基于模糊聚类和空间自相关性的河流阶地自动提取方法——以岷江上游漳腊盆地为例

传统研究方法以点、线代表区域地貌面,数据缺乏连续性和系统性,限制了对阶地演化的进一步研究。高分辨率DEM处理方法的发展使广泛精确获取地貌面的定量信息、重建阶地模型、进一步研究阶地演化成为可能。以岷江上游漳腊盆地为研究区域,采用SPOT5高分辨率数据影像构建DEM,将统一标度后的阶地横剖面作为基本研究单元。通过在不同维度使用模糊C均值聚类,得到研究区域内阶地总体形态特征。在提取各级阶地面的过程中,将阶地剖面间的空间相关性与阶地总体形态特征纳入分析,最终建立了一种基于区域总体特征和区域内部自相关的阶地提取方法。对不同级阶地面提取的精度评价表明,其结果与野外实测数据有较高的一致性。文中以实验结果为依据,进一步讨论了漳腊盆地内阶地的形态特征、河流下切速率和区域隆升之间的关系。因此,将模糊聚类分析和空间自相关性结合的区域地貌面提取方法是简捷易行的,适用于阶地等层状地貌面发育区域构造-地貌等相关问题的研究。     

龙门山断裂带北段第四纪活动的地质地貌证据

以龙门山断裂带北段中的青川断裂、茶坝-林庵寺断裂沿线的地质地貌为研究对象,在青川断裂沿线的土关铺、大安,茶坝-林庵寺断裂上的薛家沟、胡家坝等地,对断裂附近的河流地貌进行了详细的构造地貌制图。龙门山断裂带北段所在地区的河流一般发育5级阶地,T1阶地拔河高度3~5m,为全新世堆积阶地。T2阶地拔河高度10m左右,为晚更新世基座阶地。T3阶地拔河高度一般为30~35m,为晚更新世早期形成的基座阶地。T4阶地拔河高度60~70m,残留的阶地砾石层中花岗岩、砂岩砾石已经被强风化,只保留砾石的形态。T5阶地拔河高度为90m左右,阶地堆积物被剥蚀殆尽。青川断裂、茶坝-林庵寺断裂在河流的T4和T5阶地上形成宽30~180m的断层槽地,深度达8~20m,T4阶地砾石层底面落差达10~15m。T3阶地上不发育断层槽地,或断层两盘的T3阶地拔河高度一致,一些地段断层被T3阶地砾石层覆盖。因此认为,这两条断裂在T3阶地形成之前,T4阶地形成之后有过强烈的活动     

基于DEM的阶地分析方法——以安宁河断裂紫马跨地区为例

河流阶地是一种最普遍的包含构造信息的地貌现象。阶地的确定与划分对于构造运动的定量研究有重要意义。文中利用数字摄影测量软件virtuoNT提取DEM,结合地貌原理,利用DEM在ARCGIS平台上建立阶地分析的处理流程,并以四川省紫马跨地区为试验区进行了阶地划分与变形分析,得到了断裂次级冲沟阶地同步位错平均约(85·4±2)m的结果,与野外检验和变形实测的结果有较好的一致性。表明利用DEM的变形阶地面提取方法具有精度高和效率高、可视化效果全面直观等特点     

侧向侵蚀相关的走滑断裂滑动速率计算新方法

断层滑动速率是活动构造研究中的重要内容,是反映断裂活动性和地震危险性的重要参数之一。随着测年技术不断发展和测年精度大幅度提高,全新世甚至千年尺度和百年尺度的年轻地质体的位错也越来越多地被用于断层滑动速率计算。用走滑断裂带上地质体实测年龄计算滑动速率,会受到2种因素影响:1)累积位移时间是否与所测地质体年代相符合;2)地质体位移形成过程中会受到侵蚀。在利用全新世地质体计算断层滑动速率时,应将侧向侵蚀的影响剔除。因此,文中提出1种计算走滑断层滑动速率的新方法——差值法。走滑断层上河流阶地演化与断层位错分析表明,在阶地拔河高度存在较大差异的情况下,可以利用阶地拔河高度与年龄按比例进行计算。此方法在一定程度上提高了所计算滑动速率的精度,但是需要至少有3级不同阶地的拔河高度、年龄以及位错信息。若阶地拔河高度近似呈等差排列,即各级阶地上侧向侵蚀量近似相等的情况下,利用高-低阶地累积位错量之差与对应阶地年龄差来计算滑动速率,可以在一定程度上减少上述2种因素对滑动速率的影响。应用差值法计算得到阿尔金与昆仑断裂的滑动速率为4.7~8.8mm/a,与前人获得的地质学滑动速率、测地学滑动速率、缩短速率以及强震复发周期结果一致。     

