Lower Cretaceous corals from the Agrio Formation, Neuquén Basin, west-central Argentina: Family Actinastraeidae

Abstract

This contribution presents the first results of an ongoing systematic revision of the coral fauna of the Agrio Formation (upper Valanginianeupper Hauterivian) of the Neuquen Basin, west-central Argentina. Actinastraeid corals (superfamily Actinastraeoidea, that corresponds to the former suborder Archeocaeniina) are represented by eight species in three genera, namely Actinastraeopsis (two species), Stelidioseris (five species) and Stephanastrea (one species). Actinastraeopsis and Stelidioseris species records are close to or match with their first occurrences or are new first records. The last record of the genus Stephanastrea is now extended up from the Tithonian to the upper Hauterivian. The studied corals are interpreted as colonies capable of thriving in mixed carbonate-siliciclastic environments and settling on soft substrates and able to resist moderate turbidity, sedimentation, and storm influence. Correlation with other actinastraeid Lower Cretaceous coral faunas shows affinities with those that are also record from mixed carbonate-siliciclastic environments such as the Paris Basin, East Iberia, Bisbee Basin and Texas Platform.