大西洋中脊14°N段的罗加乔夫热液场     

博格达诺夫俄  陈邦彦 《海洋地质》2008,24(2)

在1993—1994年间，俄罗斯“罗加乔夫教授”号科学调查船，在大西洋15°20′N处的转换断层以南35海里处发现新的活动热液场。它的存在与原先的推测一致，曾在底水中发现异常的甲烷和锰（Klinkhammer等1985；Bougault等1993）。相似的硫化物沉积曾在14°54′N即紧靠裂谷峡谷东壁底部的摄像中出现（Eberhart等，1988）。  相似文献   

全球洋底增生构造及其演化   总被引：3，自引：0，他引：3  

马宗晋  李存梯  高祥林 《中国科学D辑》1998,(2)

根据Cande等人 1 989年发表的第 3代全球洋底磁条带图 ,以增生区和增生期的概念对全球三大洋洋底增生构造进行了系统的单元划分 ,揭示了洋底构造的演化过程 .共划分出 49个增生区和 6个增生期 .发现后期增生过程对前期增生区具有裂解和楔入等改造作用 ,从整体上看 ,洋底增生过程具有全球尺度的同步性幕式特性 ,在空间分布上则有很强的非均匀性和局部的不连续性 .  相似文献   

2019年初夏延边州一次大范围冰雹天气分析     

金春荣  马洪波  李义兰 《吉林气象》2020,27(1):5-8

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无震脊或海山链俯冲对超俯冲带处的地质效应   总被引：3，自引：1，他引：2  

鄢全树  石学法 《海洋学报》2014,36(5):107-123

全球海底分布着众多的无震脊或海山链,且在太平洋、印度洋及大西洋均存在靠近俯冲带的海岭。除小安德列斯弧外的巴拉克达脊和蒂勃朗脊起源自转换断层外,一般认为它们由与板块构造动力学迥异的地幔柱动力学所形成的。在板块汇聚边缘处,与扩张脊处所形成的正常洋壳一起,无震脊或海山链俯冲于陆缘弧或洋内弧之下,其对弧及弧后地区的地质效应(构造、地貌、地震以及岩浆作用等)有别于正常洋壳俯冲。无震脊或海山链的俯冲通常造成俯冲带地区的上驮板块的局部异常抬升、俯冲剥蚀作用效应的加强、海沟的向陆迁移以及地震强度的增加。同时,无震脊或海山链俯冲时,其携带的具富集地球化学特征的物质不仅影响着地幔地球化学,也对弧及弧后火山熔岩化学产生明显影响,并对超俯冲地区的热液矿床的形成产生重要影响。最后,本文指出了我国有关无震脊或海山链俯冲的可能的研究方向包括黄岩海山链俯冲对吕宋岛弧的可能影响、印度洋无震脊俯冲对青藏高原局部地区的影响,有我国学者参与的IODP344航次的研究对象——科科斯脊俯冲对哥斯达黎加地震成因的效应以及位于西太平洋地区靠近俯冲带的一些无震脊等。  相似文献   

西南印度洋深海热液硫化物区沉积物微生物群落结构和固氮基因多样性   总被引：1，自引：0，他引：1  

吴月红  曹佚  王春生  吴敏  Aharon Oren  许学伟 《海洋学报(英文版)》2014,33(10):94-104

A sediment sample was collected from a deep-sea hydrothermal vent field located at a depth of 2 951 m on the Southwest Indian Ridge. Phylogenetic analyses were performed on the prokaryotic community using polymerase chain reaction（PCR） amplification of the 16 S rRNA and nifH genes. Within the Archaea, the dominant clones were from marine benthic group E（MBGE） and marine group I（MGI） belonging to the phyla Euryarchaeota and Thaumarchaeota, respectively. More than half of the bacterial clones belonged to the Proteobacteria, and most fell within the Gammaproteobacteria. No epsilonproteobacterial sequence was observed. Additional phyla were detected including the Actinobacteria, Bacteroidetes, Planctomycetes, Acidobacteria, Nitrospirae, Chloroflexi, Chlorobi, Chlamydiae, Verrucomicrobia, and candidate divisions OD1, OP11, WS3 and TM6, confirming their existence in hydrothermal vent environments. The detection of nifH gene suggests that biological nitrogen fixation may occur in the hydrothermal vent field of the Southwest Indian Ridge. Phylogenetic analysis indicated that only Clusters I and III NifH were present. This is consistent with the phylogenetic analysis of the microbial 16 S rRNA genes, indicating that Bacteria play the main role in nitrogen fixation in this hydrothermal vent environment.  相似文献   

