Age and palaeoenvironment of Pliocene sediments, Cameron Inlet Formation,udeastern Flinders Island, Tasmania: implications for southeastern Australian biostratigraphy

摘要

A previously unrecorded thin unit of very Early Pliocene calcareous sediments of the Cameron Inlet Formation from two auger holes inudcentral Flinders Island, Tasmania, has yielded a very diverse fauna of benthic Foraminifera and enough planktonic forms to allow fine correlationudwith international biostratigraphic standards (N19, approximately 5.3–4.4 Ma, or Lower Opoitian in New Zealand terminology).udOstracods are also recorded. It is older than an earlier recorded sample from North Patriarch Drain a few kilometres away. It lies within theudKalimnan of southeastern Australian stage nomenclature and probably equivalent to 1985 Molluscan Assemblage XVI. The sediments andudfaunas accumulated in very shallow, fully marine conditions, initially with some possible estuarine aspect that faded with time. The fauna isudof well-known species, dominated by Parredicta kalimnensis (Parr, 1939). Other abundant and diverse forms are elphidiids and cibicidids.udAgglutinated forms are almost absent and miliolids are diverse but minor components. The fauna includes a new polymorphinid genusudand species that will be described elsewhere. The samples contain a bewildering array of unilocular forms. Water temperature appears toudhave been about 12°C. The Kalimnan Stage may encompass the entire Pliocene and two substages may be identifiable.