Landscape and environmental conditions for the late Holocene in the eastern Pampa-Patagonian transition (Argentina): a phytolith analysis of the El Tigre archaeological site

ZUCOL, ALEJANDRO; MARTÍNEZ, GUSTAVO; MARTÍNEZ, GUSTAVO A.; COSTA ANGRIZANI, RODRIGO

VEGETATION HISTORY AND ARCHAEOBOTANY

SPRINGER

Lugar: Berlin; Año: 2021

0939-6314

The El Tigre archaeological site (39°46´49´´ S; 62°22´32´´ W) is located in the south of BuenosAires province (Argentina), located in an ancient delta of the Colorado river. Its sedimentary sequence shows periods of landscape stability and pedogenetic processes during the period ca. 1,000?400 years B.P. The aim of this paper is to characterize the evolutionary history of the vegetation in order to understand palaeoenvironmental changes during the Late Holocene. The study of microremains from the sedimentary sequence indicates that cold and dry conditions predominated during 2,700?2,200 cal B.P., in accordance with the prevalence of non-pedogenetic, aggradational sediments in arid/semi-arid environments and/or poor vegetation cover. Then the climate became much warmer during ca. 2,200? 1,200 cal B.P., with greater availability of moisture and the presence of xerophytic shrubs and halophytic grasslands, and also extra-regional arboreal components. The records indicate that for ca.1,500?300 cal B.P. the climate conditions changed to temperate with periods of greater water availability and the presence of a halophyte steppe, and a greater abundance of Monte-Caldenal elements. This climatic trend is also in agreement with the pedogenetic processes defined in the archaeological site sequence. The upper section of the El Tigre site (the last 300 cal B.P.) shows lower temperatures, accompanied with variations in the availability of humidity, and with alluvial processes characterized by the presence of halophytic grasslands with xerophytic shrubs, and an increase in Asteraceae and Poaceae, continued bythe recent top samples with ruderal communities and sandy grasslands.