古尔班通古特沙漠东南部植被线形沙丘内部构造及发育模式

在野外调查基础上，应用探地雷达（GPR）对古尔班通古特沙漠东南部植被线形沙丘内部构造进行探测，获取了沙丘内部构造的雷达相图像信息，结合区域自然地理和沙丘形态特征分析，初步探讨植被线形沙丘内部构造的演化模式。结果表明：（1）GPR探测揭示了沙丘地表以下3—5 m深度的浅层构造信息，可识别沙丘中上部和丘顶部位的高倾角、上凸形和楔状交错层理、沙丘中下部和丘间地的低倾角-近水平层理构造，反映了沙丘上部风沙蚀积活动较强烈，而两翼中下部和丘间地以风沙加积为主。（2）从沙漠边缘到沙漠中心，植被线形沙丘浅层沉积构造组合由两坡不对称分布向对称分布变化，沙丘横剖面形态亦由两坡不对称向对称形态同步变化，但未发现沙丘侧向迁移的沉积构造证据。（3）依据不同规模沙丘内部构造变化序列，可将植被线形沙丘演化划分为灌丛沙丘、风影灌丛沙丘、垄状沙链、植被线形沙丘等4个发育阶段。随着叠置灌丛沙丘不断合并融入，线形沙丘宽度和高度持续增大，沙丘顶部风沙活动性增强，高倾角、上凸形、楔状交错层理增多。（4）在沙丘表层3—5 m以下块状层理以及GPR探测信号衰减、图像分辨率变差的成因，应在今后工作中进一步验证。此外，系统阐明研究区植被线形沙丘演化过程，尚需补充更多GPR探测资料并开展年代学研究。

Preliminary study on sedimentary structure and development model of vegetated linear dune in the southeastern Gurbantunggut Desert

On the basis of field survey， Ground-penetrating radar （GPR） was used to detect the internal structure of vegetation linear dunes in the southeastern Gurbantunggut Desert， and radar facies image information was obtained. Combined with regional natural geography and morphological characteristics， the evolution model of vegetation linear dunes internal structure was preliminarily discussed. The results indicate that： （1） GPR reveals the shallow （3-5 m） structure information below the dune surface， which can identify high-angle dipping， convex and wedge cross-bedding in the middle-upper part of dunes and crest， and sub-horizontal to low-angle dipping bedding in interdunes and the middle-lower part of dunes， which reflects the strong wind erosion and deposition activity in the upper part of dune， and the accretion in the middle-lower parts of dune wings and interdunes. （2） From desert edge to the center， the shallow sedimentary structure assemblage of dune slope changes from asymmetrical to symmetrical， the dune cross-section morphology showed the same variation， but no evidence of lateral dune migration have been found. （3） According to different scale dune structure sequence， the evolution mode could be divided into four stages： shrub dunes， shadow shrub dunes， longitudinal dune chains and vegetation linear dunes. With the continuous merging and integration of overlapping shrub dunes， the width and height of linear dunes increase， frequent wind activity at the dune crest， and the types of high-angle dipping， convex and wedge cross-bedding increase. （4） The causes of massive bedding （below 3-5 m， not hit the bottom） and GPR signal attenuation should be further verified. Besides， to systematic clarify the evolution process of vegetation linear dunes in study area， it is necessary to supplement more GPR data and chronology study.