Agglutinated Foraminifera from the Barremian continental rift section of the Reconcavo Basin, Brazil: a microfossil enigma

Abstract

Microfossils have been found in most of the Mesozoic basins of Brazil, allowing the establishment of important biozones. Despite being recognized for more than half century in the Barremian from the Reconcavo Basin, the taxonomy of the benthic foraminifera remained unsolved likewise its paleoenviromental implications. In this study, we have applied 2D and 3D imaging techniques to resolve this issue and have identified two agglutinated foraminiferal genera (Glomospirella and Paratrochamminoides) and a new species Paratrochamminoides kaminskii sp. nov. Moreover, based on the taxonomy, few paleoenvironmental insights on the foraminifera-bearing strata are discussed. The occurrence of the typically shallow marine species Glomospirella arctica in the studied section, does not allow the proposition of a marine ingression, since it is not supported by a marine/ transitional association of microfossils. On the other hand, the hypothesis of transport of foraminifera by birds (avian zoocoria) is plausible, although there are no further elements to corroborate it.