西南印度洋脊龙旂热液场金属硫化物的矿物学组成及指示意义

西南印度洋脊(SWIR)是当前洋底超慢速扩张洋脊的典型代表, 具有独特的热液硫化物矿床形成机理, 对位于该洋脊的龙旂热液场硫化物样品进行了系统的矿物学分析, 结果表明:该区硫化物为高温热液喷溢活动所形成的富Fe型硫化物, 目前已经历了一定程度的氧化蚀变; 硫化物矿物组合以磁黄铁矿、黄铁矿为主, 其次是少量黄铜矿、白铁矿和(铁)闪锌矿; 黄铜矿出溶等轴古巴矿现象普遍, 部分样品中可见自然金颗粒。经综合分析, 该区热液成矿作用可划分为3个成矿阶段和1个后期海底风化阶段: (1)高温的黄铁矿+黄铜矿(等轴古巴矿) +磁黄铁矿阶段, (2)中高温的黄铁矿+闪锌矿阶段, (3)低温的胶状或莓球状黄铁矿+白铁矿+自然金阶段, (4)后期硫化物海底氧化性蚀变阶段主要是形成Fe的氧/羟化物。在整个成矿期间, 流体温度有不同程度的波动, 主要硫化物矿物形成时端元流体的温度应在335℃以上, 瞬间(短时)或局部热液的最高温度推测超过400℃。本区的磁黄铁矿属于富钴型磁黄铁矿亚类, 经历了六方磁黄铁矿+黄铁矿→单斜磁黄铁矿+黄铁矿的变化, 表明该区热液流体发生了快速降温的演化过程。     

Mineralogical and geochemical variation in hydrothermal sulfides from Vienna Woods field, Manus Basin, Papua New Guinea: constraints on their evolution

Polymetallic sulfides from two hydrothermal chimneys and talus deposit from the Vienna Woods field of Manus Basin were studied for mineralogy, elemental composition, and S-isotope ratio to understand their evolution. The factors including the nature of source fluid, mineral paragenesis, and related geochemical processes have been discussed. Mineralogy and elemental concentration of Cu and Fe-rich large chimney at the central part of this hydrothermal field was completely different from the smaller Zn-rich peripheral chimney and Fe-rich talus deposit, suggesting the variable degree of alterations generate physico-chemically different source fluids responsible for these hydrothermal structures. Similarly, S-isotope ratios also indicate chemically diverse fluids and different modes of precipitation were involved in their evolution. Distinct mineral zonings and associated elemental and isotopic compositions within individual deposit confirm paragenetic shifts were involved during their growth process.     

Marine barite in sediments from deep sea drilling project sites 424 and 424a (Galapagos hydrothermal mounds field)

The distribution of barite in sediments from D.S.D.P. sites 424 and 424A at the Galapagos hydrothermal mounds field is determined and the process of its formation is deduced. Barite in these deposits is associated with calcareous sediments and is completely absent from the hydrothermal material (manganese crusts and nontronite). Its concentrations tend to increase in the deeper sediments. Since manganese crusts contain significant amounts of Ba, a lack of barite in them is probably due to low concentrations of SO₄² in the sediment-seawater interface where they form. The formation of barite occurs within buried sediments, the interstitial waters of which are saturated with SO₄². The most probable source of SO₄²⁻ is the oxidation of H₂S which is released from the hydrothermal fluids percolating upwards through the sediments. Although nontronite is formed within buried sediments the environmental conditions occurring during its formation (reducing) prevent barite formation.The association of barite with calcareous sediments is due to the release of Ba by calcareous microorganisms and/or to high concentrations of Ca in the pore waters which maintain a high pH and hence SO₄²⁻ is stable.     

