Lower to Middle Devonian radiolarian assemblages from the Gamilaroi terrane, Glenrock Station, NSW, Australia

Abstract

Five radiolarian assemblages are described from a stratigraphic succession of Lower to Middle (Emsian-Eifelian) Devonian rocks in the Gamilaroi terrane, NSW, Australia. These assemblages are, in stratigraphic order; the Helenifore laticlavium, Circulaforma admissarius n. sp., Helenifore sp. A, Protoholoeciscus hindea and Ceratoikiscum regalinodus n. sp. assemblages. Four new species of ceratoikiscid; Ceratoikiscum calvum n. sp., Ceratoikiscum paragyium n. sp., Ceratoikiscum regalinodus n. sp. and Circulaforma admissarius n. sp. are described. A Lower Emsian limestone near the middle of the stratigraphic section provides age constraints. The four assemblages in strata overlying the limestone are estimated, using inferred sedimentation rates, to be upper Emsian to Eifelian. Biostratigraphically useful ceratoikiscid forms are abundant, indicating that the potential for further refining a Lower to Middle Devonian radiolarian biostratigraphy is high.