EXEMPLOS DE RECONSTITUIÇÕES DA VEGETAÇÃO E INFERÊNCIAS DE PALEOCLIMAS NO ESTADO DO RIO DE JANEIRO ATRAVÉS DA UTILIZAÇÃO DE BIOMINERALIZAÇÕES DE SÍLICA (FITÓLITOS) E ISÓTOPOS DE CARBONO Examples of vegetation reconstructions and paleoclimate in the state of Rio de Janeiro through the use of phytoliths indicators and carbon isotopes

The comprehension of most of Brazilian primary vegetation often requires paleoenvironmental studies. This paper presents two studies in areas of the state of Rio de Janeiro where reconstructions of vegetation and paleoclimate inference were made, using phytoliths and isotopes of carbon as proxies. Phytoliths are particles of silica formed as a result of absorption of silicic acid in the soil solution by plant roots, precipitating later, mainly by transpiration of plants, within or between plant cells. They are important microfossils, with typical configurations of the vegetation source, since the shape of the phytolith remembers as a "model" the plant cell where it was formed. Carbon isotopes are used in environmental studies due to the fact that the isotopic composition varies in a predictable way as the element moves through the various compartments of an ecosystem. In plants, there is a constant fractionation for e cycle of photosynthesis. The ratio between the stable carbon isotopes can indicate which sort of plant originated the studied material, complementing efficiently the results of phytoliths