Depósitos marinos progradantes del Carbonífero Inferior de la Precordillera Occidental, San Juan, Argentina

the stratigraphy and the environmental interpretation of the rocks with fossils of the leoncito formation (late early carboniferous) of san juan′s precordillera mountain is analysed, together with a detailed geologic map and three stratigraphic profiles where the different layers were located with fossils. the basal section of the leoncito formation is interpreted as marine-transitional sedimentation, with facies of sandy barriers, channels, tidal delta and lagoon, those were affected by sands and conglomerate of glacial origin.