A preliminary study of carbon system in the East China Sea   总被引：1，自引：0，他引：1  

Shizuo Tsunogai  Shuichi Watanabe  Junya Nakamura  Tsuneo Ono  Tetsuro Sato 《Journal of Oceanography》1997,53(1):9-17

In the central part of the East China Sea, the activity of CO₂ in the surface water and total carbonate, pH and alkalinity in the water column were determined in winter and autumn of 1993. The activity of CO₂ in the continental shelf water was about 50 ppm lower than that of surface air. This decrease corresponds to the absorption of about 40 gC/m²/yr of atmospheric CO₂ in the coastal zone or 1 GtC/yr in the global continental shelf, if this rate is applicable to entire coastal seas. The normalized total carbonate contents were higher in the water near the coast and near the bottom. This increase toward the bottom may be due to the organic matter deposited on the bottom. This conclusion is supported by the distribution of pH. The normalized alkalinity distribution also showed higher values in the near-coast water, but in the surface water, indicating the supply of bicarbonate from river water. The residence time of the East China Sea water, including the Yellow Sea water, has been calculated to be about 0.8 yr from the excess alkalinity and the alkalinity input. Using this residence time and the excess carbonate, we can estimate that the amount of dissolved carbonate transported from the coastal zone to the oceanic basin is about 70 gC/m²/yr or 2 GtC/yr/area-of-global-continental-shelf. This also means that the rivers transport carbon to the oceans at a rate of 30 gC/m²/yr of the coastal sea or 0.8 GtC/yr/ area-of-global shelf, the carbon consisting of dissolved inorganic carbonate and terrestrial organic carbon decomposed on the continental shelf.  相似文献   

地层学的发展推动油气地质理论研究的进步   总被引：2，自引：0，他引：2  

许红  李思田  吴河勇 《海洋地质前沿》2002,18(2):17-21

自上个世纪50年代以来,地层学经历了彻底的变革,逐渐由“相模式”、“沉积体系”、“地震地层学”发展到目前的“层序地层学”,形成高分辨率层序地层学和事件地层学的理论体系和研究方法。文章围绕层序地层学、高分辨率层序地层学基本方法及理论体系,与含油气系统相关关系进行了讨论。  相似文献   

Growth Aspects and Magnesium Carbonate Concentrations of the Reef Building Octocoral Heliopora coerulea (Pallas) after Transplantation     

B. Velimirov 《Marine Ecology》1980,1(2):155-168

Abstract. An experiment to test C have's hypothesis on temperature dependent MgCO₃ concentrations in marine calcareous skeletons was undertaken by transplanting colonies of Heliopora coerulea. The corals were transferred from a shallow lagoon with high average temperatures to the outer bottom of a fringing reef, 16 m depth, with low average temperatures. Against expectation, a statistically significant increase of average mol % concentrations from 0.48 to 0.54 % for upper growth regions and from 0.49 to 0.62% for lower growth regions was obtained. Temperature records during the experimentation period and the above data indicate that the mol% MgCO₃ concentration in the skeleton of living Heliopora colonies increases when transplanted to an environment with a lower temperature average than that of their original growth site, and with seasonal temperature fluctuations which are smaller in the experimental site than in the control site. Temperature fluctuations at the control site were up to 2.5 times greater than at the experimental site for most of the observation months. This supports the conclusion that the parameters a) minimum temperature and b) temperature stability of the environment are essential for the incorporation of Mg into the carbonate skeleton matrix of marine organisms. Within this study the results of a quantitative chemical analysis of the carbonate skeleton of H. coerulea are presented and growth data of transplanted colonies compared with those from the control site.  相似文献   

Geodynamic Evolution of the Eastern Segment of the Azores-Gibraltar Zone: The Gorringe Bank and the Gulf of Cadiz Region     

Tortella  D.  Torne  M.  Pérez-Estáun  A. 《Marine Geophysical Researches》1997,19(3):211-230

