Vegetation and Climate in Southern South America during Marine Isotope Stage 3 (MIS 3): an Overview of Existing Terrestrial Pollen Records

Abstract

Data from terrestrial pollen records in the Chilean sector show that Marine Oxygen Isotope Stage 3 (MIS 3) was characterized by the Heinrich (stadials)/Dansgaard–Oeschger (interstadials) oscillations. At central Chile (32–38° S) an open beech/podocarp woodland was apparently established during the last ice age under cold and humid climates, where nowadays grows a semiarid, broad sclerophyllous vegetation, while episodes of aridity with rise of temperature were indicated by expansion of chenopods–amaranths. At the Southern Lake District and northern Isla Grande de Chiloé (40°–42° 30′ S), the stadial events were characterized by higher amounts of grasses indicative of the Subantarctic Parkland vegetation. This vegetation implied summer temperatures of ~6 °C (~8 °C below present). The interstadials were represented by expansion of the Valdivian-North Patagonian Evergreen Forest-Subantarctic Evergreen Forest implying summer temperatures of ~12 °C. In the Argentine sector, the steppe environmental conditions prevailed. Interstadial conditions are pointed out at 39° S, in NW Patagonia. Meanwhile, in southern Patagonia at 51°–52° S, and Tierra del Fuego at 54° S, the climatic conditions during MIS 3 are interpreted as colder and drier than today.