基于RS与GIS的干旱区绿洲景观格局变化研究——以金塔绿洲为例   总被引：35，自引：17，他引：35  

马明国  王雪梅  角媛梅  陈贤章 《中国沙漠》2003,23(1):53-58

景观生态学是宏观生态研究的一个新领域。景观格局变化研究,是目前景观生态学的研究热点。利用遥感的手段获取试验区1990和2000年景观格局的基础数据,并利用GIS做分析的工具,计算出6个指标值,采用格网化的方法,将研究区域的景观斑块转化成5m×5m的格网,进行空间分析,计算得出了景观斑块的转移矩阵,为景观格局在空间上的变化分析打下基础。分析显示:①多样性、均匀性、优势度3个指标数值上有很大的相关性,只需考虑多样性;②绿洲景观格局的变化与水资源的变化密切相关;③绿洲有沙漠化的威胁;④城镇居民点用地扩展迅速,主要在未利用土地上发展,金塔绿洲内城镇居民区有城市化的趋势;⑤城镇居民点破碎化指标值未能真正体现其景观特性,当不考虑少数几个大的斑块时,能够得到较为理想的结果。  相似文献   

Receiver function study of the Hellenic subduction zone: imaging crustal thickness variations and the oceanic Moho of the descending African lithosphere   总被引：3，自引：0，他引：3  

X. Li  G. Bock  A. Vafidis  R. Kind  H.-P. Harjes  W. Hanka  K. Wylegalla  M. van der Meijde  X. Yuan 《Geophysical Journal International》2003,155(2):733-748

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我国天然锌铜金属互化物的发现和特征   总被引：2，自引：0，他引：2  

孙燕  肖渊甫  王奖臻  温春齐  陆彦 《矿物岩石》2003,23(1):11-14

锌、铜金属互化物是罕见的天然合金矿物，由锌、铜两种元素组成。由于形成条件、环境不同及矿物中锌、铜元素含量不同，形成系列锌、铜金属互化物。经过对我国近二十年来发现的各类型天然锌、铜金属互化物产出的地质特征，物理、化学及光学性质进行的系统研究发现，目前我国在不同的地质体中出现多种不同类型的锌、铜金属互化物，该类矿物主要形成于高温、还原且缺硫的条件下，多数与造岩矿物共生，而与多数金属硫化物形成条件不同。  相似文献   

邛崃4.5级地震与震后趋势判断     

袁海良  朱昌保  宋杰  高进  任寰 《地震地磁观测与研究》2003,24(4):80-83

邛崃地震发生后，成都市地震局很快做出反应，及时开展了地震考察并做出了正确的震后趋势判断，取得了较好的社会效益。  相似文献   

湖北黄土岭麻粒岩锆石拉曼光谱和等离子体质谱研究   总被引：3，自引：0，他引：3  

程昊  陈道公  吴元保  何谋春 《地学前缘》2003,10(2):313-317

对湖北黄土岭麻粒岩中锆石同时进行了激光拉曼探针、阴极发光 (CL)观察和U ,Th及Pb Pb年龄ICPMS测定 ,发现麻粒岩中部分锆石发生的不是固态重结晶作用 ,而是部分熔蚀 /沉淀再结晶过程。结合CL图像结构特征和2 0 7Pb/ 2 0 6Pb年龄初步推断 ,麻粒岩相事件发生在 2 0亿年之后。结构、化学和同位素组成的测定表明 ,大别地区广泛存在的燕山期热事件使锆石发生不同程度的变质重结晶作用 ,使锆石晶格愈合。  相似文献   

Effect of asymmetry and irregularity of seismic waves on earthquake-induced differential settlement of buildings on natural subsoil     

Xiaoming Yuan  Rui Sun  Meng Shangjiu 《Soil Dynamics and Earthquake Engineering》2003,23(2):107-114

The effect of asymmetry and irregularity of the inputted seismic waves on the earthquake-induced differential settlement of the buildings on natural subsoil is investigated in terms of the earthquake damage phenomena, theoretical analyses, dynamic triaxial tests and shaking table tests. A conclusion can be drawn from the investigation results that, the asymmetrical and irregular character of the inputted seismic waves themselves may have a significant contribution to the differential settlement of subsoil and buildings in some cases, and this is a necessary factor to be considered in reasonable evaluation for the differential settlement and other problems relating to the soil deformation due to earthquakes.  相似文献   

