Mio-Pliocene aridity in the south-central Andes associated with Southern Hemisphere cold periods.

摘要: Although Earth's climate history is best known through marine records, the corresponding continental climatic conditions drive evolution of terrestrial life. Continental during latest Miocene are particular interest because global faunal turnover roughly synchronous with a period glaciation from ∼6.2-5.5 Ma and Messinian Salinity Crisis ∼6.0-5.3 Ma. Despite ecological significance this period, associated it remain unclear. We address question using erosion rates ancient watersheds to constrain Mio-Pliocene in south-central Andes near 30° S. Our results show two slowdowns rate, one ∼6.1-5.2 another 3.6 3.3 Ma, which we attribute periods aridity. This view supported by synchrony other regional proxies for aridity timing glacial ‟cold" as recorded proxies, such M2 isotope excursion. thus conclude that cold at high southern latitudes, perhaps due northward migration Southern Hemisphere westerlies, disrupted South American Low Level Jet delivers moisture southeastern America. Colder periods, possibly reductions atmospheric CO2, seem be an important driver transitions central Andes. Finally, study demonstrates paleo-erosion can powerful proxy climates lie beyond reach most lacustrine archives.