冲绳海槽南部表层沉积物地球化学特征及其物源和环境指示意义   总被引：9，自引：1，他引：9  

蒋富清  李安春 《沉积学报》2002,20(4):680-686

对冲绳海槽南部陆架、陆坡和海槽 33个表层沉积物进行了元素地球化学分析,结果表明研究区沉积物的主要化学组成为SiO₂ 、Al₂ O₃ 和CaO,这三种组分占沉积物总量的 6 8%左右。多数元素在陆架和陆坡的变化范围较大,在海槽区相对稳定。向海槽方向随沉积物粒径变细,SiO₂ 和CaO减少、Al₂ O₃ 和其它多数元素含量增加。常量元素和Al₂ O₃ 的比值分布特征表明,本区沉积物由物源区经由陆架向海槽输送,沉积物主要由陆源碎屑沉积组成,此外还有生物碎屑沉积和自生沉积。陆架区部分微量元素富集因子 (EF)与长江和黄河沉积物的富集因子对比结果表明,本区的沉积物与长江沉积物的关系更为密切。陆坡区Cu、Pb、Zn、Co、Ni和Cr的富集因子较高是由于生物的富集作用造成的,Mn的富集主要是自生沉积的结果。用R型因子分析方法对沉积物的化学组成进行了分析,结合元素的分布特征,给出了四个主因子所对应的沉积环境和特征元素组合,分别为 1)陆架型的元素组合 :SiO₂ 、TiO₂ 、Zr、CaO和Sr,2 )陆坡型的元素组合Fe₂ O₃ 、MgO和P₂ O₅,3)海槽型的元素组合 :Al₂ O₃ 、K₂ O、Cu、Zn、Co、Ni、Cr和Ba,4 )反映沉积环境氧化-还原属性的元素组合 :MnO和FeO。  相似文献   

建筑物震害及其抗震设计的初步研究--以姚安6.5级地震震区建筑物破坏为例     

樊跃新  非明伦  崔建文  包一峰 《地震研究》2002,25(4):391-397

对2000年1月15日姚安6．5级地震极震区（Ⅷ度）及姚安、大姚、南华和牟定等县城内的建筑物与结构物的震害做了系统的调研。本作为系列研究之二，分析了各类建筑物的地震破坏现象与相关设计，以及地震的破坏机理，讨论了地震区城镇建设中防震减灾应引起重视的有关问题；提出了在设计与施工中出现的若干问题及在这次地震灾害中获取的经验与教训。对今后多震区的城市规划、建筑物设计有一定的参考价值。  相似文献   

Reconstruction of summer temperature (June—August) at Mt. Helan, China, from tree-ring stable carbon isotope values since AD 1890     

Yu Liu  Limin Ma  Qiufang Cai  Zhisheng An  Weiguo Liu  Lingyu Gao 《中国科学D辑(英文版)》2002,45(12):1127-1136

From stable carbon isotope analysis of tree-rings of Chinese pine (Pinus tabulaeformis) from Mt. Helan, China, we found that high-δ¹³C values were related to high mean temperatures from June to August (T ₆₈), and Iow-δ¹³C values corresponded to low T ₆₈. From these data, a transfer function has been used to reconstruct summer temperatures (T ₆₈) for the Mt. Helan region. The explained variance of reconstruction is 34.9% (F=15.01, p<0.001). The time period containing the highest summer temperatures in northern China (late 1920-1930s) was confirmed by our reconstruction. The data indicate that there is a tele-connection between summer temperatures in Mt. Helan area and sea-surface-temperatures in the tropical Pacific. The extreme low temperature periods around the years of 1920 and 1947 for Mt. Helan region correspond well to the cold climate in the tropical Pacific. Along with other analyses, this suggests that climate variations in the Mt. Helan region are driven not only by local events, but also by the global climate. Significant periodicities appearing in the reconstruction are 2.56 and 2.63 years.  相似文献   

Loess in Kunlun Mountains and its implications on desert development and Tibetan Plateau uplift in west China   总被引：15，自引：0，他引：15  

方小敏  吕连清  杨胜利  李吉均  安芷生  蒋平安  陈秀玲 《中国科学D辑(英文版)》2002,45(4):289-299

Loess on the northern slope of Kunlun Mountains is the synchronous deposition of the Taklimakan Desert. The paleomagnetism and climatic records of an over 80 m loess-paleosol sequence on the highest river terrace at the foot of Kunlun Mountains show that the loess formed at ≈ 880 ka B.P., suggesting a roughly synchronous occurrence of the present-like air circulation and extremely dry climate and the initial desert. The uplift of the Tibetan-Pamir Plateau and Tian-shan Mountains may initiate these events. The rise of the plateau and adjacent mountains caused the drying and desertification of China inland and Tarim Basin, which was dramatically enhanced at ≈ 500 ka B.P., leading the desert to expand to its present scale. Global change just overprints this drying trend. Local climate response to global change both in long-term evolution and glacial-interglacial cycles manifests that the stronger the westerlies, the more the precipitation. But the heat-moisture pattern seems still similar to that in the Asian monsoon region.  相似文献   

