Produção Nacional
Caracterização da matéria orgânica particulada dos últimos 10 mil anos a partir de um testemunho do Parque Estadual do Rio Doce, MG, Brasil: implicações paleoambientais
2015; Volume: 18; Issue: 1 Linguagem: Inglês
10.4072/rbp.2015.1.11
ISSN2236-1715
AutoresFernanda Mara Fonseca-Silva, Marcelo de Araújo Carvalho, Sérvio Pontes Ribeiro,
Tópico(s)Geology and Paleoclimatology Research
ResumoThis paper presents the results of a palynofacies study from a Holocene core of a Lake (Lc2), State Park of Doce River, MG, Brazil.The analysis of palynofacies was carried out on 17 samples of a core of 90 cm (Lc2-01), dated at 80 cm depth in 10,191 cal.years BP, 65 cm in 9,640 cal.years BP, 35 cm in 7,905 cal.years BP and 10 cm 102 cal.years BP.The core Lc2-01 shows an increased level of silt/clay upwards, supporting the idea that the depositional process involved low energy.The identification of the organic components yielded three distinct palynofacies.The Palynofacies 1 (Pf1) is composed of cuticles, corresponding to a fluvio-lacustrine environment; Palynofacies 2 (Pf2) dominant elements are phytoclasts (opaque and nonopaque), representing woody components and Palynofacies 3 (Pf3) is composed of a predominance of amorphous organic matter and palynomorphs (spores, pollen grains and freshwater algae).The stratigraphic distribution of the palynofacies, allowed the identification of three phases in core Lc2-01.Phase 1 (10,375-9,351 cal.years BP) has a predominance of Pf2, suggesting a fluvio lacustrine environment of high energy and even at 9,351 cal.years BP the Doce river bed was not closed.From 9,351-7,905 cal.years BP (phase 2) there was a continuing increase in Pf2 and a severe elevation of Pf1, indicating the beginning of the closing of the valleys of the old Doce river bed.The phase (7,905-102 cal.years BP), demonstrates an abrupt rise of Pf3, suggesting anoxic-dioxic compatible with shallow lacustrine environment or paludal water.
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