A NEW RECORD OF PALEOENVIRONMENTAL CONDITIONS FROM THE NORTHEASTERN SAN MARTÍN LAKE BASIN (PATAGONIA, ARGENTINA): VEGETATION RECONSTRUCTION FROM POLLEN AND CARBON ISOTOPES SINCE 10,200 CAL. YEARS BP

BAMONTE, FLORENCIA; MARCOS, MARÍA; ECHEVERRÍA, MARCOS; SOTTILE, GONZALO; PANARELLO, HÉCTOR; MANCINI, MARÍA

Publicación Electrónica de la Asociación Paleontológica Argentina

Asociación Paleontológica Argentina

Año: 2023 vol. 23 p. 1 - 17

. In this research, we reconstruct the paleoenvironmental conditions from a sedimentary record of a wetland (mallín) located in thePatagonian steppe near to the Subantarctic forest on the northeastern shore of the San Martín Lake basin (SW Santa Cruz, Patagonia, Argentina).The Mallín Ñire (49° 00’ 23.5” S; 72° 13’ 34.5” W) presents a basal age of 10,200 cal. years BP and its pollen content, carbon isotopes, andstratigraphy were analyzed. The relationship with modern pollen assemblages from surface sediment samples allows us to interpret changesin the fossil record. Between 10,200 and 9,000 cal. years BP, we can infer a grass-shrub steppe with dwarf-shrubs under arid conditions andbetween 9,000 and 6,500 cal. years BP, a grass steppe dominated under an increase of moisture availability. Conditions became drier until4,000 cal. years BP; later, a grass-shrub steppe developed, which suggests an environmental transition like the modern ones. The last 1,400cal. years BP present high paleoenvironmental variability. The integration with other sequences allowed us to interpret the regional changesduring the Holocene related to moisture availability by precipitation changes related to the westerly variations.