北极深海沉积物中细菌和古菌群落结构研究

在北极深海沉积物生态系统中,微生物的群落结构由有机质输入、能量的可用性及其他环境因素决定.然而,全球气候变暖及其导致的冰盖提前融化正在影响微生物的多样性.为描述北极深海沉积物中的微生物群落结构及其与环境因素的相关性,我们利用罗氏454对北极深海沉积物样品的16S rDNA扩增子进行了测序,对细菌和古菌群落的丰富度、成分、结构及其系统发育分类地位进行了描述.硫还原和化能有机营养类是细菌群落中的主要类群;而古细菌群落主要是由微生物的关系最为密切的氨氧化奇古菌门(96.66%)和产甲烷古生菌界(3.21%).这项研究描述了北极极点附近深海沉积物(> 3500米)中的微生物多样性,将为以后研究类似环境中微生物代谢过程和途径等功能分析奠定基础.     

南海火山玻璃的分布特征、化学成分及源区探讨

研究了南海火山玻璃的分布特征、化学成分及源区,结果表明,表层沉积物中的火山玻璃含量基本呈南北向分布,由北部、西部、南部大陆架分别向中部、东部深海盆逐渐增加;柱样沉积物中的火山玻璃在深海盆出现的层数多、含量大.火山玻璃化学组分之间的相关性不显著,表层沉积物中的火山玻璃属于安山岩,柱样沉积物中的火山玻璃的岩石类型广泛,主要属于安山岩和流纹岩.菲律宾岛弧火山带、南海深海盆火山喷发以及印尼岛弧火山带是南海火山玻璃主要源区,火山玻璃搬运和沉积主要受台风、越赤道气流和环流的影响和控制.     

Matter composition and formation conditions of the Pliocene-Pleistocene sediments in the Kuril basin (sea of Okhotsk)

An integrated (petrographical and micropaleontological) study of the sedimentary cover samples dredged from the lower slopes of the Kuril deep-sea basin was carried out. The Pliocene-Pleistocene sediments are mainly represented by tuffaceous sedimentary rocks (tuffites, tuffaceous muds, tuffaceous diatomites, tuffaceous silts, tuffaceous sandstones, etc.). Significant admixtures of pyroclastic matter, especially of volcanic glasses, indicates that the sedimentation process was accompanied by explosive volcanism. The data obtained give evidence about the intensification of the tectonomagmatic regime within the region under study during the Pliocene-Pleistocene time. By the beginning of the Pliocene, a deep-sea basin with a well-manifested continental and/or island slope and a narrow shelf already existed. The Pliocene-Pleistocene deposits accumulated in a cold well-aerated deep-sea basin under oxic conditions and downslope sediment transport.     

The clay mineralogy of particulate material from some surface seawaters of the eastern Atlantic Ocean

The concentrations of the clay minerals montmorillonite and illite have been determined in 28 samples of particulate material from surface (0–～5 m) waters along the eastern margins of the Atlantic Ocean, and the concentrations of chlorite and kaolinite have been determined in nineteen of the samples.The average concentration of the four clays in the particulate material decreases in the following order: illite (～42%) > kaolinite (～25%) > chlorite (～19%) > montmorillonite (～14%). There are specific trends in the latitudinal distributions of illite and kaolinite in the particulate material; illite decreases and kaolinite increases towards low latitudes. These trends are also found in eolian dusts and deep-sea sediments from the same region, and these clays are considered to have a detrital origin.The concentrations of montmorillonite in the particulate material and deep-sea sediments are similar in the North Atlantic. However, in the South Atlantic the sediments contain about twice as much montmorillonite as does the particulate material. It is suggested that whereas the montmorillonite in North Atlantic deep-sea sediments is largely detrital, that in South Atlantic sediments is both detrital and authigenic.     

中太平洋西部深海沉积物中的火山碎屑与粘土矿物

对于太平洋深海沉积物的研究虽有很久的历史(如1873-1876年“挑战者”号的科学考察),但对该区开展深入系统的岩石学和矿物学研究却是六十年代以后的事.随着研究手段的发展和进步,已积累了关于该区深海沉积物的大量资料.目前我国的海洋工作者也正在努力开展这方面的科学研究工作.     

Basalts from the Solomon and Bismarck Seas

Volcanic rocks collected from the Solomon Sea Basin are mostly ferrobasalt lavas similar to evolved MORB; an exception is a single sample of basaltic crystal tuff invaded by later basalt. The rocks contain labradorite, aluminous diopsidic augite, and titanomagnetite, with olivine and pigconite in the more vitrophyric samples, and segregation vesicles in some. Cobbles dredged from Gudaraba Canyon, south of the Solomon Sea Basin, include both MORB-like glassy lava and K-metasomatised basalt and andesite(?). Two small pieces of volcanic glass from the southern Bismarck Sea are more primitive MOR-type basalts.     

