A COMPARISON OF GROUND-PENETRATING RADAR FACIES AND SEDIMENT CHARACTERISTICS IN A PLEISTOCENE PUSH MORAINE IN THE NETHERLANDS

摘要

The Pleistocene push moraines in the Netherlands were formed during the penultimate glaciation. The data presented were collected at the eastern Veluwe ridge. Based on extensive 50 MHz ground-penetrating radar surveying, three architectural styles are distinguished. In order to deduce relationships between these structural styles, sediment facies and radar facies, the GPR surveys were complimented by data from continuously cored boreholes. Additional borehole logging served the same purpose. In this paper GPR facies of two glaciotectonic styles are analyzed: gently folded parallel fluvial sequences and imbricated thrusts in fluvial sequences. It is shown that coherent reflectors, using 50 MHz central frequencies, can be related to relatively thin (8-20 cm) fine-grained sedimentary layers. These layers are not necessarily clay, but more often silty fine sand. The presented radar facies show strong relationships with sedimentary facies as evidenced by lithology in the core and the accompanying gamma-ray borehole logs. The result leads to the conclusion that ground-penetrating radar is an excellent tool for mapping the complex architecture of Pleistocene push moraines and that a combination of techniques is particularly powerful.