OFR 151.pdf - CRC LEME

northern New South Wales. The assemblage is dominated by monolete and trilete ferns and
fern allies, associated with infrequent Casuarinaceae, Euphorbiaceae, Nothofagus and (one
specimen) Tiliaceae.
Inferred climate
The source vegetation appears to have been fern-dominated wet scrub growing under
uniformly wet (perhumid) and probably cool (lower mesotherm) conditions. Whether the
cryptogam dominance reflects a recent wildfire (fire succession) or highly fertile soils
(edaphic disclimax) is unknown.
2.2.3 Central Australia
Tertiary basins in the Alice Springs district and Lake Eyre Basin (Eyre Formation) preserve
thin carbonaceous units of probable Early Eocene age (age range latest Paleocene-late Early
Eocene).
Many of these preserve very diverse microfloras, some of which also include dinoflagellate
species that are usually associated with saline conditions (Sluiter 1991, Macphail 1996c,
1997a, Alley 1998). The reason for this is unclear but salinity levels may have been raised
due to discharge of saline groundwater, leaching of salt from outcrops of Early Cretaceous or
older marine sediments, e.g. the Bitter Springs Formation, or deposition within
hydrologically-closed basins. Microfloras from the Eyre Formation are similar to those
recorded in the Late Paleocene and, apart from the absence of mangroves, are also similar to
Early Eocene assemblages found in coastal northwestern Australia.
1. Alice Springs district
Early Eocene microfloras from the Santa Teresa and Ti-tree Basins, Alice Springs district are
dominated by Casuarinaceae, Proteaceae including large (mostly described) and many small
(undescribed) types, and tricolporate types. These are associated with occasional high values
of monolete spores, Acrostichum-type (Cyathidites splendens), Gleicheniaceae and other
trilete fern spores, and Euphorbiaceae (Malvacipollis). Araucariaceae, Dacrydium,
Lagarostrobos (Phyllocladidites reticulosaccatus), Cupanieae and a member of the otherwise
wholly Northern Hemisphere Triprojectites group (Integricorpus) are frequent in some
samples. Rare taxa include Pteris, Lygodium, Lagarostrobos, Palmae (Arecipites,
Longapertites, Nupharipollis), Anacardiaceae (Striacolporites cf. cephalus), Anacolosa
(Anacolosidites acutullus), Beauprea, Callitrichaceae, Gunnera, Ilex, Sapotaceae
(Sapotaceoidaepollenites latizonatus) and Tiliaceae. Nothofagus is very rare and the records
may be due to downhole contamination.
2. Lake Eyre Basin
Microfloras dated as Paleocene in Lake Eyre Bore 8A drillhole (Alley 1983a) are more likely
to be Early Eocene, based on Myrtaceidites tenuis and Proteacidites pachypolus, which first
occur in the Gippsland Basin in the Lower Malvacipollis diversus Zone. The assemblages are
dominated by small angiosperm pollen types (possibly Cunoniaceae, Elaeocarpaceae)
associated with Gleicheniaceae, Cupressaceae, Podocarpaceae (Dacrydium, Lagarostrobos,
Microcachrys, Podocarpus-Prumnopitys), Ascarina, Casuarinaceae, Euphorbiaceae,
Myrtaceae, Nothofagus (Nothofagidites flemingii), and diverse Proteaceae.
Pollen data from the Muloorina-2 and Poonarunna-1 wells (Sluiter 1991) hint that Myrtaceae,
Proteaceae, a wholly extinct lineage of Lagarostrobos (Phyllocladidites reticulosaccatus) and
Podocarpus-Prumnopitys expanded at the expense of Cunoniaceae, Cupressaceae-
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