Evaluating high-frequency ground-penetrating radar for 3D characterization of burrow networks in carbonate strata

Bioturbation strongly modifies sedimentary rock heterogeneity by altering burrow geometry, connectivity, porosity, and permeability, yet three-dimensional characterization of burrow networks remains difficult at representative rock-block scales. Computed tomography (CT) provides high-resolution imaging but is limited by sample size and laboratory constraints. This study evaluates whether high-frequency ground-penetrating radar (GPR) can provide comparable three-dimensional characterization of burrow networks in carbonate rocks. A limestone block from the Hanifa Formation, Saudi Arabia, containing abundant fine Thalassinoides burrows, was surveyed using a 2.7 GHz GPR system, acquiring 200 parallel profiles with 3 mm line spacing in approximately 90 minutes. The processed GPR volume was compared with CT scans acquired from twelve sub-blocks of the same sample. Despite a theoretical vertical resolution of only 1–2 cm, which approaches the diameter of many burrows, the GPR data successfully resolved the principal burrow architecture, including major interconnected zones and the overall vertical and lateral distribution of the burrow network. Quantitative comparison shows that the CT-derived burrow volume fraction ranges from \\(0.9\\%\\) to \\(10.0\\%\\) , while the calibrated GPR estimates range from \\(2.1\\%\\) to \\(11.5\\%\\) , with both methods exhibiting nearly identical spatial trends among the twelve sub-blocks. These results demonstrate that, although CT provides superior spatial resolution, high-frequency GPR can produce reliable quantitative estimates of burrow distribution and connectivity over substantially larger sample volumes, making it an effective non-destructive complement to CT for laboratory investigations and a promising technique for future field-scale characterization of bioturbated carbonate reservoirs.