复杂地形景区三维导览图的设计与实现     

吴思锴  李百寿  郭家豪  李雪  张卫平 《北京测绘》2020,(1):38-43

为满足复杂地形景区对三维地图导览的需求,构建更为清晰的三维地图模型,提供良好的三维导览地图设计方案显得尤为重要。为了更好地与卫星影像进行贴合,DEM数据的采样密度要与卫星影像的分辨率一致。本文通过对比当下常用的四种空间插值方法的适用范围与运用特点,设置相关阈值及权重,直观比较了四种插值方法产生的插值结果,选择更适合复杂景区DEM插值的插值方法并对其进行精度提升,以此得到符合精度要求的DEM数据。最后利用相应地区的卫星影像进行地图投影及影像贴图,两种数据结合构建复杂景区的三维地图模型,给游客带来更为精确直观的定位信息和空间要素信息。  相似文献   

全球尺度水文模型： 机遇、 挑战与展望   总被引：4，自引：2，他引：2  

高红凯  赵舫 《冰川冻土》2020,42(1):224-233

水循环发生在全球尺度， 局地和流域水问题的解决也往往需要全球视角， 因此全球尺度水文模型应运而生。从科学意义和国家需求等多个视角， 论述了全球水文学研究的意义和巨大的发展潜力， 系统总结了现有全球尺度水文模型发展现状， 剖析了十余个主流全球尺度水文模型的结构和功能， 以及全球水文-气象-地理信息等全球模型所需数据集。进而分析了现有全球尺度水文模型存在的主要问题和挑战， 为进一步完善模型提供参考。最终分别从模型机理、 大数据、 新技术、 多部门模型耦合等几个方面， 探讨了全球尺度水文模型未来发展的重要方向。  相似文献   

海洋表层沉积物中金属镉的来源解析     

谭赛章  杨涛  可愚  刘材材  张昊飞 《海洋通报》2019,38(6):683-689

利用2015年8月份对长江口及其邻近海域表层沉积物的监测数据,基于主成分分析/绝对主成分分数(PCA/APCS)受体模型定量解析了重金属元素镉(Cd)的可能来源,并结合地统计学插值了Cd的源贡献量的空间分布状况,结果表明沉积物中镉污染主要存在3个可能来源,源头及贡献率分别为工业污染(18.8%)、陆地径流输入(66.0%)、生物活动等自然因素(13.6%),并且各个源头贡献量具有不同的空间分布状况,其中工业污染的高值区主要集中在靠近陆地区域,陆地径流输入的分布呈现由近岸向外海逐减降低的特征,生物活动等自然因素的高值区主要集中在远离陆地的外海区域。  相似文献   

老挝帕莱通铁矿床西矿段磁铁矿地球化学特征及其成矿意义     

孙策  彭惠娟  熊富浩  侯林 《矿床地质》2020,39(3):523-546

帕莱通铁矿床是老挝万象—呵叻中新生代盆地中最大规模的铁矿床,分为东、西2个矿段,西矿段为豆状、块状富磁铁矿矿体,东部则主要发育角砾状贫赤铁矿矿体。其中,西矿段主要产于新生代富铁质玄武岩中。文章对西矿段中豆状、块状磁铁矿进行了详细的野外地质调查和显微结构分析,发现块状磁铁矿具有细粒他形结构特征,豆状磁铁矿具有球粒同心圆状结构特征。对较为新鲜的磁铁矿进行电子探针(EPMA)以及激光剥蚀电感耦合等离子质谱(LA-ICP-MS)分析显示:帕莱通铁矿床磁铁矿TiO_2-Al_2O_3-MgO三角图落入岩浆岩区域;微量元素富集V、Ti、Cr、Co、Ni及Ga等元素,亏损Sr、Ba及Mg等不相容元素;w(Co)和w(Ni)较高,且较高的Ni/Co比值可以反映成因与深源物质;w(Ti)较高且Ni/Cr比值≤1,在Ti-Ni/Cr图中落入了热液型磁铁矿的范围;Ga-Sn图解表明磁铁矿属于斑岩型热液成因;(Ca+Al+Mn)-(Ti+V)或Ni/(Cr+Mn)-(Ti+V)成因判别图显示该矿床兼具Kiruna型和斑岩型矿床的特征;w(V)表明磁铁矿在较低氧化环境中形成;(Al+Mn)-(Ti+V)形成温度判别图表明磁铁矿形成温度处于300～500℃范围内。文章认为帕莱通铁矿床成矿物质主要源于岩浆演化作用形成的富铁流体,后期由于岩浆热液流体的交代作用,使得磁铁矿具有了热液成因的特征。岩浆型矿床类型在老挝及邻区分布较为广泛,研究帕莱通铁矿的成因,对于总结区域成矿规律,指导同类型矿床找矿预测具有重要意义。  相似文献   

