El Ciclo Ándico de Groeber en la cuenca Neuquina, una revisión y actualización.
Résumé
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.