First description of Tithonian corals from the Picún Leufú Depocentre, Neuquén Basin, west-central Argentina

Abstract

A scleractinian coral fauna from the Upper Jurassic (Tithonian) of the Neuquén Basin (west-central Argentina) is described for the first time. It comprises only two species: Eocolumastrea octaviae (Prever, 1909) and Stelidioseris columbaris (Scott and Aleman, 1984). The first was reported previously from the Lower Cretaceous of this region, and the second is a newly reported register for the basin. The new record of Eocolumastrea octaviae reported here extends the stratigraphic range of the genus to the late Tithonian. Both corals are colonial and, when favourable conditions arose, thrived in a mixed carbonate-siliciclastic environment above or slightly below the storm wave base level. The coral fauna of the Picún Leufú Formation presents, regarding its taxonomy and type of growth form, a great similarity to that of the Valanginian-Hauterivian Agrio Formation of the same basin. It differs notably from that of the Oxfordian La Manga Formation, suggesting a change in palaeoenvironmental conditions probably due to a general increase in the sedimentation rate in the studied basin between the Oxfordian and the Hauterivian, among other possibilities.