Quarternary ecological and geomorphic changes associated with rainfall events in presently semi-arid northeastern Brazil

Augusto S. Auler, Xianfeng Wang, R. Lawrence Edwards, Hai Cheng, Patrícia S. Cristalli, Peter L. Smart, David A. Richards

Research output: Contribution to journalArticlepeer-review

96 Scopus citations

Abstract

Several geomorphic features and palaeobiotic remains in now semi-arid northeastern Brazil indicate major palaeoenvironmental changes during past periods of increased rainfall. 230Th mass spectrometric ages of speleothems and travertines have allowed the determination of the timing and duration of wetter than present conditions. The data demonstrate that wet events have occurred throughout much of the Pleistocene, present dry conditions having been established at the end of the Younger Dryas. A markedly different fauna comprising megafaunal elements not adapted to the present low arboreal scrubland caatinga vegetation existed in the area. Palaeobotanical remains embedded in travertine indicate forested vegetation at these wetter intervals, suggesting that the caatinga was then replaced or mixed with a semi-deciduous forest. Due to the abundance of travertine sites containing fossil botanical remains in northeastern Brazil, it is believed that forest expansion occurred over large areas of the now semi-arid zone, showing that the long hypothesised forested links between biodiversity-rich Amazon and Atlantic rainforests may indeed have existed during these moister phases.

Original languageEnglish (US)
Pages (from-to)693-701
Number of pages9
JournalJournal of Quaternary Science
Volume19
Issue number7
DOIs
StatePublished - Oct 1 2004

Keywords

  • Fossil vertebrates
  • Northeastern Brazil
  • Palaeobotanical remains
  • Speleothem growth phases
  • Travertine

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