三峡库区作辑托背斜和巴东断裂与滑坡类型的关系

三峡库区作为地质灾害的多发地区,有关构造特征与滑坡之间的因果关系及相同局部构造上多个滑坡个体之间的因果关系研究很少。在应用断层相关褶皱理论方法的基础上,结合工程地质研究现状,以作辑托背斜和巴东断裂为研究重点,对局部构造与滑坡类型之间的关系进行了深入研究。结果表明：大型滑坡发生与局部构造类型及河流切割局部构造的部位相关,不仅体现于对单个滑坡的控制,更体现在对整体岸坡演化规律、个体滑坡演化因果关系的控制上。对研究区而言,滑坡的形成与作辑托背斜构造样式和巴东断裂的反转活动相关,也与长江切割局部构造位置相联系,使滑坡类型在局部地段发生根本性转变,表现出岸坡破坏发展空间演化过程有很强的方向性。     

基于分形的滑坡易发程度区划方法

本文发展了一种基于分形统计的滑坡易发程度评价方法,该方法仅使用已有的滑坡数据,首先通过分形统计获得滑坡分布的分形丛集关系,再通过GIS的空间操作与分析生成滑坡易发程度区划图。提出一种对滑坡易发程度区划图的可信度和预测效果进行评价的方法。本文介绍了这些方法及其在浙江地区应用的结果。     

基于RS与GIS的层次分析法在滑坡危险性评估中的应用——以四川宣汉天台乡滑坡为例

基于遥感(RS)和地理信息系统(GIS)技术,采用多层次分析(AHP)法,以四川宣汉天台乡为研究区,根据该区实际情况,选取线性构造、道路、土地利用、坡度、坡向5种影响滑坡灾害发生的因素作为评价因子,进行区域滑坡危险性评估。在ArcGIS的空间分析环境中运行权重叠加,把研究区划分成滑坡极易发生区、易发生区、一般发生区、可能发生区、难发生区和极难发生区。通过实地调查和与研究区的滑坡灾害实证研究结果进行比较,发现评估结果与实际状况较为吻合,研究方法能够准确地评估区域滑坡灾害危险性的程度。     

上海及邻区地震活动特征及地震构造区划

为进一步理解上海及邻区的地震活动规律和地震地质背景,对地震的空间分布、时间序列和震源深度特征进行了分析,并划分了地震构造区。结果表明,地震在空间上具有很强的丛集性、重复性、分块性和条带性,震源深度多在5-20km,存在5-10km、15-20km两个优势层。在时间上表现出相对平静期和显著活动期的交互特征。弱震震级与震源深度无相关性,其他地震震源深度与震级总体呈一定线性关系。研究认为:空间分布特征与变质基底、盖层结构的差异有关,且分块和条带性主要受北西向和北东向断裂带联合控制;北东向断裂带和复式背斜是主要控震构造,北西和北北西向断裂是重要发震构造;区内未来数年至十余年有发生6级左右地震的可能;部分地震震源深度较浅,会对局部地区产生明显影响。     

三峡库区谢家包背斜与滑坡分布关系

三峡库区作为地质灾害的多发地区,有关构造特征与滑坡之间关系以及相同局部构造上多个个体滑坡之间的因果关 系研究很少。在应用相关理论方法的基础上,结合工程地质研究现状,以谢家包断层传播褶皱为研究重点,对局部构造与滑 坡类型之间的关系进行深入研究,上盘断坡形态特征控制着长江流域和青干河流域滑坡群分布,使其在整体空间演化上表 现出从西向东滑坡体规模逐渐减小的变化规律;长江流域滑坡群规模明显大于青干河流域滑坡群,这与断层传播褶皱两翼 倾角变化密切相关,南翼青干河流域岩层倾角明显大于北翼长江流域岩层倾角。研究表明大型滑坡发生与局部构造类型及 河流切割局部构造的部位相关,这种相关性不仅体现在对单个滑坡的控制,还在于对整体岸坡带演化规律、个体滑坡演化 之间因果关系的控制上。     