西北太平洋采薇海山富钴结壳矿物学和地球化学特征

富钴结壳是一种富含Mn、Co、Ni和稀土元素（镧系元素加钇,简称REY）等元素的海底矿产资源。本文研究的富钴结壳样品是“科学”号在2018年HOBAB5航次于西北太平洋采薇海山的山顶边缘上通过电视抓斗获得的。利用扫描电镜、X射线衍射仪（XRD）、电感耦合等离子体发射光谱仪（ICP-OES）和电感耦合等离子体质谱仪（ICP-MS）分析了富钴结壳的显微构造、矿物学特征和地球化学特征,并探讨了其成因类型和形成机制。富钴结壳的结构从内到外可分为土黄色的疏松层（C8-5）、黑色铁锰致密层（C8-2、C8-3和C8-4）和发育葡萄状球体的粗糙表面（C8-1）。土黄色疏松层孔隙度较高,主要组成矿物为水羟锰矿、石英、钙长石、钠长石、钙十字沸石和钡镁锰矿,Mn的含量较低,Al的含量较高。黑色的铁锰致密层孔隙度较低,呈柱状构造,主要组成矿物为水羟锰矿、石英、钙长石和钠长石,Al含量有所下降,Mn含量升高, 说明陆源物质的供应逐渐变少。在富钴结壳的生长后期,其主要显微构造由柱状构造向斑杂构造转变,二者的过渡区域为铁锰氧化物与富Si碎屑物质组成的层状构造。富钴结壳各层位的Mn/Fe比值为1.16～1.85,且各层位Ce呈正异常,Y呈负异常,以上特征表明富钴结壳为水成成因型,其金属元素来源于氧化性海水,未受到热液活动的影响。依据富钴结壳的年代学数据,可知从渐新世末期到上新世中期,富钴结壳的生长过程一直受控于太平洋深层水。Co/(Fe+Mn)和Co/(Ni+Cu)的不断升高表明富钴结壳一直在氧化性较高的海水环境中生长。相较于其他大洋和海区,采薇海山富钴结壳具有高含量的Co、Ni和REY,具有极高的经济价值和开采价值。     

A contribution to the reconstruction of Miocene seepage from authigenic carbonates of the northern Apennines (Italy)

Authigenic carbonates from outcrops of the northern Apennines consist of small and irregular lenses and exhibit numerous features indicative of cold-seep settings. Detailed petrographic, mineralogical and geochemical studies from two Miocene deposits are presented. The first carbonate outcrop, named Fosso Riconi, is located in the foredeep basin of the Apenninic chain, whereas the second deposit represents a satellite basin called Sarsetta. The stable isotope data from specific carbonate minerals show a wide range of values well known from other palaeoseeps of the Apennine Mountains. The majority of seep carbonates are formed by low-Mg calcite and ankerite. Those minerals have δ¹³C values between ?7 and ?23‰ V-PDB, suggesting variable amounts of carbonate derived from oxidized methane, seawater (dissolved inorganic carbon) and sedimentary organic matter. Dolomite samples have the lowest δ¹³C values (?30.8 to ?39.0‰ V-PDB), indicating methane as the main carbon source. The findings suggest an evolutionary formation of the seeps and development of authigenic carbonates influenced by the activity of chemosynthetic organisms, of which large lucinid clams are preserved. Bioirrigation by the clams controlled the sediment–water exchange, and is here considered as an explanation for the anomalous Mg content of the calcite. We hypothesize that the seep carbonates were formed during periods of active methane-rich seepage, whereas during periods of slow seepage carbonate formation was reduced. Despite different geological settings, the two examined deposits of Sarsetta and Fosso Riconi show similar features, suggesting that a common pattern of fluid circulation played a major role in carbonate formation at both seep sites.     

大西洋中脊赤狐热液区热液产物矿物学特征及其地质意义

赤狐热液区是2019年中国在南大西洋中脊23.7°S发现的一个位于拆离断层上盘的热液区.本文利用光学显微镜、电子探针、TerraSpec?Halo矿物鉴别仪和XRD粉晶衍射仪,对该区热液产物进行了矿物学和矿物成分研究.结果表明,赤狐热液区热液产物可分为硅质硫化物、硅质矿化角砾岩和碳酸盐质矿化角砾岩.这些产物均由不等量蚀...     

Numerical analysis of hydrophysical fields on the northwestern shelf of the Black Sea

A numerical experiment with assimilation of hydrological observational data from a survey in October 2007 on the northwestern shelf of the Black Sea was carried out using the hydrodynamic model with nonlinear equations of motion, equations of heat and salt advection, and data assimilation. The results of this calculation are compared with thermohydrodynamic fields obtained without taking into account temperature and salinity measurements. It is shown that allowance for the observation data leads to qualitative and quantitative differences in the structure of the hydrophysical fields. Mesoscale eddies and intense jet streams that agree with satellite observations were found in the field of currents and were investigated. These eddies are not resolved in low-resolution field experiments.     

