Calcareous Nannofossils from the la Barca Formation (Paleocene/Eocene Boundary), Tierra Del Fuego, Argentina

AGUDELO, ERIKA L. BEDOYA; OLIVERO, EDUARDO B.; CONCHEYRO, ANDREA; CARBONELL, PABLO J. TORRES; MARTINIONI, DANIEL R.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Año: 2018 vol. 55 p. 223 - 229

0002-7014

DEEP marine Paleocene to Oligocene turbidites are exposedin several localities along the Atlantic coast of PenínsulaMitre, Tierra del Fuego (Olivero and Malumián, 2008; TorresCarbonell et al., 2009). At Cabo Leticia (Fig. 1), the Paleocenesandstone-conglomerate package of the Cabo Leticia Formationis transitionally covered by the La Barca Formation,which consists of two members: a lower upper Paleocenesandstone-and mudstone-dominated LB1 Member and anupper organic-rich mudstone-dominated LB2 Member. AtPunta Noguera (Fig. 1.1), the La Barca Formation is interpretedto underlie the lowermost Eocene turbidites of thePunta Noguera Formation (Olivero et al., 2002; Malumiánet al., 2009). The late Paleocene age of the lower LB1 Memberof the La Barca Formation was initially established onthe basis of foraminifera and dinocysts (Malumián andCaramés, 2002; Olivero et al., 2002 Malumián and Caramés,2002). New studies at Punta Ainol (Fig. 1.2) have also founda diagnostic late Paleocene assemblage of calcareous benthicforaminifera contained in organic-rich mudstones interpretedas part of the LB2 Member, which suggests a latePaleocene age for the whole formation (Sample PT Sur, TorresCarbonell et al., 2009).Agglutinated foraminifera are dominant in the La BarcaFormation, and only two isolated horizons preserve calcareousbenthic foraminifera (Malumián and Jannou, 2010)whereas planktonic foraminifera and calcareous nannofossilshave not been previously found in the formation(Malumián and Jannou, 2010). As part of ongoing researchdevoted to the study of calcareous nannofossils from Tierradel Fuego, we analyzed samples from the La Barca Formation,both at its type locality in Cabo Leticia and from themudstones exposed at Punta Ainol. None of the samplesprocessed from the type locality of the La Barca Formationwere fertile. Nevertheless, the organic-rich mudstone samplesfrom Punta Ainol are fossiliferous and contain calcareousnannofossils that correlate with other Paleocene?Eocene assemblages from the Southern Hemisphere. Thus,the main goal of our study is to document the nannofossilassemblages and to interpret the