Lower and Middle Devonian radiolarian biozonation of the Gamilaroi TerraneNew England Orogen, eastern Australia

Seven distinctive radiolarian assemblages defined from the Gamilaroi terran e of eastern Australia form the basis of an uppermost Lower to Middle Devon ian radiolarian biostratigraphy. In ascending order these are the: Stigmosp haerostylus horrida, Helenifore laticlavium, Circulaforma admissarius, Hele nifore pilosidiscus n. sp., Protoholoeciscus hindea, Ceratoikiscum regalino dus, and Trilonche minax assemblages. Gamilaroi terrane sedimentation occur red during the interval Early (Pragian) to Late (Frasnian) Devonian in a vo lcanic island are environment in which radiolarians were abundant but sedim entary facies were locally variable. Radiolarian assemblages can be used fo r terrane-wide correlation. Although assemblages are dominated by spumellar ians they also include more distinctive ceratoikiscid forms. Two new cerato ikiscid taxa: Circulaforma davidi n. sp. and Helenifore pilosidiscus n. sp are described.