The evolution of the Chilean-Argentinean Andes

FLORENCIA BECHIS; ANDRES FOLGUERA; ALFONSO ENCINAS

The late Oligocene-early Miocene marine transgression of Patagonia

SPRINGER

Año: 2018; p. 431 - 462

The most important Cenozoic marine transgression in Patagonia occur-9 red during the late Oligocene?early Miocene when marine waters of Pacific and10 Atlantic origin flooded most of southern South America including the present11 Patagonian Andes between *41° and 47° S. The age, correlation, and tectonic12 setting of the different marine formations deposited during this period are debated.13 However, recent studies based principally on U?Pb geochronology and Sr isotope14 stratigraphy, indicate that all of these units had accumulated during the late15 Oligocene?early Miocene. The marine transgression flooded a vast part of southern16 South America and, according to paleontological data, probably allowed for the first17 time in the history of this area a transient connection between the Pacific and18 Atlantic oceans. Marine deposition started in the late Oligocene?earliest Miocene19 (*26?23 Ma) and was probably caused by a regional event of extension related to20 major plate reorganization in the Southeast Pacific. Progressive extension and