青藏高原东缘深切河谷区古滑坡:判识、特征、时代与演化

青藏高原东缘是全球古滑坡最发育的地区之一。基于大量地面调查、遥感解译和年龄测试资料,总结了青藏高原东缘深切河谷区古滑坡的判识方法、主要发育特征、形成时代和分布规律。结果表明,古滑坡具有规模巨大、高位起动、物质组成和结构复杂等特征,其空间分布与地形地貌、岩性组合和活动构造等因素关系密切。古滑坡在区域上受气候变化影响较明显,一般形成于河流强烈下切阶段,与河流阶地具有较好的对应关系,多数已发现的古滑坡与T₂阶地时代相当,时间跨度为40~10 ka,集中分布于30~20 ka。构造活动和地震造成古滑坡在不同区段的分布具有差异性,一般在活动断裂带附近密集发育,现今发现的古滑坡多为这种成因。这些认识对于科学认知古滑坡的形成演化过程和未来巨灾风险预测具有重要的指导作用。     

中国活动构造研究的进展与展望

在简要介绍中国活动构造基本特征的基础上,分析了21世纪以来中国大陆7级以上大地震活动出现的2个新特点：一是大地震主要沿青藏地块区的巴颜喀拉活动地块边界断裂带丛集发生;二是在活动盆地内部或盆山交界地带发生了多次逆断裂–褶皱型地震。面对新的地震活动特点以及工程建设和社会公众对防灾减灾的新需求,分析了活动构造研究中的一些关键环节或研究薄弱领域,探讨了进一步加强相关研究的发展方向和技术途径。一是要注重活动构造研究自身的理论提升与应用实践,包括活动断裂几何学的精细研究,注重断裂活动习性与破裂分段性相结合的运动学研究,切实加强古地震探槽和断错微地貌的互补性研究,更为重要的是应切实加强活动构造研究与构造地貌、地球物理勘探、地壳形变、地震学等相关学科的交叉融合与应用实践。二是强化区域活动构造研究与大震丛集迁移规律和动力学机制的认识,提升对活动块体及其边界断裂带强震构造活动的整体认识。认真梳理和分析我国各活动地块区发生丛集地震各自的孕震构造环境和发震机制,综合历史地震和古地震详细研究结果,识别可能存在地震丛集活动的活动构造带或地震构造区,为巴颜喀拉活动块体大地震主体活动区结束之后可能的迁移地区将面对的大震灾害风险做好科技支撑。三是关注逆断裂–褶皱型地震构造研究等薄弱环节。除采用传统的活动构造研究技术之外,应结合构造地貌学开展地表地貌变形特征研究,以及开展深部地震构造探测和地震学研究等,以获取其深部结构构造特征,综合分析其深浅构造关系、构建变形模式和讨论发震机制等。重点关注上述关键技术环节和未来发展趋势,为活动构造深入研究和防灾减灾提供参考依据。

     

喜马拉雅山东南地区地质灾害发育规律初步研究

利用遥感手段,结合MapGis,研究了喜马拉雅山东南地区地质灾害的发育情况,发现本区发育的主要地质灾害有滑坡、崩塌、泥石流、冰湖以及堰塞湖。其中崩塌、滑坡、泥石流斜坡地质灾害是本区最重要的地质灾害类型,占到总灾害数量的95.3%。在此基础上对喜马拉雅山东南地区地质灾害发育规律初步研究,发现本区地质灾害的发育在空间上的分布并非均匀,而是具有丛集性的特点。滑坡灾害主要发育在隆子和朗县。泥石流灾害比较严重的有米林、隆子和洛扎3县,而崩塌则主要集中在隆子县。研究发现,本区滑坡发育与地层、地形坡度以及土地类型关系密切,其中修康群、日当组和念青唐古拉群是本区的易滑地层。涅如组由于面积大,其中发育的滑坡较多,但是滑坡的发育率只略高于本区的平均水平。统计表明,16～30的坡度范围是滑坡最容易发生的。大于45以上的坡段很少发生滑坡。灌木林和天然草地这两种土地类型滑坡发育率最高。对于泥石流,研究表明,涅如组中泥石流发育面积最大,发育率也最高。泥石流发育的最适宜坡度也是16～30这样一个坡度范围。冰川和永久积雪区则最易发生泥石流。崩塌发育与地层类型、坡度的关系较为密切,崩塌主要发育在涅如组中,并且集中在坡度大于60以上的陡坡段中。这些初步成果的取得,是以后进行该区地质灾害空间预测的基础。     

