CONICET | Buscador de Institutos y Recursos Humanos

The palynological analysis of the 2548-3628 m interval of the San Antonio x-1 Borehole, northern Argentina, is presented. The illustrated palynoflora is composed of 96 species represented by diverse palynological groups such as trilete spores and cryptospores (46 species), microplankton (39 species), chitinozoans (7 species), scolecodonts and some remaining specimens in open nomenclature and as incertae sedis. One new species, Retusotriletes ottonei, is described. Thirty-four species are first records in the Argentinean Devonian. Three assemblages (SA1, SA2, and SA3) are defined on the presence, absence as well as abundances of group of taxa. The presence of Grandispora protea and Grandispora douglastownense among others in the assemblage SA1 is indicative of a late Emsian to mid-Eifelian age. The concurrence of Acinosporites macrospinosus and A. acanthomammillatus in the assemblage SA2 is indicative of a late Eifelian-mid Givetian also supported by the appearance of several other species such as Chomotriletes vedugensis, Dibolisporites farraginis and Biharisporites parviornatus. An early Frasnian age is akin to the assemblage SA3 on the basis of the appearances of Lunulidia micropunctata, Pseudolunulidia laevigata, Verrucosisporites bulliferus and the abundance of Maranhites. The assemblages SA1 and SA2 reflect a nearshore, shallow marine depositional conditions, characterized by a high terrestrial input and variable marine influence, while the assemblage SA3 could represent a transgression during that time. The assemblages are composed of many cosmpolitan index species that support a partial correlation with Brazilian and Euramerican zonations resulted from the effects of palaeolatitude and the configuration of land and sea for that time, with a narrow Rheic Ocean between northern Gondwana and Euramerica.

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