CORRELATION OF CENOZOIC SEQUENCES OF SOUTHEASTERN BUENOS AIRES PROVINCE: BIOSTRATIGRAPHY AND MAGNETOSTRATIGRAPHY

SOIBELZON, E., PREVOSTI, F. J., BIDEGAIN J. C., RICO, Y., VERZI, D. H., Y TONNI, E. P.

QUATERNARY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2009 p. 51 - 56

1040-6182

Correlations among stratigraphic sequences of the continental late Cenozoic of southeastern BuenosAires province have been historically based on lithostratigraphy and paleontological content. Recentmagnetostratigraphic studies supplied new evidence which, together with biostratigraphy, allowedimprovement of the chronostratigraphic framework. Recent studies were conducted at four localities ofsoutheastern Buenos Aires province: Playa Santa Elena, Punta Hermengo, Mar del Sur and Centinela delMar. The studied sequences at Santa Elena and Mar del Sur show normal magnetic polarity, while PuntaHermengo and Centinela del Mar display levels of reverse polarity. Discontinuities in the sequence of Mardel Sur might explain the absence of sediments of reverse polarity. Thus, some units (the lower ones)could correspond to the normal magnetic events C1r1n and/or C2n, as the fossil fauna collected here hasno typical Pliocene components that could suggest an age older than the Gauss–Matuyama boundary(i.e., >2.58 Ma). The basal levels of the profile at Punta Hermengo, with reverse polarity, display Ensenadanfauna. This may be the most recent section of C1r (C1r1r, 0.90–0.78 Ma), which took place after thenormal Jaramillo event (C1r1n). The lower unit of Playa Santa Elena, of normal polarity (C1n), bearsmammal remains suggesting a late Ensenadan age (<0.78 Ma). The base of the Centinela del Marsequence that shows reverse polarity levels and bears bones of mammals probably is of undifferentiatedPleistocene age