Variations in glacier volume and snow cover and their impact on lake storage in the Paiku Co Basin,in the Central Himalayas     

Xingxing Zhang  Rui Wang  Zhijun Yao  Zhaofei Liu 《水文研究》2020,34(8):1920-1933

Glaciers and snow cover are important constituents of the surface of the Tibetan Plateau. The responses of these phenomena to global environmental changes are sensitive, rapid and intensive due to the high altitudes and arid cold climate of the Tibetan Plateau. Based on multisource remote sensing data, including Landsat images, MOD10A2 snow product, ICESat, Cryosat-2 altimetry data and long-term ground climate observations, we analysed the dynamic changes of glaciers, snow melting and lake in the Paiku Co basin using extraction methods for glaciers and lake, the degree-day model and the ice and lake volume method. The interaction among the climate, ice-snow and the hydrological elements in Paiku Co is revealed. From 2000 to 2018, the basin tended to be drier, and rainfall decreased at a rate of −3.07 mm/a. The seasonal temperature difference in the basin increased, the maximum temperature increased at a rate of 0.02°C/a and the minimum temperature decreased at a rate of −0.06°C/a, which accelerated the melting from glaciers and snow at rates of 0.55 × 10⁷ m³/a and 0.29 × 10⁷ m³/a, respectively. The rate of contribution to the lake from rainfall, snow and glacier melted water was 55.6, 27.7 and 16.7%, respectively. In the past 18 years, the warmer and drier climate has caused the lake to shrink. The water level of the lake continued to decline at a rate of −0.02 m/a, and the lake water volume decreased by 4.85 × 10⁸ m³ at a rate of −0.27 × 10⁸ m³/a from 2000 to 2018. This evaluation is important for understanding how the snow and ice melting in the central Himalayas affect the regional water cycle.  相似文献   

Nanpanjiang basin: A window on the tectonic development of south China during Triassic assembly of the southeastern and eastern Asia     

《Gondwana Research》2020

As the largest siliciclastic sink in the South China block, the Triassic Nanpanjiang basin is generally thought of as a foreland basin related to Indosinian collision between the South China and Indochina blocks. Our basin analysis, spanning an eight years period, provides details of Lopingian to Middle Triassic stratigraphic fill and tectonic subsidence of the basin. Field observation and sedimentological analyses reveal that the basin was not filled by a monotonous turbidite system and suggest instead the development of five primary depositional units constituted by deep-water turbidite systems, mass-transport deposits, condensed drapes, shallow-water isolated carbonate platforms, and volcano-volcaniclastic rocks. The stratigraphic completeness of the basin, the coexistence of widespread but localized carbonate platforms within axially filled deep-water basin, tectonically generated cyclothems of transverse mass-transport deposits along intrabasinal faults and basin fill of extrusive rocks of bimodal composition together apparently call in question the claim that crustal shortening prevailed during the Late Permian to pre-Norian Triassic. Patterns of basin fill, differential tectonic subsidence and very high subsidence rate of the region adjacent to master fault are more closely match the pattern expected for extensional to transtensional basin in a back-arc setting. The crustal extension in the southwestern South China was not consistent with hypothesized Indosinian collision between South China and Indochina blocks, but more likely developed in response to northwestward subduction of the paleo-Pacific plate. Our results, combined with regional considerations, lead to a new model for the Triassic tectonic evolution of South China during Triassic assembly of the southeastern and eastern Asia.  相似文献   

