Early Devonian miospores and organic geochemistry from the Alto Garças Sub-basin (Paraná Basin), Brazil: Biostratigraphic, paleogeographical and paleoenvironmental implications

Abstract

The present study concerns the palynology (mainly miospores), and geochemistry of the Jaciara section, situated 5 km from the town of Jaciara, Mato Grosso, in the Paraná Basin of Brazil. The age of this outcrop is considered to be Early Devonian. A study of the whole assemblage has highlighted a diversified association of miospores. Their distribution throughout the samples is somewhat erratic, which sometimes complicates the determination of the biostratigraphic attribution. However the following markers have been identified: Apiculiretusispora brandtii, Brochotriletes bellatulus, Cymbohilates baqaensis, Cymbosporites asymmetricus, Cymbosporites wellmanii, Devonomonoletes sp. 1 in Breuer and Steemans (2013), Dibolispotites sp. 2 in Breuer and Steemans (2013), Dictyotriletes subgranifer, Distaverrucosisporites steemansii, Latosporites ovalis, Scylaspora costulosa, Verrucosisporites nafudensis, Verrucosisporites onustus, Verruciosisporites stictus, Zonotriletes brevivelatus, and Zonotriletes simplicissimus. The finding of these miospores allowed recognition of the following biozones established in Saudi Arabia: the papillensis-baqaenisis Biozone, Pragian in age; the ovalis-biornatus Biozone (ovalis, milleri, asymmetricus subzones), late Pragian to early Emsian in age; and possibly the lindlarensis-sextantii Biozone, middle Emsian in age. The presence of many taxa in common with other Gondwanan basins, particularly those from Saudi Arabia, North Africa and South America, corroborates the paleogeographical relationship between different regions of Gondwana, even between those located in very different paleolatitudes. New geochemical analyses were also performed and add more information toward the understanding of the local paleoenvironmental evolution.