Temporal variations of shear-wave splitting in field and laboratory studies in China   总被引：1，自引：0，他引：1  

Yuan Gao  Stuart Crampin   《Journal of Applied Geophysics》2003,54(3-4):279

Observations of shear-wave splitting at seismic stations above a swarm of small earthquakes on Hainan Island, China, and other examples world-wide, suggest that the time-delays of split shear-waves monitor the build up of stress before earthquakes and the stress release as earthquakes occur. Rock physics experiments on marble specimens also show variations of shear-wave time-delays with uniaxial pressure analogous to the field observations. The rock experiments show an abrupt decrease in time-delays immediately before fracturing occurs. Similar precursory behaviour has been observed before earthquakes elsewhere, and is believed to be important for two reasons. Precursory changes in shear-wave splitting could be used for short-term forecasting, but of greater importance may be the information such behaviour provides about the source processes in earthquake preparation zones.  相似文献   

Characteristics of Tectonic Deformation and Mechanisms for the Active Maxianshan-Xinglongshan Fault System in the Lanzhou Area     

Yuan Daoyang  Liu Xiaofeng  ZHENG Wenjun  Liu Xiaolong  Liu Baichi 《中国地震研究》2003,17(4):315-323

A detailed investigation permitted us to obtain quantitative data concerning fine geometric structures of 4 faults of the active Maxianshan-Xinglongshan fault system and the latest movement along them. Of them the northern Maxianshan border fault is a large-scale, strongly active Holocene reverse sinistral strike-slip fault, the other 3 faults, the southern Maxianshan border fault and the southern Xinglongshan border and the northern Xinglongshan border faults are the accompanying active late-Pleistocene thrust faults, which are incorporated into the main strike-slip fault, the northern Maxianshan border fault at depth. It is the most important earthquake-controlling fault in the Lanzhou area, the fault influences and constrains the seismic activity in the area.  相似文献   

鄱阳湖组(第四系)的修订及特征   总被引：3，自引：0，他引：3  

马振兴  蒋玉珍  魏源  李均辉  李长安 《地层学杂志》2003,27(3):212-215

根据对鄱阳湖地区 Zk0 1钻孔柱状剖面的研究 ,对鄱阳湖组的定义进行修订、补充 ,认为鄱阳湖组为一套以青灰色淤泥质粘土、黄褐色粘土、粉质粉土为主夹少量粉砂或细砂的湖泊—河口三角洲相沉积。年代地层为第四系全新统 ,底界年龄约 6 2 10± 12 5 a B.P.,开阔湖泊沉积始于 32 4 0± 180 a B.P.,且由北向南时代渐新 ,具有明显的穿时性  相似文献   

Absence of Archean basement in the South Kunlun Block: Nd-Sr-O isotopic evidence from granitoids   总被引：3，自引：0，他引：3  

Chao Yuan  Min Sun  Mei-Fu Zhou  Hui Zhou  Wenjiao Xiao  Jiliang Li 《Island Arc》2003,12(1):13-21

Abstract   The West Kunlun mountain range along the northwestern margin of the Tibetan Plateau is crucial in understanding the early tectonic history of the region. It can be divided into the North and South Kunlun Blocks, of which the former is considered to be part of the Tarim Craton, whereas consensus was not reached on the nature and origin of the South Kunlun Block. Samples were collected from the 471 Ma Yirba Pluton, the 405 Ma North Kudi Pluton and the 214 Ma Arkarz Shan Intrusive Complex. These granitoids cover approximately 60% of the Kudi area in the South Kunlun Block. Sr, Nd, and O isotope compositions preclude significant involvement of mantle-derived magma in the genesis of these granitoids; therefore, they can be used to decipher the nature of lower–mid crust in the area. All samples give Mesoproterozoic Nd model ages (1.1–1.5 Ga) similar to those of the exposed metamorphic complex of this block but significantly different from those of the basement of the North Kunlun Block (2.8 Ga). This indicates that the South Kunlun Block does not have an Archean basement, and, thus, does not support the microcontinent model that suggests the South Kunlun Block was a microcontinent once separated from and later collided back with the North Kunlun Block.  相似文献