利用DEM技术自动提取龙门山南段青衣江阶地面的研究

河流阶地面是一种时间性、连续性非常高的层状地貌面,利用跨断层地区的河流阶地变形可以定量地判别一个地区的断层活动性。青衣江横跨龙门山断裂带南段是一条区域性大河,由于龙门山南段构造活动强烈且河流阶地被侵蚀程度严重,为了在室内更好、更快地解译青衣江河流阶地,使野外调查工作更具有针对性,本文在龙门山南段青衣江流域小关子至飞仙村一段,采用航测遥感技术制作的2m分辨率DEM和1/5万数字高程模型,基于Arc GIS和MATLAB平台进行了阶地面提取和聚类分析,以模拟野外测量阶地的流程,试图通过计算机提取,快速获取该地区更多的残余地貌面,建立起较为完整的河流阶地纵剖面。研究结果表明:野外测量数据与计算机自动提取结果相似度较高,具有较好的一致性;在完整的阶地剖面中发现了芦山盆地内部阶地具有疑似拱曲现象;在大川-双石断裂附近阶地有翘起现象,推测芦山盆地西缘阶地拱曲是由大川-双石断裂东侧的一条未知断层引起的,大川-双石断裂附近阶地的翘起现象可能是在断层逆冲推覆过程中形成的,同时结合区域年代历史数据,推测该地区(芦山盆地至大川-双石断裂)至少在晚更新世曾发生过构造活动。     

基于SPOT影像的安宁河阶地数字地形分析

介绍了SPOT立体像对提取DEM的基本原理和数据处理流程,利用安宁河区域两景SPOT影像提取了DEM,并利用所得DEM对安宁河进行阶地分析;通过对安宁河阶地数字地形分析,揭示了安宁河谷两岸阶地的不对称是安宁河东侧构造运动抬升的结果。     

渭河陇西段第七级阶地年代的确定及其构造意义

昆黄运动是发生在中更新世时期青藏高原及其邻区一次重要的构造抬升事件,河流阶地及地层记录能够较好地反映这次构造事件。渭河陇西段第七级阶地沉积了104.5m厚的黄土,通过对其上覆黄土剖面的古地磁、粒度研究表明,此级阶地形成年代为距今870ka,阶地拔河高度说明自中更新世以来地面至少抬升了205m,其抬升速率约为0.2m/ka。这次构造事件在时间上与昆黄运动相一致,是对青藏高原强烈抬升的响应。     

采用立体像对和差分GPS揭示民乐-永昌隐伏断裂地表变形特征

为高效获取民乐-永昌断裂西段活动构造研究的定量参数,利用ERDAS软件,基于SPOT6立体像对提取高分辨率点云数据,经过滤波和插值生成2m分辨率的数字高程模型(DEM);DEM数据线性高程精度达1m。基于DEM数据提取的高地貌面上的3条廊带剖面显示,区域存在明显的褶皱变形,后续通过高精度差分GPS实测河流阶地纵剖面进一步揭示T2阶地存在高度约2.0m的构造抬升。廊带剖面和河流阶地纵剖面显示断裂-褶皱变形整体走向为311°,与小震精定位反演拟合断层参数和震源机制解结果相近,其位置也与地震应急科考资料显示现场情况吻合。上述结果表明,民乐-永昌隐伏断裂西段民乐—大马营段存在明显的构造变形,支持该断裂为2003年民乐-山丹MS6.1和5.8级地震发震断层的认识。立体像对对于活动构造研究具有重要的作用,可为室内确定构造变形的空间位置和野外详细考察提供重要指导。     

