Mesozoic Radiolaria

Radiolaria are the most abundant fossils in Mesozoic eugeoclinal terranes along the Circum-Pacific margin. They are often present and well-preserved where most other fossils are absent.

During the last fifteen years radiolarian biostratigraphy has had a great impact on unraveling the stratigraphy and in turn the structure of many eugeoclinal terranes in Western North America and elsewhere in the world. In addition, it is now apparent from recent investigations in North America that Radiolaria can be utilized in paleobiogeographic reconstructions and to document the presence of Mesozoic displaced terranes.

Little or is known about Jurassic Radiolaria from the Southern Hemisphere. The recent discovery of well-preserved Radiolaria in the Lower, Middle and Late Jurassic strata of the Neuquén Basin of west-central Argentina shows promise of establishing a detailed system of radiolarian biozonation for the Southern Hemisphere which can be related directly to ammonite-based chronostratigraphy. Moreover, data resulting from the proposed study should help resolve serious problems relating to the time assignment of radiolarian biozones between North America and Europe. These same problems of chronostratigraphic assignment have great impact on plate tectonic models, dating of magnetic anomalies in the ocean basins, calculation of sea floor spreading rates, and determination of age of the ocean basins.

Pantanellium neuquensis

Spumellaria Pantanellidae recovered from the Tithonian of Vaca Muerta Formation, Neuquén Basin. Central-West, Argentina.

Radiolaria from the Southern Hemisphere