EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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2 resultados
Resultados da Pesquisa
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 Modern pollen spectra of the Cerrado vegetation in two national parks of Central Brazil, and implications for interpreting fossil pollen records.(2015) Cassino, Raquel Franco; Martinho, Caroline Thaís; Caminha, Silane Aparecida Ferreira da SilvaTwenty four surface sampleswere collected for palynological analysis fromdifferent environments in the Cerrado biome, which extends over a vast area in Central Brazil. These samples were used to investigate the relationship between vegetation and pollen spectra in the Cerrado and, thereby, contribute to amore precise interpretation of fossil pollen records from this region, particularly those collected on palm swamps. Pollen grains from the phytophysiognomy that surrounds the palm swamp generally occur in low percentages in surface samples, whereas local plants are very abundant in the pollen spectra. Although local taxa tend to predominate, two aspects of the landscapemay be reconstructed fromthe pollen spectra using numericalmethods: the local environment of the deposition site and the surrounding regional vegetation. Using PCA and dissimilarity coefficient analysis, a group of seventeen taxa and a group of fourteen arboreal taxa are proposed as those that provide improved results when investigating the local environment and regional vegetation, respectively. Because herbaceous taxa are very abundant in the palm swamps, an analysis of the content of arboreal taxa in the pollen spectra is more appropriate for reconstructing the openness of the regional vegetation.