OFR 151.pdf - CRC LEME

common (up to 5-6%) in the middle sample only. Rare taxa in this sample include
Mimosaceae (Acacia) and Asteraceae (Tubuliflorae). Nothofagus (Brassospora) decreases
from being common (~10%) to uncommon (1-5%) in the uppermost microflora, which also
includes Cupanieae and Eucalyptus.
Inferred climate
The floristic succession implies relatively cool (lower mesotherm) and uniformly wet (humid)
conditions in the Oligocene were succeeded by warmer (mesotherm range) conditions with a
dry season.
4.2.6 South-East Australia
The epicontinental Murray Basin preserves the only geographically extensive and detailed
record of Oligo-Miocene floras and vegetation in Australia (Truswell et al. 1985, Macphail
and Truswell 1989, 1993, Macphail and Kellett 1993, Macphail et al. 1993, Martin 1994,
Macphail 1999). Thick carbonates accumulating in the offshore Gippsland Basin during
Oligo-Miocene time form the seal for hydrocarbons accumulating in the underlying Latrobe
Group. As such they are seldom sampled for palynology. Exceptions are (1) a thin sequence
of earliest Oligocene (Foram Zone J-2) marls in the south-west of the basin and (2)
geotechnical cores obtained during construction of the Flounder-5 and Hapuku-1 production
platforms (Rexilius 1985, Macphail 1997b, A.D. Partridge and M.K. Macphail unpubl.
results).
Palaeobotanical studies of the Morwell-Yallourn brown coal deposits in the onshore
Gippsland Basin are complemented by analyses of the associated microfloras (Luly et al.
1980, Sluiter and Kershaw 1982, Bolger 1991, Holdgate and Sluiter 1991, Kershaw et al.
1991, Blackburn and Sluiter 1994, Holdgate et al. 2000). Other sites occur on the central and
south-west slopes, Southeastern Highlands and South Coast of New South Wales.
1. Northern Tableland of New South Wales
Sediments near Inverell on the New England Tableland are associated with Early Oligocene
and Early Miocene basalts (Wellman and McDougall 1967, McMinn 1987, 1988, 1989f,
Pickett et al. 1990). The associated Oligo-Miocene microfloras (some of which include
Canthiumidites bellus) are wholly dominated by Nothofagus (Brassospora) spp. (37-89%).
Other commonly occurring taxa are Blechnaceae, Cyatheaceae, Podocarpaceae (Podocarpus-
Prumnopitys), Casuarinaceae, Ericales and Myrtaceae. Rare taxa include the fern Lophosoria
(Cyatheacidites annulatus).
Inferred climate
The data indicate cool (microtherm range) and uniformly wet conditions. These conditions
are likely to have been created by cloudy conditions or frequent mists due to uplift of moist
air from the Tasman Sea.
2. Central slopes of New South Wales
McMinn (1981b) has described a probable Canthiumidites bellus Zone equivalent microflora
from the Home Rule Kaolin Pit near Dubbo. Commonly occurring taxa are Nothofagus
(Brassospora) spp. (18-63%), Proteaceae (up to 16%), non-eucalypt Myrtaceae (up to 5%),
Dacrydium (4%), Calochlaena (up to 56%) and Blechnaceae (7-19%). Rare taxa include
Araucariaceae (Araucaria) and Symplocos. Plant impressions are common in carbonaceous
clay units. The source vegetation is likely to have been a gallery rainforest.
255