OFR 151.pdf - CRC LEME

Dacrydium and its extinct relation Lygistepollenites balmei) and Ephedra. Uncommon to rare
angiosperms include: Anacolosa (Anacolosidites cf. A. acutullus), Beauprea (Beaupreaidites
elegansiformis, B. verrucosus), Callitrichaceae, Chloranthaceae (Clavatipollenites hughesii),
Ericaceae-Epacridaceae, Gambierina, Integricorpus, Liliaceae, Trimeniaceae
(Periporopollenites demarcatus), tricolporates including Neoscortechinia-type (Tricolporites
lilliei, Tricolporites cf. T. lilliei), and Winteraceae (Pseudowinterapollis). Four probable
palm genera are present (Arecipites, Longapertites, Nupharipollis, Spinizonocolpites).
Inferred climate
These assemblages are difficult to interpret ecologically since palms, which imply very warm
to hot, upper mesotherm temperatures, were growing in the Ayers Rock Basin, at
approximately the same time as Sphagnum bog, which imply microtherm range conditions
surrounded the Huckitta Basin. The most likely explanation is that microclimates in the two
basins were different. For example the Ayers Rock microflora includes a dinoflagellate that
is usually found in marine sediments (Ceratopsis obliquipes) and discharge of warm saline
groundwater may explain the presence of a possible mangrove palm (Spinizonocolpites), even
if mean air temperatures were cool (lower mesotherm). The presence of podocarp-dominated
Austral Conifer Forest is evidence regional climates were seasonally humid-perhumid in both
basins.
6.2.4 South-West Australia
1. Carnarvon Basin
Microfloras preserved in marine sediments in Alpha North-1 provide a record of the Late
Campanian to Maastrichtian plant communities growing on the margins of the Carnarvon
Basin (M.K. Macphail unpubl. results). Fossil spores and pollen are uncommon relative to
dinoflagellates but the sequence has the advantage that the individual microfloras have been
precisely dated using nannofossils (Rexilius 1989).
Samples yielding statistically significant (>150) numbers of miospores range in age from the
latest Late Campanian to basal Middle Maastrichtian. Dominant taxa are Proteaceae and
cryptogams. The angiosperm component lacks many of the distinctively ornamented
Proteacidites spp. found in the northern and southern margin basins and, apart from
Proteaceae, only unidentified tricolpate and tricolporate types occur in above-trace numbers.
Rare taxa include Beauprea, Chloranthaceae (Clavatipollenites hughesii, C. sp. cf. C.
glarius), Gambierina, Ilex and Liliaceae. Uncommon to rare cryptograms include Lophosoria,
Anemia and Lycopodiaceae. Palms and temperate rainforest taxa such as Nothofagus are
absent. The only frequent to common gymnosperms are podocarps (Podocarpus-
Prumnopitys, Podosporites microsaccatus) and possible pteridosperms (Alisporites).
Uncommon to rare gymnosperms include cheirolepidiacean conifers, Ephedra, podocarps
(Dacrydium including Lygistepollenites balmei, Lagarostrobos, Microcachrys) and
araucarians (chiefly Agathis/Wollemia). Common cryptogams include Cyatheaceae,
Gleicheniaceae (Clavifera, Gleicheniidites) and Sphagnum.
The palaeovegetation appear to have been a floristically impoverished variant of the fern
heath and Austral Conifer Forest communities recorded further to the north in the Browse and
Bonaparte Basins.
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