Cambro-Ordovician sponges and spicule assemblages from Northwest Argentina: additional data from the siliciclastic platforms of western Gondwana.

MATILDE BERESI SERGIO NIEVA,; GUILLERMO ACEÑOLAZA; SERGIO NIEVA

NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN

E. Schweizerbart'sche

Lugar: Sttutgart; Año: 2005 p. 403 - 420

0077-7749

     Abstract.- This study provides the first report of Cambrian/Ordovician sponges in the Sierras Subandinas,  and a new locality with spicule assemblages in the Cordillera Oriental of Northern Argentina and the Eopaleozoic Central Andean Basin of South America. The part and counterpart of a complete rounded thin-walled sponge assigned to Diagoniella sp. was recovered along abundant fragmentary material in the shales of the Orcomato Formation cropping out at the Sierra de la Candelaria of southern Salta Province. Associated faunas suggest a Furongian? – Early Ordovician age for the unit. In addition,  spicule assemblages preserved on sandstone slabs were found in the lower levels of the Saladillo Formation at the Angosto de la Quesera in the Cordillera Oriental of Salta Province. Spicules share stratigraphic position with the graptolite Bryograptus kjerulfi, resticting its age to the early Upper Tremadocian. The recognition of the first protospongiid in the Sierras Subandinas and the record of additional spicule assemblages in the Cordillera Oriental of Northern Argentina provide valuable information on the spreading of the protosponges in the Lower Paleozoic seas of western Gondwana.