High-resolution Holocene South American monsoon history recorded by a speleothem from Botuverá Cave, Brazil

J. P. Bernal, Francisco W. Cruz, Nicolás M. Stríkis, Xianfeng Wang, Michael Deininger, Maria Carolina A Catunda, C. Ortega-Obregón, Hai Cheng, R. Lawrence Edwards, Augusto S. Auler

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34 Scopus citations

Abstract

A Holocene stalagmite from Botuverá Cave, southeastern Brazil was analyzed by LA-ICPMS for Mg/Ca, Sr/Ca, Ba/Ca. The observed variability in the record was demonstrated to be modulated by prior calcite precipitation, and, thus, is interpreted to reflect monsoon intensity. We find that the calcite δ18O is strongly correlated with Sr/Ca, indicating that atmospheric circulation over South America and monsoon intensity have been tightly correlated throughout most of the Holocene, both directly responding to solar precession. Comparison with other contemporaneous high-resolution hydroclimate records reveals that SAMS has shown a degree of complexity during the Holocene not previously detected, with periods where the South American Convergence Zone (SACZ) expanded to cover most of the South American sub-continent, and coincident with periods of low-SST in the north Atlantic. We also detect periods where rainfall amount in northeastern and southeastern Brazil are markedly anti-phased, suggesting a north-south migration of SACZ, which it appears to be mediated by solar irradiance. The high-resolution nature of our record allow us to examine the effect that Holocene climate anomalies had upon SAMS dynamics and hydroclimate in southeastern Brazil, in particular the 8.2 ka event and the Little Ice Age. In addition to confirm the internal structure of the events, we also detect the possible consequences of the climatic anomalies upon ocean–atmosphere interactions through its effects upon SAMS.

Original languageEnglish (US)
Pages (from-to)186-196
Number of pages11
JournalEarth and Planetary Science Letters
Volume450
DOIs
StatePublished - Sep 15 2016

Bibliographical note

Funding Information:
The authors wish to thank two anonymous reviewers and Dr. Heather Stoll that provided insightful comments on an earlier version of this manuscript. Funding for this project was provided by UNAM/PAPIIT project IN105713 and CONACyT 78828 to JPB, from NASA/FAPESP through the Dimensions of Biodiversity Program Grants 2012/50260-6 and 2013/5029-7 and PRIMO cooperative program ( CNPq 590172/2011-5 ) to FWC, Singapore NRFF2011-08 to XW, and NSF Grant 1103403 to RLE and HC.

Keywords

  • Brazil
  • Holocene
  • SAMS/SACZ
  • stalagmite
  • trace-elements

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