SOBRE LAS GRAPTOFAUNAS DEL SILURICO DE SAN JUAN, ARGENTINA

Alfredo J. Cuerda

Abstract


The results of a bio-stratígraphical research on Silurian deposits of Los Espejos Formation in the San Juan Precordillera are here given. Two graptolith-bearing 1evels ere recognized at 148-180 and 298-305 meters above the lower limit of the formation. The first one is characterized by Monograptus uncinatus notouncinatus n. sp., and the second one by Monograptus argentinus n. sp. Respective descriptions and affinities with forms of the Northern Hemisphere are consigned. The age of the middle and upper section of the Los Espejos Formation is asigned to the lower Ludlowian, while de lower section is tentatively ascribed to the Wenlockian.

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