南大西洋沉积物中多环芳香化合物的组成特征研究   总被引：1，自引：0，他引：1  

黄鑫  曾志刚  陈帅  殷学博  王晓媛  马瑶  杨宝菊  荣坤波  舒云超  姜涛 《海洋学报(英文版)》2014,33(11):150-154

10 samples of sediments obtained from the South Mid-Atlantic Ridge were measured for the abundances and distributions of polycyclic aromatic compounds(PAHs). The total concentrations of PAHs(∑PAHs) ranged from 2.768 to 9.826 μg/g dry sediment. The ∑PAHs was higher in sample 22V-TVG10 and sample 26V-TVG05 which were close to hydrothermal fields, with the lowest value in sample 22V-TVG14 which was farthest from hydrothermal fields, suggesting a probable hydrothermal origin of ∑PAHs of samples. Approximately nine kinds of PAHs were identified, and low molecular mass tricyclic and tetracyclic aromatic compounds were predominant in the samples. The concentrations of fluoranthene which were typical as hydrothermal alteration compounds were the highest among PAHs with dry weight between 0.913–3.157 μg/g. The phenanthrene homologue was most abundant in the samples, and the ratios between parent phenanthrene and methylphenanthrene which probably reflected the degree of hydrothermal alteration ranged from 0.097 to 1.602. The sample 22V-TVG10 possessing a maximum ratio value showed the intense influence of the hydrothermal alteration on this sample, which might further imply that PAHs in sediments were mainly derived from the hydrothermal alteration.  相似文献   

2012年秋季白脊管藤壶在江苏如东互花米草盐沼向附着及分布     

李润祥  高抒  王丹丹  赵秧秧  朱冬  许振  左平 《海洋学研究》2014,32(3)

互花米草Spartina alterniflora自1979年引入至今,已在我国海岸带大范围扩张并对盐沼湿地生态系统产生了很大影响.本研究以附着生物藤壶为例,研究了互花米草扩张对附着生物的影响.通过对5个断面共28个样方的米草植株、附着藤壶以及藤壶在互花米草上的最大附着高度调查,获得结果如下:藤壶在互花米草滩上的附着范围位于潮沟两侧,且呈宽度约为5 m的带状分布;潮沟规模越大,其向陆方向的延伸范围越宽;每个站位藤壶附着的相对最大高度都位于同一水平.附着藤壶均为白脊管藤壶Fistulobalanus albicostatus,平均干重237±69g·m-2,大部分藤壶直径在2～10mm之间.互花米草的平均干重为981±81g·m-2,潮沟附近互花米草高壮但密度较小,远离潮沟互花米草矮小但密度较大.分析表明,互花米草为藤壶提供了附着基质,并影响藤壶在潮间带的平面分布格局(尽管藤壶的生态位保持不变).影响白脊管藤壶分布特征的原因主要是海水浸没时间的差异;负地形的浸没时间更有利于藤壶的附着和生存;另外潮沟较高的潮水流速除了利于白脊管藤壶幼体的附着外,还可以通过水流的涨、落为其带来充足的食物.  相似文献   

Effect of salinity on growth and first sexual maturity of Exopalaemon carinicauda (Holthuis, 1950)   总被引：1，自引：0，他引：1  

