Google Scholar: citations
Holocene paleoclimatic reconstruction based on the Lagoa Dourada deposits, southern Brazil
Melo, M.S. (Universidade Estadual de Ponta Grossa)
Giannini, P.C.F. (IGUSP - Instituto de Geociências da USP)
Pessenda, L.C.R. (CENA - USP - Centro de Estudos Nucleares na Agricultura)
Brandt Neto, M. (Universidade Estadual Paulista)

Date: 2003
Abstract: The Lagoa Dourada is a circular-shaped pond formed on the Furnas Formation (Devonian of the Paraná Basin), filled by late Pleistocene - Holocene sediments. It lies in the hydrographic basin of the Guabiroba River, a tributary of the Tibagi River situated in the Campos Gerais region of the State of Paraná, southern Brazil. The pond is about 200 m in diameter and the maximum water depth is 5. 4 m. Geological, chemical, textural and mineralogical studies on a core sample of the sediments collected from the Lagoa Dourada, 12. 2 m thick, was obtained for investigations of paleoenvironmental changes as well as to provide additional data to support previous reconstructions based on palynomorphs and diatoms. Within the period recorded in the core, the pond has been filled by sandy material introduced by springs at the northern edge of the pond as well as by muddy material brought in by floodwaters of the Guabiroba River. Thus, the sandy layers could be interpreted as evidence of drier climates with consequent diminution of fluvial overflow, but with maintenance of the sandy deposits coming from springs. The occurrence of euhedral pyrite in the sediments, locally associated with gypsum, may indicate periods of increase in the organic matter content or an increase in the water salinity, what could be related to greater evaporation under drier paleoclimate regimes. Three "cycles" defined by an increase in the total carbon content of the sediments of the pond were observed. These cycles seem to correspond to an increase in the isotope ratio 13C /12C (d13C). Several hypotheses can be suggested to explain the presence of these "cycles", including the alternation of wetter or drier climatic phases. The convergence of the sedimentological data obtained during this study with previous microfossil paleoclimatic (pollens and diatoms) indicators and radiocarbon dating suggests that a drier paleoclimatic phase occurred around 8720±150 years B. P. The evidence for a second drier phase in more recent times is less consistent. This subsequent phase could correspond to the drier phase in southern and southeastern Brazil between 5000 and 3000 years B. P. as suggested by other paleoclimatic studies.
Rights: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original. Creative Commons
Language: Anglès.
Document: article ; recerca ; publishedVersion
Subject: Pond sedimentology ; Holocene paleoclimatology ; Carbon isotopes
Published in: Geologica acta, Vol. 1, Núm. 3 (2003) , p. 289-302, ISSN 1696-5728

Adreça alternativa:
DOI: 10.1344/105.000001616

14 p, 519.1 KB

The record appears in these collections:
Articles > Published articles > Geologica acta
Articles > Research articles

 Record created 2012-02-07, last modified 2019-07-20

   Favorit i Compartir