Climate, dust, and fire across the Eocene-Oligocene transition, Patagonia.

SELKING P.; STRÖMBERG C.; DUNN R.; KHON, M; CARLINI A.; DAVIES-VOLLUM S.; MADDEN R.H.

GEOLOGY

GEOLOGICAL SOC AMER, INC

Lugar: Boulder; Año: 2015 vol. 2015 p. 1 - 4

0091-7613

The Eocene-Oligocene transition (EOT) is typically interpreted as a time of drastic globalcooling and drying associated with massive growth of a glacial icecap in Antarctica and theshift to an ?icehouse? climate. The effects of this transition on the terrestrial environments,floras, and faunas of the Southern Hemisphere, however, have been unclear. Here we documentsimultaneous changes in fire regime and plant community in Patagonia, Argentina. Decreasesin the concentration of magnetite in loessites from the Eocene-Oligocene Vera Member of theSarmiento Formation correlate with decreases in the fraction of burnt palm phytoliths aswell as more consistently palm-dominated phytolith assemblages. Association of magnetiteand burnt palm phytoliths suggests intense wildfires, which appear to have been suppressedfor ~200 k.y. shortly after the EOT. The disappearance of fire-related characteristics near theEOT is possible if changes in regional wind patterns?consistent with observed changes insediment particle sizes?caused changes in seasonal precipitation. These results imply a moreimportant role for fire in structuring Eocene-Oligocene landscapes than previously thought.