Estratigrafía y paleoecología del Pleistoceno Tardío - Holoceno del área del arroyo Las Brusquitas, Buenos Aires, Argentina: una revisión

PRIETO, A.R.; VILANOVA, I.; CLAUDIO GERMAN DE FRANCESCO

Tucumán

Congreso; 2º Congreso Argentino de Cuaternario y Geomorfología; 2003

Sedimentary sequences 14C dated from the arroyo Las Brusquitas area; southeastern Buenos Aires province, provied records of the Late Pleistocene - Holocene paleoenvironmental history. Stratigraphical, malacological and palynomorphs analyses allowed to explain the environmental changes especially .in relation to sea-level variations, as well as to re-evaluate previous interpretations carried out by other authors. During the Late Pleistocene (Lujanense) a continental environment is developed in relation to a seashore located more eastward than its present position. Between ca 7000 and 6000 14c yr B.P. an environment highly influenced by tides is developed during the maximum Holocene sea level. Between ca. 6000 and 3900 yr 14C B. P. a change from a saltmarsh to a shallow brackish lagoon with tidal influence occurred. An intertidal environment changed into an environment with predominant freshwater conditions between 3900 and 2000 yr 14C B.P. During this time, tide influence was still acting but only in extraordinary occurrence. This data show a· higher altitude for tide influence than other synchronous coastal sequences in Buenos Aires province, which confirm that a tectonic control affected the area. Transgressive - regressive sedimentary cycle during the Holocene is represented by the Querandinense (transgressive facies ca 7000 and 6000 years 1•c B.P.) and by the Platense (regressive facies, between ca 6000 and 2000 14C years B.P.).