MICROFOSSILS OF THE YANGTZEPLACOGNATHUS CRASSUS ZONE IN THE MIDDLE DARRIWILIAN OF THE ARGENTINE PRECORDILLERA.

MESTRE A.; BERESI, M; HEREDIA S.; NESTELL G

PUBLICACION ESPECIAL - ASOCIACION PALEONTOLOGICA ARGENTINA

ASOCIACIÓN PALEONTOLÓGICA ARGENTINA

Lugar: Buenos Aires; Año: 2013 p. 79 - 83

0328-347X

Microfossils associated to the Y. crassus Zone are represented by a demosponge spicule, foraminifers and gastropod protoconchs. Foraminifer assemblage consists of the monothalamous agglutinated genera Lakites, Amphitremoida, Lavella, Ordovicina and Pelosina (Nestell et al. 2009). In the Cerro La Chilca section also large assemblage of foraminifers was recovered, these foraminifers will be studied in futures works. However, in the Villicúm´s section were not recovered foraminifers. The absence or presence of these microfossils allows suggesting that this fossil group would be controlled paleoenvironmental conditions, preferring shallow or more oxygenated sector of the ramp. The sponge spicule discovered from the Middle Ordovician limestones of the Del Aluvión creek represents the second mention of the family Hindiidae for the Middle Ordovician carbonates of the Precordillera. The protoconch morphotypes represent death assemblages of microgastropods from two localities of the Central Precordillera.