基于数字图像的中国西北地区戈壁表面砾石形貌特征研究

doi:10.7522/j.issn.1000-694X.2013.00365

摘要/Abstract

摘要： 中国戈壁面积约66.08万km²，超过了流动沙丘和半固定沙丘的面积之和，但目前对戈壁沉积特征的研究程度相对较低。本文采用ImageJ软件，对中国西北地区戈壁原位无干扰的表面数字图像进行量算，获取了砾石覆盖度、粒径、磨圆度和形状比率等形貌参数。结果表明：中国西北地区戈壁表面的砾石覆盖度介于31.5%～84.6%，以中覆盖度为主，70%的戈壁属于空气动力学稳定表面；90%以上的戈壁表面砾石平均粒径为细砾和中砾。不同区域戈壁表面砾石磨圆度的平均值介于0.50～0.76，形状比率变化范围在1.38～2.46。戈壁表面砾石形貌特征与其成因类型密切相关：以剥蚀（侵蚀）-洪积作用为主形成的戈壁，砾石粒径较粗、形态比率较大、磨圆度低、覆盖度较高；以冲洪积为主形成的戈壁，砾石粒径和形态比率变小，磨圆度变好而覆盖度降低。砾石形貌特征可为追溯戈壁物源区和反演沉积物的搬运堆积过程提供参考。

关键词: 戈壁, 砾石, 形貌特征, 砾石覆盖度, 粒度

Abstract: Gobi (deseret pavement) occupies an area about 660800 km² which is more than the total areas of mobile and semi-fixed sandy lands in China. However, the research of the sedimentary characteristics of gobi is not comparable to its extensive distribution. In this paper, we analyzed the morphometric features (such as the gravel coverage, grain size, roundness and aspect ratio, etc.) which were derived from the digital images of in-situ, undisturbed gobi surfaces by means of particle tracking with ImageJ software. In the northwestern China, the gravel coverage of different gobi surfaces ranges between 31.5%-84.6% and most of the surfaces are moderately covered by gravels. Aerodynamically, 70% of the gobi surface is stable and non-eroded by wind. According to the mean grain size, the gobi surfaces are mainly composed of fine to medium gravels. The roundness and aspect ratio of gravels vary with gobi types, the mean values of the two parameters change from 0.50 to 0.76 and from 1.38 to 2.46, respectively. The gravel morphometric features of different gobi surfaces are closely related to their erosional/depositional processes. The gobi surfaces which composed of denuded or weathered fragments and diluvial deposits are characterized by larger grains and aspect ratio, bad rounded and high gravel coverage. Otherwise, the fluvial-proluvial gobi surfaces have smaller grain size and aspect ratio, better rounded and low gravel coverage. The morphometic characteristics of gravels derived from these digital images could provide some useful significance to determining the source region of gobi deposits and to interpreting the transport/deposition processes.

Key words: gobi, gravel, morphometric characteristics, gravel coverage, grain size

中图分类号:

P931.3

钱广强, 董治宝, 罗万银, 冯益明, 吴波, 杨文斌. 基于数字图像的中国西北地区戈壁表面砾石形貌特征研究[J]. 中国沙漠, 2014, 34(3): 625-633.

Qian Guangqiang, Dong Zhibao, Luo Wanyin, Feng Yiming, Wu Bo, Yang Wenbin. Gravel Morphometric Analysis Based on Digital Images of Different Gobi Surfaces in Northwestern China[J]. JOURNAL OF DESERT RESEARCH, 2014, 34(3): 625-633.

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