Environmental changes in the Pampean area of Argentina at the Matuyama–Brunhes (C1r–C1n) Chrons boundary

The so-called Pampean sediments are the uppermost sedimentary levels of the Chacopampean basin. They record the sequence of geologic changes that occurred during the late Cenozoic.In the Pampean area, the most important environmental and faunistic changes occurred close to the end of the Matuyama Chron and beginning of the Brunhes Chron. The relatively wet climate recorded in the region at the end of Matuyama Chron turned to drier and colder conditions during the beginning of the Brunhes Chron, which also seems to be characterized by an important volcanic activity in the Cordillera de los Andes. An important faunistic turnover (between Tolypeutes pampaeus and Megatherium americanum biozones) coincides with lithostratigraphic changes (between the Ensenada and Buenos Aires formations). The change of polarity Matuyama–Brunhes is observed below this boundary.