基于多源遥感影像的柴达木盆地雅丹几何学和控制因素

发布时间：2018-02-04 10:30

本文关键词： 柴达木盆地雅丹几何学剥蚀量　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：雅丹地貌是一种典型的风蚀地貌,主要分布在除大洋洲和南极洲以外的干旱、半干旱沙漠及其周边地区。柴达木盆地发育有我国分布面积最广的雅丹地貌,且类型丰富,这为定量提取雅丹几何形态和分析雅丹类型及控制因素提供了条件。由于柴达木盆地地理位置偏远,气候干旱炎热,传统的野外地质调查难以获取全面的、大尺度的雅丹几何学信息。因此,本文基于Google EarthTM、Landsat 8多光谱影像、无人机影像和数字高程模型(DEM,DigitalElevationModel),结合地质资料,对该区不同类别的雅丹进行几何学分析,并在此基础上讨论构造、岩性、风场与雅丹发育和形态的关系,通过雅丹形态还原古风场及变化规律,估算以风营力为主的柴达木盆地中的剥蚀量与侵蚀速率,探讨柴达木风蚀作用与黄土高原沙土堆积之间的关系。主要内容和结论如下:(1)利用多源遥感影像,在柴达木盆地提取了 16,749条雅丹,统计了包括长宽比、走向、密度、宽度等几何学信息。柴达木盆地雅丹主要走向为N-NW,整体都呈现为近平行状排布。雅丹单体长3.5-4803 m,平均长106 m;单体宽1.5-309 m,平均宽24 m。单体长宽比207:1-1.03:1,平均长宽比3.8:1。(2)基于长宽比,将柴达木雅丹分为四种类型,短轴状(1:1-2:1),长3.5-182 m,宽 2.4-114 m;鲸背状(2:1-6:1),长 3.8-1159 m,宽 1.5-309 m;拱背状(6:1-10:1),长 13-2013 m,宽 2-264m;长垄状(10:1-210:1),长 57-4803 m,宽 5.4-171 m。(3)对雅丹形态及发育位置的统计发现,近69%的长垄状和拱背状雅丹集中分布于向斜区域,而73%的短轴状雅丹集中分布于背斜区域;在同一背斜中,迎风坡雅丹的长宽比小于背风坡。反映了地质构造类型,岩层软硬层的交替,地层的倾角,地层走向与风向的夹角均对雅丹几何形态及分布有控制作用。(4)在柴达木盆地北部(鄂博梁一号独立自然区)和西部(长尾梁至碱石山区域),存在多个不同方向的风场控制的雅丹群。在北部区域NNW和NNE两个方向风场的交汇区域,风场叠加改变了部分雅丹的展布方向;而在西部区域NW和NNE方向风场的交汇区,显示雅丹的交替切割的关系,即早期形成的长垄状的雅丹被切割成若干短轴状雅丹,反映了该区不同方向的风场强度交替变化。(5)利用山脊线估算的剥蚀量和侵蚀速率,其结果是最小的参考值,仅为利用地层对比法计算结果的十分之一。利用地层对比法,通过恢复六条地质剖面估算出柴达木盆地的平均侵蚀速率为0.22 mm/yr,对应的总剥蚀量为2.2×104 km3。
[Abstract]:Yadan geomorphology is a typical wind-eroded landform, mainly distributed in arid, semi-arid desert and its surrounding areas except Oceania and Antarctica. This provides conditions for quantitative extraction of Yadan geometry and analysis of Yadan types and control factors. Due to the remote geographical location of the Qaidam Basin and the arid and hot climate, it is difficult for traditional field geological surveys to obtain comprehensive information. Therefore, based on Google EarthTM Landsat 8 multispectral image, UAV image and digital elevation model, combined with geological data, this paper carries out geometric analysis of different types of Yadan in this area, and discusses the structure on this basis. The relationship between lithology, wind field and the development and morphology of Yadan. Through the reduction of paleo-wind field and its variation law, the erosion amount and erosion rate in Qaidam basin, which is dominated by wind force, is estimated. This paper discusses the relationship between wind erosion of Qaidam and the accumulation of sandy soil on the Loess Plateau. The main contents and conclusions are as follows: (1) using multi-source remote sensing images, 16,749 Yadan were extracted from Qaidam Basin, including aspect ratio, strike, density, etc. The main strike of Yadan in the Qaidam Basin is N-NW.The whole is arranged in a nearly parallel pattern. The length of Yadan is 3.5-4803 m, the average length is 106 m, the monomer width is 1.5-309 m, the average width is 24 m, the aspect to width ratio of monomer is 2071-1.03: 1, and the average aspect to width ratio is 3.8: 1.2.The ratio of length to width is based on the aspect ratio. Qaidam was divided into four types, 1: 1: 1: 1: 1, 3.5-182 m in length and 2.4-114 m in width; 2: 1: 6: 1 in length, 3.8-1159 m in length, 1.5-309 m in width; 61-10: 10: 1 in length, 13-2013 m in length, 2-264 m in width; 10: 10: 1 in long ridges, 57-4803 m in length, 5.4-171 M. 3 in width). Nearly 69% of the long ridges and arches are concentrated in the syncline region, while 73% in the short axis are concentrated in the anticline area, and in the same anticline, the aspect ratio of the upwind slope is smaller than that of the leeward slope, which reflects the type of geological structure. The alternation of hard and soft strata, the dip of strata, The angle between stratigraphic strike and wind direction controls the geometry and distribution of Yadan. 4) in the northern part of Qaidam basin (Oberliang No.1 natural area) and west (Changweiliang to Jishishan area), there are many different directions. The Yadan Group controlled by the wind field. In the northern region, the intersection of the wind fields in the NNW and NNE directions, The superposition of the wind field changed the distribution direction of some Yadan, while in the intersection region of the wind field in the NW and NNE directions in the western region, the relationship between the alternating cutting of Yadan was shown, that is, the early formation of long ridged Yadan was cut into a number of short axis Yadan. It reflects the alternating variation of wind field intensity in different directions in this area.) the erosion amount and erosion rate estimated by ridge line are the smallest reference value, which is only 1/10 of the result calculated by stratigraphic correlation method. The stratigraphic correlation method is used. The average erosion rate of Qaidam basin is estimated to be 0.22 mm / yrand the total denudation amount is 2.2 脳 10 ~ 4 km ~ (3) by restoring six geological sections.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P931;P237

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