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Three Portuguese limestones (two grainstones, Semi-rijo and Moca Creme commercial types, and a travertine) were subjected to salt crystallisation test (EN 12370:1999). Grainstones specimens showed higher weight loss than the travertine ones. Results are discussed, using parametric and nonparametric statistics, in relation to pore space characteristics that have been considered durability predictors, evaluated at the macroscopic (water imbibition) and microscopic (mercury injection porosimetry) levels. Several of the pore-space parameters indicate differences between grainstones and travertine, but these differences are much lower than the differences in weight loss. Results of the durability dimensional estimator (DDE) seem to present a discrepancy, with higher values in the rock type having lower weight loss (travertine). Additionally, weathering patterns of travertine samples show marked irregularities (a feature that is not assessed by weight loss). These irregularities are attributed to heterogeneous spatial distribution of detritic components (a feature that is not assessed by pore-space parameters). Comparing the grainstones, Moca Creme showed higher values of mass loss and several durability predictors suggested noteworthy differences in relation to Semi-rijo. However, these differences are much lower than differences in weight loss. Calculated crystallisation pressures are even higher for Semi-rijo. It is proposed that petrographical aspects of Moca Creme, namely heterogeneity related to the presence of bioclasts and veinlets, could contribute to explain the higher weathering susceptibility of this rock type. These results highlight the need to include petrographical features in assessments of durability and the usefulness of visual description on the characterization of salt weathering.

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Geochemical and isotopic studies have been undertaken to assess the origin of CO 2 -rich waters issuing in the northern part of Portugal. These solutions are hot (76°C) to cold (17°C) Na-HCO 3 mineral waters. The d 2 H and d 18 O signatures of the mineral waters reflect the influence of altitude on meteoric recharge. The lack of an 18 O-shift indicates there has been no high temperature water-rock interaction at depth, corroborating the results of several chemical geothermometers (reservoir temperature of about 120°C). The low 14 C activity (up to 9.9 pmC) measured in some of the cold CO 2 -rich mineral waters (total dissolved inorganic carbon) is incompatible with the presence of 3 H (from 1.7 to 4.1 TU) in those waters, which indicates relatively short subsurface circulation times. The d 13 C values of CO 2 gas and dissolved inorganic carbon range between )6& and )1& versus Vienna-Peedee Belemnite, indicating that the total carbon in the recharge waters is being diluted by larger quantities of CO 2 ( 14 C-free) introduced from deep-seated (upper mantle) sources, masking the 14 C-dating values. The differences in the 87 Sr/ 86 Sr ratios of the studied thermal and mineral waters seem to be caused by water-rock interaction with different granitic rocks. Chlorine isotope signatures ()0.4& < d 37 Cl < +0.4& versus standard mean ocean chloride) indicate that Cl in these waters could be derived from mixing of a small amount of igneous Cl from leaching of granitic rocks.