淮北市抗震地基稳定性分析     

刘运标  孙庆安  龚安平 《安徽地质》2002,12(2):129-135

在大地构造分析的基础上,对淮北市基岩及构造进行详细研究,结合历史地震的地震部位,确定出地震多发生在断裂构造的交汇部位及其邻近地区.经分析研究,确定研究区震害的来源,并将研究区基岩稳定性划分出稳定、较稳定和次稳定(或不稳定)三种类型地带,为城市建设规划提供科学依据.  相似文献   

黄河上游阿尼玛卿山区冰川波动与气候变化   总被引：19，自引：13，他引：19  

刘时银  鲁安新  丁永建  姚檀栋  丁良福  李刚  Hook Roger L 《冰川冻土》2002,24(6):701-707

以黄河上游阿尼玛卿山的冰川为研究对象, 通过应用航空相片、卫星遥感影像、地形图和数字高程模型(DEM), 分析了末次冰盛期、小冰期、自1966年及2000年的冰川范围及变化情况. 结果表明, 末次冰盛期的冰川范围是现代冰川的3.1倍; 小冰期以来, 冰川已经开始退缩, 尤其在1966-2000年期间退缩有加速趋势. 介绍了一种提取冰川雪线高度的方法, 并根据现代气候数据, 探讨了研究时段雪线高度上的夏季平均气温变化趋势. 结果表明, 末次冰盛期时, 雪线下降了420 m左右, 相应的夏季平均气温比现代低1.9 ℃, 小冰期盛时夏季平均气温比现代低0.6 ℃.  相似文献   

塔北隆起-库车坳陷区中新生代基底-盖层构造变形机理   总被引：3，自引：1，他引：3  

曲国胜张宁  刘洁李亦纲  李岩峰 《地质通报》2004,23(2):113-119

利用三维建模软件获取了塔北隆起-库车坳陷区现今及不同时期基底构造格局，为基底构造分析提供了新的技术方法。研究表明，三叠纪-古近纪，塔里木盆地北部块体的基底构造基本处于稳定状态，基底-盖层构造变形不明显；新近纪，克拉苏背斜带以北的塔里木盆地基底明显向天山倾斜，库车基底俯冲变形导致基底转折带逐渐向南迁移，库车前陆盆地形成；第四纪时期，库车-拜城盆地的基底整体向天山下倾斜，基底构造的强转折带迁移到塔北隆起带；新近纪以来库车坳陷的基底转折期与塔北隆起盖层的负反转构造形成期在时间上一致，在空间上，库车坳陷的基底在强烈沉降俯冲的同时，相邻塔北隆起的基底相对隆起，形成库车新生代前陆盆地的前隆；库车前陆冲断带的形成是在库车基底斜坡上伴随天山的推覆而形成的；塔北隆起为库车前陆盆地的前隆，基底俯冲变形及其转折带迁移导致塔北隆起盖层负反转构造的形成。  相似文献   

Coastal currents and eddies and their interaction with topography     

Byoung Woong An  N.Robb McDonald 《Dynamics of Atmospheres and Oceans》2005,40(4):237-253

The nonlinear interaction of vorticity driven coastal currents and eddies with topography is studied. The topography is either a semi-infinite escarpment perpendicular to the coast (such that topographic waves propagate toward the coast) or a semi-circular canyon or seamount attached to the coast. Assuming a piecewise constant potential vorticity distribution, the quasigeostrophic equations are solved using contour dynamics. Offshore propagating dipole eddies occur, whenever a coastal current or eddy interacts with escarpment and canyon topographies. The size and frequency at which dipoles form are found to depend on the vorticity of the current and amplitude of the topography. However, for a seamount, little eddy shedding is observed and the coastal current or eddy skirts around topography.  相似文献   

大庆外围深层实施气体钻井的可行性分析          下载免费PDF全文

杨智光  赵德云  刘永贵  陆凤德  安明玉 《探矿工程》2005,32(9):55-58

总结了气体钻井的优缺点，结合大庆地质特点以及钻井技术状况对在大庆外围深层实施气体钻井的地质条件、钻井条件、技术条件和经济条件的可行性进行了分析。分析结果表明，在大庆外围具备进行气体钻井的条件，利用气体钻井来提高大庆外围深层的钻井速度是完全可行的，并有利于发现和保护储层。  相似文献   

Assessment of the spatial-temporal eutrophic character in the Lake Dianchi   总被引：1，自引：0，他引：1  

XING Kexia  GUO Huaicheng  SUN Yanfeng  HUANG Yongtai 《地理学报》2005,15(1):37-43

Water-quality deterioration and eutrophication of the Lake Dianchi have acquired more and more attention in the last few decades. In this paper, the spatial and temporal eutrophication status of the Lake Dianchi was assessed. The comprehensive trophic state index was chosen to assess the trophic status of the Lake Dianchi in the past 13 years. The result reveals that the trophic condition of Caohai is more serious than that of Waihai. Most of time Caohai was in extremely hypereutrophic state from 1988 to 2000. The trophic condition of Waihai had a worsening tendency from 1988 to 2000. Waihai was in eutrophic state before 1995, but it got in a hypereutrophic state after 1995. It was pointed out that TN and TP were the two biggest contributors of CTSIM in both Caohai and Waihai.  相似文献