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11.
The correlation of opal content and MAR with oxygen isotopic records of benthonic foraminifera at Site 1143, southern South China Sea indicates that,since about 900 ka,the increasing opal content and MAR during the interglacial periods is inferred to reflect the bigher surface productivity ,for the intensified summer monsoon during the interglacial periods would result in the enhanced upwelling and nutrient supply,Time-sequence spectral analyses of oxygen isotopic record ,opal content and MAR at intervals of 0-900 ka reveal that the changes of surface productivity were dominantly forced by the variations of the earth orbital cycles.  相似文献   
12.
Analysis of the taxonomy and stratigraphic distribution of the Early Cambrian eodiscoid trilobites of the Yangtze Platform indicates that species of Tsunyidiscus and Hupeidiscus can be used for biostratigraphic correlation. T. aclis occurs only in the lower Qiongzhusian, T. armatus occurs in the lower and middle Qiongzhusian, while T. niutitangensis and T. tingi occur mainly in the middle and upper Qiongzhusian, with only T. tingi extending upward into the lower Canglangpuian. H. orientalis first appears in the upper Qiongzhusian, reaching peak abundance in the lower Canglangpuian and becoming extinct above the Drepanuroides Zone. Biostratigraphic and lithostratigraphic correlations indicate that the limestone in the lower part of the Mingxinsi Formation, the Upper Member of Jiumenchong Formation, and the upper part of the Middle Member of the Huangbailing Formation, can be correlated with each other as Hupediscus, an index fossil of the lower Canglangpuian, is abundant in all these units. The lower part of the Niutitang and Jiumenchong formations in eastern Guizhou, which mainly represent Qiongzhusian strata, can be correlated with the Lower Member of the Huangbailing Formation. The basal part of the Niutitang Formation, which may be equivalent to the Upper Meishucunian Shiyantou Formation in eastern Yunnan, is very condensed. Well-preserved sponge faunas and non-mineralized fossils in the lower part of the Niutitang and Hetang formations are not older than Qiongzhusian in age.  相似文献   
13.
The Mg/Sr ratio in a stalagmite, which is directly proportional to DMg/Ca, the solid-liquid distribution coefficient of Mg, is proposed as a geochemical thermometer to estimate paleotemperature changes. The paleotemperature changein eastern Beijing over the past 3000 years has been reconstructed by using this thermometer in the stalagmite ZFFS-1 from Jingdong Cave. The records can be divided into two periods: 3000-2000 aBP, cool and wet, the air temperature averaging 9.8℃; and 2000 aBP-present, hot and dry, the air temperature being 1℃ higher than the mean value (11.7℃) of the past 3000 years. During 500-200 aBP, the air temperature was about 1.2℃ lower than that of the present, corresponding to the Little Ice Age in Europe. Like δ18O and δ13C, Mg/Sr (or DMg/Ca) reflects an obviously warming trend of the past 200 years. These results are supported by historic records.  相似文献   
14.
As the third summary report of ODP Leg 184 to the South China Sea (SCS), this paper discusses the evolution of the East Asian monsoon and the SCS basin. A multi-proxy approach, involving geochemistry, micropale-ontology, pollen and other analyses, was adopted for reconstructing the evolutionary history of the East Asian monsoon, which was characterized by a series of paleo-climate events especially at 8, 3.2, 2.2 and 0.4 Ma. The new record indicates similar stages in the development of the East and South Asian monsoons, with an enhanced winter monsoon over East Asia being the major difference. The rich spectrums of monsoon variability from the southern SCS also reveal other characteristic features of the low latitude ocean. Evidence for the evolution of the SCS includes the hemipelagic Oligocene sediments, implying the existence of deep water environments during the early seafloor spreading stage of the SCS basin. The four major unconformities and some remarkabl ediagenetic features in upper Oligocene deposits indicate the strongest tectonic events in the region. From a careful comparison of lithologies and sedimentation rates, we conclude that the prominent differences in sedimentary environments between the southern and northern SCS were established only by ~3 Ma.  相似文献   
15.
南海海底特征、资源区位与疆界断续线   总被引:9,自引:0,他引:9  
根据南海海底的成因与地形特征 ,并通过建立和分析南海海底数字地形模型 ,将南海的海底分为中央的深海盆地、两侧的阶梯状大陆坡、以及周边亚洲大陆延伸的大陆架 3个地貌单元 .再据 194 7年“南海诸岛位置图”精确计算出二战后依据波茨坦公告为国际认可的断续线疆界的经纬度坐标 ,阐述了中国对南海主权的历史延续性 .最后 ,论述了南海区位与资源的优势 ,论证了其海域具体位置与巨大的经济政治战略意义 .  相似文献   
16.
北京东灵山地区鸟类群落与栖息环境的关系研究   总被引:4,自引:0,他引:4  
于1999-03—2001-06对北京东灵山地区鸟类群落进行了研究,共发现鸟类84种,依据营巢位置和取食部位的不同可以划分为6个集团.对鸟类种群密度、集团丰富度、物种多样性等群落指标与植被结构关系的研究发现,地面取食集团的物种数、种群密度与灌木丛的高度和盖度成正比.影响鸟类密度的栖息地参数对于不同物种存在较大差别.对地面营巢集团鸟类而言,随着灌木高度和盖度的增加,鸟类数量明显上升;而林冠营巢集团鸟类的数量却随着灌木高度和树种多样性的增加而下降.鸟类种群密度和均匀度受到灌丛高度异质性和乔木高度的显著影响,而鸟类群落的物种多样性则与灌木高度异质性以及乔木密度密切相关.  相似文献   
17.
社会主义市场经济条件下,在城市的发展中,规划是龙头和前提,建设是基础和重点,管理是灵魂和关键,经营是理念和手段。城市经营和城市管理应同时统领着城市的规划和建设过程。目前,北京城市经营的步伐相对滞后,建议以迎奥运为契机,采取以下措施,做好北京的城市经营与管理工作:1)在城市管理中树立正确的城市经营理念;2)完善城市经营机制,尽快制定有关城市经营与管理的总体政策、办法呼法规;3)重点做好奥林匹克公园、中关村科技园区、商务中心区、旧城区等重点区域的经营和管理工作;4)在城市经营与管理工作中充分注意细节,处处体现以人为本的“人文奥运”理念。  相似文献   
18.
对南水北调中线的一个调蓄水库--瀑河水库环境质量现状进行评价,利用实验室模拟和WQRRS模型预测蓄水后不同情景下的水库水质状况,分析水库对生态环境、水文泥沙、环境地质等影响,从环境角度论证水库建设项目的可行性。提出了环境改善和保护的对策和建议,为南水北调中线工程的决策提供依据。  相似文献   
19.
通过对中国传统伦理文化的阐述,分析了北京故宫的建筑布局及空间营造,说明中国古代建筑是几千年传统文化积淀的产物,是传统文化意识在建筑及空间布局上的体现。  相似文献   
20.
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