The Ensenada and Buenos Aires formations (Pleistocene) in a quarry near La Plata, Argentina

Abstract

An interdisciplinary study of a section in a quarry near La Plata sheds new light on the geologic, climatic, and biologic evolution of the northeastern Pampean area of Argentina. The stratigraphic succession is composed of seven mainly eolian levels, each one including a soil and separated by a disconformity. Two geosols defined in northern Buenos Aires Province (Hisisa and El Tala) are identified in the Ensenada Formation. The boundary between the Ensenada and Buenos Aires formations is defined by a conspicuous disconformity which overlies the El Tala Geosol. In the section, the boundary between the Tolypeutes pampaeus (Ensenadan) and Megatherium americanum (lower Lujanian) biozones coincides with that of Ensenada and Buenos Aires formations. The boundary between the Matuyama and Brunhes zones of polarity occurs in the upper part of the Ensenada Formation above the Hisisa Geosol. According to geologic evidence, most of the succession was deposited under semiarid to arid climate.