滇东、滇西地区主要河流低阶地地貌面的年代学研究

在流水沉积物热释光测年适用性和测年数据可靠性研究的基础上 ,对滇东、滇西地区几条主要河流的低阶地进行了系统采样和多方法的综合测年 ,获得了该区主要河流低阶地沉积物的堆积年代及其阶地面的形成时代 ,该区I级支流T1阶地堆积于 4 50 0～ 110 0 0aB .P .,其阶地地貌面形成于 4 50 0～ 50 0 0aB .P .;T2 阶地堆积于 90 0 0～ 2 2 0 0 0aB .P .,该级地貌面形成于 90 0 0～ 10 0 0 0aB .P .;主流T1阶地的堆积年龄为 90 0 0～ 170 0 0aB .P .,阶地面形成于 90 0 0～ 10 0 0 0aB .P .;T2 阶地的沉积年龄为 150 0 0～ 4 50 0 0aB .P .,阶地地貌面形成于 150 0 0aB .P .左右。同时 ,通过阶地堆积时期古气候、古环境的分析 ,探讨了该区低阶地地貌面的成因     

永定河上游晚更新世晚期以来的堆积阶地年代测定

应用1 4 C测年法和热释光方法对采自永定河上游晚更新世晚期以来形成的堆积阶地样品进行了年代测定。研究结果表明 ,永定河上游三条一级支流的低阶地形成时代具有一定的同时性 ,第三级阶地的下切时间大约在 30 0 0 0aB .P .;第二级阶地的下切时间大约在 10 0 0 0aB .P .;第一级阶地的下切时间大约在 4 0 0 0aB .P .。气候变暖对第二级阶地形成起主导作用 ,构造作用对最新阶地形成有一定的影响     

COMPARISON OF METHODS FOR DISTINGUISHING DIFFERENT GRADES OF GEOMORPHOLOGIC SURFACES BASED ON SEDIMENT PARTICLE SIZE FEATURES: TAKING THE QINGYIJIANG RIVER BASIN AS AN EXAMPLE

When using river geomorphology to study tectonic deformation, it is often difficult to distinguish the same level geomorphology in areas with severe weathering. In this paper, we take the geomorphologic surfaces of the Qingyijiang river basin as an example and try to distinguish the geomorphic surfaces by the sediment features that make up them. In order to distinguish different geomorphic surfaces, the traditional particle-size analysis method, SOFM network method and system clustering analysis method are taken to classify 29 samples from different geomorphic surfaces. The classification results of the three methods are different to a certain extent. We analyzed and compared the classification results of the three methods in detail. The results show that the traditional particle size analysis method, SOFM network method and cluster analysis method all can distinguish the geomorphic surface of different genesis, besides, they also can distinguish low-level terraces(T₁, T₂)and high-level terraces(T₃, T₄)for different grades of river terraces. Furthermore, the results also show that SOFM network method and cluster analysis method can make a certain distinction for the low-level terraces(T₁, T₂), while the traditional particle size analysis method is difficult to distinguish them. In addition, we analyzed and compared the three methods from the classification results, the results presentation, the operation process, and the error transmission. The results suggest that the advantages and disadvantages of the three methods are obvious. From the perspective of the classification results, the three methods all can distinguish the river terraces and alluvial fans and can make certain discrimination for different levels of river terraces. From the presentation of the results, the result of SOFM network is simple and clear. From the operation process, the traditional particle-size analysis method is relatively cumbersome, and the SOFM network method and the cluster analysis method are relatively simple to operate. From the perspective of error transmission, the traditional particle-size analysis method calculates the partial particle size feature value of the sample, which has a certain loss for the particle size distribution information of the whole sample. The error of the clustering analysis method has cumulative features and the influence exists consistently. The classification results of the SOFM network are independent of each other, which effectively avoids the problem of such error transmission of clustering analysis method. Overall, the classification results of the SOFM network method are simple and clear, the operation is simple, and the error is small. It has stronger adaptability to identifying different levels of different geomorphic surfaces. The results of this study will provide a simple and effective means for distinguishing different levels of geomorphic surfaces.     

