成马草夼榴辉岩呈条带状或透镜状产出于大理岩中,对其进行了岩石学和地球化学研究。研究表明,其原岩可能为辉石质岩石,且经过了一定程度的分异作用,暗色矿物发生堆晶作用,在微量元素原始地幔标准化蛛网图中,Th明显的亏损,U强烈富集,Ce也呈微弱程度亏损,在稀土元素球粒陨石标准配分模式图中,呈左倾分布模式。岩石的原岩构造环境分析表明其接近板内构造环境,其原岩可能为结晶分异之后矿物堆晶作用形成的辉石质岩石。     

南极中山站和企鹅岛变质岩类造岩矿物的矿物化学及其变质作用

本文利用电子探针分析了南极中山站和企鹅岛变质岩类岩石中主要造岩矿物(石榴石、斜长石、黑云母和角闪石)的化学组成,利用矿物地质温度计和各种成因判别图解,确定中山站变质岩类岩石的变质程度为高角闪岩相;企鹅岛变质岩类岩石的变质程度为低角闪岩相。     

南极乔治岛某些火山岩的岩石学和地球化学特征

本文报道了南极乔治岛中国长城站玄武岩和欺骗岛粗安岩的岩石学和地球化学特征。利用中子活化分析测定了岩石中的稀土元素、微量元素和过渡族金属含量;利用电子探针、扫描电镜等手段观测了它们的造岩矿物特征和物质组成,最后推测南极乔治岛具有大陆地壳结构向大洋地壳结构过渡的特征。     

长江与黄河黏土粒级沉积物地球化学特征及其物源指示意义

本文对长江与黄河口黏土粒级沉积物主微量元素的地球化学特征进行了研究。结果表明:长江相对富集Al、K、Fe、Ti等常量元素以及Cr、V、Li、Zn、Ni和Rb等微量元素,黄河以高Ca、Sr和Ba为特征;长江沉积物中稀土元素含量高于黄河沉积物,长江与黄河黏土粒级沉积物中稀土元素的分馏程度相同,均具有轻稀土元素富集、重稀土元素亏损的右倾的球粒陨石标准化配分模式,上陆壳标准化配分模式为中稀土元素富集,黄河沉积物的Ce负异常和Eu正异常程度较长江沉积物偏弱。长江沉积物中元素含量变化较大,而黄河沉积物中元素含量较为稳定。黏土粒级沉积物的稀土元素更接近其物源区,2μm的黏土粒级沉积物中的REE可以作为判识长江与黄河沉积物的地球化学指标。ΣREE、δCe可以作为长江、黄河入海沉积物的判别指标。长江与黄河黏土粒级沉积物的地球化学特征受源区岩石类型、化学风化、水动力分选等因素的控制。化学风化引起河流沉积物相对其源岩发生地球化学分异,水动力分选使矿物在不同粒级沉积物中富集,从而引起地球化学组成在不同粒级沉积物中的分异。     

太平洋东部CC48孔沉积物稀土元素地球化学研究

研究样品于１９８８年采自太平洋东部ＣＣ４８孔。通过对沉积物稀土元素地球化学特征的分析发现：（１）各种类型深海沉积物的稀土含量有所差别，以稀土元素总量而论，深海粘土＞硅质软泥＞硅钙质软泥＞钙质软泥；沉积物中的自生矿物、硅质生物成因的非晶质ＳｉＯ２及碎屑矿物对稀土元素起富集作用，而生物ＣａＣＯ３则起分散作用。（２）稀土元素含量随深度发生变化。为地层划分提供了依据，应用元素地层学方法将岩芯分成５个层段。     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

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。     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

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.     

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.