Toward a chronostratigraphy of the Paleocene-Eocene sedimentary record in northwestern Argentina

DEL PAPA, CECILIA; BABOT, MARÍA JUDITH; DAHLQUIST, JUAN; GARCÍA LÓPEZ, DANIEL ALFREDO; DERACO, MARÍA VIRGINIA; HERRERA, CLAUDIA MARCELA; BERTELLI, SARA; ROUGIER, GUILLERMO WALTER; GIANNINI, NORBERTO PEDRO

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2022 vol. 113

0895-9811

The Santa Barbara Subgroup of the Salta Group in northwestern Argentina represents a key sedimentary recordto understand the geological, biological, and climatological changes that occurred in South America during thePaleogene. However, the lack of absolute ages in these non-marine successions have prevented conclusive interpretationsand correlations at a regional-scale. In this contribution, we present an integrative study based onsedimentological and stratigraphic approaches, a paleontological review, and, for the first time, an absolute agefrom a tuff level in the upper section of the Mealla Formation. We propose the following scenario: 1) Cycles oflow and high accommodation stages that can be tracked at basin-scale providing a criterion to regional correlations;2) An U?Pb zircon age of 58 Ma, which combined with previously estimated ages for Santa B´arbaraSubgroup indicate that this unit is constrained between 61 and 49? Ma; 3) On view of this new age the fossilbearinglevels of the Mealla Formation fill a hiatus of more than 4 Myr in the South American vertebrate recordfor the middle to late Paleocene, reshaping our understanding of the early evolutionary stages of this fauna.Our results represent a robust first step to achieve reliable regional correlations and an integrative comprehensionof the evolution of the Salta Basin and its fossil biota.