Seismic Imaging of the Mesozoic Bedrock Relief and Geological Structure under Quaternary Sediment Cover: The Bolmin Syncline (SW Holy Cross Mountains, Poland)

The clear and detailed images of geological structures that can be obtained by seismic methods are one of the main drivers of their popularity in geological research. The quality of final geophysical images and models relies strongly on the amount of data that goes into them. Analysing several complementary seismic datasets allow an improved interpretation. Responding to this challenge, this article proposed an optimal combination of geophysical methods for near-surface applications. Multi-channel analysis of surface waves, first-arrival travel-time tomography, and ground-penetrating radar were the key supports for standard reflection seismic imaging. Ease of use and fast and cheap acquisition are some of the advantages of the mentioned methods. Considering that all recorded wave fields required minimal additional processing while offering a significant improvement in the final stack, it was worth the extra effort. Thanks to that, the better-estimated velocity filed allowed high quality images to be obtained up to 200 m. The Mesozoic bedrock was a distinct and very strong reflector in the resulting reflection seismic imaging. There was also a clearly visible depression of the horizon corresponding to erosion or a structure (syncline). Deeper, it was possible to track two or even four detachments of faulting origin.