Detailed structural interpretation of the recently acquired deep seismic multichannel profiles along the Iberian Atlantic Margins (IAM Project) provides new results on the geodynamic evolution of the eastern part of the Azores-Gibraltar plate boundary. Thrusting and folding of the oceanic basement and of Mesozoic and Cenozoic sedimentary cover of the Gorringe Bank region are consistent with the N–S convergence of Iberia and Africa. Compressive structures in the Gorringe Bank region are spread over a wide area. Deformation under compression took place mainly in Tertiary times, as is evidenced by a basal unconformity and several discontinuities in Tertiary sediments, although some deformation has also been recorded in Quaternary sediments. The compressive structures in the Gulf of Cadiz are E–W oriented thrusts, folds and related diapiric structures. N–S oriented transpressive deformation is likely to occur in the western Portuguese platform. There is no continuity of structures from the oceanic to the continental domain, suggesting that deformation transfers from one side to the other through a transcurrent fault zone. The fault contact between the two domains is located in the ocean-continent transition zone.  相似文献   

南海西部表层沉积物钙质浮游生物分布与碳酸盐溶解   总被引：1，自引：0，他引：1  

陈芳  李学杰  陈超云  郑凯清  黄雪华 《海洋地质与第四纪地质》2003,23(2):33-38

对南海西部300多个表层沉积样品中的浮游有孔虫和钙质超微化石定量分析表明，几乎所有样品均含浮游有孔虫、钙质超微化石，但丰度相差十分悬殊，浮游有孔虫丰度介于0．5～36673个／g之间，钙质超微化石丰度为0～1725个／10个视域，两者的分布规律相似。在陆坡区钙质浮游生物最富集，尤其在西沙群岛西南、南沙西部礁滩附近海区丰度最高；向深海盆区和陆架浅水区，钙质浮游生物丰度均下降。但从两者的丰度分布来看，其溶解程度不同，浮游有孔虫更容易溶解，在200～2000m水深区，丰度最高，2000m以下丰度锐减；而钙质超微化石的最富集区在500～3000m，且3000m以下仍较丰富。从碳酸盐的分布来看，本区碳酸盐的临界补偿深度(CCrD)为3500m，而CCD大于4300m，碳酸盐的溶解主要由有孔虫和钙质超微化石构成。  相似文献   

台湾岛及其邻域地层和构造特征   总被引：1，自引：0，他引：1  

郑彦鹏  韩国忠  王勇  张政民 《海洋科学进展》2003,21(3):272-280

台湾碰撞造山带作为世界上最年青的造山带之一，具有其独特的地质环境。它位于菲律宾海板块和亚欧板块的交汇处，东北面为东北-近东西走向的琉球沟-弧-盆系，东侧为西北向运动的菲律宾海板块，向南为近南北走向的吕宋岛弧，并与冲绳海槽和马尼拉海沟的形成演化密切相关，从而造就了众多形态复杂、成因各异的区域地层和构造现象。台湾岛自东向西可划分为海岸山脉带、台东纵谷、中央山脉、西部山麓带和沿海平原带五个构造-沉积单元。以台东纵谷为界，两侧在地形地貌、地层组成、岩石性质、重力、磁力等地质地球物理特征上均表现为明显不同，分别隶属于不同的板块构造单元，西侧属于欧亚板块的中国大陆边缘，东侧的海岸山脉带则是北吕宋火山岛弧的向北延伸。  相似文献   

东海钙质生物骨屑的矿物学特征     

朱而勤  李建华 《中国海洋大学学报(自然科学版)》1987,(4)

通过电镜、电子探针和X射线等项分析,对东海沉积物中的有孔虫、腹足类、双壳类、苔藓、珊瑚、海胆等骨屑进行了矿物学研究,确定了矿物成分与生物属种的关系,并基于有孔虫壳体化学成分将壳体分为均质壳和异质壳,生物碳酸盐中镁主要富集在方解石及镁方解石中,锶在方解石和镁方解石中的分配系数(D)相似,为0.11—0.14;在文石质骨屑中D=1.09-1.20。碳氧同位素组成与生物属种有明显关系。据一些有孔虫壳体氧同位素偏差值计算的水温来看,本次测定的有孔虫属种的骨屑不能作为理想的骨屑温度计。  相似文献   

Large-scale environmental influences on the benthic macroinfauna of the southern Gulf of Mexico     

Hector A. Hernndez-Arana  Ashley A. Rowden  Martin J. Attrill  Richard M. Warwick  Gerardo Gold-Bouchot 《Estuarine, Coastal and Shelf Science》2003,58(4):825-841

