Capillary imbibition behaviour in volcanic rocks from Madeira Island, Portugal: Preliminary results

This study assesses the influence of petrophysical properties, petrographic features, and depth on capillary imbibition of basalts and lapillistones from the Upper and Middle Volcanic Complexes of Madeira Island, Portugal, via multivariate statistical analyses and machine learning methods approach. Results demonstrated that the combined effect of mesofabric, porosity, and pore-type connectedness controls capillary imbibition in lapillistones and revealed that there is a strong direct relationship between porosity degree and water absorption coefficient by capillarity, C, in all basalts. The tendency for spontaneous imbibition to decrease with increasing depth is as expected in the studied basalts, except for the sections 23.70-27.20 m and 31.5-34.8 m in two different samples where evidence of fracturing episodes was found which leads to a dual-porosity system that favours water absorption. C is proposed as a complementary coefficient in geotechnical studies of volcanic rocks.