OFR 151.pdf - CRC LEME

Dacrycarpus), Euphorbiaceae (Austrobuxus-type), Ericales, non-eucalypt Myrtaceae and
Nothofagus (Fuscospora). Taxa occurring in low to trace numbers in most samples are
Proteaceae, Sapotaceae, Santalum, Sapotaceae, unidentified tricolporates and two extinct
morphotypes (Dicotetradites meridianus, Polyorificites oblatus). Less frequent taxa are:
Araucariaceae (Araucaria), Podocarpaceae (Lagarostrobos), Anacolosa (chiefly
Anacolosidites sectus), Cupanieae, Euphorbiaceae (Micrantheum), Ilex, Loranthaceae
(Gothanipollis, Tricolpites thomasii), Meliaceae (cf. Dysoxylum) Proteaceae (Beauprea,
Musgraveinae, Xylomelum occidentale-type) and Sapindaceae (Dodonaea). Rare records
include Halocarpus (Parvisaccites catastus), Phyllocladus, Alangiaceae, Palmae
(Dicolpopollis), Eucalyptus, Nothofagus (Lophozonia, Nothofagus), Menyanthaceae
(Striacolpites laxus), Polygalaceae, Sterculiaceae (Cissus) and Strasburgeriaceae.
Occurrences of cryptogam spores are equally variable, with Cyathea (Cyathidites paleospora,
C. splendens) being present in many samples and Sphagnum, lycopods, Dicksonia,
Gleicheniaceae Histiopteris and Pteris being present only in a few samples.
Unlike the highlands to the east, trends in relative abundance appear to be somewhat
systematic. For example, between 127 to 116 m depth in Darling Bore DWR Casuarinaceae
decrease from 30% to 8%, Dacrydium decreases from 9% to trace values and Lagarostrobos
disappears from the pollen record. Taxa showing consistent increases over the same interval
are Araucaria (trace to 4%), Nothofagus (Fuscospora) spp. (2% to 7%), Myrtaceae (2% to
5%), Sapotaceae (trace to 2%) and Trimeniaceae (3% to 13%). Whether climatic change is
responsible or whether the succession is due to a switch from one sediment source to another
source in unknown.
Inferred Climate
Conditions within the pollen source area (palaeovalley) were relatively cool (lower
mesotherm) with year-round high humidity probably maintained by river water. The Darling
Bore data hint that climates became warmer (mesotherm range) and seasonally drier during
the period represented by the interval 116-127 m.
3.2.3 Central Australia
Thin carbonaceous units are preserved below the weathering front (>30 m) in many of the
small Cenozoic Basins in the Alice Springs district (Kemp 1976b, Truswell and Marchant
1986, Macphail 1996c, 1997a) and in the much larger Lake Eyre and Torrens Basins to the
south (Harris 1971b, Sluiter 1991, Alley et al. 1996, Martin 1998b).
In a number of instances, reworking of plant microfossils may have resulted in mixed-age
assemblages, e.g. in the Santa Teresa and Ti-tree Basins. An exception occurs in the Hale
Basin where carbonaceous clays and lignites of the Ulgnamba Lignite Member of the Hale
Formation are impervious to water due to hydrocarbons derived from Botryococcus and other
algae. The result is excellent preservation of plant microfossils at depths as shallow as 15 m.
All assemblages are dominated by Casuarinaceae and/or Nothofagus (Brassospora) spp.
Species whose first occurrence is used to distinguish between the Lower and Middle
Nothofagidites asperus Zone in the Gippsland Basin, e.g. Anacolosidites sectus, Proteacidites
reticulatus, and Tricolpites thomasii, may have extended ranges in central Australia,. For this
reason Middle Nothofagidites asperus Zone Equivalent microfloras are assigned a broader
(Middle-Late Eocene) age range.
1. Alice Springs district
Middle Nothofagidites asperus Zone Equivalent microfloras in the Hale and other basins near
Alice Springs are dominated by Nothofagus (Brassospora) spp. but include variable relative
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