Paleoenvironmental reconstruction of the Carrasco Da Raposa Palm Swamp, Parque Estadual Da Serra Do Cabral, Mg, Brazil, By Means Of Palynological And Isotopic Studies

Abstract

Pollen and stable isotopes (C and N) analyses from sediments of Carrasco da Raposa palm swamp (VCR) allowed the paleoenvironmental reconstruction of the last 21,000 years in the region of the Parque Estadual da Serra do Cabral- PESC, MG, Brazil. The results demonstrated that during the influence of Last Glacial Maximum, between 21,150 and 18,850 cal. years BP, the climate conditions in the Serra do Cabral were colder and less humid than in the present; between 1,850 and 3,550 cal. years BP a warmer and wetter climate was recorded; from 1,650 cal. years BP the establishment of the palm swamp occurred in the studied area. Concerning the phytophysionomic changes, a succession of vegetation with a predominance of grassland formations was observed: “Campo Limpo” associated with forest formations at the base, “Campo Sujo” and “Campo Rupestre” associated with Cerrado forest formations in the middle, and the installation of the palm swamp with the presence of Mauritia flexuosa trees towards the top. The isotopic data (C and N) indicated that between 21,150 and 6,500 cal. years BP, there was a probable mixture of C3 and C4 plants as sedimentary organic matter source, but with the predominance of C3 plants, with δ13C values of ~-24 ‰ to -21.5 ‰. Values of C/N (1.5 to 11.5) suggested the predominance of phytoplankton and the δ15N values (3.5 ‰ to ~1.0 ‰) evidenced the mixture of algae and land plants. Around 3,550 cal. years BP to the present, there has been a decrease in the values of C/N (1.5 to ~6), confirming a flooded environment with greater influence of algae in the sedimentary organic matter.