Customising the geological timescale for use in Australasia

Abstract

The global standard geological timescale (GTS 2004) is largely built around northern hemisphere datasets. Consequently, a large proportion of the biozones used in Australia were not included, thus hampering its implementation in the region. Previously, most of the Australasian biozonal schemes had been tied to the Australian Geological Survey Organisation timescale (AGSO 1996) but each of these needed to be recalibrated to tie with the updated and globally standardised GTS 2004. This process was complicated by the fact that several of the local biozonal schemes have been revised in the intervening period. The updates of Australian biozones to GTS 2004 compliance were accomplished using extensive literature searches as well as targetted reviews of some biozonal schemes. These recalibrated and amended schemes have now been included in Geoscience Australia’s Timescales Database, which acts as a core lookup table for numerous databases across the organisation. In 2010, GTS 2004 will be replaced by an updated standard timescale. To facilitate this transition and other future revisions, Geoscience Australia’s Timescales Database is being revised to store the relationships between biozones and the geological timescale in a format that will allow essentially automatic, rather than protracted manual, updates. A public visualisation software package, Time Scale Creator, is available on the web from the International Commission on Stratigraphy (ICS) to display user-selected intervals from an ICS database suite of over 20,000 biological, geomagnetic, sea-level, and other events with ages consistent with GTS 2004. Geoscience Australia (GA) has compiled a customised datapack for Time Scale Creator which includes most Australian biozonal schemes. In addition, Geoscience Australia is using the lithostratigraphic capabilities of this software package to generate basin biozonation and stratigraphy charts, which supersede those published nearly a decade ago.