El ciclo Ándico de Groeber en la cuenca Neuquina, una revisión y actualización

Abstract

A state of the knowledge of the Andean cycle is presented, mainly based on our recent works, but also on highlights of recent research of many colleagues. This synthesis allowed us to update the geochronology of its different units. New absolute ages through U-Pb analysis in zircons by different methods complement those previously carried out and made possible to accurately limit the age of these units. We have been able to define the boundary between the Tordillo and Vaca Muerta Formations very precisely between 147 and 146 Ma; the age of the Agrio Formation between 132 and 126 Ma, and to present the first absolute ages of the Huitrín Formation. All these data are screened through precise biostratigraphy, sequence stratigraphy and astrochronology. The Troncoso Member of the Huitrín Formation yielded an age of 123 Ma that placed it in the Barremian. This is partially corroborated by the finding of fossils in the La Tosca Member with trigonioids and foraminifera of undoubted marine origin, dated with nannofossils of early Barremian age indicating the permanence of communication with the Pacific during the deposition of the Huitrín Formation.