Magnetostratigraphy in Aldea Brasilera, entre Rios, Argentina

Abstract

Upper Cenozoic marine, fluvio-lacustrine and continental-eolian deposits are exposed in river banks and quarries within the province of Entre Rios in northern Argentina. A 26 m sequence from a quarry at Aldea Brasilera has been investigated as to sedimentological and environmental changes, and subjected to paleomagnetic analysis. The magnetostratigraphy established includes six polarity reversals and is interpreted to cover tha last about 3.3 Ma. The deposition of marine and fluvio-lacustrine deposits from 3.3 to about 1.5 Ma seems to have been fairly continuous, whilst the land surfaces and eolian (loess) deposition reflect sporadic deposition. The magnetostratigraphy established may serve as a regional standard section. A final marine transgression of Late Pliocene age is established right on top of the Kaena Reversed Polarity Event The close association between this geomagnetic event and final marine event may serve as a very useful chronostratigraphic marker level and horizon. It has been recorded in other sections under studies, too.