DEGEO - Departamento de Geologia
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/8
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Item A Late Quaternary palynological record of a palm swamp in the Cerrado of central Brazil interpreted using modern analog data.(2018) Cassino, Raquel Franco; Martinho, Caroline Thaís; Caminha, Silane Aparecida Ferreira da SilvaThe fossil pollen record from a Late Quaternary peat core collected in the São José palm swamp, in the northwest region of Minas Gerais state (Central Brazil), is interpreted using a dataset of modern pollen spectra as modern analogs. Principal component analysis and dissimilarity coefficients were used to compare fossil and modern samples, supporting the interpretation of past environmental dynamics. The results suggest that at ca. 15,700 and ca. 15,400 cal years BP, the buriti (Mauritia flexuosa) palm (that characterizes the palm swamps today) was absent and the climate was colder. Around 15,200 cal years BP, the increasing occurrence of buriti and the development of the Cerrado stricto sensu, a savanna woodland, indicate a warmer climate. At the end of the Late Pleistocene and during the Pleistocene-Holocene transition, the palm swamp central zone expanded and a dense Cerrado stricto sensu developed, suggesting a warm and humid climate. By the end of the Early Holocene, a much drier climate is suggested by the shrinkage of the palm swamp and a more open regional vegetation. Subsequently, and until ca. 4400 cal years BP, a wetter climate is indicated by the extended central zone of the São José palm swamp that reached a maximum expansion at ca. 6500 cal years BP. After 3500 cal years BP, the predominance of the Campo Sujo, a herbaceous-shrubby vegetation, indicates the return of relatively dry conditions. In the last two millennia, a decrease in the extent of the humid zone of the palm swamp suggests an intensification of drier conditions. Lower precipitation inferred at the end of the Holocene, and the predominantly humid conditions in the Middle Holocene, is different from the general pattern observed in southern and western Cerrado sites, but is in agreement with paleoclimate data from Northeastern Brazil.Item Morfologia de grãos de pólen e esporos de níveis holocênicos de uma vereda do Chapadão dos Gerais (Buritizeiro, Minas Gerais), Brasil.(2011) Cassino, Raquel Franco; Meyer, Karin Elise BohnsEsporos de briófitas e pteridófitas e grãos de pólen de gimnospermas e angiospermas foram obtidos em quinze amostras de um testemunho de sedimentos holocênicos, de 150 cm de profundidade, coletado em uma vereda no Chapadão dos Gerais, em Buritizeiro (Minas Gerais, Brasil). As idades radiocarbônicas variaram entre 11.370+70 anos AP na base do testemunho e 1440+25 anos AP no nível do topo. Os 92 taxons identificados foram descritos em suas características morfológicas e abordados em seu habito e habitat, a partir das informações existentes para as plantas modernas relacionadas. As formas identificadas e ilustradas contribuem para o conhecimento da flora polínica do Cerrado e constituem material de referencia na identificação de palinomorfos em trabalhos de reconstituição do paleoambiente em áreas hoje cobertas ou relacionadas a este bioma.