Australian geology

Western Australia has one of the most diverse floras in the world. From the giant Karri and Tingle forests in the south, to the scattered tropical rainforests in the north; from the incredibly species-rich sand heath flora in the south-west, to the desert floras of the inland parts of the State, more than 12,000 species of vascular plants are estimated to exist. The changing pattern of the fossil floras in Western Australia is a legacy of both their evolutionary history and of the changing environments in which they grew. In this booklet we provide an illustrated overview of Western Australia’s fossil plant record, based on fossil collections of the Western Australian Museum, the Department of Geology and Geophysics in the University of Western Australia, and the Geological Survey of Western Australia. Although many fossil plants that have been collected over the last 30 years still remain to be described, sufficient is known to provide a broad overview of the ancestors of the state’s highly diverse modern flora.

Strata of Jurassic age occur extensively across onshore Australia, but they are predominantly of non-marine origin. Marine Jurassic strata have only limited onshore exposure in northwestern and central-western Australia, with thick marine sequences lying offshore on the North West Shelf. The richest petroleum province in Australia is located at the shelf's southern end, where the Dingo Claystone represents an important source rock for oil and gas. By and large, non-marine deposits, including economic coals, are distributed in the eastern states. Jurassic stage boundaries, in the main, are poorly constrained with respect to the Australian sedimentary succession. New work on microfossils, plants, fish, and zircon dating is providing a basis for improved correlation across Australian basins, with overseas successions, and recent international IUGS geologic timescales.

The northern Perth Basin lies between about 27 and 31 30'S adjacent to the Yilgarn Craton on the western margin of Western Australia. The basin contains up to 12 km of Ordovician and mid-Carboniferous to Cretaceous, primarily nonmarine to shallow-marine strata below extensive thin, mostly non-marine, Cenozoic cover. This guide describes 37 localities in the basin, from Kalbarri to Gingin, including access and land tenure, and emphasizes stratigraphy, sedimentology, and palaeontology. These localities constitute ...

Fossil assemblages are described from the Tyers River Subgroup (late Berriasian to Hauterivian), Gippsland Basin, Victoria. The assemblages include plant macrofossils referable to 33 form-species including five new species (Isoetites abundans Tosolini & McLoughlin, Coniopteris victoriensis Nagalingum & McLoughlin, Otozamites douglasii Drinnan, Brachyphyllum tyersensis Tosolini & Nagalingum, Otwayia hermata Tosolini & McLoughlin) and three new combinations [Medwellia lacerata (Douglas) Nagalingum & McLoughlin, Rintoulia variabilis (Douglas) McLoughlin & Nagalingum, Pachydermophyllum austropapillosum (Douglas 1969) McLoughlin & Nagalingum]. Macrofossil assemblages include representatives of the Hepaticales, Isoetales, Equisetales, Filicopsida, seed-ferns, Coniferales and unionid bivalves. Co-preserved mesofossil suites include dispersed cuticle fragments, seed coats, seed megaspore membranes, microspore clusters, fern leptosporangia, charcoalified wood, resin blebs, epiphyllous fungal shields, clitellate annelid cocoons, insect exoskeleton fragments and coprolites. Sixteen lycophytic megaspore taxa were identified from the succession including six newly described species (Erlansonisporites confertus Tosolini, Favososporites brevis Tosolini, Hughesisporites australis Tosolini, Paxillitriletes rintoulensis Tosolini, Striatriletes imperfectus Tosolini, Trikonia locmaniensis Tosolini). These represent the first Neocomian megaspores formally described from Australia and their diversity and abundance indicates that lycophytes represented a significant component of the Early Cretaceous vegetation. The Tyers River Subgroup shares some taxa with the well-studied Koonwarra Fossil Bed (Aptian) flora of the Gippsland Basin but lacks several key elements (Ginkgoales, angiosperms and large-leafed araucarian conifers) and is more closely comparable to Jurassic floras of eastern Australia in its strong representation of bennettitalean, pentoxylalean and other seed-fern remains. The Tyers River Subgroup flora differs from coeval northwestern Australian floras by possession of smaller-leafed bennettites, Komlopteris and Pachydermophyllum species and by the lack of dipteridacean and gleicheniacean/lophosoriacean fern macrofossils. This intra-Australian provincialism is interpreted to be largely a function of palaeolatitude-induced climatic differences. Six major biofacies (one divisible into four sub-facies) are recognized in the Tyers River Subgroup and are attributable to three broad environmental settings within fluvial depositional tracts. Channel deposits host principally detrital plant remains derived from a broad range of riparian, upland, and reworked floodbasin communities. Silty floodbasin deposits typically host a mixture of pteridosperm-, fern- and lycophyte-dominated assemblages derived from a mosaic of herb-, shrub- and small tree-dominated communities developed mainly in perennially or seasonally wet environments. Better-drained, intervening levee, crevasse splay and neighbouring upland environments are interpreted to have hosted a conifer-dominated flora contributing to conifer-, root/rhizome-, megaspore-and clitellate-rich fossil associations. The floristic diversity, foliar morphology of selected species, strong representation of deciduous taxa and sedimentological data collectively suggest that seasonally cold conditions prevailed during the Neocomian-Aptian compared to the Albian in southeastern Australia.

