Chronostratigraphic significance of microfloral assemblages from the Lower Cretaceous of Brazil

Abstract

The nonmarine Lower Cretaceous represents a challenge in various parts of the world owing to the absence of good índex fossils for use in international correlations. Due to the impossibility of identifying stages of the standard chronostratigraphic column in Brazil, the option was to use local stages: the Dom João, Rio da Serra, Aratu, Buracica, Jiquiá, and Alagoas. AIl of these are Cretaceous except for the Dom João, which is at least partially attributable to the Jurassic. Correlating these local stages with those of the standard column requires painstaking care, and the majority of correlative schemes so far proposed are not convincing. This study takes a brief retrospective look at the origin and evolution of concepts related to local stages of the Brazilian Mesozoic and also offers an attempted correlation

based on nationally available palynological data supplemented by information on other continents, published mainly during recent decades. ln addition to presenting this correlation, some problematic questions which need to be solved in future investigations are raised.