OFR 151.pdf - CRC LEME

Professor B. Balme (Geology Department: University of Western Australia). Industry
colleagues, in particular Drs. R. Helby (Sydney) and A.D. Partridge (Melbourne) provided
important information on the few open file samples from the North West Shelf, which
preserve diverse Late Cretaceous and Tertiary terrestrial spores and pollen in dinoflagellatedominated
microfloras.
Conversely only old reports, general comments and informal ‘notes’ seem to have been have
been archived regarding microfloras recovered from Tertiary sub-basins in northern Tasmania
(cf. Evans 1970a, 1970b, Forsyth 1979a, 1979b). Samples from the important Paleocene-
Eocene Kings Park Shale (onshore Perth Basin), which had been sought for a previous review
(Macphail et al. 1994), arrived too late to be analysed for this review. Shedding of
experienced palaeontological staff within the State and Commonwealth geological
organisations has resulted in the loss of many unrecorded observations as well as
irreplaceable samples. An example is the only non-marine Late Cretaceous sediment found
so far in New South Wales. Similarly, much potentially fossiliferous drillcore and cuttings
samples have been discarded to minimise storage costs and some important core holdings
have survived only because they were stored in remote locations, e.g. the Lemonthyme Tillite
sequence in Tasmania (Macphail et al. 1993).
Few organisations now support in-house drilling rigs and it is unlikely that any of the sites
will be re-drilled in the foreseeable future. For this reason, the review concludes by
suggesting techniques that will improve the 'extraction' of palaeoclimatic information from
the existing palaeobotanical database.
c. Methodology
The procedure used in this review is similar to the chronostratigraphic column (time series)
method used by Langford et al. (1995) to reconstruct the Cenozoic palaeogeography of
Australia. The six key steps are:
1. Subdivision of the Australian continent into broad bioclimatic regions.
2. Subdivision of the Cretaceous and Tertiary Periods into time slices that are
commensurate with the existing age control.
3. Identification of sections and drill-holes that have yielded Cretaceous and/or
Cenozoic fossil sequences, using published and unpublished reports.
4. Revision of all accessible palaeobotanical and other relevant proxy-climatic evidence
for each geographic region and time slice, including where possible, the analysis of
additional material to fill known gaps in the chronostratigraphic or geographic record.
5. Use of a modified version of the NLR method to reconstruct past vegetation and climate
patterns (references in Hill 1994a, Macphail et al. 1994).
A related proposal, to plot the palaeoclimatic interpretations onto the palaeogeographic baseline
maps of Langford et al. (1995), could not be undertaken in the time available.
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