Fluvial systems and geoarcheology. San Luis, Argentina. Rock magnetic studies.

What is it about?

The ephemeral streams of the semiarid piedmont environments linked to the Sierras Pampeanas of Argentina have received little attention to date. The detailed study of these fluvial systems in the eastern piedmont of Sierra de Las Quijadas range has made it possible to differentiate two types of ephemeral streams and assimilate them to continuous ephemeral streams or “arroyos” and discontinuous ephemeral systems (DES). The stream locally known as Arroyo Los Hornos has morphological and morphodynamic features that allow it to be classified as a DES. The finding of kiln remains on the old alluvial surfaces has geoarchaeological relevance because of the association of such archaeological remains and their distribution in the piedmont. Rock magnetic analysis indicates that no superparamagnetic grains control the assemblages of magnetic particles. The main magnetic carrier is (titano)magnetite with a concentration of around 0.045% and magnetic grain size of 4–8 m. Radiocarbon dates (14C) for materials extracted from the edaphic horizon developed in the alluvial deposits of paleo valleys and one of the hearths or stoves (hornillos or hornitos), dated to circa 1800 and 500 years BP, respectively, allowed us to define a new stratigraphic unit for the Late Holocene in the region.

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