汶川MS 8.0地震前龙门山断裂带的水平形变和应变特征

根据1999年,2001年,2004年和2007年的GPS观测资料计算得到的1999--2007年全球框架下的站点速率,使用块体运动模型公式,根据青藏亚板块和华南亚板块上的GPS站点速度,分别计算两个块体的运动参数,并用来反算龙门山断裂带的运动参量。结果表明龙门山断裂带的活动速率为9．38mm／a。其中,右旋走滑速率为3．22mm/a,压缩速率为-8．81mm／a。     

滇黔桂“金三角”地区晚三叠世地层碎屑物源示踪

三叠系是滇黔桂分布最广泛的岩系,赋存卡林型金矿等各种低温矿产。在前人研究基础上,运用LA-ICP-MS分析技术,对滇黔桂"金三角"地区的碎屑锆石进行了U-Pb测年。结果显示,大部分锆石具岩浆环带,Th/U值大于0.4,锆石U-Pb年龄集中在308~396 Ma、440~680 Ma、727~930 Ma、1004~1266 Ma、1400~1880 Ma、2360~2724 Ma六个区段。通过对比研究区及周围地块的碎屑锆石年龄分布特征,结合研究区岩相古地理、古海流及古流向,综合分析认为,研究区物源以越北古陆为主,同时湘粤桂构造山系和云开地区也可能提供了部分物源。该物源印证了古特提斯洋在印支期逐渐闭合,华南陆块与印支地块沿松马缝合带发生碰撞。     

倾斜平面二维渗流与隧道涌水量计算基本理论

倾斜平面内的渗流问题在倾斜岩层与裂隙岩层地区,特别是在这类岩层地区开凿隧道、巷道等地下工程时是常见的。但是,这类问题的系统基本理论则很少见到,特别是将这类问题与隧道涌水量计算相联系的理论则更罕见。就此问题,给出了这类渗流问题的坐标系的选取与各种基本方程、定解条件、数学模型、隧道在倾斜剖面中的形体变态理论和两类隧道单宽涌水量的转化等较系统、较完整的一套基本理论。这些理论对实际工程和理论发展都有重要意义。     

砼地基施工质量的CT检测技术

建筑工程板状砼地基属地下工程,其施工质量的检测与控制难度较大。根据该类工程的特点（面积大,厚度小）,可将其视为二维结构,采用弹性波ＣＴ成像方法检测其施工质量,在工程实践中取得了满意的效果。本文将结合工程实例介绍板状砼地基浇注质量的ＣＴ检测技术,包括弹性波ＣＴ的基本原理、野外数据采集系统的设计以及数据处理方法。     

Upper Cretaceous alluvial fan deposits in the Jianglangshan Geopark of Southeast China: implications for bedrock control on Danxia landform evolution

The Jianglangshan Geopark in the western Zhejiang Province of Southeast China is well-known for its spectacular red-colored sandstone landforms. Little is known about the depositional processes of the conglomerate-dominated Fangyan Formation, the lithologic base of the Danxia landforms in this geopark. Based on detailed field investigation of lithology, sedimentary structures, bed thickness and geometry, five facies are recognized: facies A (matrix-supported cobble conglomerate), facies B (pebble conglomerate), facies C (pebbly sandstone), facies D (fine-grained sandstone) and facies E (mudstone). The results show that streamflow-dominated fans were the main depositional processes responsible for the accumulation of the Fangyan Formation along the mountain fronts. These fan conglomerates form the base for the evolution of the Danxia landscapes owing to the uplift and erosion of the study area. In contrast, the fine-grained sedimentary successions produced by fluvial floodplains in the distal part of the fans were thinner and more easily weathered. Such sedimentary facies distribution patterns were thought to be similar during Late Cretaceous across Southeast China. The Danxia landforms are largely the geographical expressions of the conglomerate-dominated redbeds in the proximal-middle fans.     

Temporal changes in wetland plant communities with decades of cumulative water pollution in two plateau lakes in China’s Yunnan Province

Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteristics of changes in wetland plant communities in two of the largest lakes in Yunnan Province, Dianchi and Erhai lakes. We collected records of native and alien plant communities in the two lakes from literature published from the 1950s to current period. We calculated plant community types and their area in some historical periods when related data were reported, and analyzed the relationship between changes in plant communities and water pollution. In Dianchi Lake, 12 community types of native plant communities, covering over 80% of the surface in the 1950s and 1960s, were reduced to four types covering 2.4% by the late 2000s. Alien plant communities started to appear in the lake in the late 1970s, and have since come to cover 4.9% of the lake surface, thereby becoming dominant. In Erhai Lake, 16 community types of native plant communities, covering 47.1% of the lake surface in the late 1970s, declined to 10 community types, covering 9.3% of the surface, by the late 2000s. Alien plant communities appeared in the middle 1980s, and at present cover 0.7% of the surface area. It was indicated that changes in plant communities were significant related to water eutrophication. The area occupied by native and alien plant communities was, respectively, negatively and positively related to the content of nutrients in water. This showed lacustrine pollution played an important role in native plant loss and alien plant invasion in the two plateau lakes.     

在社会发展的层面上认识“数字地球”

 本文讨论了“数字地球”的有关问题。指出“数字地球”是人类社会及其活动在网络空间的延伸和拓展,是信息技术带来的社会发展趋势。关于“数字地球”的讨论不应局限在空间信息技术领域,而应该在社会发展的层面上认识它     

ESTIMATION AND EXPLOITATION OF WATER RESOURCES IN THE SANJIANG PLAIN

According to practical measurement and related data, the writer discusses the main features of rivers in the Sanjiang Plain and the change of water balance with time and space, and then estimates water resources of five types, namely, runoff, ground water, soil water, and water supplied by three rivers and lakes (or reservoirs).The total volume of the above-mentioned water resources can be up to 31.5 billion m3. But they are rather unevenly distributed and the annual change is considerable, too. Up to now, only 8.3% of water resources have been utilized. According to a programme, 17.5 billion m3 will be utilized in the future in the district. Rationally exploiting water resources in the district should be combined with protection and management, and the sole criterion for judging rationality of utilization is that whether it is beneficial to economic, ecologic and social aspects.     

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