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

- A high-resolution Holocene record of hydroclimate variability from SE Brazil.
- Correlation between Sr/Ca and δ18O ties atmospheric circulation and monsoon intensity.
- Mega-SACZ conditions during cold North Atlantic stadials, including 8.2 ka event.
- SACZ north-south migration linked to solar radiance during 7-8 ka B.P.
- AMO and solar modulation of SAMS have been intermittent during the Holocene.

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.