Mineralogical and geochemical constraints on the origin of ferromanganese crusts from the Rivera Plate (western margin of Mexico)

Marine hydrogenetically precipitated ferromanganese crusts are widespread in the Pacific Ocean. They occur as pavements coating volcanic or sedimentary hard-rock substrates, mainly on the slopes of seamounts, plateaus and hills in ocean basins and continental margins. We studied three ferromanganese crusts from one dredge haul from the Rivera Plate (western margin of Mexico), which are up to 15 mm thick and grow directly on a substrate of pillow basalt fragments. They consist of laminated, botryoidal, porous aggregates mostly of Fe and Mn oxyhydroxides and up to 10% silicates. XRD analysis showed the predominance of poorly crystallized mineral phases in the crusts that include Mn-feroxyhyte and vernadite, and an authigenic smectite-like clay. Detrital minerals probably derive from granodiorites of the eastern wall of the neighboring Middle America Trench. Scattered barite grains occur on the crust surface and suggest plume fall-out derived from hydrothermal vents, although a possible pelagic source cannot be dismissed. Ratios between major (Fe, Mn, Si) and trace (Co, Ni, Cu) elements reveal that such crusts are predominantly hydrogenetic in origin, although they show a hydrothermal influence that increases in the outer layers. Iron contents range from 16.2 to 25.2 wt.%, and manganese from 3.4 to 14.5 wt.%. The Fe/Mn ratio ranges from 1.6 to 7.0. The SiO₂/Al₂O₃ ratio ranges from 4.3 to 6.6, indicating the presence of biogenic silica (radiolarians). The concentrations of copper (up to 383 ppm) and cobalt (up to 534 ppm) are significantly below those of the typical hydrogenetic crusts, whereas Ni (up to 1320 ppm) is about the same or slightly lower. REE normalized profiles and ΣREE values (486 to 732 ppm) match those reported for hydrogenetic crusts, but suggest a hydrothermal contribution for the later crust layers. The inferred crust growth rates using the Co-chronometer (44 and 229 mm/Myr) are higher than those reported for pure hydrogenetic crusts (mostly 1 to 6 mm/Myr), thus indicating an increasing hydrothermal influence. The highest growth rate (229 mm/Myr, corresponding to the outer crust layers) suggests a regional hydrothermal input of iron and manganese to seawater. The intensification of regional submarine hydrothermal activity began about 13,000 yr ago, and may be related to the tectonic activity in the complex junction of the Rivera, Cocos, Pacific and North America plates.     

Spatial and temporal variability and monitoring of hydrophysical fields of the Black Sea

As part of the Russian-Ukrainian program “The Black Sea as a Simulation Model of the Ocean,” the monitoring of the marine environment is considered using modern measuring systems. On the basis of historical and contemporary observation data, we estimate the spatial and temporal scales of dominant processes in the Black Sea. We describe the main measuring systems used to monitor the structure and variability of the hydrophysical fields. Examples characterizing the specific features of the Black Sea processes are presented.     

Manifestations of the Black Sea undercurrent in the density and hydrostatic pressure fields

Vertical kinematic structure of the geostrophic currents has been found to be correlated to the distribution of seawater density and hydrostatic pressure over depth. The conditions necessary for the existence of the undercurrent have been defined. On this basis, hydrological survey data compiled by the Marine Hydrophysical Institute in the Black Sea have been treated. Examples are given, which support theoretical deductions about the possible existence of the undercurrent beneath the Black Sea rim current. The undercurrent's parameters have been determined, along with the depths of the upper and lower boundaries and the mainstream velocity. Translated by Vladimir A. Puchkin.     

