Diagenesis and intersticial clays of the late Paleozoic Paganzo Group - La Rioja

Abstract

In this paper the most important diagenetic clay-related processes that take place in the sandstones from the Neopaleozoic units of the Paganzo Group are described. They include both clay minerals in the wackes and in the pores of clean sandstones (caolinite, illite, chlorite, interestratified clay minerals), processes of neoformation (caolinite to dickite) and of cementation (hematite, calcite). The tuffs and pisolithic tuffs with chalazolites in the Patquía and La Colina formations have planar, curviplanar and branched vitroclasts and vesicular pumites and they are also altered into smectite and analcime, while the tuffs of La Antigua Formation, are altered into kaolinite and analcime.