地质雷达探测技术在浅覆盖活动构造区填图中的应用——以宁夏青铜峡地区1:5万新构造与活动构造区填图为例

地质雷达探测以其分辨率高、定位准确、快速经济、灵活方便、剖面直观、实时图像显示等优点,成为地质调查中广泛使用的一种探测方法。本次宁夏青铜峡地区1∶5万新构造与活动构造区填图中运用地质雷达探测技术对第四系和隐伏断层进行了探测。结果表明,40 MHz地质雷达可以有效地探测地表以下30 m内的第四系结构,可清晰地识别出3套第四纪地层。这一地层结构划分被第四系浅钻证实,其为第四系全新统灵武组,自下而上由泥岩、砂砾石层和含砾的砂或泥等3套地层组成。对测区主干断裂——柳木高断裂南段的地质雷达探测表明,断裂带表现为近地表发散向下汇聚的正花状结构,这与探槽揭露的特征一致,表明地质雷达探测可以准确标定隐伏断层平面位置与垂向精细结构。本次宁夏地质填图证实,地质雷达技术是浅覆盖活动构造区进行隐伏断裂调查和第四纪地层层序划分的可行、高效、便捷的技术方法之一。

THE APPLICATION OF GROUND PENETRATING RADAR TECHNOLOGY IN GEOLOGICAL MAPPING OF SHALLOW COVERED ACTIVE TECTONICS REGION:A CASE STUDY OF 1:50000 MAPPING OF NEOTECTONIC ZONE AND ACTIVE TECTONIC ZONE IN QING TONGXIA AREA, NINGXIA

Ground Penetrating Radar (GPR) detectionisa widely-used detection method in geological survey owing to its advantages of high-resolution, accurate positioning, high speed, flexibility, convience, profile visualization, real-time image display and so on. GPR detection technology is applied to detect Quaternary system and blind faults in the mapping of 1:50000 shallow covered active tectonics zone of Qingtongxia,Ningxia. Detection results show that 40MHz GPR can effectively detect the quaternary system structure within 30 m below the surface, and 3 sets of Quaternary strata can be clearly defined. Drilling results confirm that Holocene Lingwu formation (Ql) from bottom to top is comprised of mudstone, gravel layer, and sand or mud with gravel. The radar image reveals that the south of the Liumugao fault of main fault has structural features of upward divergence and downward convergence with flower structure, which is consistent with the results of trench investigation.It shows that GPR can accurately demarcate the plane position and vertical detail structure of blind faults. This work indicates that GPR technology is feasible, effective and convenient for blind fault investigation and sequence division of the upper part of the Quaternary in shallow covered active tectonic zone.