Last glacial emplacement of methane-derived authigenic carbonates in the Sea of Japan constrained by diatom assemblage,carbon-14, and carbonate content

We studied diatom assemblages and CaCO₃ contents of methane-derived authigenic carbonates from the eastern margin of the Sea of Japan and assessed the formation time of these samples. Radioactive ¹⁴C date was determined in selected samples to obtain the maximum age of the time. The results of our study suggest mass formation of carbonate nodules in a glacial period within ∼40 ky, consistent with a published U/Th dating result of carbonate nodules in the study area. Diatom assemblages and contents in the carbonate nodules (abundance of ∼10⁶/g, dominance of neritic-littoral species, warm/cold water species ratio lower than ∼25) differ from the near-seafloor sediments in the study area, which have characteristics of Holocene sediments in the Sea of Japan, and suggest cementation of glacial sediments. Laminated sediments in some nodule samples are glacial sediments because laminations are records of a low sea level period in the semi-enclosed ocean. Similarity of diatom assemblages and contents in all carbonate samples is another evidence of glacial sediments in nodules. Glacial sediments with oceanic cold water species as low as Holocene sediments restricts the sediment age to before 20 cal. ky BP. Carbonate contents higher than 78 wt% suggest the cementation of poorly compacted sediments near the seafloor, and the date of carbonate cementation is, therefore, close to that of the cemented sediments. Most carbonate nodule samples in this study were formed in a glacial period and detection of ¹⁴C restricts this period to within ∼40 ky.     

Statistical structure of the large-scale fields of temperature and salinity in the Black Sea

In order to reconstruct the large-scale temperature and salinity fields by the method of optimal interpolation of the archival data, we compute the correlation functions and analyze the space and time variations of the statistical structure of the fields. On the sea surface, the thermohaline fields are spatially inhomogeneous. Thus, the correlation functions are anisotropic in the region of the northwest shelf and close to isotropic in the inner parts of the sea. The values of correlation length vary from season to season. In the layer of pycnocline, the temperature and salinity fields are anisotropic. In the zonal direction, the correlation length is 2–3 times greater than in the meridional direction. The indicated anisotropy becomes stronger in the winter season and weaker in the summer season as a consequence of the seasonal variability of large-scale circulation. We study the dependence of the error of reconstruction of the fields by the method of optimal interpolation on the form of approximation of the correlation functions with regard for anisotropy. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 51–65, January–February, 2008.     

A numerical experiment on computations of the Black Sea density fields and current velocities during summer

A near-bottom pressure equation consistent with the original set of difference equations is derived in the framework of a numerical energetically-balanced model. The model is used to simulate numerically three-dimensional density and current velocity fields and in the Black Sea for a specific season. The climatic values of temperature, salinity, and tangential wind stress during summer are applied as the original conditions. Analysis of the hydrophysical fields at the final moment of integrating is performed. The difference between new data and data derived earlier is demonstrated.Translated by V. Puchkin.     

Manganese carbonates in the upper quaternary sediments of the Deryugin basin (Sea of Okhotsk)

The mineral and chemical compositions of authigenic carbonates are studied by several methods in a sediment core obtained from the axial zone of the Deryugin riftogenic basin. Manganese carbonates (kutnahorite, rhodochrosite) associated with manganiferous calcite, manganiferous pyrite, and nontronite are first identified in the Sea of Okhotsk. Manganese carbonates in the Holocene diatomaceous ooze were presumably formed due to diagenetic transformation of sedimentary manganese hydroxides, organic matter, and biogenic silica, while those found in the underlying turbidites precipitated owing to the intermittent influx of endogenic fluids migrating along sand interbeds.     

About the relationship between acoustic fields and hydrological fields in the area of a mesoscale eddy in the Black Sea

This paper discusses the application of acoustic sounding with the purpose of identifying vortical features in the sea. Analysis of the results of a multidisciplinary acoustic/hydrological experiment conducted in the Black Sea has revealed a stable recurrent correlation between the amplitudinal variance of echo signals, on the one hand, and the peculiarities of water temperature fields, on the other. Given these characteristics, the peripheral and the central areas of a mesoscale eddy essentially differed. This allows us to apply acoustic sounding to identify mesoscale eddies in the sea. Translated by Vladimir A. Puchkin.     

冲绳海槽南部海底热液活动区地形地貌特征及成因分析

为了进一步理解构造地质过程对弧后盆地热液活动及成矿作用的影响和控制,以实测和收集的多波束资料为基础,对冲绳海槽南部多个海底热液活动区的地形地貌特征进行了精细刻画。结合前人研究成果,从构造地质学的角度分析了热液区地形地貌的成因机制。结果表明,冲绳海槽南部热液区均为海底火山成因地貌,不同热液区的海底地貌分属于不同类型岩浆作用的产物：D海丘受岛弧和弧后盆地岩浆作用的双重影响,A海丘群由岛弧为主的多源岩浆作用产生,C海丘和B海丘群属于琉球火山岛弧,雨花海丘形成于造山期后地壳伸展导致的岩浆上涌。冲绳海槽中央地堑与琉球火山岛弧的交汇处有利于形成大规模岩浆和地热活动。琉球火山岛弧的岩浆活动存在时空迁移,与海槽构造演化过程中由分散式裂陷向中心式裂陷的转换有关。唐印热液区的存在表明台湾北火山带在槽底北缘及陆坡区仍具有较强的岩浆和地热活动性,是未来冲绳海槽南部海底热液调查的重要靶区之一。     

