城市边缘区建设用地扩张空间特征及影响因素定量研究——以南京市江宁区为例     

吕蕾  周生路  任奎 《地域研究与开发》2008,27(3):103-107

城市边缘地区内部建设用地扩张空间特征及影响因素研究是当前城市用地空间扩展研究的薄弱环节.以南京市江宁区为例,构造城市扩张综合指数(UICI)反映城市边缘区内部建设用地扩张的空间差异,并按计算结果将各镇(街道)城市用地扩张归纳为剧变型、快变型、缓变型及相对稳定型4种类型.在建立城市用地扩张影响因素因子体系的基础上,运用主成分分析与通径分析相结合的方法,得出以下结论:推动城市边缘区建设用地扩张的因素中科技水平是决定因素,经济水平、人口状况间接影响大于直接影响;主城关联因素不可忽略.  相似文献   

Planktonic stages of the teleost family carapidae in eastern New Zealand waters     

D. A. Robertson 《新西兰海洋与淡水研究杂志》2013,47(3):403-409

The occurrence of planktonic carapid eggs in Otago waters, of young stages of Echiodon rendahli off Castlepoint, and the possible presence of unrecorded members of the family Carapidae in New Zealand waters is discussed. Young E. rendahli possess a long spine which originates dorsally to a distinctive suspended gut.  相似文献   

The man swimming against the stream knows the strength of it : Hydraulics and social relations in an Argentinean irrigation system     

Maurits W. Ertsen  Ronald van Nooijen 《Physics and Chemistry of the Earth》2009,34(3):200-208

In this paper we discuss hydraulic behavior of irrigation infrastructure within a context of spatially distributed power relations in an Argentinean irrigation system. In the Río Dulce basin, the irrigation area known as the Proyecto Río Dulce (PRD, command area 350,000 hectares) is the main irrigated area. An interesting characteristic of the PRD is that the larger landowners are mainly situated in tail end areas. Despite this potentially disadvantageous position, downstream farmers do not encounter problems in terms of water availability. This should not be regarded as self-evident: the hydraulic properties of the canals induce a need for downstream farmers to take deliberate action to ensure proper water delivery to their farms. When upstream farmers do not irrigate, too much water can flow downstream; when they irrigate too much, or manipulate cross regulators, downstream water scarcity can be the result; when canals are not maintained, extensive plant growth will increase hydraulic resistance and decrease discharges. It is not a coincidence that the downstream farmers invest heavily in canal operation and maintenance. These investments appear to be appropriate, as larger farmers tend to irrigate much more on average, compared to the smaller farmers upstream. The Argentinean case brings up issues on the structuring effects of irrigation systems, which need stronger theoretical understanding.  相似文献   

南京河西地区岩土体剪切波速与土层深度的关系   总被引：3，自引：0，他引：3  

陶小三  杨伟林  高志兵  洪海春 《地震学刊》2009,(3):320-324

南京河西地区是南京市重点开发的新市区,该区域工程地质条件相似,主要为长江高河漫滩地质地貌单元。本文选取该地区47个典型钻孔的岩土体剪切波速资料,采用三种数学模型进行统计回归分析,运用相关系数R（或测定系数R^2）检验Vs-H之间的线性相关关系,并根据计算的SD值选择较优的数学模型。统计结果表明,该地区各类岩土体的Vs-H线性相关关系显著,说明采用上述数学模型进行Vs-H回归是可行的。对两个工程场地进行剪切波速预测,并对场地类别作出划分,检验结果表明,该地区各类岩土体的Vs-H经验关系是可靠的,符合当地岩土特征,在样本深度范围内有足够的工程应用精度,可以应用。  相似文献   

