New palynological information from the Poti Formation (upper Visean) at the Roncador creek, Parnaíba Basin, northern Brazil. Boletín Geológico y Minero (in press).

DI PASQUO, M.M.; IANNUZZI, R.

BOLETIN GEOLOGICO Y MINERO

Instituto Geológico y Minero España

Lugar: Madrid; Año: 2014 vol. 125 p. 405 - 435

0366-0176

This contribution presents the results of the palynological analysis of six surface samples of the Poti Formation cropping out at the Roncador creek (Jerumenha, Piauí), northeastern Brazil. This unit unconformable overlies the upper Famennian-Tournaisian Longá Formation and it is unconformable overlain by the lower Pennsylvanian Piaui Formation. Carbonaceous shales and siltstones yielded a diverse assemblage of well-preserved palynomorphs, composed of 95 species: 58 indigenous spore, and 5 algal species, and 9 reworked spore and 23 reworked microplankton species mostly from Devonian strata. Three new species are described (Verrucosisporites iannuzzii, V. roncadorense, V. souzai). First records for the Mississippian of Brazil (24 species) and South America (7 species) are also documented. Several age diagnostic species recorded in the Poti Formation (Anapiculatisporites amplus, A. concinnus, Foveosporites pellucidus, Grandispora maculosa, Reticulatisporites magnidictyus, Verrucosisporites morulatus and Waltzispora polita), completed with others not previously documented in subsurface deposits of this unit (Apiculiretusispora microseta, Densosporites spinosus, Knoxisporites ruhlandi, Punctatisporites subvaricosus, Retusotriletes mirabilis and Tricidarisporites phippsae), confirms a late Visean age and its correlation to the R. magnidictyus Melo and Loboziak Zone. Worldwide comparison of the Roncador association indicates greater affinity with coeval palynofloras with similar paleolatitudinal position in South America, North Africa and Australia (Paracas Realm). Sedimentologic (e.g., sandstones with sigmoidal cross and wave ripples beddings) and paleontological features (e.g., plant remains and abundant terrestrial organic matter) along this section document a shallow estuarine depositional environment.