1972-2013年北欧海深层水增暖

The warming of deep waters in the Nordic seas is identified based on observations during Chinese 5th Arctic Expedition in 2012 and historical hydrographic data. The most obvious and earliest warming occurrs in the Greenland Basin(GB) and shows a coincident accelerated trend between depths 2 000 and 3 500 m. The observations at a depth of 3 000 m in the GB reveal that the potential temperature had increased from-1.30°C in the early 1970 s to-0.93°C in 2013, with an increase of about 0.37°C(the maximum spatial deviation is 0.06°C) in the past more than 40 years. This remarkable change results in that deep waters in the center of the Lofton Basin(LB) has been colder than that in the GB since the year 2007. As for the Norwegian Basin(NB), only a slight trend of warming have been shown at a depth around 2 000 m since the early 1980 s, and the warming amplitude at deeper waters is just slightly above the maximum spatial deviation, implying no obvious trend of warming near the bottom. The water exchange rate of the Greenland Basin is estimated to be 86% for the period from 1982 to 2013, meaning that the residence time of the Greenland Sea deep water(GSDW) is about 35 years. As the weakening of deep-reaching convection is going on, the abyssal Nordic seas are playing a role of heat reservoir in the subarctic region and this may cause a positive feedback on the deep-sea warming in both the Arctic Ocean and the Nordic seas.     

Depositional environment of near-surface sediments,King George Basin,Bransfield Strait,Antarctica

Four sediment cores were collected to determine the depositional environments of the King George Basin northeast of Bransfield Strait, Antarctica. The cored section revealed three distinct lithofacies: laminated siliceous ooze derived from an increased paleoproductivity near the receding sea-ice edges, massive muds that resulted from hemipelagic sedimentation in open water, and graded sediments that originated from nearby local seamounts by turbidity currents. Clay mineral data of the cores indicate a decreasing importance of volcanic activity through time. Active volcanism and hydrothermal activity appear to be responsible for the enrichment of smectite near the Penguin and Bridgeman Islands.     

Age and composition of the Amanay Seamount, Canary Islands

A number of samples have been dredged from the upper parts of Amanay and El Banquete Seamounts, yet volcanic materials have been collected only on Amanay Seamount. Based on textural features and the presence or absence of kaersutite, two main types of olivine pyroxene basaltic rocks have been identified. The rocks are basanites with high enrichment in the most incompatible elements, similar to that displayed by Ocean Island Basalts. Samples from Amanay Seamount formed due to a low degree of melting of an enriched mantle, very similar to that which probably caused the Miocene volcanic activity of Fuerteventura. The age of Amanay volcanic rocks, 15.3 ± 0.4 and 13.1 ± 0.3 Ma, is similar to those of the older volcanic units exposed in the nearby islands (Gran Canaria, Fuerteventura and Lanzarote). This proves the formation of a separate submarine volcanic edifice coeval with the other edifices of the Eastern Canarian Volcanic Ridge. Volcanic activity on the submarine edifice is thought to have ceased at about 13 Ma, simultaneous with the adjacent main volcanic construction.     

Vertical structure of low-frequency currents in the southwestern East Sea (Sea of Japan)

The vertical structure of low-frequency flows in the central Ulleung Interplain Gap of the southwestern East Sea (Sea of Japan) is analyzed based on full-depth current measurement during November 2002–April 2004. Record-length mean flows are directed toward the Ulleung Basin (Tsushima Basin) throughout the entire water column. Upper current variability above the permanent thermocline with a dominant period of about 50–60 days is shown to be closely related to the displacement of an anticyclonic warm eddy associated with the westward meander of the Offshore Branch. Fluctuations of deep currents below the permanent thermocline have a dominant period of about 40 days. Coherence between the current near the seabed and shallower depths is statistically significant up to 360 m for a period range between 15 and 100 days, but less significantly correlated with currents in the upper 200 m. Data from the densely equipped mooring line reveal that mean and eddy kinetic energies are minima at 1000 m, where isotherm slopes are also relatively flat. Empirical orthogonal function (EOF) analyses suggest that more than 79% of total variances of upper and deep currents can be explained by their respective first EOF mode characterized by nearly depth-independent eigenvectors. Spectral and EOF analyses of observed currents suggest that most of the deep current variability is not directly related to local upper current variability during the observation period.     