APPLICATION OF SEMIAUTOMATIC EXTRACTION OF FLUVIAL TERRACES BASED ON R LANGUAGE-AN EXAMPLE FROM THE YELLOW RIVER TERRACES AT MIJIA SHAN

The generation, abandonment and preservation of terraces formed in active tectonic areas are important to the analysis of the role of the tectonics and climate along the temporal variations, so it appears significant as how to use the effective quantitative methods to extract and accurately depict these terraces. The increasingly convenient acquisition of high-precision topographic data has greatly promoted the advancement of quantitative research in geoscience, making it possible to analyze mid-micro-geomorphic features on a large scale, especially by studying the temporal and spatial evolution of tectonic deformation through accurate capture of micro-geomorphic features. Over the past decade, the rapid development of LiDAR(Light Detection and Ranging)technology has provided unprecedented opportunity to access high-precision topographic data(up to centimeter in vertical and horizontal directions). However, its relatively high cost and relatively complex data processing techniques limit its widespread application in the field of earth sciences. In recent years, with the continuous innovation and advancement of topographic measurement technology, the three-dimensional structure of motion reconstruction technology(Structure from Motion, SfM)has gradually been introduced into the field of digital topographic photogrammetry due to its rapid advantage in providing quick, convenient and cost-effective methods for obtaining high-density geospatial point data. This method thus shows great potential for providing high resolution topographic data with comparable resolution and precision. Therefore, with the acquisition of more and more high-resolution terrain data in recent years, it is an important development trend to explore automated or semi-automated quantitative geomorphological analysis methods. R language, as an excellent programming language, has not been used in the geology and geomorphology, although is widely applied in medicine and meteorology based on its powerful capability of statistician and graphic visualization. In this paper, we focus on the Yellow River multi-terraces formed to the east of the Mijia Shan, which belongs to the Jingtai-Hasi Shan segment of the Haiyuan Fault. With the analysis and visualization of the high-resolution topographic data collected from the SfM in the environment of the R language, we implement the semiautomatic classification and mapping of the Yellow River multi-terraces. The method identifies 20 terraces with different elevation. Our results also imply that the younger terraces have better continuity and elongation, and the older terraces have more deformation, which can be demonstrated from their gradually notable semi-parabolic shape. Besides this, it also suggests the diverse evolution stages of the Yellow River terraces. Our study indicates that R language is expected to become an efficient tool of statistics and visualization of the high-resolution topographic data.     

应用“构造-气候旋回”年代学方法确定河流阶地形成时代的初步研究

应用“构造－气候旋回”年代学方法确定了祁连山地区河流阶地形成时代和抬升速率,探讨了应用该方法确定阶地形成时代的可能性,结果表明：应用该方法确定河流阶地形成时代基本可行,只是对于低级阶地形成时代的拟合结果需用实测值来校正,第四纪以来祁连山地区的构造抬升呈间歇性,经历了4个较强烈的构造抬升期。     

华山山前断裂中段晚第四纪活动的地貌表现及响应

调查了华山山前断裂中段（石堤峪-杜峪）晚更新世以来,尤其是全新世以来的断层构造地貌,讨论了它们的成因、特点及对断裂活动的响应关系。断层构造地貌主要包括：断层三角面、断层陡坎、洪积阶地、埋藏型洪积扇以及冲沟裂点。对各大沟峪峪口的洪积阶地进行了大比例尺微地貌测量,并在部分沟峪两侧沿断层崖陡坎及冲沟沟床布置了测线。结合T1、T2级洪积阶地位错测量结果及其14C年龄计算得到,华山山前断裂中段6000a-2000aB.P.的垂直滑动速率为1.485mm/a;2000aB.P.以来的垂直滑动速率为3.73mm/a。最后结合野外调查与理论认识,建立了正断层作用下洪积阶地与埋藏型洪积扇的演化模式。本研究结果支持华山山前断裂是1556年华县814级地震发震构造的观点。     

阿尔金断裂带西段莫勒切河河口阶地的构造及气候意义

通过对阿尔金断裂带西段莫勒切河河口附近卫星影像解译、野外调查测量及地貌面样品年龄测定,利用宽谷阶地、堆积阶地获取构造隆升速率、构造变形方式及加积速率,并结合区域气候资料探讨该区阶地发育对气候变化的响应.莫勒切河出山口发育4级阶地(T<‘4>,T<‘3>,T<‘2>,T<‘1>),其中T<‘4>、T<‘3>为宽谷阶地,T...     