内蒙古狼山山前台地成因及其新构造运动意义   总被引：3，自引：0，他引：3  

何泽新  张绪教  贾丽云  武法东  周轶群  鲍淑燕  包智强  殷志刚  郭斌 《现代地质》2014,28(1):98-108

内蒙古狼山地处阴山造山带西段、河套断陷带的西北缘,晚新生代以来狼山山前断裂广泛发育、构造抬升强烈。研究晚更新世以来狼山的构造隆升对深入了解河套断陷带的形成演化机制及其隆升过程对河套盆地古地理格局的影响具有重要的意义。狼山山前翁格勒其格和乌兰敖包台地的沉积学、地貌学和年代学研究表明,T1台地形成于47.4 kaB.P.,其沉积物为晚更新世河套古大湖沉积;T2台地形成于69 kaB.P.,其沉积物可能为黄河流经狼山山前的冲积物。台地特征的分析显示,狼山山前台地主要由构造抬升形成,两级台地记录了狼山晚更新世晚期(Qp^3-2)以来的构造隆升过程。69 kaB.P.到47.4 kaB.P.翁格勒其格和乌兰敖包地区的隆升速率分别为1.34 m/ka和1.25 m/ka,47.4 kaB.P.以来分别为0.81 m/ka和1.18 m/ka,狼山南段(翁格勒其格地区)构造抬升有减小的趋势。晚更新世晚期(Qp^3-2)以来由于狼山的快速隆升,导致黄河河道不断东迁,河套平原的古河道是其迁移的证据。狼山山前湖岸阶地的研究进一步证实晚更新世晚期河套地区发育统一古大湖。  相似文献   

城市边缘区空间发展探讨——以北京市海淀区为例     

姚月 《地球信息科学学报》2014,16(2):214-224

在快速城镇化时期,城市边缘区是城市扩张过程中空间结构变化最大、土地利用转变最快的地区,以过渡性、复杂性、动态性为突出特征。研究城市边缘区的空间演变对认识城镇化、优化城市空间结构等具有重要意义。本文在总结海淀区空间发展历史渊源的基础上,采用了RS/GIS技术对20世纪80年代以来海淀城市边缘区的范围、空间扩张进行了定量分析;并结合系统论方法,探索影响海淀城市边缘区空间演变的若干因素。研究发现：海淀城市边缘区空间发展有独特的地理优势和文化渊源,且在政策、经济、人口、交通等因素的综合作用下,处于不断动态变化之中;呈现出沿环线不规则分布、边界由清晰变模糊、整体向西北推移的空间特征;总面积逐渐增加、年扩张速率先升后降;1995-2007年以向外扩张为主,其他阶段以内部填充型发展为主;空间分布及扩张强度在不同乡镇街道具有区域差异性等。本文将RS/GIS技术与系统分析相结合,来研究城市边缘区相关问题的技术可行性。  相似文献   

新疆石河子农区土壤含盐量定量反演及其空间格局分析   总被引：2，自引：0，他引：2  

陈实  高超  徐斌  金云翔  李金亚  马海龙  赵芬  郭剑  杨秀春 《地理研究》2014,33(11):2135-2144

盐渍化严重威胁着土地持续耕作和粮食生产安全,土壤含盐量的快速反演和及时监测,对新疆石河子农区农业可持续发展有着重大意义。以Landsat-8 OLI遥感影像与野外采样测定的72个样点土壤含盐量为数据基础,引入土壤亮度指数、土壤湿度指数、土壤盐盖度指数和土壤辐射水平指数等构建的特征遥感指数定量反演新疆石河子农垦区土壤含盐量,并对其空间布局进行了分析。研究表明：① 利用遥感影像像元特征遥感指数值反演地面对应土壤含盐量的精度较好,反演方法可行,反演精度为66%;② 反演得到土壤含盐量空间分布图在空间上等级明显,层次分明,呈现出“一带一区”的格局,“一带”是玛纳斯流域形成的盐渍化程度较高的条带,“一区”是内在土质形成的严重盐渍化区域;③ 在新疆石河子农区中,35.40%的棉田适合耕作,64.60%的棉田耕地需要进行改良,农区土壤盐渍化治理仍十分紧迫。  相似文献   

