Cretaceous foraminiferal biostratigraphy of Queensland

The distribution of foraminiferids within Aptian-Albian marine deposits of the Laura, Carpentaria, Eromanga, and Surat Basins in Queensland is described. The foraminiferal distribution patterns are largely a reflection of environmental differences which existed within the basins. Among the benthonic foraminiferids, two major faunal associations are recognized: the Ammobaculites association reflecting hyposaline, cool, shallow water conditions; and the Marssonella association indicating normal marine, open continental shelf environments. As the faunal content of these associations is markedly different, separate time-stratigraphic zonations are proposed: the Ammobaculites association is divided into the Textularia cushmani zone (early Aptian), T. cushmani-Bigenerina pitmani zone (late Aptian), B. pitmani zone (late Aptian), B. pitmani-Riyadhella crespinae zone (early Albian), and R. crespinae zone (early-late Albian); the Marssonella association contains the Anomalinoides intermedia zone (early-middle Albian in Queensland), and the A. cenomanica zone (late Albian in Queensland). Planktonic foraminiferids, which occur with both benthonic associations, are used to correlate the benthonic zonal schemes, and are themselves zoned separately: Hedbergella planispira zone (early-middle Albian), H. infracretacea zone (middle-early late Albian), and the H. delrioensis zone (late Albian). International stage correlations are based on certain foraminiferids and associated ammonites.

The distribution of foraminiferids in Queensland during the late Early Cretaceous suggests that 1, climate exerted a uniform influence over the region; 2, cool, hyposaline, shallow water conditions prevailed over much of Queensland; 3, open marine shelf conditions (of normal salinity) existed during the Albian in the Laura and northeastern Carpentaria Basins; and 4, during the Albian, at least, there was a northern seaway to the open ocean.