青藏高原东缘晚新生代大邑砾岩的 物源分析与水系变迁*

成都盆地晚新生代碎屑沉积物的快速堆积是青藏高原东缘强烈隆升的产物,同时为青藏高原东缘晚新生代的隆升提供了强有力的证据。文章以盆地底部的大邑砾岩作为研究切入点,详细研究了它的物源区,以深化对青藏高原东缘晚新生代隆升过程的理解。通过砾石成分统计、砂岩薄片鉴定、重矿物分析以及古流向恢复等方面的研究表明,成都盆地北部和南部的大邑砾岩分别受不同的物源区和河流所控制。其中北部的大邑砾岩受控于出口在都江堰南约4km处向南流的河流所控制,其物源区为玉堂镇以西、汶川-茂汶断裂以东的流域范围内。而南部的大邑砾岩则主要受向东流的古青衣江的控制,其物源区即为现代青衣江流域。大邑砾岩的物源分析表明晚新生代期间岷江和青衣江都曾发生河流改道。     

Allocating local groundwater monitoring stations for South Korea using an analytic hierarchy process

A national groundwater-monitoring network consisting of 320 stations has been operated by the Ministry of Construction and Transportation and the Korea Water Resources Corporation since 1995. The network was established as a result of the Groundwater Act of Korea, and a supplementary local groundwater monitoring network containing 10,000 stations will be established throughout the country by the year 2011. A method of allocating stations and organizing the local monitoring network has been developed, based on the analytic hierarchy process (AHP), using pairwise comparison. Several evaluation criteria were selected for determining the required number of the monitoring stations at specific local districts. Weights of the selected criteria were assigned by the pairwise comparison, reflecting hydrogeological conditions and supported by pertinent questions to 93 groundwater experts. To evaluate appropriateness of this method, an example city, Jeonju, was selected where groundwater levels were monitored; seven stations were determined as to be required for the supplementary groundwater-monitoring network. The study demonstrated the usefulness of the AHP. The concepts of the development and the structure of the AHP model can be applied to site or well selections within a particular district.     

Distribution, migration and derivation of Mesozoic-Cenozoic regional fault systems in the central continental margin of eastern China

Deep-large faults in the central continental margin of eastern China are well developed. Based on the regularity of spatial and temporal distribution of the faults, four fault systems were divided: the Yanshan orogenic belt fault system, the Qinling-Dabie-Sulu orogenic belt fault system, the Tanlu fault system and the East China Sea shelf basin-Okinawa trough fault system. The four fault systems exhibit different migration behaviors. The Yanshan orogenic belt fault system deflected from an EW to a NE direction, then to a NNE direction during the Indo-Chinese epoch-Yanshanian epoch. The thrust-nappe strength of the Qinling-Dabie orogenic belt fault system showed the tendency that the strength was greater in the south and east, but weaker in the north and west. This fault system faulted in the east and folded in the west from the Indo-Chinese epoch to the early Yanshanian epoch. At the same time, the faults also had a diachronous migration from east to west from the Indo-Chinese epoch to the early Yanshanian epoch. On the contrary, the thrust-nappe strength was greater in the north and west, weaker in the south and east during the late Yanshanian epoch-early Himalayan epoch. The Tanlu fault system caused the basin to migrate from west to east and south to north. The migration regularity of the East China Sea shelf basin-Okinawa trough fault system shows that the formation age became younger in the west. The four fault systems and their migration regularities were respectively the results of four different geodynamic backgrounds. The Yanshan orogenic belt fault system derived from the intracontinental orogeny. The Qinling-Dabie-Sulu orogenic belt fault system derived from the collision of plates and intracontinental subduction. The Tanlu fault system derived from the strike-slip movement and the East China Sea shelf basin-Okinawa trough fault system derived from plate subduction and retreat of the subduction belt. Translated from Journal of Jilin University (Earth Science Edition), 2005, 35(5): 554–563 [译自: 吉林大学学报 (地球科学版)]     

中国东北地区土地荒漠化与气候变化研究进展

地处中高纬度的中国东北地区西部正在发展的土地荒漠化,已经引起国内学者的共识和关注.综述了近十几年这一领域研究的进展.侧重介绍土地荒漠化与区域气候变化的研究成果,并对将来研究中应思考的问题提出某些建议.在全球变暖的背景下,对东北地区西部生态环境的恶化趋势,如何采取系统和大规模的工程整治和保护措施,不仅对保障国家重要的东北地区中部产粮区的安全生产有重要战略意义,而且对人类适应、减缓和应对气候变暖具有典型的示范作用.进一步鼓励和支持开展东北地区土地荒漠化与气候变化的研究是十分必要的,建议加强有关气候变化、环境干旱化、土地覆盖变化的固定和野外观测系统建设,加强多要素的气候系统观测工作,加强多学科交叉研究立项工作,不仅要掌握卫星遥感信息,更要掌握器测的地表有关要素的信息,从中准确得出该区土地覆盖变化的频繁和敏感区的分布,为研究土地覆盖动力学和制定对策奠定科学基础.     