基于有效降雨强度的滑坡灾害危险性预警

选取湖北省恩施地区1 000 km2区域作为典型研究区, 在全面分析该区域历史滑坡资料的基础上, 根据该区滑坡生成与地层岩性之间的关系, 将研究区地层划分为高、中、低3类易发性岩组.分岩组统计降雨监测数据与历史滑坡信息, 得出有效降雨强度与关键降雨持续时间的散点图, 由此确定不同滑坡发生概率的有效降雨强度阈值, 提出该区的滑坡灾害危险性预警判别模型.基于样本区统计数据建立滑坡预测指标体系, 运用GIS得出研究区域的滑坡空间易发性区划结果, 并根据不同易发岩组-有效降雨强度模型, 叠加滑坡灾害易发性分区结果与降雨危险性预警等级分级结果, 对研究区的滑坡灾害危险性进行了预测预警.结果表明: 不同易发岩组-有效降雨强度模型所得预警结果与实际情况吻合, 预警模型具有考虑全面和预警精度高的特点, 在实际预警中切实可用.      

四川汶川Ms 8 级地震引发的滑坡与地层岩性、坡度的相关性

震后遥感影像解译与调查结果表明,在大约48678km2的区域内,汶川Ms 8.0级地震诱发了不低于48000处滑坡灾害。基于GIS的空间分析方法,使用滑坡面积百分比(LAR)与滑坡密度(LC)2个参数,对地震滑坡的空间分布与地层岩性、坡度之间的关系进行统计分析。在整个研究区范围内,滑坡面积百分比约为1.4622%,滑坡密度约为0.9862个/km2。结果表明,滑坡多发生在坡度25~50°的区域内,滑坡易发性随着坡度的增加而升高。寒武纪地层中滑坡易发性最大,LAR约10%,LC约6.5个/km2,震旦系、奥陶系和侵入岩次之,这些地层和岩石对地震滑坡的发生均是敏感的。综合分析坡度、地层岩性与滑坡空间分布的关系,结果表明,在以较破碎岩石为主的地层中,滑坡多发生在坡度小于30°的部位;在以较坚硬岩石为主的地层中,滑坡多发生在坡度大于40°的部位。     

Analysis of lineaments within the Wajid Group,SW Saudi Arabia,and their tectonic significance

The Wajid Group is a Cambro-Permian sedimentary succession in southwest Saudi Arabia. This group is a well-known groundwater aquifer in the Wadi Al-Dawasir and Najran areas. The group also represents siliciclastic hydrocarbon reservoirs in the Rub' Al-Khali Basin. The Wajid Group is exposed in an area extending from Wadi Al-Dawasir southward to Najran city. This study aims to map and characterize the lineament traces of the Wajid Group outcrops. Landsat-8 OLI/TIRS satellite images with 30-m resolution, Spot-5 satellite images with 2.5-m resolution and SRTM digital elevation models (DEM) with 30-m resolution were used for lineament trace detection. Those lineament traces supplemented by aeromagnetic lineaments detected from reduced to pole magnetic anomaly map of the studied outcrop. Multi-scale lineament trace maps were generated, and the lineament datasets, including orientation and length, were analyzed statistically. Eight lineament trace trends were identified including NW-SE, NNW-SSE, N-S, NNE-SSW, NE-SW, ENE-WSW, E-W, and WNW-ESE. The northerly, northwesterly, and northeasterly trending lineament traces are predominant. The lineament trace lengths are generally followed the power law distribution. The lineament trace trends were validated through field investigation of the Wajid Group outcrop. The reported outcrop fracture trends are consistent with major lineament trace trends. Lineaments within the Wajid Group outcrop are also consistent with those of the southern portion of the Arabian Shield. The results of this study provide insight into the tectonic origin of the Wajid Group outcrop lineaments, and understanding of the lineaments distribution which can help to predict the fluid flow behavior within the groundwater fractured aquifers or hydrocarbon fractured reservoirs in Rub’ Al-Khali Basin.     

