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Water-rock Interaction Ascribed to Hyperalkaline Mineral Waters in the Cabeço de Vide Serpentinized Ultramafic Intrusive Massif (Central Portugal)

2017; Elsevier BV; Volume: 17; Linguagem: Inglês

10.1016/j.proeps.2016.12.173

1878-5220

José M. Marques, Orquídia Neves, Ana Z. Miller, C.S.A. Rocha, S. Vance, L. E. Christensen, Giuseppe Etiope, Paulà M. Carreira, Shino Suzuki,

Geology and Paleoclimatology Research

The conceptual model of Cabeço de Vide mineral waters, issuing at the contact metamorphism zone developed by the local mafic/ultramafic pluton, is described. These mineral waters discharge with a temperature between 17 and 20°C, show a very alkaline pH (up to 11.8), and have: Na-Cl/Ca-OH facies; dry residuum ≈ 200mg/L; Ctotal < 3.0mg/L; and extremely low Mg2+ and silica concentrations (< 0.3 and 6.5mg/L, respectively). CH4 isotopic composition (-24.4 o/oo < δ13C-CH4 < -14.0 o/oo and -285 o/oo < δ2H-CH4 < -218 o/oo) falls in the range of typical abiotic gas. In the case of Cabeço de Vide mineral waters, the understanding of the resource will help to preserve the mineral water quality, creating public interest.