Integrated study of fauna and microflora from the Early Devonian (Pragian–Emsian) of northwestern Argentina

Abstract

The Devonian System in northern Argentina has been broadly analysed, but details of its lithologies, biostratigraphy and fossil content have not been presented in a comprehensive study. We performed the first integrative analysis of the palynological and macrofossil content from the Pescado Formation at the Zenta Range, Argentina. We define a new species of cryptospore and extend the stratigraphic record of the ichnogenus Psammichnites isp. for South America. The stratigraphic ranges of the palynomorphs suggest a time span from the ?late Lochkovian to Pragian -earliest Emsian, but the co-occurrences of key invertebrates narrow the age of the beds to the late Pragian and early Emsian. Moreover, sedimentary analysis indicates a proximal shoreface -foreshore depocenter during this time range for the Zenta region. The contraction phase of the basin during the middle Pragian and Emsian is evidenced by the presence of sand bodies at the top of the column and the higher supply of terrigenous components. During this regression event, a low diversity Malvinokaffric Realm brachiopod assemblage occurs, with dominance of Australospirifer hawkinsi. The predominance of the latter species during this event is coeval with the first decline of the Malvinokaffric Realm in the neighbouring Paraná basin.

All post-Cambrian ichnospecies of Psammichnites Torell, 1870 belong to Olivellites Fenton and Fenton, 1937 b

“…Davies and Shillito (2018) documented the ichnogenus in tidal deposits from the Silurian of Australia. The records in the Devonian of Bolivia by Gaillard and Racheboeuf (2006) are from shoreface deposits, while in the Devonian of Argentina they correspond to shallow marine deposits (Noetinger et al 2016). The Devonian of Antarctica also contains records of the ichnogenus where a new ichnospecies was proposed (Bradshaw 2010).…”

“…Mángano et al 2003;Baucon and Neto de Carvalho 2008;Alonso-Muruaga et al 2013;Baucon et al 2015;Singh et al 2017;Muszer 2020). However, records in the Devonian of South America are also in non-tidal deposits (Gaillard and Racheboeuf 2006;Boyd 2016;Noetinger et al 2016;Sedorko et al 2019).…”

“…Thus, in the future it might be relocated in O. grumula. In the Lower Devonian of Argentina Noetinger et al (2016) described specimens preserved as positive epireliefs and exhibiting a medial ridge, but each side lobe shows convex downward rounded mounds, unusual in the ichnogenus; they were nevertheless assigned to Olivellites isp. The material described by Baucon et al (2015, fig.…”

Middle-Upper Devonian palynofloras from Argentina, systematic and correlation

“…The Pescado and Piedras formations, exposed in the Eastern Cordillera (Fig. 2), have yielded poor Early Devonian assemblages (Noetinger and Di Pasquo, 2010;Noetinger et al, 2016). Close to the Argentinian-Bolivian boundary there were two studied localities where Early to Middle Devonian palynofloras were recovered Di Pasquo and Noetinger, 2008).…”

“…Northwestern Argentina: E, Noetinger and di Pasquo (2010). F, Noetinger et al (2016). G, di Pasquo et al (2015).…”