乌鲁木齐大气混合层厚度和稳定度与大气污染的关系          下载免费PDF全文

李振杰  金莉莉  何清  缪启龙  买买提艾力·买买提依明 《干旱区地理》2019,42(3):478-491

利用乌鲁木齐市4座10层100 m梯度气象塔2013年6月~2014年4月气象观测资料和7个环境监测站[WTBX]AQI[WTBZ]资料，计算并分析了大气混合层厚度和稳定度特征，探讨了大气混合层厚度和稳定度与污染的关系。结果表明：乌鲁木齐市混合层厚度夏季郊区高、城区低，冬季从南郊—城区—北郊随地势降低依次降低；夏季和冬季分别在1 559～1 772 m和526～1 156 m之间。地面至2 km以上每500 m高度间隔统计混合层厚度，500～1 000 m出现频率最多；月变化为6～9月基本在500 m以上，且每个高度区间其概率均超过10%，10月～次年2月1 500 m以上区间概率明显减小；日变化为中午13:00～16:00达到最高值，下午和傍晚迅速下降。白天较大的感热输送提供充足的热力条件，这也体现出白天以不稳定层结为主，夜间则以稳定层结为主。大气稳定度分类结果，夏季郊区和城区不稳定（A～C类）所占比例差不多，冬季北郊稳定（E、F类）所占比较最大、城区最弱。[WTBX]AQI指数冬季最大，从南郊—城区—北郊依次增大，这与采暖期污染物多、南郊比北郊地势高有利于扩散输送有关。总体来看，乌鲁木齐大气混合层厚度空间分布与气象要素、大气稳定度、地形等密切相关，对AQI[WTBZ]指数分布有重要影响，这对近地层大气污染状况预报有着重要的指导意义。  相似文献   

Redox evolution of western Tianshan subduction zone and its effect on deep carbon cycle     

《地学前缘(英文版)》2020,11(3):915-924

Knowing the phase relations of carbon-bearing phases at high-pressure(HP) and high-temperature(HT) condition is essential for understanding the deep carbon cycle in the subduction zones.In particular,the phase relation of carbon-bearing phases is also strongly influenced by redox condition of subduction zones,which is poorly explored.Here we summarized the phase relations of carbon-bearing phases(calcite,aragonite,dolomite,magnesite,graphite,hydrocarbon) in HP metamorphic rocks(marble,metapelite,eclogite) from the Western Tianshan subduction zone and high-pressure experiments.During prograde progress of subduction,carbonates in altered oceanic crust change from Ca-carbonate(calcite) to Ca,Mg-carbonate(dolomite),then finally to Mgcarbonate(magnesite) via Mg-Ca cation exchange reaction between silicate and carbonate,while calcite in sedimentary calcareous ooze on oceanic crust directly transfers to high-pressure aragonite in marble or amorphous CaCO3 in subduction zones.Redox evolution also plays a significant effect on the carbon speciation in the Western Tianshan subduction zone.The prograde oxygen fugacity of the Western Tianshan subduction zone was constrained by mineral assemblage of garnet-omphacite from FMQ-1.9 to FMQ-2.5 at its metamorphic peak(maximum P-T) conditions.In comparison with redox conditions of other subduction zones,Western Tianshan has the lowest oxygen fugacity.Graphite and light hydrocarbon inclusions were ubiqutously identified in Western Tianshan HP metamorphic rocks and speculated to be formed from reduction of Fe-carbonate at low redox condition,which is also confirmed by high-pressure experimental simulation.Based on petrological observation and high-pressure simulation,a polarized redox model of reducing slab but oxidizing mantle wedge in subduction zone is proposed,and its effect on deep carbon cycle in subduction zones is further discussed.  相似文献   

