The mid to late Holocene transition in Barrancas, Jujuy, Argentina: Regional climate change, local environments and archaeological implications

This paper presents the preliminary results of a multiproxy analysis of the Cruces 2 record (PCC2), located in the area of Barrancas, Dpt. of Cochinoca, Province of Jujuy, Argentina. Our studies included geomorphology, organic matter and carbonate content, magnetic properties of sediments, diatoms and pollen analysis, with the purpose of exploring the environmental characteristics of the locality from the mid-to late Holocene transition (ca. 4500 BP) to 1000 BP. This research contributes to an ongoing effort to model resource structure during the Holocene in the South-central Andes highlands of Argentina, thus allowing a more informed debate regarding the availability, distribution and characteristics of human habitats in this region, contributing to predict and explain patterns in the archaeological record both at regional and local scales. The PCC2 record indicates that the mid-to late Holocene transition in the locality implied a change from more regionally dry and mostly stable conditions to more humid but unstable conditions. During the regionally wetter late Holocene the energy of the Barrancas hydrological system increased, including frequent torrential events, but these conditions were punctuated by discrete, recurrent and/or intense regionally dry episodes. Locally, these dry events manifested as episodes of paludization/paleosoil formation in Barrancas and other localities of the dry Puna, which took place at 3260, 3000, 2500, 2100, 1490/1460, and 1050 cal BP. The consolidation of a group of cultural traits locally known as "the Formative Period" in the South-central Andes - village settlements, pottery, agriculture and/or pastoralism - may have been part of a sociocultural strategy to cope with resource uncertainty and economic risk brought on by late Holocene environmental instability from ca. 3500 BP on.