Resumo

ETCHEVERRIA, Mariela P  e  FOLGUERA, Alicia. Los calcretes del sudeste de la provincia de La Pampa: caracterización y origen. Rev. Asoc. Geol. Argent. [online]. 2014, vol.71, n.1, pp.92-99. ISSN 0004-4822.

The landscape in the southeastern extreme of La Pampa province in Argentina is characterized by highly dissected plateaus with to large shallow areas, which end in calcretes partially covered by eolian deposits. Regionally, there are three levels of calcretes distinguished according to their relative height and the different degrees of preservation of their primary geomorphologic features. Each level represents the end of a depositional cycle, which took place during the late Miocene-Pliocene. The aim of this contribution is to characterize the two oldest levels and to determine their origin. For that purpose, the regional context was analyzed, profiles were described in detail and some samples were collected for their microscopic studies. The profile morphology, their thicknesses and the evidence of biological activity (thinning and beta fabric) coincide with the typical features of pedogenic calcretes which, in turn, demostrate the existence of well-drained soils and also indicate that this region had periods of reduced clastic input, tectonic stability and a semiarid climate during those periods and termic soil.

Palavras-chave : Pedogenic calcrete; Beta fabric; Pisolith; Peloid.

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