Utilities of Landsat 7 data and selective image processing in characterization of radioactivity zones of Wadi Baba–Wadi Shalal Area, Westcentral Sinai, Egypt

Wadi Baba–Wadi Shalal area locates in the westcentral part of Sinai, Egypt. It is covered by a Precambrian basement rocks comprise the northern part of the Precambrian Arabo-Nubian crystalline massive. The lithologic and structural setting of the investigated area was interpreted from the digital Landsat-7 Enhanced Thematic Mapper Plus (ETM+) data. The structural lineament analyses for the lithologic units and their relationships to the high-radioactivity zones (HRZ) and the characterizations of HRZ of the study area are the main tasks of this article. Extraction algorithm was applied using Geomatica PCI package under the user defined parameters. The extracted structural lineaments have been evaluated and chicked using the visual interpretation and published works. The short-wave infrared spectral ETM+ band-7 was selected as an optimum data for automatic lineaments extraction since it scored the highest lineament frequency (1856) compared to the other visible and near infrared bands. The aeroradiometric color raster total count equivalent thorium (eTh) and equivalent uranium (eU) maps were used to delineate the highest radioactivity zones of the study area. A selective image processing technique (SIPT) is a new approach in Geomatica (9.1), which gives rise to valuable results in this work. The SIPT was carried out for the subset of the ETM+ data of the highest radioactivity zones. The spatial distribution of the structural lineament pattern maps for some low-radioactivity zones (LRZ) and for the highest radioactivity zones of the study area are prepared with their frequency rose diagrams. The NE–SW trend is the predominant structural lineaments trend in the investigated area. The NE–SW to the ENE–WSW directions are the predominant structural lineament trends in both the LRZ and the HRZ. These high-radioactivity zones of the investigated area are characterized by high lineaments density and lineaments-intersection density, restricted to Um Bogma Formation and younger granitic rocks and are not controlled by structural lineament trends.     

Correlation of lineaments and groundwater quality in Dasht-e-Arjan Fars,SW of Iran

The NE-oriented Dasht-e-Arjan graben is located 65 km west of Shiraz and has resulted from the active Kare-e-Bas fault segmentations. This extensional graben bounded by two fault system east-Arjan and west-Arjan to the Shahneshin and Salamati anticline. In these study using Landsat 7 ETM images with resolution 2.5 m and directional filtering in the four azimuths and semi-automatic technique for linear structure in the study area. Using the obtained data from extracted lineaments, the rose diagrams of the main strike lineaments are well confirm with field measurements of faults with N56° ± 4°E direction. The structural lineaments of the study area show that the Dasht-e-Arjan area is underlain by the limestone, sandstone, and marl. LANDSAT imagery of the area has been analyzed and interpreted in order to determine the lineament and groundwater quality across the area. The fracture is structurally controlled and mostly influences both the groundwater and surface water pollution and flow directions in the Dasht-e-Arjan. Using visual interpretation, determining the lineaments on the satellite image is very difficult and subjective, and it requires an experienced interpreter. In this study, the lineament analysis is undertaken to examine the orientation of the lineament, the relationship between lineaments and tectonic features and groundwater quality. Lineament density maps show that the lineament density is high around areas. Areas having high lineament density represent areas with relatively high groundwater pollution. Field observations agreed with the results from the analysis of the imagery.     

WCoE/IPL projects in West Africa: application of Landsat ETM+ and ASTER GDEM data in evaluating factors associated with long runout landslides in Benue hills,North-central Nigeria