胶东燕山期大型超大型金矿集区形成的壳幔结构探讨：来自致矿火成岩(组合)的约束     

刘翠  邓晋福  李胜荣  肖庆辉  金天杰  孙浩  狄永军  刘勇  赵国春 《地学前缘》2018,25(6):296-307

大型超大型金属矿床形成的深部物质组成和壳幔结构一直是地学研究中被关注的焦点和难点问题。胶东地区发育很多(燕山期)的大型超大型的金矿,是我国著名的金矿集区。本文基于板块构造理论,通过揭示区域火成岩、致矿火成岩组合及其特征,探讨金矿发育时的深部物质组成和壳幔结构。区域上成矿前的侵入岩组合为含少量英云闪长岩+奥长花岗岩(TT)的花岗闪长岩+花岗岩(G1G2)组合;区域上发育的青山群为含有高镁安山岩(HMA)和镁安山岩(MA)的玄武安山岩安山岩英安岩流纹岩以及粗安岩玄粗岩粗面岩组合;矿集区的致矿火成岩组合为含有高Mg闪长岩类(HMgδ)+Mg闪长岩类(Mgδ)的宽谱系岩墙群(WSDS),岩性从基性到酸性均有。上述火成岩组合,以及TTG1、HMA与MA系列火山岩、HMgδ和Mgδ的存在,指示弧火成岩的组合,其各种岩石地球化学特征亦具有弧的特征,因此,上述火成岩及金矿形成于洋俯冲环境,具有俯冲带的壳幔结构和物质组成。各种不同的火成岩指示其可能分别来源于俯冲带不同部位的局部熔融,指示洋壳、上覆地幔楔以及上覆陆壳具有异常热的壳幔结构,即热的洋壳、热的上覆地幔(软流圈)、热的陆壳。致矿火成岩事件、成矿事件均在大规模的壳源(或壳幔)侵入岩浆活动之后。  相似文献   

Metavolcanic host rocks,mineralization, and gossans of the Shaib al Tair and Rabathan volcanogenic massive sulphide deposits of the Wadi Bidah Mineral District,Saudi Arabia     

John C. Volesky  Robert J. Stern  Jan M. Peter  Daniel Layton-Matthews  Sarah Rice 《International Geology Review》2017,59(16):1975-2002

The Wadi Bidah Mineral District of Saudi Arabia contains more than 16 small outcropping stratabound volcanogenic Cu–Zn–(Pb) ± Au-bearing massive sulphide deposits and associated zones of hydrothermal alteration. Here, we use major and trace element analyses of massive sulphides, gossans, and hydrothermally altered and least altered metamorphosed host rock (schist) from two of the deposits (Shaib al Tair and Rabathan) to interpret the geochemical and petrological evolution of the host rocks and gossanization of the mineralization. Tectonic interpretations utilize high-field-strength elements, including the rare earth elements (REE), because they are relatively immobile during hydrothermal alteration, low-grade metamorphism, and supergene weathering and therefore are useful in constraining the source, composition, and physicochemical parameters of the primary igneous rocks, the mineralizing hydrothermal fluid and subsequent supergene weathering processes. Positive Eu anomalies in some of the massive sulphide samples are consistent with a high temperature (>250°C) hydrothermal origin, consistent with the Cu contents (up to 2 wt.%) of the massive sulphides. The REE profiles of the gossans are topologically similar to nearby hydrothermally altered felsic schists (light REE (LREE)-enriched to concave-up REE profiles, with or without positive Eu anomalies) suggesting that the REE experienced little fractionation during metamorphism or supergene weathering. Hydrothermally altered rocks (now schists) close to the massive sulphide deposits have high base metals and Ba contents and have concave-up REE patterns, in contrast to the least altered host rocks, consistent with greater mobility of the middle REE compared to the light and heavy REE during hydrothermal alteration. The gossans are interpreted to represent relict massive sulphides that have undergone supergene weathering; ‘chert’ beds within these massive sulphide deposits may be leached wall-rock gossans that experienced silicification and Pb–Ba–Fe enrichment from acidic groundwaters generated during gossan formation.  相似文献   

Mineralogical,petrographic and fluid inclusion evidence for the link between boiling and epithermal Ag-Au mineralization in the La Luz area,Guanajuato Mining District,México     

《Ore Geology Reviews》2017

Theoretical, experimental and observation data provide strong evidence that boiling is the dominant depositional mechanism in many low to intermediate sulfidation epithermal precious metals deposits. Textural and petrographic features that are evidence for boiling in the epithermal environment include the presence of coexisting liquid-rich and vapor-rich fluid inclusions, assemblages consisting of only vapor-rich fluid inclusions, colloform quartz, adularia and bladed calcite. We have examined 213 samples collected from surface outcrops, underground workings and drill cores from the central part of the La Luz vein system in the Guanajuato mining district, Mexico. In each sample, the various features that are evidence of boiling have been recorded. These observations have been quantified using a Boiling Confidence Factor that provides a means of scoring and rating each sample or area relative to the likelihood that boiling occurred.Homogenization temperatures of liquid-rich fluid inclusions within assemblages of coexisting liquid-rich and vapor-rich fluid inclusions have been measured to estimate the depth of trapping of the inclusions, and these data have been used to estimate the depth to the 300 °C isotherm along the La Luz vein system.Fluid inclusions and mineral textural features show strong evidence of boiling in the deepest levels sampled in the La Luz system. This observation suggests that the bottom of the boiling zone is at some depth beneath the deepest levels explored and opens the potential for additional resources at depth.  相似文献