DEEP TECTONOTHERMAL MECHANISM FOR THE TECTONIC EXTENSION OF THE EASTERN ASIAN CONTINENTAL MARGIN

The continental marginal extension concept developed by Chinese geologists recently may be applied to the explanation about the Cenozoic extension and divergent movement of the Eastern Asian continental margin. From the viewpoint of continental marginal extension, this paper discusses the deep tectonothermal mechanism of the tectonic extension of the Eastern Asian continental margin. The Eastern Asian continental margin is an extensional belt with intensive magmatism and structural deformation, geophysically characterized by continual earthquakes and obvious geothermal anomaly. Seismic tomographical results about the Eastern Asian continental margin imply that the Pacific Plate is subducted toward the Eurasian Plate at a low angle and the diving Pacific Plate lies on the surface of the 670-km phase transitional zone. We interpret this feature to be resulted from retrogressive subduction followed by continental marginal extension. Our thermal modeling and geodynamical computation results suggest that the retrogressive subduction occurred at about 76Ma and the withdrawal of the trench served to supply the volume for the continental growth, which led to the formation of the growing front of the Eastern Asian continental margin. The growth width of the Eastern Asian continental margin is about 700 km.     

东海北部和黄海南部小黄鱼年龄与生长的研究

采用2002年11月~2003年10月在东海北部、黄海南部(31°N~34°N,126°E以西)所获取的小黄鱼渔获样品,合计采集1 064尾,通过每月对小黄鱼鳞片生长轮的观察和基础生物学测定,研究了小黄鱼的年龄和生长,并对渔业生物学状况进行了动态分析。结果表明:东海北部、黄海南部小黄鱼的体长范围在75~220mm,平均体长为135.42mm;年龄组成为当龄鱼~4龄鱼,共5个年龄序列,并以当龄鱼和1龄鱼为主,占81.39%,1~4轮组的年轮形成时间为2~6月;体长与体重的关系雌雄间无明显差异;Von Bertalanffy生长参数在性别方面无显著性差异,雌雄合并估算的L∞=233.23mm,K=0.29/a,t0=-1.4a。分析和比较了东海北部、黄海南部小黄鱼的渔业生物学历史状况,目前小黄鱼较以往任何年代渔获个体小型化、低龄化现象明显;小黄鱼个体生长速度较20世纪80年代变慢,低年龄段的个体生长速度较20世纪90年代加快,生长参数随资源状况的变化而发生了较大变化。     

Biomass Production in PioneerSpartina anglicaPatches: Evidence for the Importance of Seston Particle Deposition

Salt marsh formation can be initiated by the colonization of bare tidal flats by pioneer halophytes such asSpartina anglica. In the present study, growth ofS. anglicain the edge and centre zones of pioneer patches colonizing a tidal flat in a marine bay in the south-west Netherlands was investigated. Average biomass and shoot length was significantly lower in centre zones than in edge zones of the patches. Multiple linear regression showed that 84% of the variance in aboveground biomass in the centre zones could be explained by sediment phosphorus and nitrogen concentrations. No such relationship existed in the edge zone. This suggests that biomass production in the centre zones of the patches is nutrient limited, but that factors other than sediment nitrogen and phosphorus content determine growth ofSpartinain the edge zones.The sediment nitrogen and phosphorus concentrations in the centre zones of the patches were significantly related with sediment carbon concentrations, indicating that the pool of particle-bound nutrients in the sediment to an important extent is associated with organic particles. Determination of stable carbon isotope signatures of the sedimentary organic matter showed that an increasing carbon content of the sediment in the centre zone of the patches (and a rise in plant biomass) coincides with a higher contribution of non-Spartinaderived carbon to the sedimentary organic matter pool. Sustained biomass production in the centre zones of the patches, thus, probably depends on deposition of allochthonous organic particles and the nutrient inputs inherent in this process. Due to the construction of large-scale hydro-engineering works, however, conditions for deposition of waterborne particles are currently unfavourable. The consequences of reduced carbon and nutrient inputs into the patches will be particularly in the (older) centre zones, where the nutrient pools in non-refractory organic matter have been drained in the years of previous growth. Accordingly, it is hypothesized that the canopy-enhanced sedimentation for whichSpartinais well- known, via positive feed-back effects on plant growth can be crucial for plant vitality, and, hence, for successful colonization of unvegetated areas.     

