The alteration of Miraflores Basalt (Panama): Mineralogical and textural evolution

Samples of The Miraflores Basalt sub-volcanic rocks (Miocene Late Formation) collected from different quarries on the Isthmus Panama and several samples excavation third set locks in New Channel were characterised this study. All studied had similar petrological mineralogical characteristics; however, substantially degrees alteration, which varied NW–SE direction. most altered areas located at SE (Sosa Hill Quarry), next to Pacific Ocean, while Cerro Escobar rocks, further inland, showed only slight alteration. Cocolí Aguadulce Hills area, middle study region, exhibit features consistent with intermediate alteration between two aforementioned extreme cases. Images data stages obtained using optical microscopy, electron microprobe (EMP), scanning microscopy (SEM). earliest stage was by presence iddingsite, almost product As progressed, generalisation smectites throughout rock characteristic. glass disappeared transformed palagonite, plagioclase pyroxene crystals became both edges inside crystals. also numerous nanofractures, mainly perpendicular longer faces that filled smectite. In advanced state, all deeply affected. Crystals into smectite, porosity increased a process conserved volume. Smectite appeared as end-alteration major minerals (olivine, plagioclase, pyroxenes), well glass.