Criptospore assamblages from the Ordovician/Silurian boundary in the Puna, northwest Argentina.

RUBINSTEIN, C. V.; VACCARI, N. E.

PALAEONTOLOGY

The Paleontological Association

Lugar: Londres; Año: 2004 vol. 47 p. 1037 - 1061

0031-0239

Palynomorph assemblages have been recovered from deposits believed to straddle the Ordovician/Silurian boundary, from the upper member of the Salar del Rincon Formation, in the Puna region of north-west Argentina. The palynomorph assemblages are dominated by terrestrial cryptospores, but also contain marine elements (acritarchs, prasophycean algae and chitinozoans). The cryptospore assemblages are similar in composition to those described from coeval deposits wordwide, suggesting that the producers were cosmopolitan and tolerated a wide range of climatic conditions. They are correlated with the Imperfectotriletes spp. intervale biozone (sub-biozone ) of the Imperfectotriles spp-Laevolanctis divellomedia Assemblage Biozone, indicating a hirnantian (latest Ordovician) age. Acritarchs include late Ordovician species such as Eutpoikilosusa striata and Vilosacapsula cf. setosapellicula, that coexist with the Llandovery species Dactylofusa estillis. based on the lithological and palynological evidence, an early Llandovery, or a late Hirnantian (post-glacial) age is proposed for the basal part of the upper member of the Salar del Rincon Formation.