南海盆海山火山碎屑岩的发现及其地质意义

海山火山碎屑岩是水下爆发性火山作用的产物。南海盆两座海山上发现火山碎屑岩表明海山顶部曾经一度高于PCL(压力补偿深度)。岩相学特征显示这些火山碎屑岩的胶结物主要为一混合相,包括粘土矿物和黑色铁质矿物等,这从一个侧面反映海山的正地形限制了粗粒外生碎屑到达海山顶部。岩石的单矿物组分、主量元素化学特征与同海山玄武质熔岩具有可比性,属碱性岩浆系列。计算获得海山平均最小下沉速率为0.06mm/年,最大可能达0.30mm/年。海山岩石的机械风化产物对周围海盆的沉积作用作出重要贡献。

Observations of near surface current at the Luzon Strait in winter

One hundred and ninety-one Argos satellite-tracked drifters deployed at the Luzon Strait in winter during 1991 to 2004 were analyzed to understand the near surface current in northern South China Sea (SCS). Several major track patterns of these drifters have been found. There are:(1)shelf slope landing way (SLW); (2)deep basin way (DBW);(3) weak loop current pattern;(4) northward movement directly driven by the Kuroshio. These observations show the effects of the basin scale gyre circulation, mesoscale eddies and the Kuroshio on the drifters'ovement.

The difference analysis of physical-mechanical properties of sediments in the central South Yellow Sea and Zhe-Min coastal area in China

The difference analysis of physical-mechanical properties of muddy sediments is made in the central South Yellow Sea and the Zhe-Min（Zhejiang Province to Fujian Province of China） coastal area. The results show that sediments in the two regions are both dominated by mud. There are perfect negative power function correlations between the water content and the density, the compression coefficient and the compression modulus; a good positive power function correlation between the liquid limit and the plastic limit, a perfect positive linear correlation between the water content and the void ratio, and a perfect polynomial function correlation between the miniature vane shear strength and the pocket penetration resistance. In general, compared with sediments in the Zhe-Min coastal area, sediments in the central South Yellow Sea possess high water content, high void ratio,low density, high plasticity, high compressibility, low shear strength. The causes of the differences between physical-mechanical properties of sediments are analyzed from the topographic features, material sources,hydrodynamic conditions, deposition rate, and material composition. Compared with the Zhe-Min coastal area,the central South Yellow Sea is far from the Mainland and low-lying; has poor hydrodynamic condition; the materials diffused to the area are less and dominated by fine clay, have the high content of smectite and organic matters. These factors lead to sediments of the central South Yellow Sea has the higher water content, the higher plasticity, the lower density, and the lower strength than sediments in the Zhe-Min coastal area.

The Effect of Organic Carbon on Soil Bacterial Diversity in an Antarctic Lake Region

This study assessed the effects of changes in organic carbon content on soil bacterial community composition and diversity in the Antarctic Fildes Peninsula.16 S rRNA gene sequencing was performed to investigate bacterial community composition.Firstly,we found that organic carbon(OrC)and nutrients showed an increasing trend in the lake area.Secondly,soil geochemistry changes affected microbial composition in the soil.Specifically,we found 3416 operational taxonomical units(OTUs)in 300 genera in five main phyla:Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi,and Bacteroidetes.Although the diversity was similar among the four sites,the composition was different.Among them,Hungateii content changed very significantly,from 16.67% to 33.33%.Canonical correspondence analysis showed that most measured geochemical factors were relevant in structuring microbiomes,and organic carbon concentration showed the highest correlation,followed by NO3^--N.Hungateii was significantly correlated with the content of organic carbon.Our finding suggested organic carbon played an important role in soil bacterial communities of the Antarctic coastal lake region.

Shifts of the Kuroshio axis over the last 20 000 years

Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years. During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the Kuroshio indicator Pulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted easterly for a short period or the Kuroshio was weakened and that moment.

Paleocurrent of the tidal sand body in Subei coastal plain

Based on analysis of magnetic febric and magnetic relict, the paleocurrents recorded in drilling cores in Subei coastal plain are bidirectional. NE_SW in the northern core and NW_SE in the southern core. The paleocurrent pattern in the area is similar to that of the tidal current system in the South Yellow Sea. So it is inferred that the convergent_divergent tidal current system existed during stage of sand body formation, and they should be radial in plane.