Lower Cretaceous corals from the Agrio Formation, Neuquén Basin, west-central Argentina: Families Latomeandridae, Madreporidae, Thamnasteriidae, and Holocoenia Group

Abstract

This contribution is the third contribution to the systematic description of the coral fauna recorded in biostromes (patch-reefs and coral meadows) from mixed carbonate-siliciclastic sedimentary facies of the Agrio Formation (upper Valanginian–Hauterivian) of the Neuquén Basin, west-central Argentina. The studied specimens belong to the superfamily Cyclolitoidea (former suborder Microsolenina), family Latomeandridae (Ovalastrea dubia and Stylomaeandra neuquensis sp. nov. and S. cf. pseudominima); superfamily Madreporoidea (former suborder Faviina), Madreporidae indet.; superfamily Rhizangioidea, (former suborder Fungiina), family Thamnasteriidae (Ahrdorffia vaughani), and the informal Holocoenia Group (former suborder Fungiina), (Holocoenia collinaria, H. triboleti and H. cf. triboleti). First record of family Madreporidae is here extended from the Barremian down to the upper Hauterivian, and records of the species are close or match with their first appearances worldwide. 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. The total coral fauna of the Agrio Formation, including the present study, reaches a total of 22 species grouped in nine genera and six families. Correlation of the Agrio Formation coral fauna with other Early Cretaceous coral faunas shows affinity with those faunas recorded in the Paris Basin (north of France) and Puebla Basin (San Juan Raya southwest of Tehuacán, central Mexico). This is in agreement with what has been inferred on other Agrio macroinvertebrates, like bivalves, gastropods, and ammonoids, which show close relationships with those from the European Tethys region. In particular the corals show similarities with those regions having similar sedimentary settings (under clastic influence) than with nearby basins or regions.