The prehistory of the Australian vegetation is summarized – from the earliest traces of life in the Precambrian to the events of the Cenozoic that shaped the continent’s modern flora. Australia’s oldest land plants appear in the Silurian with the rise of the lycophyte-dominated Baragwanathia flora. A succession of late Palaeozoic and Mesozoic pteridophyte- and gymnosperm-dominated floras followed, successive floras being punctuated by phases of major climate change and/or global mass-extinction events. For much of its Phenerozoic history, Australia has been part of the supercontinent Gondwana, thus it has shared broadly similar floras with the other Southern Hemisphere continents. The rise of the angiosperms in the Early Cretaceous was coincident with or slightly preceded the later stages of Gondwanan breakup. The modern angiosperm-dominated flora, therefore, developed during progressive isolation of Australia and its eventual collision with landmasses of southeast Asia. This history of isolation and amalgamation, together with the great climatic changes that have affected the continent over the past 100 million years, has set up intriguing scenarios for explaining the past and present distribution of a broad range of Australia’s plant taxa.

Permian non-marine strata in the southern Bowen Basin, Queensland, Australia, yield abundant plant megafossils preserved as impressions, coalified compressions, siliceous petrifactions, and mudstone casts. Plant megafossi1s (excluding glossopterid leaves and fruits) are described from 11 lithostratigraphic units and five subprovinces of the southern Bowen Basin. Several new fossil localities (including a deposit of silicified peat) are described, yielding typical Gondwanic plant assemblages and extending the stratigraphic and geographic ranges of some common pteridophyte and gymnosperm species. New species of gymnospermous seeds (viz., Samaropsis carinata, S. cometensis, S. excellens and S. minniensis) are described. Several plant genera, including Lelstotheca, Puudoctenis, and Pterophyllum, are recorded for the first time from the southern Bowen Basin. Comparison with other Australian and Gondwanic assemblages indicates a Late Permian age for the studied floras.

Although the major features of the evolution of life have shaped the flora and fauna on whichever continent one explores, each has its own peculiarities. These are largely because of differences in each continent’s tectonic and climatic history, coupled with the timing of evolutionary events. So, in its own way, each continent is unique. But of all the continents, Australia is special, at least in part because of its recent relative isolation from other large continental masses—an isolation that is only now coming to an end. The changing biosphere has also had a profound effect on the atmosphere, hydrosphere and lithosphere.

The fertile glossopterid Senotheca is represented by linear fructifications with broad wings attached to the midribs of Glossopteris leaves. The architecture of the reproductive structures supports their placement within the Dictyopteridiaceae. The genus is emended, the validity of two established species (Senotheca murulidihensis and S. kingii) is confirmed, two new species (Senotheca keiraensis and S. magna) are formally defined and one taxon characterized by an attached leaf with coarse venation is retained under open nomenclature. Senotheca is distributed from northeastern India to eastern Australia and ranges from the (?)Artinskian to Changhsingian but the biostratigraphic utility of the genus is constrained by its rarity. Several other reports of the genus from Antarctica and southeastern Australia remain doubtful.