Novel active kinetoplastids associated with hypersaline anoxic basins in the Eastern Mediterranean deep-sea

The combination of nearly saturated salt concentration and corresponding high density, high hydrostatic pressure, absence of light, anoxia, and a sharp chemocline make the deep hypersaline anoxic basins in the Eastern Mediterranean Sea some of the most polyextreme habitats on Earth. Using kinetoplastid-specific primers, we detected kinetoplastid flagellates in some of the harshest deep-sea environments known to date, including some whose small subunit ribosomal RNA gene sequences are not closely related to cultured representatives. Kinetoplastids, including presumably novel representatives appear to be specialists of halocline environments in the Eastern Mediterranean, and to comprise a significant fraction of the protist communities in the brines and haloclines of several basins. Fluorescent in situ hybridization data indicate a novel ‘unidentified’ sequence clade of kinetoplastids related to bodonids represents as much as 10% of the total protist community in the Discovery Basin halocline. Different kinetoplastid groups are unevenly represented in the different basins and habitats we sampled, which we discuss as a result of environmental selection.     

Metal concentrations and metallothionein-like protein levels in deep-sea fishes captured near hydrothermal vents in the Mid-Atlantic Ridge off Azores

The knowledge of metal contamination in deep-sea fishes living in the surroundings of hydrothermal vents is very scarce, along with the detoxification mechanisms that allow them to live near one of the most metal contaminated marine environments. Six deep-sea fish species, although not vent endemic were collected near three Mid-Atlantic Ridge (MAR) hydrothermal vents (Menez Gwen, Lucky Strike and Rainbow) and the gills, muscle and liver were selected for this study due to their importance in metal metabolism and storage. The concentrations of seven metals (Ag, Cd, Cr, Cu, Fe, Mn, and Ni) and a metal-related biomarker (metallothionein-like proteins–MTL) were assessed. Major differences in metal accumulation among fish species are related to their feeding habits and vent site of their capture. The liver and gills are in general the most important tissues for metal accumulation compared to the muscle, but tissue partitioning is very dependent on the fish species considered. Compared to other deep-sea fishes, fish capture in the vicinity of hydrothermal vents accumulates higher amounts of metals in general. However, MTL levels are not considerably different from what is found in commercial coastal fishes, and is poorly correlated with metal concentrations in the tissues. Therefore, MTL may not constitute one major detoxification system for deep-sea species living in the vicinity of three important MAR vent sites.     

菲律宾海钱洲深海峡谷沉积物中元素的地球化学特征

作者研究了钱洲深海峡谷柱状沉积物中常量元素和微量元素的垂直分布及它们的相关关系。研究表明,大多数化学元素随岩芯深度的垂直分布变化不大,且元素明显的分为两组：Ca,Sr组和Al,Fe,Ti,Mg,Ni,V,Co,Li,Rb组,该区的物质来源为多源的,即生物来源、陆源和火山源。     

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.     

Petrography,Geochemistry and Physical Properties of a Continuous Extrusive Section from the Sarami Massif,Semail Ophiolite

As opposed to ocean crustal drilling that often yields a discontinuous core, ophiolites provide a unique opportunity to study continuous sections of oceanic basalts. In order to provide high frequency constraints on the construction of the upper oceanic crust, a continuous 280 m thick volcanic transect was sampled in the Semail ophiolite in Oman. The analyzed section is located in the Sarami Massif, in the central part of the ophiolite, and exposed along Wadi Shaffan. A multidisciplinary study was carried out after sampling in the field. Core measurements including porosity, grain density, compressional velocity, magnetic susceptibility and electrical resistivity for over 100 samples from this transect have been made. Geochemical analyses including major, trace and Rare Earth Elements were also performed on 23 selected samples from this transect. The Wadi Shaffan transect appears as composed of two main petrological and geochemical members providing the main lithostratigraphic signal. The boundary between the two sequences is marked by the presence of a massive flow unit equating to the most primitive lava and across which significant changes in mineralogy and texture are observed. The physical properties equally record significant changes. In all, the section is characterized by chemical compositions coherent with that of V1-Geotime volcanism and appears as built through two main sequences of volcanic activity. The magnetic susceptibility profile correlated to geochemical variations present the most detailed evolution allowing to individualize a succession of at least 4 volcanic phases. These phases are interpreted as magmatic cycles characterized by differentiation processes, allowing one to place high frequency constraints on the volcanic behavior of fast spreading ridges. Some of the physical properties also reflect this series of differentiation trends, as noticed in the past from downhole measurements recorded in the context of deep ocean drilling into the crust.     

