Early Cretaceous Radiolarians from southernmost Patagonia, Argentina

Resumen

A radiolarian assemblage found in the lowermost strata of the Río Mayer Formation, as exposed at
Estancia La Federica in Santa Cruz Province, Argentina, is described. The biostratigraphic markers of this
assemblage indicate a late Berriasian-early Barremian age (early Early Cretaceous). The radiolarians have
faunal affinities with early Cretaceous assemblages reported from offshore northwestern Australia and the
western Pacific, northeast of New Zealand. A cool-water affinity is suggested for the Patagonian assemblage.
Ten meters below the levels with radiolarians sediments bearing continental palynomorphs are found. They are
referred to the Springhill Formation of Berriasian to Valanginian age.