基于EGM2008重力场模型的GPS高程转换方法及精度分析

研究利用重力场模型直接进行GPS高程转换的方法,即模型高程异常法和模型重力位法.根据误差传播定律,导出了由重力场模型位系数方差计算模型高程异常以及模型正常高的误差公式,并对影响两种GPS高程转换方法精度的因素进行分析.利用具有代表性的EGM96、EIGEN-51C和EGM2008重力场模型及某线路GPS/水准数据对两种方法进行实验研究与精度分析,结果表明:理论公式及实验结果都显示两种高程转换方法是等价的,转换精度相当;两种方法使用过程中,均可能需要系统偏差校正;EGM2008重力场模型具有非常好的分辨率及精度,在局部区域,基于EGM2008模型的GPS高程转换精度有望达到cm级.     

西宁城市活动断裂地表特征初步研究

在详细的野外地质调查基础上, 通过开挖探槽剖面揭露了断层的基本性质, 初步展示了西宁市北川河东岸断裂、 南川河断裂和湟水河断裂的地表特征。 结合前人的阶地测定年代结果初步判断, 北川河东岸断裂错断相当于湟水河Ⅱ至Ⅲ级阶地, Ⅱ级阶地形成不晚于0.05 Ma, Ⅲ级阶地形成不晚于0.12 Ma, 说明该断裂是晚更新世活动断裂; 南川河断裂错断相当于湟水河Ⅳ、 Ⅴ级阶地, Ⅳ级阶地形成不晚于0.54 Ma, Ⅴ级阶地形成不晚于0.78 Ma, 说明该断裂是早中更新世活动断裂; 湟水河断裂错断其Ⅱ、 Ⅲ级阶地砾石层, 说明该断裂是晚更新世活动断裂。 这些断裂规模小、 活动性弱, 可能为盖层断裂。     

THE EXTRACTION OF HOUSE DISTRIBUTION BASED ON PHOTOGRAMMETRY METHOD:TAKING THE COUNTRYSIDE IN THE WEST OF CHINA FOR EXAMPLE

The key parameters of houses such as distribution, area and height play an important role for urban-rural planning, earthquake emergency and disaster mitigation. The computer automatic extraction method is an effective way to acquire large area house information using satellite-borne or airborne optical remote-sensing images. However, because of the similarity of spectral characters for different land cover types or the influence of snow coverage, the classification accuracy of house type using traditional spectral based method can be decreased. To acquire the accurate houses distribution, a method based on the height information is proposed using unmanned aerial vehicle(UAV)in this study. With UAV flying at the height of 100m above ground, the route of the UVA was planned with the heading direction overlap of 77% and side direction overlap of 50%for the nearby pictures. Taking Qionghalajun Village in Xinjiang Uygur Autonomous Region for example, 69 pictures of the study area were obtained with DJI Phantom 3 professional. With those pictures input into the EasyUAV software, the Digital Elevation Model(DEM), Digital Surface Model(DSM), and Digital Orthophoto Map(DOM)were acquired based on photogrammetry method using the overlapped optical remote-sensing images of UAV. After that, the house distribution and height were acquired with the differences between DSM and DEM images larger than 2.6m. To eliminate the influences of disintegrated pixels on the house extraction, mainly caused by the trees or noise point, the classification aggregation tool of ENVI software was used with the disintegrated pixels' area less than 4m². Compared with visual interpretation result, the user accuracy and mapping accuracy of the house extraction method proposed in this study is 88.69% and 97.42%, respectively. In addition, to evaluate the performance of the proposed method, the result of traditional supervised classification method using DOM data acquired previously was compared with the result of new method. The results show that the new method is more accurate the user accuracy and mapping accuracy of the supervised classification method, which is 43.23% and 85.30%, respectively. Besides the study area in this study, the performance of the proposed method will be evaluated at the other places in the further study.     

地-井方位激电观测异常特征研究

为系统了解地-井方位激电异常特征,利用有限单元法对地-井方位激电观测在立方体、板状体等典型地电异常体上的响应进行正演计算,分析了异常体位置、方位距离等变化对观测的影响规律,讨论了地形、钻孔本身对地-井方位观测的影响等.研究结果表明地-井方位观测是探测井旁和井底盲矿体行之有效的方法,利用不同方位上的异常曲线特征,遵循异常场定性分析和"先井口、后其它方位"的分析方法,可大致确定异常体的电性特征和空间展布;地形和钻孔本身对地-井方位观测的影响主要集中在浅部区域.