Nuevos datos en torno a la historia paleoambiental del centro-sur de Chile. El registro sedimentario y palinológico del "Humedal Laguna Verde" (36°47'S), Península Hualpén, Región del Bío-Bío, Chile.

Abstract

This work presents a new sedimentological and palynological record that reconstructs the elusive environmental history during the mid to late Holocene transition in south central Chile (34°-38°S). The study site corresponds to a small wetland called Laguna Verde (36º47'S, 73º09'W; 22 m.a.s.l.; ~4 ha), which is located in a micro-basin (136 ha) surrounded by native vegetation (i.e. sclerophyllous forest).  Sediment cores obtained from the wetland, allowed us to reconstruct its evolution during the post-glacial period, showing that site formation take place around 6,800 cal years BP, as a result of a damming process by dunes. Subsequently, a significant increase in the concentration of lithic materials mobilized by wind and precipitation is recorded, resulting in the formation of a permanent body of water around 4000 cal years BP. The palynological record shows a predominance of arboreal and aquatic taxa during this period, indicating the development of forest ecosystems into the basin, in response to increased rainfall. Finally, an abrupt change in the sedimentological and palynological record is observed around 1850AD, related to a transformation in the vegetal landscape and the sedimentary regime due to anthropogenic activity. In summary, this study provides new and relevant information to understand the paleoenvironmental history of the coastal ecosystems of south central Chile.