Under the WCoE/IPL project, Landsat Enhanced Thematic Mapper plus (ETM+) and ASTER GDEM data were used to analyze factors associated with frequent debris flow and rock-debris avalanche on the Nigeria-Cameroon mountain range. Detailed processing of the ETM+ imageries of the vulnerable portions on the western part of Adamawa plateau was carried out to identify structural trends relatable to the slope failures. The processing identified the structural characteristics of the study area and clearly distinguished the lineaments associated with the debris flow and rock-debris avalanches. The strongly weathered and fragmented gneissic rocks, shallow groundwater table, as well as the distribution of faults and joint sets were significant factors predisposing the slopes to rapid movements. Recent landslides occurred at the locations with high lineament density and in areas close to major faults and long lineaments. The interaction among the moving mass, slope geometry, local geology, topography, and drainage then resulted in a long runout and a high degree of spreading. Analysis of the ASTER–GDEM delineated landforms, slope morphology, and drainage patterns, which was not possible with conventional mapping techniques. Integration of these results yielded reasonable interpretation of the predisposing factors for the long runout failures and provided logical basis for future landslide susceptibility analysis in the area. Accurate investigation of the predisposing factors and characteristics of landslides in environments that have experienced past failures is therefore important in understanding areas that may be susceptible to landsliding in future.     

Using Remote Sensing Data to Delineate the Lineaments for Hydrothermal Mineral Prediction in Heqing Area, Northwest Yunnan Province, China

Lineament extraction and analysis is one of the routine work in mapping medium and large areas using remote sensing data, most of which are satellite images. Landsat Enhanced Thematic Mapper （ETM） of 945×1 232 pixels subscene acquired on 21 March 2000 covering the northwestern part of Yunnan Province has been digitally processed using ER Mapper software. This article aims to produce lineament density map that predicts favorable zones for hydrothermal mineral occurrences and quantify spatial associations between the known hydrothermal mineral deposits. In the process of lineament extraction a number of image processing techniques were applied. The extracted lineaments were imported into MapGIS software and a suitable grid of 100 m×100 m was chosen. The Kriging method was used to create the lineament density map of the area. The results show that remote sensing data could be useful to extract the lineaments in the area. These lineaments are closely correlated with the faults obtained through other geological investigation methods. On comparing with field data the lineament-density map identifies two important high prospective zones, where large-scale deposits are already existing. In addition the map highlights unrecognized target areas that require follow up investigation.     

Methodological Validation for Automated Lineament Extraction by LINE Method in PCI Geomatica and MATLAB based Hough Transformation

Spatial distribution and pattern recognition of geologic lineaments are very effective in hazard risk evaluation. To make the process automated, various algorithms with various data sources were applied. This paper aims to make a review on such algorithms as well as data sources used. Comparative analysis of the LINE algorithm in PCI Geomatica and Hough Transformation in MATLAB has been conducted to explore the procedural accuracy with reference to existing landslides in the Darjeeling Himalayan region. Another comparison was made based on data sources like Landsat-8 OLI and digital elevation model, with reference to the same. As lineament density affects the landslide occurrences predominantly, the output lineament density by these two methods as well as with ground reflection and ground elevation data, were correlated with that of the landslide inventory map. A relational illustration was also done in between the lithological thrust direction and the direction of the individual lineament outputs. Hence, this study provides a decision on the use of a reliable method and data source for the automated lineament extraction which can be considered as generating an output with higher accuracy and, hence, safer for using it in the structural planning and execution of projects on various natural hazard studies.     

月球线性构造分类体系研究

月球线性构造是月球科学研究中的重要组成部分,建立月球线性构造分类体系是月球地质图编研的关键。前人对月球线性构造的分类研究主要基于月表的形貌特征,划分的线性构造类型参差不齐,尚未形成一个公认的、规范的、具有普适性的线性构造分类体系,以至于分类结果的可对比性差、参考性和易操作性较低,不利于月球线性构造纲要图的编制。并且月球线性构造的概念混乱、术语不统一,存在"同物异名、同词异义、异词同义、涵义不明"的现象,不利于全球性的统一制图和成果的展示及使用。鉴于此,本文采用多指标组合的分类方法,以成因机制和形貌特征作为主要指标,兼顾物质组成,再结合线性构造形成的动力学机制,建立了符合月球动力学演化背景的、统一规范的线性构造类型划分的新方案,避免了单以形貌特征为依据来分类出现的混乱状态,具有较好的科学性和可操作性。将月球的线性构造类型划分为:内动力地质作用形成的线性构造,包括皱脊、月溪、地堑、断裂;外动力地质作用形成的线性构造,包括坑缘断裂和坑底断裂,以及多成因机制、多动力来源作用形成的特殊类型如坑链等。在此基础上,并利用多源遥感数据建立了易于判别且具有代表性的线性构造识别标志,可为全月球线性构造的统一制图提供识别依据。     

