Abstract

The Vaca Muerta Formation deposited in a retro-arc setting, favored by an under filled depocenter and uplifted peripheral zones. The onset of the deposition corresponds to a rapid flooding of oceanic water penetrated through sudden ruptures along the incipient Andean arc, as a consequence of the Late Jurassic extension during the thermal subsidence stage. The Vaca Muerta Formation forms part of the Lower Mendoza Subgroup, and is defined as the organic-rich calcareous mudstone (av. 5% TOC) deposited above the sharp contact of the continental Tordillo and the Quebrada del Sapo formations; the upper contact with the Quintuco Formation is gradational and diachronous. The Vaca Muerta Formation spans the early Tithonian Virgatosphinctes andesensis to the early Valanginian Lissonia riveroi ammonite Zones. In association with classical stratigraphic characteristics of this unit, this chapter presents a cyclostratigraphic and magnetostratigraphic study displaying an unprecedented accurate time scale for the Vaca Muerta deposition, which took place from Chron M22 to Chron M15 in a timespan of ∼10 My (4.86 My within the Tithonian and 5.27 My within the Berriasian).