徐闻南山镇红树林沉积物及红树植物中重金属的累积特征与迁移规律     

罗松英  梁艺琼  陈碧珊  林梦婷  梁家新  邱锦坤 《热带地理》2019,39(3):347-356

为探究重金属在红树林沉积物及红树植物中的分布累积及迁移规律，选取了徐闻南山镇红树林为研究对象，通过测定红树林沉积物及红树植物不同部位（根、茎、叶）的重金属质量分数，运用富集因子、生物富集系数、转移系数及相关性分析等方法进行分析。结果表明：1）红树林沉积物重金属质量分数表现为铬（Cr）＞锌（Zn）＞镍（Ni）＞铜（Cu）＞铅（Pb）＞砷（As）＞汞（Hg）＞镉（Cd），为中等变异程度；除了镍（Ni）元素外，其余7种重金属未超过国家一级标准，除了铅（Pb）元素外，其余7种重金属均超过广东省土壤环境背景值，说明研究区沉积物中重金属具有一定的积累效应。2）沉积物中砷（As）、铜（Cu）、锌（Zn）、汞（Hg）、镍（Ni）、铬（Cr）富集因子值均＞1.5，说明受到轻微人为活动影响；各站位镍（Ni）富集因子值均＞5，结合研究区背景，反映了镍（Ni）受到自然和人为输入的共同影响。3）白骨壤体内重金属主要集中在根部，而红海榄体内重金属在根茎叶中分布相对均匀。白骨壤根茎叶部位的大多数重金属质量分数远高于红海榄，说明白骨壤对重金属的吸附能力比红海榄强。汞（Hg）集中分布在植物的叶片部位，且与其他重金属之间相关性不明显；推测汞（Hg）主要通过叶片吸收进入植物体内，与交通运输污染有关。4）不同红树植物对不同重金属富集能力各异，白骨壤对重金属的富集能力表现为：镉（Cd）＞砷（As）＞铜（Cu）＞锌（Zn）＞汞（Hg）＞铅（Pb）＞镍（Ni）＞铬（Cr），红海榄表现为：镉（Cd）＞铜（Cu）＞汞（Hg）＞锌（Zn）＞铅（Pb）＞砷（As）＞镍（Ni）＞铬（Cr）。白骨壤和红海榄对汞（Hg）的运移能力都较强；红海榄对镉（Cd）的富集能力和转运能力都较强，而白骨壤对镉（Cd）富集能力较强，转运能力却较弱，这说明红树植物对重金属元素的富集能力与转运能力不存在正比关系。  相似文献   

北京十三陵地区青白口系长龙山组含铁建造的发育特征及成因^*          下载免费PDF全文

张琴  王柏寒  周琛  孙祖宇  梅啸寒  原成帅  王凯 《古地理学报》2020,22(3):570-586

含铁建造在整个前寒武纪的地质记录中分布广泛,但针对华北地区青白口系长龙山组出露的含铁建造目前还没有报道。文中通过野外观察及室内XRD、SEM、ICP-MS等手段,对北京十三陵地区出露的长龙山组含铁建造的分布规律、矿物组成、成矿物质来源等开展研究,并探讨含铁建造的成因机制。结果表明,含铁建造的铁质主要为赤铁矿,与石英、海绿石等矿物伴生。含铁建造存在2种分布模式: Ⅰ型含铁建造,与海绿石伴生,产出厚度变化大(1~50 cm),偏光显微镜下海绿石砂岩和铁质条带呈互层状产出,赤铁矿具近球形结构;Ⅱ型含铁建造,无海绿石伴生,产出厚度相对较大(一般大于10 cm),镜下见黑色的富铁层夹碎屑石英透镜体,赤铁矿常发育针状或雪花状结构。依据构造演化和微量元素分析,认为含铁建造的铁质来源主要为下马岭组顶部的铁质风化壳。Ⅰ型含铁建造为化学胶体沉淀与海绿石风化的混合成因;Ⅱ型含铁建造主要属于胶体化学沉积成因,后期可能经受了糜棱化改造作用。这一结论为华北地区前寒武纪含铁建造的找矿提供了沉积地质依据,对于完善含铁建造成矿机理及华北地区元古代构造演化具有重要的意义。  相似文献