Marine sediments of the Barranca Final Formation (Middle-Upper Miocence of the Colorado Basin) in south-east La Pampa province, Argentina

Abstract

This paper describes Miocene carbonatic, siliciclastic and evaporitic sedimentary rocks of the Colorado Basin, from southeast of La Pampa Province, Argentina. Seven facies and two facies assemblages of shallow marine (intertidal and supratidal settings) and fluvial environments are inferred on the basis of lithology, sedimentary structures, and fossil content. The thin marine level underlies the fluvial sandstones of the Río Negro Formation, and is considered contemporary with the Barranca Final Formation (middle-upper Miocene), of the Colorado Basin, which is the depositional record of the "Entrerriense" transgression. The occurrence of these sedimentary rocks confirms the presence of the "Entrerriense" sea in the south-east of La Pampa Province during the Miocene.