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951.
A prediction system is employed to investigate the potential use of a soil moisture initialization scheme in seasonal precipitation prediction through a case study of severe floods in 1998. The results show that driving the model with reasonable initial soil moisture distribution is helpful for precipitation prediction,and the initialization scheme is easy to use in operational prediction. 相似文献
952.
The status of the ecological environment and a proposed protection strategy in Sanya Bay,Hainan Island,China 总被引:8,自引:0,他引:8
Huang L Tan Y Song X Huang X Wang H Zhang S Dong J Chen R 《Marine pollution bulletin》2003,47(1-6):180-186
Sanya Bay encompasses a high diversity of natural habitats, ranging from coral reefs, rocky and sandy shores and mudflats to mangroves. Seasonal physicochemical and biological investigations were conducted from 1998 to 1999 and again in April 2000. Water-related environmental quality in Sanya Bay is in good condition. The levels of dissolved oxygen, nitrogen, phosphorus and heavy metals are within the first class of National Seawater Quality Standards for China. Annual mean values of chlorophyll a of 0.93 mg m(-3) and phytoplankton primary productivity of 440.8 mgC m(-2)d(-1), respectively, were found in the waters, both of which show a significant correlation with inorganic nitrogen. A mean new productivity of 144.6 mgC m(-2) d(-1) was recorded in summer. Sanya Bay is rich in natural resources and biodiversity with 235 species of phytoplankton and 129 species of zooplankton identified in the survey. The annual mean abundance of phytoplankton and zooplankton were 1564 x 10 cells m(-3) and 121 individuals m(-3), respectively, with an annual mean zooplankton biomass of 129 mg m(-3). A total of 243 species of fish were sampled in the survey including many of high economic value. Three hundred and eighty-four species of benthos in 121 families were found by mud sampling and trawling. The average biomass of benthic organisms was 11.55 gm(-2), with a density of 31 individuals m(-2). Molluscs were the dominant group, followed by crustaceans; coelenterates exhibited the lowest biomass. One hundred and twenty-six species from 48 families of intertidal organisms were collected by frame sampling, with a mean annual biomass of 644.7 gm(-2) and average density of 816 individuals m(-2). The highest biomass of 1673.5 gm(-2) was collected in a coral reef region, while the highest density of 1219 individuals m(-2) occurred in a mangrove region. The coastline is characterized by coral reefs that accounts for 30% of the total coastline length in the bay, so coral reefs are a key ecosystem that are important for maintaining the regional marine resources and biodiversity. We need to pay much more attention to such diverse marine resources to maintain the integrity and function of these coastal ecosystems. 相似文献
953.
Petrova V. V. Nginh Le Thi Stukalova I. E. Sokolova A. L. Huyen Nguyen Xuan Pha Phang Dong 《Lithology and Mineral Resources》2003,38(3):209-222
Sedimentary rocks of the section in the Red River fold zone of northern Viet Nam are considered. It is shown that secondary mineral parageneses formed in two stages. The first stage (35–17 Ma ago) corresponded to the period of structure extension and sediment subsidence to a depth of about 6 km. This period and subsequent 10 Ma were marked by the formation of a usual dia- and catagenetic zoning of metasedimentary rocks. The second stage (5–7 Ma ago) corresponded to processes of compression that were responsible for the deformation of rocks into gentle folds and 1.5 to 2.2 times contraction of the section thickness in different places. The sequential–mineralogical zoning was disturbed at this stage. Smectites and mixed-layer minerals were replaced by chlorites and hydromicas. Organic material also responded to compression simultaneously with inorganic components. The bituminous component was released from humic matter and rocks became enriched in hydrocarbons. 相似文献
954.
955.
龙门山前陆褶皱冲断带构造解析与川西前陆盆地的发育 总被引:57,自引:2,他引:55
通过详细的野外地质调查和精细的地震剖面构造解析。揭示了龙门山前陆褶皱冲断带的基本构造特征。对比分析了龙门山北段与南段构造变形几何学和运动学的差异。提出龙门山北段主要表现为一系列复杂的逆冲推覆构造,晚三叠纪变形强于新生代;龙门山南段则以基底卷入的叠瓦状冲断为特点,晚白垩纪-早第三纪变形尤为突出。与前陆褶皱冲断带相对应的是,川西晚三叠纪时期的周缘前陆盆地主要表现在整个龙门山褶皱冲断带的前渊地区;而晚白垩纪-早第三纪再生前陆盆地却局限在川西盆地的南部,并且印-藏碰撞的持续挤压作用使得晚新生代构造变形不断向东扩展进入川西盆地南部。 相似文献
956.
由于地幔柱的作用,新元古代晚期至古生代早期在塔里木板块东北部曾发育一个坳拉谷,称之为库—满坳拉谷。在库鲁克塔格和满加尔凹陷地区,从早震旦世到奥陶纪发育中酸性和基性双峰火山岩建造、深水碳酸盐岩和复理石沉积体系,具坳拉谷盆地沉积特征;志留系—石炭系具有坳陷盆地沉积特征;上石炭统—二叠系缺失;中生代发育陆相沉积体系,标志着强烈造山运动盆地隆起消亡。这些地层层序构成了典型的坳拉谷盆地沉积体系,完整地记录了库—满坳拉谷从产生至消亡的构造发育史。 相似文献
957.
958.
论中国东部大型盆地区及邻区地质-地球物理复合尺度解析 总被引:7,自引:3,他引:4
作为对中国东部陆缘地带大型盆地区及邻区地质-地球物理综合研究的部分结果,本文的基本认识:(1)穿过松辽盆地的1孙吴-双辽断裂可能是东倾伯低角度壳内断裂;(2)松辽盆地和渤海湾盆地可能属于“混合型裂谷盆地”;(3)东海盆地台北坳陷处在多期次张性应力场环境中,使在其西部附近产生张性正断层系;(4)欧亚大陆东部新生代区域构造运动总体处于右旋走滑拉张环境,其动力因素包括板块运动和地幔物质运动;(5)研究区莫霍面具有较为复杂的变化;(6)复合尺度研究方法是地质-地球物理综合分析的必要手段。 相似文献
959.
960.