Delineation of the 85°E ridge and its structure in the Mahanadi Offshore Basin,Eastern Continental Margin of India (ECMI), from seismic reflection imaging

The passive Eastern Continental Margin of India (ECMI) evolved during the break up of India and East Antarctica in the Early Cretaceous. The 85°E ridge is a prominent linear aseismic feature extending from the Afanasy Nikitin Seamounts northward to the Mahanadi basin along the ECMI. Earlier workers have interpreted the ridge to be a prominent hot spot trail. In the absence of conclusive data, the extension of the ridge towards its northern extremity below the thick Bengal Fan sediments was a matter of postulation. In the present study, interpretation of high resolution 2-D reflection data from the Mahanadi Offshore Basin, located in the northern part of the ridge, unequivocally indicates continuation of the ridge across the continent–ocean boundary into the slope and shelf tracts of the ECMI. Its morphology and internal architecture suggest a volcanic plume related origin that can be correlated with the activity of the Kerguelen hot spot in the nascent Indian Ocean. In the continental region, the plume related volcanic activity appears to have obliterated all seismic features typical of continental crust. The deeper oceanic crust, over which the hot spot plume erupted, shows the presence of linear NS aligned basement highs, corresponding with the ridge, underlain by a depressed Moho discontinuity. In the deep oceanic basin, the ridge influences the sediment dispersal pattern from the Early Cretaceous (?)/early part of Late Cretaceous times till the end of Oligocene, which is an important aspect for understanding the hydrocarbon potential of the basin.     

Some aspects of volcanic ash layers in the Central Indian Basin

Intercalated volcanic ash layers in two deep-sea sediment cores from the Central Indian Basin (CIB) are examined for the possibility of an in situ source of suboceanic volcanism. An in situ source has been predicated based on the bottom morphological structures and activation of seamounts during the geological past. The tentative correlation between depositional ages of the ash layer horizons and the period of global climatic cooling events reinforces the hypothesis that the suboceanic volcanic episode might have been initiated during the onset of glaciation.     

Clay minerals in the deep-sea cores from the North Pacific

Clay minerals in the <2 fraction of the four deep-sea cores collected from the northeast and central North Pacific are studied. In the surface layers of the cores, illite is more dominant in the pelagic samples than in the near-shore ones, and montmorillonite is vice versa. Chlorite in the near-shore sample is relatively abundant in the areas of higher latitude than in those of lower latitude. Kaolinite content is less than 10 percent in all samples. The presence of particles of amphibole in the clay-size was confirmed by X-ray analysis in the whole of the core-st. 18 taken from the northeastern portion of the area. This fact suggests that, for a long time probably since the Tertiary age, particles of amphibole have been supplied from source areas. In the three cores except the core-st. 18 it is shown that montmorillonite clearly increases downward. It is suggested that montmorillonite has been derived from volcanic glassy material by a diagenetic change. Montmorillonite in the bottom layer (400–405 cm) of the core-st. 9 is particularly rich in iron.     

Volcanism and Tectonics of the Central Deep Basin,Sea of Japan

The paper presents the results of a study on the geomorphic structure, tectonic setting, and volcanism of the volcanoes and volcanic ridges in the deep Central Basin of the Sea of Japan. The ridges rise 500–600 m above the acoustic basement of the basin. These ridges were formed on fragments of thinned continental crust along deep faults submeridionally crossing the Central Basin and the adjacent continental part of the Primorye. The morphostructures of the basin began to submerge below sea level in the Middle Miocene and reached their contemporary positions in the Pliocene. Volcanism in the Central Basin occurred mostly in the Middle Miocene–Pliocene and formed marginal-sea basaltoids with OIB (ocean island basalt) geochemical signatures indicating the lower-mantle plume origin of these rocks. The OIB signatures of basaltoids tend to be expressed better in the eastern part of the Central Basin, where juvenile oceanic crust has developed. The genesis of this crust is probably related to rising and melting of the Pacific superplume apophyse.     

Some aspects of volcanic ash layers in the Central Indian Basin

 Intercalated volcanic ash layers in two deep-sea sediment cores from the Central Indian Basin (CIB) are examined for the possibility of an in situ source of suboceanic volcanism. An in situ source has been predicated based on the bottom morphological structures and activation of seamounts during the geological past. The tentative correlation between depositional ages of the ash layer horizons and the period of global climatic cooling events reinforces the hypothesis that the suboceanic volcanic episode might have been initiated during the onset of glaciation. Received: 20 June 1995 / Revision received: 11 May 1998