Holocene geochronology, paleoenvironments and paleosoils in the Pampean region.

Abstract

The palaeoenvironmental conditions in the Pampean region during the Holocene, generated different surfaces of landscape stabilization, making possible the formation of soils in coastal marine plains and continental environments. The analyses of different geological profiles in four localities and areas of influence (NE and E of Buenos Aires province), permitted to identify pedogenetic events: 1) in coastal marine plain environments, located among circa 4500 - 3500 14C years BP and circa 1700 14C years BP; 2) in flood plains, located chronologically later to circa 8500 - 8000 14C years BP, finalizing circa 2000 14C years BP. Besides, the radiocarbon chronology permitted: 1) to locate the end of the depositation of the Guerrero Member of the Luján Formation inside the early Holocene, circa 8500 14C years BP; 2) to establish the age of the beginning of depositation of the Recent alluvial sediments, circa 2500 14C years BP ; 3) to date a pedogenetic event into the Recent alluvial, circa 1700 14C years BP; 4) to estimate the retreat of the Holocene transgressive maximum and the beginning of fluvial conditions, circa 4500 - 4200 14C years BP.