Radon-based fault detection in marine sediments of Khor Abdullah: Integrating geophysical and statistical approaches

This study integrates radon surveys with geophysical and statistical methods to detect hidden faults in Khor Abdullah's marine sediments, analyzing 184 seafloor samples for passive radon (80–789 Bq/m 3 ), exhalation rate (0.0008–0.2791 mBq·kg −1 ·h −1 ), and effective radon (0.24–15.17 Bq/kg) using CR-39 detectors. Trend-surface analysis separated regional backgrounds from residual anomalies, with positive thresholds of +100 Bq/m 3 , +0.05 mBq·kg −1 ·h −1 , and +5 Bq/kg indicating enhanced gas migration through fault zones and salt diapirs. Statistical analyses including correlation (R = 0.86 between concentration and exhalation), hierarchical clustering (background, intermediate, and high-anomaly groups), and factor analysis (two factors explaining 88.9% of variance, with Factor 1 representing permeability-controlled transport and Factor 2 the radon source term) demonstrated that radon mobility is governed by structural pathways rather than source alone. A composite fault map revealed 28 inferred faults clustered in eastern (48.65–48.66°E, 29.65–29.69°N) and central-western sectors (48.30–48.38°E, 29.85–29.86°N), with dominant NW–SE and NE–SW strikes that closely correspond to previous studies related to Basrah Block fault systems. High-anomaly Cluster C stations spatially matched known fault zones and diapirs, validating earlier interpretations while refining continuity and revealing secondary fractures through a polymodal rose diagram. This framework integrates geophysical and radiometric evidence for the first time in this marine environment and links to hydrocarbon studies demonstrating fault-controlled vertical migration essential for accumulation and seepage. The study provides a cost-effective, rapid, non-invasive tool for mapping hidden subsurface structures obscured by thick Quaternary cover, supporting hydrocarbon exploration, neotectonic hazard assessment, and coastal infrastructure planning in the northern Arabian Gulf.