Using 2-D and 3-D georadar to characterize karst collapse as a basis for high-resolution reservoir-analogue models

Paleokarst collapse-breccias are known to significantly influence fluid flow in carbonate rocks in aquifers and hydrocarbon reservoirs. However, few 3D studies of breccia-pipe properties exist and more detailed knowledge about these structures can help to improve present-day fluid-flow models. To investigate collapse breccias which crop out on the Wordikammen plateau (Spitzbergen), we performed both extended 2-D and 3-D georadar measurements achieving 40 m penetration. From the grid of 2-D sections we determined the spatial distribution and sizes of collapse bodies characterized by complex diffraction patterns interrupting bedding-related continuous reflections. Images of the 3-D survey enabled us to determine accurately the actual shape of one breccia pipe. Comparison with electrical resistance tomography (ERT) shows that the breccia pipes coincide with regions of both anomalously-high and -low resistivities. This may indicate that breccia pipes can act as flowpaths for water in the permafrost