Chitinozoans and acritarchs from the Ordovician peri-Gondwana volcanic arc of the Famatina System, northwestern Argentina.

ACHAB, A; RUBINSTEIN, C.V.; ASTINI R.A.,

REVIEW OF PALAEOBOTANY AND PALYNOLOGY

Elsevier

Lugar: Roterdam; Año: 2006 vol. 139 p. 129 - 149

0034-6667

The Early Ordovician Suri and Molles formations of the Famatina Group in northwestern Argentina contain distinct assemblages of acritarchs and chitinozoans. The lower Suri Formation yields peri-Gondwana organic microfossils. The acritarch microflora consists of typical cold-water taxa such as Arbusculidium filamentosum, Striatotheca and Vavrdovella in association with temperate water taxa such as Ampullula and Rhopaliophora. The formation also yields two distinct Gondwanan chitinozoan assemblages, one characterized by Conochitina decipiens and the other by Eremochitina brevis. Both groups of organic-walled microfossils undergo important changes in composition in the succeeding Molles Formation. Baltisphaeridium and RhopaliophoraArbusculidium filamentosum, Striatotheca and Vavrdovella in association with temperate water taxa such as Ampullula and Rhopaliophora. The formation also yields two distinct Gondwanan chitinozoan assemblages, one characterized by Conochitina decipiens and the other by Eremochitina brevis. Both groups of organic-walled microfossils undergo important changes in composition in the succeeding Molles Formation. Baltisphaeridium and RhopaliophoraAmpullula and Rhopaliophora. The formation also yields two distinct Gondwanan chitinozoan assemblages, one characterized by Conochitina decipiens and the other by Eremochitina brevis. Both groups of organic-walled microfossils undergo important changes in composition in the succeeding Molles Formation. Baltisphaeridium and RhopaliophoraConochitina decipiens and the other by Eremochitina brevis. Both groups of organic-walled microfossils undergo important changes in composition in the succeeding Molles Formation. Baltisphaeridium and RhopaliophoraBaltisphaeridium and Rhopaliophora with subordinate species of Peteinosphaeridium are dominant in acritarch assemblage, while small, smooth or weakly ornamented species of Conochitina characterize the chitinozoan populations. These changes are considered to be related to paleogeographic and paleoenvironmental conditions.Peteinosphaeridium are dominant in acritarch assemblage, while small, smooth or weakly ornamented species of Conochitina characterize the chitinozoan populations. These changes are considered to be related to paleogeographic and paleoenvironmental conditions.Conochitina characterize the chitinozoan populations. These changes are considered to be related to paleogeographic and paleoenvironmental conditions.