遥感技术在邹城市地壳稳定性评价中的应用

根据线性构造的影像特征,利用多种计算机图像处理方法提取邹城市线性构造信息,共解译出5组不同走向的线性构造,并且对其相对活动关系进行了分析。在此基础上,结合地震资料对该市所属地区的地壳稳定性进行了评价,认为南北向线性构造和北西向线性构造为主要的控震构造,并且圈定了一些地壳稳定性较差的地段,从而为邹城市的城乡发展规划和工农业建设等各项工作提供了重要依据。      

Recognition of the regional lineaments of Iran: Using geospatial data and their implications for exploration of metallic ore deposits

The relationship between major structural lineaments and locations of ore deposits in Iran has been investigated using geospatial data. In the course of lineament extraction, satellite images, aeromagnetic data, digital elevation model (DEM) and structural maps were processed and the lineaments and large-scale faults were identified. The extracted lineaments, based on subjective assessment, from each dataset were imported into GIS software and the “lineament map of Iran” was prepared by data integration. The analysis for selecting significant lineament was mainly based on fault correlated lineament and lineament with field map fractures, which was sets as benchmarks for compiling a final output map. Four major regional lineament trends of N–S, E–W, NW–SE and NE–SW were identified in the data of all images, which are corresponded to the structural zones and the major fault systems of Iran. The mineral deposits (active and abandoned) and mineral indications database compiled are based on the published maps, papers, reports and the ore deposits data files of Geological Survey of Iran. Integrating the output of these two datasets by GIS software resulted in the “Combined Map of Lineaments and Gold, Copper, Lead, Zinc and Iron Deposits of Iran”. The number and distance of ore deposits toward the lineaments were processed by the counting and cumulative methods in the GIS software's. Approximately, over 90% of the ore deposits of Iran are located in the central part of the lineaments (15 km on each side) which are concordant with a definition of large lineament. About 50% of these mineral deposits are closer than 5 km to the lineaments. There are significant correlations between lineament density and intersections with ore deposits occurrences. The observed associations at this scale are informative in establishing exploration strategy and decreasing exploration risks for detailed work on ore deposit scale.     

欧亚大陆风云影像线性构造信息提取及其地质分析

通过欧亚大陆风云影像的空间增强、光谱增强、辐射增强等系列处理和地质解释 ,提取了发育于该区的各种线性构造的相关信息。根据性质和规模将线性构造划分为大洋俯冲带、大陆俯冲带、大陆碰撞带、巨型线性构造、区域线性构造和局部线性构造等六类。文中重点介绍了乌拉尔—阿曼巨型线性构造带和阿尔卑斯大陆碰撞带的影像特征和地质意义。根据各类线性构造的特征和相互关系 ,突出了乌拉尔—阿曼和伊尔库茨克—横断山两条巨型线性构造带的地位 ,并以它们为界划分了三个构造域 :西亚构造域以印度板块的俯冲为特色 ,导致青藏高原的隆升和陆内强烈变形 ;东亚构造域最为重要的特征是太平洋板块的俯冲 ,形成一系列岛弧体系 ,并使大陆内部出现大量岩浆活动和强烈的构造变动 ;欧洲构造域主要为非洲—阿拉伯板块与欧洲板块的碰撞 ,二者之间没有明显的俯冲带 ,而有一个较宽广的接触带 ,强烈的变形集中在这一带内 ,而大陆内部的构造变动比较微弱。这种构造格局在欧亚大地水准面异常图上有明显反映 ,表明与深部地质作用过程有关。三个构造域的主导线性构造的方向组成了一个向南弯曲的弧形 ,弧顶位于西亚构造域。大陆巨型线性构造带呈经向和纬向展布 ,具长期发育特征 ,从更大尺度上看 ,板块边界线性构造也是呈经向和纬?