MULTIPROXY RECORDS OF MID-HOLOCENE ENVIRONMENTAL CHANGES IN NORTHEAST PATAGONIA (BAJO DE LA QUINTA), ARGENTINA

Paleoecology is a useful tool in the exploration of changes occurring in the environment over time. Particularly, multi-proxy studies provide a more comprehensive picture of climatic conditions in the past. This work is a new contribution to the currently available paleoenvironmental information on the northern Patagonian Atlantic coast. It aims to reconstruct the paleoenvironmental history of Bajo de la Quinta (northeastern Patagonia) using pollen, diatoms, organic matter, carbonates and geomorphological studies. The section suggests changes in climate and vegetation occurring since the middle Holocene, revealing an important change from arid to semiarid conditions during the late Holocene -at 3000 years cal. BP. This may be related to more frequent contributions of moisture from the Atlantic and a weakening of the western winds. These environmental conditions favored the development of the shrub communities known as Monte. Such a development was synchronous with geomorphological changes of the coast, where connection to the sea was interrupted to originate a lagoon. The diatom content suggests the deposit represents a shallow fresh-brackish environment possibly exposed to periodic desiccation. This multi-proxy study improves and complements the current paleoenvironmental offsetting accepted for the northern coast of Rio Negro Province.