Relation between the sedimentary organic record and the climatic oscilations in the Holocene attested by palynofacies and organic geochemical analyses from a pond of altitude in southern Brazil

Anais da Academia Brasileira de Ciências

Gabrielli T. Gadens-marcon¹  JoÃo G. MendonÇa-filho¹  Margot Guerra-sommer¹  Marcelo A. Carvalho¹  Etiene F. Pires¹  LÉo A. Hartmann¹ 

关键词: continental environment;    pond;    organic matter;    palynofacies analysis;    total organic carbon;    total sulfur;    ambiente continental;    alagado;    matéria orgânica;    análise de palinofácies;    carbono orgânico total;    enxofre total;   

DOI  :  10.1590/0001-3765201420130268

来源: SciELO

【 摘 要 】

This paper presents the quantitative and qualitative results obtained from palynofacies and geochemistry analyses carried out on a core covering approximately 8000 years of sedimentation of a pond of altitude located at the mining district of Ametista do Sul, southernmost Brazil. The main objective of this paper is to consider the paleoclimatic and paleoenvironmental significance of these analyses. The hydrological isolation renders this pond climatically sensitive to variations in pluviometric regime and this enabled infer rainfall events during the early Holocene, which was responsible for the beginning of the processes of water accumulation in the gossan and the sedimentation of the pond. Changes in the pattern of moisture over the time become the drier environment, resulting in the intermittent pattern of water depth that currently exists at the site. The fluctuations in water depth are inferred from the frequency of Botryococcus and other algae, which tend to decrease progressively toward the top where the autochthonous elements are replaced by parautochthonous and allochthonous elements. Pseudoschizaea, in turn, appears to act as a biological marker of these transitional intervals. The present results are of great importance for understanding the extent of climate change and its environmental impacts at regional and global levels.

【 授权许可】

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