Geochemistry and genesis of brine emanations from Cretaceous strata of the Mamfe Basin, Cameroon |
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| Authors: | E Eseme CM Agyingi J Foba-Tendo |
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| Institution: | a Department of Geology and Environmental Science, University of Buea, P.O. Box 63, Buea, Cameroon;b Department of Chemistry, University of Buea, P.O. Box 63, Buea, Cameroon |
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| Abstract: | The geochemistry of 5 salt springs in the southwestern Mamfe Basin was investigated in order to infer the mineral content of their source and to relate the genesis of the springs to the local geology. Field observations revealed that, they are cold springs (23–28 °C), and are composed of secondary brines that are neutral to alkaline with pH values ranging from 7 to 8.7. Results of chemical analysis show that the springs contain major ions that form evaporite minerals, as well as chalcophile elements. The dominant cation is Na+ (>96%), and the dominant anion is Cl− (>99%). Based on correlation coefficients between ions that form evaporites and field occurrence of efflorescences of halite, it is suggested that the ancient evaporites in the Mamfe Basin are composed entirely of carbonate and chloride salts. Meteoric and convective fluid flow processes are responsible for the dissolution of ancient evaporites and subsequent migration of brines to the surface from underground. The brines migrate through permeable strata with migration pathways resulting from a combination of fracture porosity created by post––Cretaceous tectonism and intergranular porosity enhanced by the chemically aggressive migrating brines. |
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| Keywords: | Geochemistry Cretaceous Brines Porosity Meteoric flow Convective flow |
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