OFR 151.pdf - CRC LEME

Polypodiaceae, Palmae (Dicolpopollis), Casuarinaceae, Cupanieae, Ericales, Ilex,
Loranthaceae, Myrtaceae (including Eucalyptus), Proteaceae (Banksia/Dryandra, Beauprea,
Embothrium, Xylomelum occidentale-type), Quintinia, Trimeniaceae and Winteraceae.
b. Late Early to early Late Miocene
Canthiumidites bellus Zone Equivalent microfloras are more widespread on the Southeastern
Highlands. Sites for which detailed microfloral information is available are Elands (M.K.
Macphail unpubl. results), Kiandra at about 1400 m elevation (Owen 1988), and Palaeolake
Bunyan, at about 780 m elevation near Cooma (Tulip et al. 1982). Dating of the last site is
insecure due to lack of age-diagnostic taxa.
The Elands microflora is dominated by Casuarinaceae (29%), Araucaria (14%), Dacrycarpus
(13%), with lesser amounts of Nothofagus (Lophozonia) spp. (5%) spp., Podocarpus-
Prumnopitys (4%), Blechnaceae (8%) and Cyathea (7%). Nothofagus (Brassospora) spp. are
uncommon (2%). The diversity is moderately high, with some 17 cryptogam, 6 gymnosperm
and 40 angiosperm species being recorded. Modern affinities range from cool temperate, e.g.
Dicksonia, Lophosoria and Winteraceae, to warm temperate-subtropical, e.g. Pteris, Palmae
(Dicolpopollis), Caesalpinaceae, Cupanieae, Euphorbiaceae (Mallotus-type), Malpighiaceae,
Mimosaceae (Acaciapollenites miocenicus) and Rubiaceae (Guettarda, Randia).
Microfloras preserved some 4 degrees to the south, at Palaeolake Bunyan and Kiandra, are
dominated by Nothofagus (Brassospora) spp. (maximum values 65% and 80%, respectively).
Sporadically common to abundant taxa are (maximum values in parentheses): Sparganiaceae
(29%), Nothofagus (Fuscospora) spp. (17%), Nothofagus (Lophozonia) spp. (15%), Ericales
(23%), Podocarpus-Prumnopitys (16%), an extinct form of Microcachrys (Podosporites
microsaccatus) (55%), Blechnaceae (31%) and an unidentified inaperturate type (42%).
Araucariaceae (Araucaria, Wollemi-type), Phyllocladus and Casuarinaceae are relatively
uncommon (1-9%). Sporadically common taxa are Kiandra are Gleicheniaceae (47%), trilete
types (16%), Dicksonia (7%) and non-eucalypt Myrtaceae (9%). Whilst the cryptogam and
gymnosperm components are moderately diverse, ‘thermophilous’ taxa only occur in trace
numbers and then only in one to few occasional sample, e.g. Ilex and (Kiandra) Cupanieae,
Mallotus-type, Randia and Sapotaceae.
The data imply rainforest communities at high elevations remained dominated by Nothofagus
(Brassospora) spp. throughout the Oligo-Miocene but it is uncertain whether these were
forest or wet scrub.
Inferred climate
Climates at lower elevations in the north of the area (Elands) are likely to have been weakly
seasonal whilst mean air temperatures were adequate (upper mesotherm range) to support a
form of araucarian (dry) rainforest which included palms. Climates at higher elevations in the
south of the area were relatively cool (lower mesotherm range) and uniformly wet to very wet
(perhumid). Despite its lower elevation, the Palaeolake Bunyan microfloras are distinctly less
temperate than those recovered at Kiandra. Possible reasons are that vegetation around the
former (a very large deep lake) was shaped by cold air drainage or that the microfloras postdate
the mid Miocene thermal maximum.
5. South-west slopes of New South Wales
Microfossil evidence from the Southeastern Highlands is complemented by analyses of
correlative sediments in broad river valleys draining the south-west slopes, e.g. the Lachlan
Valley (Martin 1973, 1987, 1991b). Nothofagus (Brassospora) spp., which are abundant
during P. tuberculatus Zone Equivalent time, are replaced by Myrtaceae as the dominant
257