张成松  李富花  相建海 《中国海洋湖沼学报》2014,32(1):65-70

To determine the optimal salinity for growth and first sexual maturity of ExopaIaemon carinicauda, the effects of salinity on growth and reproductive performance of early juvenile prawns of E. carinicauda were evaluated under laboratory conditions. Postlarvae from the same female broodstock were reared at six salinity levels （5, 10, 15, 20, 25, and 30） for 12 weeks. The specific growth rate （SGR） and survival rate （SR） under different salinity levels in the first 6 weeks were calculated and compared. SGR was significantly influenced by salinity. Prawns reared in salinity of 10 grew significantly faster （P〈0.05） than those reared in salinities of 5, 20, 25, and 30. However, ANOVA confirmed that there was no significant effect among the six salinity levels on SR. For the next 6 weeks, the body length （BL）, body weight （BW） at the first sexual maturity, and the age at median sexual maturity （As0） of females were measured and compared. Female prawns reared at salinity of 10 presented significantly shorter A50, but no significant differences among the six salinity levels for BL and BW at the first sexual maturity were observed. Based on the above information, the optimal salinity for growth and first sexual maturity of juvenile E. carinicauda is approximately 10.  相似文献   

现代海底热液过程及成矿          下载免费PDF全文

李军  孙治雷  黄威  崔汝勇 《地球科学》2014,39(3):312-324

原始的海水成分、基岩的组分及结构、热源性质等因素决定着现代海底热液喷口系统的流体成分, 同时, 各种地质构造背景下的岩浆脱气作用也在不同程度上影响热液流体的组成.热液流体一旦喷出海底, 就能形成不同类型的热液沉积体, 包括高温流体形成的金属硫化物或硫酸盐烟囱体、热液丘以及由低温弥散流及非浮力羽流形成的含金属沉积物堆积体.高温烟囱体的形成受控于海水和热液的混合比例, 常常表现为典型的两阶段模式, 即先形成环状硬石膏表层, 然后在其内部发生富Cu硫化物的沉淀.这一模式在更大尺度上也可以观察到, 如TAG热液丘.含金属沉积物遍布海底, 除热液羽流外, 金属硫化物烟囱体在氧化环境中氧化蚀变的产物也是其重要来源.生物的活动贯穿于现代热液过程的始终, 并在烟囱体的形成、分解以及羽流的扩散沉淀过程中起到了重要作用.当前, 热液生物矿化机理、Lost City型热液场以及超慢速扩张洋脊的有关研究是海底这一系统研究的热点, 前两者研究能使人们更好地理解地球早期的演化和生命的起源, 而后者的考察和研究能进一步丰富海底热液成矿理论, 并有助于寻找更大规模的热液矿体.   相似文献   

Geochemistry of mafic rocks and melt inclusions and their implications for the heat source of the 14.0°S hydrothermal field,South Mid-Atlantic Ridge     

Bing Li  Xuefa Shi  Yaomin Yang  Jun Ye  Jingjing Gao  Wenqin Zheng 《中国地球化学学报》2014,33(4):325-335

Fresh rocks sampled from the 14.0°S hydrothermal field of the South Atlantic Ridge can be divided into two categories： olivine-gabbro and basalt. The olivine-gabbro is composed mainly of three types of minerals： olivine, clinopyroxene and plagioclase, while a multitude of melt inclusions occur in the plagioclase phenocrysts of the basalts. We analyzed the whole-rock, major and trace elements contents of the basaks, the mineral chemistry of phenocrysts and melt inclusions in the basalts, and the mineral chemistry of olivine-clinopyroxene-plagioclase in the olivine-gabbro, then simulated magma evolution within the crust using the COMAGMAT program. The whole-rock geochemistry shows that all the basalts exhibit typical N-MORB characteristics. In addition, the mineral chemistry characteristics of the olivine-gabbro （low-Fo olivine, low-Mg# clinopyroxene, high-TiO2 clinopyroxene, low-An plagioclase）, show that strong magma differentiation occurred within the crust. Nevertheless, significant discrepancies between those minerals and phenocrysts in the basalts （high-Fo olivine, high-An plagioclase） reflect the heterogeneity of magma differentiation. High Mg# （-~0.72） melt inclusions isobaric partial crystallization simulations suggest that the magma differentiation occurred at the depth shallower than 13.03 km below the seafloor, and both the vertical differentiation column shows distinct discrepancies from that of a steady-state magma chamber. Instead, a series of independent magma intrusions probably occurred within the crust, and their corresponding crystallized bodies, as the primary high-temperature thermal anomalies within the off-axis crust, probably act as the heat source for the development of the 14.0°S hydrothermal system.  相似文献