Mesoscale structure of the fields of vertical velocity and vorticity of winds over the Black Sea

On the basis of a simple stationary linear model and a contemporary nonlinear model, we study the mesoscale characteristics of the fields of vertical velocity and vorticity of winds over the Black Sea. It is shown that, in the idealized case (without taking into account the coastal features), the temperature contrast between the land and the sea in both models leads to the formation of circulation cells in the coastal zone. However, the mountainous features prove to be the main factor affecting the process of circulation for the actual synoptic situations. We present the map of monthly average vorticity of the surface winds constructed according to the nonlinear mesoscale model with a resolution of 30 km for January 1996–2001. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 1, pp. 52–61, January–February, 2005.     

Reconstruction of the three-dimensional salinity and temperature fields of the Black Sea on the basis of satellite altimetry measurements

The methodology of joint processing of the satellite altimetry and occasional hydrological observations in the Black Sea for 1993–2012 is developed. The original technique for reconstruction of the 3D temperature and salinity fields in the deep-sea part is proposed and implemented. This technique makes it possible to identify the depths at which a contribution of adiabatic processes to the deformation of the temperature and salinity profiles of the sea is predominant. Daily-averaged 3D fields of the seawater temperature and salinity in a baroclinic layer on a regular grid are reconstructed. The evaluation of accuracy of the reconstructed temperature and salinity arrays is performed by comparing them with the data of hydrological exploration. Structures of the temperature and salinity fields are correlated naturally with topography of the altimetric level and clearly indicate the synoptic variability. Seasonal and interannual variabilities of the kinetic energy (averaged over horizons of the 63–400 m layer) of the geostrophic currents calculated using the dynamic method makes it possible to reveal a sharp increase in the kinetic energy of the currents in the winter season of 2002. A high correlation is found between the interannual variability of the ERA-Interim wind stress curl averaged over the surface of the deep sea part and the kinetic energy of the geostrophic currents in the 63–400 m layer.     

Short-period internal waves in the frontal zones of non-tidal seas (the Black Sea and the Aegean Sea)

This paper reports empirical data on short-period internal waves in the Black Sea and Aegean frontal zones, collected through the use of distributed temperature sensor arrays. Peculiar features of the behaviour and propagation of the internal waves in these zones are shown. It is shown that the wavefield is anisotropic and reduction of the wave lengths diminishes during the climb up a sloping pycnocline. The energy level of the spectra of internal wave oscillations in the frontal zones of non-tidal seas was found to be lower than that relating to oceanic frontal zones.Translated by Vladimir A. Puchkin.     

Study of long-term variations in the Black Sea fields using an interdisciplinary physical and biogeochemical model

Using an interdisciplinary three-dimensional physical and biogeochemical model developed for the Black Sea, the long-term evolution of marine dynamics and ecosystem is investigated. The hydrophysical fields were calculated from a model of Black Sea circulation with assimilation of hydrographic survey and satellite measurement data from 1971 to 2001. The circulation model reproduces well processes of various scales in both space and time (particularly the seasonal course and interannual variability of main hydrophysical fields). The resulting flow fields are then used to calculate the long-term evolution of the components of the lower level of the food chain in the Black Sea ecosystem. The biogeochemical model used in the calculations is based on the nitrogen cycle and includes a parameterization of the main biological and chemical interactions and processes in the upper layer of the Black Sea. The numerical experiments indicated that the biogeochemical component of the model rather successfully reproduces the main features and evolution trends in the Black Sea ecosystem for the period under consideration: the growth in the phytoplankton biomass during eutrophication and changes in seasonal cycles of the main ecosystem components. Also, the hydrophysical processes were shown to be important for a reliable reproduction of long-term changes in the ecosystem.