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

Abstract

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.

Analysis of Particulate Organic Matter in Holocene Sediments of Coastal Plain From Pero Beach, Cabo Frio, Rio De Janeiro, Brazil

“…The values of TOC and Phy-TOC ratio are low throughout the studied core when compared to other studies conducted in other coastal regions of Brazil (Zocatelli et al, 2012;Boussafir et al, 2012;Lorente et al, 2014;Gadens-Marcon et al, 2014a). However, Amaral et al (2012) analyzed three coastal cores, collected in the State of Santa Catarina, also observing low TOC values.…”

The “Lagoa do Camargo 1” Paleoindian site: some implications for tropical geomorphology, pedology, and paleoenvironments in southeastern Brazil

“…The mid‐Holocene high soil accretion rate (around 5 ka) can be compared to similar results obtained at Sumidouro site, central Brazil (Araujo et al., ), and could be linked to rhesistatic conditions ( sensu Knox, ) related to the mid‐Holocene hypsithermal (Fairbridge, ). Additionally, the second peak is very close to the so called 8.2 ka event, another instance of climatic disruption that was identified in several paleoclimatic studies in southeastern (Bernal et al., ; Cheng et al., ; Sallun et al., ) and southern Brazil (Gadens‐Marcon et al., ). However, given the dynamic nature of the slope processes that we are proposing, it is still premature to assign soil accretion rates to paleoenvironmental events.…”

Droughts during the last 2000 years in a tropical sub‐humid environment in central Mexico

“…ad 300 ± 200). There is also an increase in Pseudoschizea , an indicator of warm conditions and seasonal drying (Gadens‐Marcon et al 2014), and a reduction of the riparian taxa. Zea pollen grains are absent during this drought period.…”