This paper presents an overview of the space and time distributions of Lopingian strata and biotas in Australia, New Zealand, Timor and New Caledonia. Based on this review, we propose a new schematic Late Permian (Lopingian) regional palaeogeographical reconstruction and marine palaeobiogeographical synthesis. The latter also incorporates some key features of the ocean circulation patterns around southeastern Gondwana, inferred primarily from the distribution of regional marine Lopingian faunas.
Across Australasia, Lopingian successions accumulated in a wide range of tectonic, palaeoenvironmental and palaeolatitudinal settings. In New Zealand, Lopingian strata are found in several tectonostratigraphical terranes, notably the Brook Street, Dun Mountain–Maitai, Caples, Waipapa and Torlesse terranes/superterranes, each originating as a distinctive basin, island arc or ocean ridge. For the most part, these successions represent displaced segments of volcanic arcs, arc-flanking clastic aprons, intra- and fore-arc basins and accretionary complexes, some of which have been traced via stratigraphical, biostratigraphical and petrological correlations into New Caledonia and eastern Australia. This spectrum of Lopingian tectono-sedimentary environments in New Zealand is interpreted to have been originally located near northeastern Australia on a convergent continental margin (i.e. the Panthalassan margin of southeastern Gondwana). Brachiopod and bivalve faunas occur widely throughout the Lopingian successions of New Zealand and have been closely studied. A total of five successive faunal zones are recognized, ranging in age from mid-late Wuchiapingian to the end of the Changhsingian.
In Australia, Lopingian deposits are dominated by non-marine successions in a large number of widely distributed sedimentary basins; onshore exposures of marine deposits are known only from the Gympie Terrane in eastern Australia and the Canning and Bonaparte basins in Western Australia. Lopingian terrestrial sediments are most extensively represented in eastern Australia within a major meridional foreland basin complex (the Tasmania, Sydney, Gunnedah and Bowen basins), for which the evolution through the Lopingian and Early Triassic was governed by the dynamics of the New England Orogen along the Panthalassan margin of southeastern Gondwana. Most of the non-marine successions in eastern Australia are rich in coal measures and plant fossils and locally contain well-preserved non-marine invertebrate and vertebrate fossils. A succession of six palynostratigraphical zones has been recognized in eastern Australia spanning the Lopingian through the Early Triassic. Several of these palynozones have also been recognized in Western Australia, allowing the discrimination and correlation of Lopingian deposits in both onshore and offshore successions. In contrast to eastern Australia and New Zealand, the marine Lopingian successions of Western Australia and Timor are dominated by carbonates that are only locally interbedded with siliciclastic sediments and sparse volcaniclastics; these successions accumulated in a giant sedimentary basin located on a passive and actively rifting continental margin. Marine connections and free and frequent biotic interchanges between this Western Australian superbasin (including Timor) and the Himalayan region of Nepal, southern Tibet and northern India throughout the Lopingian are evident from the shared occurrences of many shallow-marine invertebrate species.

Glossopterid gymnosperms dominate the Late Permian floras of the Bowen Basin, Queensland, Australia. Seven new species of Glosopteris (viz., G. indicoides, G. kingii, G. linguiforma, G. plumata, G. rhombimaculata, G. truncata, and G. xiphophylla) are described together with G. rectinervis Dun 1897 emend. Banerjee 1978 and a form comparable to the Antarctic G. schopfii Pigg 1990. Analysis of the distribution of 62 megaplant species recorded from 11 lithological units in the southern Bowen Basin offers the potential for improved phytostratigraphic zonation of the Australian Permian. The megaplant assemblages of the upper Blenheim Subgroup (Back Creek Group) and Blackwater Group, Bowen Basin, are correlated with the floras of the Tomago and Newcastle Coal Measures and their equivalents in the Sydney Basin. Few glossopterid species are shared among the Bowen Basin and extra-Australian basins. The studied megafloras show best intercontinental correlation (via shared glossopterid genera and sphenophyte species) with the Raniganj and Kamthi Formations, India, and Estcourt Formation, South Africa.