The influence of large-scale natural disturbance from winter storms (‘northers’) and river runoff on the macrobenthic community structure of the southern Gulf of Mexico was investigated in both carbonate and transitional carbonate–terrigenous sedimentary environments. Samples of the infauna were obtained in three seasons from 13 stations from two 250 km transects along 80–170 and 20–50 m water depth. Samples after the northers season had the lowest total number of families and individuals, 114 and 2940, respectively, compared to the dry and rainy seasons with 129 and 132 families and 11580 and 15266 individuals, respectively. Spatial patterns of macroinfauna composition varied across and along the shelf as a response to sedimentary environments and depth. Coarser sediments from the carbonate area harboured the highest mean densities per station with 500–24,000 individuals m⁻² and 108–122 families in total, compared to the transitional sediment with 500–8200 individuals m⁻² and 56–74 families across the three seasons. Univariate and multivariate statistical techniques demonstrated that low densities and number of taxa were associated with winter storms, but storm influence was dependent on depth and sediment type. Multiple linear regression analysis and BIOENV analysis indicated that sediment mean grain size, percentage of clay and organic matter best explained the macroinfauna spatial patterns, although BIOENV indicated that depth has an overriding role. An increase in densities of opportunistic taxa (numerous polychaetes of small sizes) was observed four months after the ‘northers’ and this was more evident in the area of carbonate sediment. Additionally a combined disturbance from northers and river runoff is suspected to be responsible for a naturally impoverished macroinfauna community in the transitional sedimentary environment.  相似文献   

闽江口第四纪地层中的孢粉、有孔虫、硅藻组合及其古地理意义   总被引：7，自引：1，他引：7  

杨蕉文  华棣  吴立成 《海洋地质与第四纪地质》1991,11(3):75-82

本文通过对闽江口琅岐岛钻孔的孢粉,有孔虫及硅藻的综合分析,发现第四纪地层中有五个孢粉组合带,五个硅藻组合带与一个微体化石层。结合~(14)C测年资料与沉积物特征认为该地区第四纪地层可以划分为晚更新世晚期与全新世(早期、中期、晚期)。气候演化依次为:冷干→温暖略干→温暖湿润→炎热潮湿→温暖略干。沉积相发展顺序为:冲积相、冲洪积相→河流相、湖沼相→湖沼相、河口相→海湾相→河口相。  相似文献   

Patterns and controls of surface sediment distribution: west-central Florida inner shelf   总被引：2，自引：0，他引：2  

Gregg R. Brooks  Larry J. Doyle  Richard A. Davis  Nancy T. DeWitt  Beau C. Suthard   《Marine Geology》2003,200(1-4):307-324

The west-central Florida inner shelf represents a transition between the quartz-dominated barrier-island system and the carbonate-dominated mid-outer shelf. Surface sediments exhibit a complex distribution pattern that can be attributed to multiple sediment sources and the ineffectiveness of physical processes for large-scale sediment redistribution. The west Florida shelf is the submerged extension of the Florida carbonate platform, consisting of a limestone karst surface veneered with a thin unconsolidated sediment cover. A total of 498 surface sediment samples were collected on the inner shelf and analyzed for texture and composition. Results show that sediment consists of a combination of fine quartz sand and coarse, biogenic carbonate sand and gravel, with variable but subordinate amounts of black, phosphorite-rich sand. The carbonate component consists primarily of molluskan fragments. The distribution is patchy and discontinuous with no discernible pattern, and the transition between sediment types is generally abrupt. Quartz-rich sediment dominates the inner 15 km north of the entrance into Tampa Bay, but south of the Bay is common only along the inner 3 km. Elsewhere, carbonate-rich sediment is the predominate sediment type, except where there is little sediment cover, in which cases black, phosphorite-rich sand dominates. Sediment sources are likely within, or around the periphery of the basin. Fine quartz sand is likely reworked from coastal units deposited during Pleistocene sea-level high stands. Carbonate sand and gravel is produced by marine organisms within the depositional basin. The black, phosphorite-rich sand likely originates from the bioerosion and reworking of the underlying strata that irregularly crop out within the study area. The distribution pattern contains elements of both storm- and tide-dominated siliciclastic shelves, but it is dictated primarily by the sediment source, similar to some carbonate systems. Other systems with similar sediment attributes include cool-water carbonate, sediment-starved, and mixed carbonate/siliciclastic systems. This study suggests a possible genetic link among the three systems.  相似文献