Author(s)

Gabrielli Teresa Gadens-Marcon, Margot Guerra-Sommer, João Graciano Mendonça-Filho, Joalice de Oliveira Mendonça, Marcelo de Araújo Carvalho, Léo Afraneo Hartmann

1Unidade Litoral Norte, Universidade Estadual do Rio Grande do Sul, Osório, Brasil 2Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Instituto de Geociências, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.

This paper focuses on the interpretations in the analyses of palynofacies and organic geochemistry carried out on a sedimentary profile covering 9542 cal yr BP from a pond located at the mining district from Ametista do Sul, southernmost Brazil. The hydrological isolation renders this pond, located on a hilltop, highly sensitive to climatic change because the water entering in the system is subsidized exclusively by the rainfall. The main goal of this study is to establish relationships between the sedimentary organic record and climatic fluctuations in the Holocene, trying to correlate the alterations in the particulate organic matter with regional climatic changes or perhaps even events on a global scale. Fluctuations in water depth are inferred from the frequency of the autochthonous elements (algae), which predominate in the basal intervals, but tend to decrease progressively toward the top, when begining to alternate periods of high and low frequency with the parautochthonous (spores) and allochthonous (pollen grains) elements, due to changes in the patterns of moisture. Pseudoschizaea seems to have a closer relationship with the spores than with all other algae and can serve as a biological marker of transitional intervals or have some role in the successional process of vegetation. The variety of spores of ferns and pollen grains on the topmost interval indicates increased vegetal diversity, and is probably related to the process of successional evolution of the area. An increased rainfall event detected between 8.6 to 7.4 ka yr BP can be responsible for the beginning of the process of water accumulation in the gossan and sedimentation of the pond and can be related with the “Bond Events”. The saturation level of the pond, in turn, remained relatively constant until 6.8 ka yr BP, when changes in the patterns of moisture make the environment drier and resulted in an intermittent pattern of water depth, currently existing on the site.

Organic Matter (OM); Total Organic Carbon (TOC); Total Sulfur (TS); Paleoclimatic Change; Rainfall Influence

Gadens-Marcon, G. , Guerra-Sommer, M. , Mendonça-Filho, J. , Mendonça, J. , Carvalho, M. and Hartmann, L. (2014) Holocene Environmental Climatic Changes Based on Palynofacies and Organic Geochemical Analyses from an Inland Pond at Altitude in Southern Brazil. American Journal of Climate Change, 3, 95-117. doi: 10.4236/ajcc.2014.31009.