Early Carboniferous brachiopod zones of eastern Australia

Abstract

The Early Carboniferous brachiopod zones of eastern Australia are defined from reference sections in New South Wales. The zones include the Tulcumbella tenuistriata, Spirifer sol, Schellwienella cf. burlingtonensis, Orthotetes australis, Delepinea aspinosa, and Rhipidomella fortimuscula Zones. Two contain subzones: the Pustula gracilis Subzone is recognized in the upper part of the Schellwienella cf. burlingtonensis Zone in the Rouchel district, New South Wales; and the Inflatia elegans and Gigantoproductus tenuirugosus Subzones are recognized in the lower and upper portions respectively of the Delepinea aspinosa Zone. Reinterpretation of the zones from new information on the ranges of brachiopod species and on detailed stratigraphy has resulted in changes in the identification of certain zones, particularly the Spirifer sol Zone, and alterations to stratigraphic correlations within both New South Wales and Queensland. Three zones, the Tulcumbella tenuistriata, Schellwienella cf. burlingtonensis, and Rhipidomella fortimuscula Zones, are widespread throughout eastern Australia. The Spirifer sol Zone is identified only in New South Wales, faunas from Queensland previously assigned to the zone being referred to local zones. The Orthotetes australis Zone is absent in Queensland, and the Delepinea aspinosa Zone is represented by two occurrences tentatively identified as the tenuirugosus Subzone. Modifications have been made to the correlation of particularly the Namoi Formation and the Hill 60 Member of the Merlewood Formation in New South Wales, and of the Three Moon Conglomerate and lower part of the Cania Formation in Queensland. The lower three brachiopod zones have ages consistent with those indicated by conodonts, but there is conflict between the ages of the upper three zones and the ages suggested by conodonts.