Progress in isotope paleohydrology using lake sediment cellulose

Recent advances in sample preparation techniques and mass spectrometry have fostered more routine oxygen isotope analysis of aquatic cellulose in lake sediment cores, a proxy for lake water oxygen isotope history. These methodological developments have significantly increased the feasibility of incorporating this approach into high-resolution, multi-site, and multi-proxy studies, which are frequently necessary to answer complex hydrological, hydroecological and hydroclimatic questions requiring a paleoenvironmental perspective. Direct translation of lake sediment aquatic cellulose oxygen isotope composition into lake water oxygen isotope composition offers appreciable opportunity for quantitative paleohydrological reconstructions, as evidenced by studies conducted over the past 15 years that span Holocene and pre-historical timescales.     

基于SPOT VEGETATION数据的中国西北植被覆盖变化分析

 基于遥感和地理信息系统的技术,利用SPOT-VEGETATION NDVI(Normalized Difference Vegetation Index)数据对我国西部地区植被覆盖的情况进行了动态监测。采用MVC（Maximum Value Composites）、一元线性回归趋势分析和变化幅度百分比等方法分析西部地区植被变化特征,并结合西北五省土地利用类型图,分析不同植被类型的年最大化NDVI(MNDVI)变化趋势及特点。其结果是:近7 a来植被覆盖存在普遍退化的趋势,且2000-2001与2001-2002年度的变化幅度较大。在局部区域植被有改善的趋势, 但总的改善幅度小于退化幅度。分析结果表明, 植被改善的区域主要分布在陕西和宁夏的大部分地区以及新疆西北部和西南部地区。大部分地区植被退化。而且不同植被的MNDVI在相同的年份表现出相似的变化特点和趋势。     

Origin of gray-green sandstone in ore bed of sandstone type uranium deposit in north Ordos Basin

Dongsheng sandstone-type uranium deposit is located in the northern part of Ordos Basin, occurring in the transitional zones between gray-green and gray sandstones of Jurassic Zhiluo Formation. Sandstones in oxidized zone of the ore bed look gray-green, being of unique signature and different from one of ordinary inter-layered oxidation zone of sandstone-type uranium deposits. The character and origin of gray-green sandstones are systematically studied through their petrology, mineralogy and geochemistry. It is pointed out that this color of sandstones is originated from secondary oil-gas reduction processes after paleo-oxidation, being due to acicular-leaf chlorite covering surfaces of the sandstone grains. To find out the origin of gray-green sandstone and recognize paleo-oxidation zones in the ore bed are of not only theoretical significance for understanding metallogenesis of this kind of sandstone-type uranium deposit, but also very importantly practical significance for prospecting for similar kind of sandstone-type uranium deposit.     

基于SICAD／Open空间拓扑结构的地籍空间实体图形变更处理

简要介绍了一种GIS平台SICAD/Open，详细描述了SICAD/Open空间拓扑结构，给出了基于SICAD/Open空间拓扑结构的地籍空间实体图形变更处理方法，为在地籍信息系统中利用地理信息系统技术实现地籍空间实体图形变更提供了一种切实可行的操作方法。文中描述的处理方法已成功应用于上海市地籍管理信息系统中。     

利用精密星历进行单点定位的数学模型和初步分析

精密单点定位(Precise Point Positioning,简称PPP),是相对于一般的单点定位而言的,它是利用GPS的精密星历和钟差文件,以载波相位和伪距为观测资料,进行独立的单点精密定位.它的特点在于各站的解算相互独立,计算量远远小于一般的相对定位.尝试以伪距为观测值,利用JPL给出的精密星历(*.sp3)和钟差(*.clk),进行精密单点定位的试验,取得了初步的结果.     

光电测距仪测距标准差校准结果的不确定度评定

介绍光电测距仪的测距标准差计量校准方法并对校准结果的不确定度进行了评定,给出了测距仪的测距标准差校准结果的表示形式和20台测距仪的测距标准差校准结果及测量不确定度.