A new coral reef province in the Gulf of Carpentaria, Australia: Colonisation, growth and submergence during the early Holocene

Multibeam sonar mapping, drill cores and underwater video data have confirmed the existence of a previously unknown coral reef province in the Gulf of Carpentaria, Australia. Seven reefs, comprised of coral limestone that support living corals have been mapped so far and as many as 50 other reefs may exist in the region. U/Th ages show that reef growth commenced shortly after limestone pedestals were submerged by rising sea level around 10.5 kyr BP, making them the oldest Holocene reefs known in Australia. Reef growth persisted for ~ 2.0 kyr but it had ceased at most locations by ~ 7.0 kyr BP. Measurements of reef growth rates (0.95 to 4 m kyr^− 1), indicate that the reefs were unable to keep pace with contemporaneous rapid sea level rise (> 10 m kyr^− 1), which is consistent with a “give up” reef growth history. Core samples from reef platforms demonstrate that Pleistocene limestone is exposed at depths of 27 and 30 m below present mean sea level. These depths represent regionally significant phases of reef growth during a prolonged sea level still stand. We conclude that the reefs are therefore mostly relict features, whose major phase of growth and development relates to an earlier, pre-Holocene sea level still stand.     

海洋光合细菌的分离鉴定及其生长条件的研究

用红色硫细菌培养基从青岛沿海潮间带海泥中分离出8株光合细菌,经鉴定菌株HD_1属最小着色菌(Chromatium minutissimum),HD_2、HD_4为细着色菌(Chromatium gracile);菌株SL_1、SL_1x、PL_1和PL_2为嗜酸红假单胞菌(Rhodopseudomonas acidophila),菌株HCx为沼泽红假单胞菌(Rhodopseudomonaspalustris)。分离菌株均具运动性,不需生长因子。菌株HD_1、HD_2和HD_4在厌氧光照条件下利用硫化物,且在细胞内贮存硫粒。菌株HD_1、HD_2的最适盐度为4.0％,最适pH为7.0,8.0。当培养基中硫化物含量为0.01—0.04％时,菌株HD_1、HD_4生长良好。菌株PL_2在初始pH为6时生长最好。酵母膏对菌株HCx具有明显的促生长作用。     

中国城市土地扩张与人口增长协调性研究

基于城市建成区面积和城区人口数据,构建城市土地扩张与人口增长关系模型,对2000年和2010年中国657个城市的土地扩张与人口增长之间的协调性进行了评价。结果表明:①中国城市用地扩张和人口增长之间的协调性较弱,土地显著扩张是中国城市发展的主要类型,数量占城市总量的1/3;其次是人口显著增长类型,占城市数量的1/4,两极分化明显。②在空间分布上,土地显著扩张的城市主要集中在东部沿海、沿江、沿线等经济相对发达地区;人口显著增长的城市分布重心则相对西移,主要处于胡焕庸线以东的中西部地区。③从不同规模城市用地扩张与人口增长的协调性来看,特大城市、大城市发展以土地快速扩张为主,且土地显著扩张所占比例最大;中、小城市发展以人口快速增长为主,并以人口显著增长占优。④由城市规模变动来看,小城市规模晋升多以人口快速增长实现,大、中城市规模晋升则更多通过土地快速扩张推进,特别是以房地产、新城建设等带动的用地驱动型城市化来完成。     

高铁影响下城市群空间关联形态与经济增长效应研究

以长三角、珠三角、辽中南城市群为例,选取2009-2018年各城市群地级及以上城市相关数据,借助社会网络分析和空间计量方法,实证研究高铁建设对各城市群的空间关联结构和经济增长的影响.结果显示,在空间关联形态方面,通过高铁建设,各城市群内所辖城市的节点中心度均有所提升、城市之间的关联更为紧密,但各城市在城市群中的排名位序...     

基于理论模型与美国经验证据的城市增长序贯模式(英文)

City growth patterns are attracting more attention in urban geography studies. This paper examines how cities develop and grow in the upper tail of size distribution in a large-scale economy based on a theoretical model under new economic geography framework and the empirical evidence from the US. The results show that cities grow in a sequential pattern. Cities with the best economic conditions are the first to grow fastest until they reach a critical size, then their growth rates slow down and the smaller cities farther down in the urban hierarchy become the fastest-growing ones in sequence. This paper also reveals three related features of urban system. First, the city size distribution evolves from low-level balanced to primate and finally high-level balanced pattern in an inverted U-shaped path. Second, there exist persistent discontinuities, or gaps, between city size classes. Third, city size in the upper tail exhibits conditional convergence characteristics. This paper could not only contribute to enhancing the understanding of urbanization process and city size distribution dynamics, but also be widely used in making effective policies and scientific urban planning.     

洪湖日本沼虾种群生长的研究

１９９４年５月至１９９５年６月对洪河日本沼虾种群的生长进行了研究。日本沼虾群体的平均体长,平均体重在３－６月逐渐增大,之后逐渐降低,分别在８月,９日达到最小值,其后又逐渐增大反映出世代交替的过程。日本沼虾群体的生长存在明显的阶段性,第一阶段的生长可以用Ｌｏｇｉｓｔｉｃ生长模式来描述：（♂）Ｌｔ＝６．８５（１＋ｅ＾０．３１８６－０．２３８６ｔ）,Ｗｔ＝７．５０／（１＋ｅ＾２．３８４５－０．３２５０ｔ