OFR 151.pdf - CRC LEME

Contrary to global cooling trends during the Late Campanian-Maastrichtian, the Jacaranda
sequence is ecologically more consistent with the development of seasonally humid-perhumid
(possibly monsoonal) and very warm (upper mesotherm-megatherm) conditions. Conditions
along the coast in the Browse Basin to the south-west were slightly cooler unless the better
representation of gymnosperms is due to the Neves Effect. The data are inadequate to
determine whether very warm to hot conditions on the palaeo-northwestern margin are due to
local factors, e.g. warm water currents, or whether global cooling did not affect low
palaeolatitude regions. The only (very weak) evidence that temperatures decreased during the
Late Maastrichtian is a small increase in Dacrydium at the top of the Bonaparte Basin section.
3. Kimberley region
Possible Maastrichtian microfloras preserved in lignitic sediments in the Goats Paddock
meteor crater provide a record of a local microclimate on the inland (southeastern) margin of
the Kimberley Block (L. Sharman unpubl. data).
Re-examination of the assemblages (M.K. Macphail unpubl. data) confirms that the diversity
is high, with some 34 cryptogam, 8 gymnosperm and 68 angiosperm taxa being present.
Pollen dominance is shared between the Proteaceae and Araucaria; rare taxa include
Dacrydium (Lygistepollenites florinii), Lagarostrobos, Anacolosa, Beauprea, Gunnera, Ilex,
Lactoridaceae, Liliaceae and Sphagnum. Most of these taxa are likely to have grown on or
around the (swampy) site. An exception is Araucaria, which may have formed woodland or
scrub communities on the crater walls. Palms are absent but otherwise the sequence is not
dissimilar to the Prudhoe-1 assemblages.
Inferred climate
The microflora is evidence that microclimates within the crater were humid to perhumid.
This may or may not have been the case regionally since the moisture available to plants
growing on the floor of the crater almost certainly will have been enhanced by the inward
drainage of rainwater. It is not improbable that deep fracturing of the subsurface rocks will
have allowed groundwater to discharge within the crater. The absence of palms is weak
evidence that mean annual temperatures were cooler (lower mesotherm) or the temperature
range was more extreme than on the coast.
6.2.2 North-East Australia
No known record.
6.2.3 Central Australia
1. Alice Springs district
Thin organic-rich strata, which preserve Late Maastrichtian (Upper Forcipites longus Zone
Equivalent) microfloras, have been intersected in boreholes drilled in two informally named
microbasins (Ayers Rock Basin, Huckitta Basin) located on the margins of the Arunta Block
(Twidale and Harris 1977, Harris and Twidale 1991, Truswell 1987a, Macphail 1997a).
Pollen dominance is variably shared between podocarps (Microcachrys, Podocarpus-
Prumnopitys, Podosporites microsaccatus), Proteaceae and cryptogams, including (Huckitta
Basin) high frequencies of Sphagnum and Gleicheniaceae. Uncommon to rare taxa include
fern allies and ferns (Camarozonosporites, Cyatheaceae), possible pteridosperms
(Alisporites), cheirolepidacean conifers, araucarians (Araucaria), podocarps (Lagarostrobos,
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