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Application of Principal Components Analysis to the study of CO2-rich thermomineral waters in the aquifer system of Alto Guadalentín (Spain)
- CERóN, JUAN CARLOS, PULIDO-BOSCH, ANTONIO, BAKALOWICZ, MICHEL
- Hydrological sciences journal 1999 v.44 no.6 pp. 929-942
- Miocene epoch, aquifers, carbon dioxide, gases, hot springs, hydrogeochemistry, nitrates, principal component analysis, rocks, salinity, sulfates, Spain
- The southeast of the Betic Cordilleras has long been recognized as an area with numerous geothermal anomalies of regional character. Many thermal springs appear related to currently tectonically active fault systems. Carbon dioxide and other gases in these waters have been mobilized through those fault systems. The great depth of these “slip-strike zones” affects the entire thickness of the lithosphere and leads to contrasting crustal domains of different natures and structures. In this area, the detrital aquifer of the Alto Guadalentín has thermal waters with high salinity and unusually high contents of CO2 gas. The utilization of Principal Components Analysis (PCA) in the hydrogeochemical study of this aquifer has revealed that the origin of the salinity of its waters is due essentially to processes of dissolution of the Miocene evaporite rocks, principally sulphate, and to the contribution of deep hydrothermal waters that show signs of endogenous CO2 contamination. To a lesser extent, infiltration waters also form an input, with elevated sulphate, chloride and nitrate content. Likewise, PCA has enabled the differentiation of distinct groups of water to which these processes have had a variable contribution.