Lelstotheca lanceolata and Sphenophyllum morganae are newly described from the Irwin River Coal Measures (Artinskian), northern Perth Basin. The distribution of Raniganjia minima Rigby, 1966 is extended to the Muja Member, Collie Coal Measures (Kungurian-Ufimian?), Collie Basin. A large collection of Sphenophyllum rhodesii Rigby, 1966 specimens from the Irwin River Coal Measures has permitted more detailed circumscription of this abundant herbaceous species. Reinterpretation of the morphology of Gondwanophyton daymondii Rigby, 1992 suggests that the plant possessed reniform leaves borne in pairs
at the nodes of slender articulate axes. Bed-transecting, striate, weakly jointed, flanged axes from the Irwin River Coal Measures probably represent subterranean rhizomes associated with Paracalamites australis Rigby, 1966 stems. Tabulation of the distribution of Permian Gondwanic bowmanitaceans indicates that radially symmetrical Sphenophyllum species were predominant in the Early Permian whereas bilaterally symmetrical Trizygia or bifid-leafed Benlightfootia species dominated the Late Permian.

Though the oldest terrestrial plant remains in Western Australia are of Devonian age, the first abundant fossil floras were preserved during the Permian. Thick accumulations of these plant remains constitute the economically important resources of the Collie and Irwin River Coal Measures in the state's southwest. The Permian floras were dominated by glossopterid gymnosperms showing morphological adaptations to growth in high latitude mire communities. Sphenophytes, lycophytes and ferns represented the dominant herbaceous components of the Permian vegetation.
Triassic and Jurassic fossil plants are poorly represented in Western Australian sedimentary sequences, but Early Cretaceous floras dominated by araucarian and podocarp conifers, bennettitaleans, pteridosperms, ferns and isoetalean lycophytes are known from a number of locations. Though no angiosperm macrofossils of this age have yet been found in Western Australia, the Lower Cretaceous deposits record the first appearances of several conifer and pteridophyte families characteristic of the extant Australian flora. Prominent growth banding in Cretaceous conifer woods implies marked seasonality of the climate.
Western Australian Tertiary floras are best represented in Eocene-Oligocene sedimentary rocks of the Bremer Basin and palaeodrainage channels on the Yilgarn Craton in the State's South-West. Silicification and lateritization of the sediments has removed most of the carbonaceous material from these fossils although in some cases replacement of the organic matter by iron oxides has produced remarkable replication of leaf cuticles enabling reliable generic identification. The Early Tertiary floras contain a number of taxa (e.g., Nothofagus, Gymnostoma, Agathis, Dacrycarpus, ?Phyllocladus) now absent from this State which are characteristic of humid closed forest communities elsewhere in Australia and other Gondwanan land masses. An abundance of Banksieaephyllum and other proteacean leaves also reflects strong contributions from plants now characteristic of local heath vegetation. On a broad scale, clear similarities exist with Eocene-Oligocene macrofloras in eastern Australia but specific differences are evident, notably in the diversity and abundance of myrtacean and to a less extent proteacean remains. Poorly differentiated growth bands in both angiosperm and conifer woods of this age suggest a climatic regime with subdued seasonal variation. Nevertheless, some plant groups (e.g., Nothofagus) Show evidence of a deciduous habit. The Western Australian Early Tertiary macrofloras offer support for the argument that the Australian sclerophyll flora evolved initially in response to low soil nutrient levels and was pre-adapted to developing xeric conditions.

Plant remains occur in all post-Devonian, lowland, terrestrial depositional systems, with distinctive assemblages characterizing discrete environments. Glossopterid gymnosperms dominate most Australian Permian coal-bearing sediments. Herbaceous pteridophytes, sphenophytes, and lycophytes are best represented in lower deltaic lacustrine and paludal deposits. Non-glossopterid gymnosperms mostly colonized drier floodplain and upland environments and are poorly represented in Australian Permian sequences. Fresh- and brackish-water algae are abundantly preserved in paludal and lacustrine facies in both alluvial and delta plain environments. Seasonal productivity and taphonomic factors undoubtedly influenced the composition of interseam compression/impression floras but integration of information from these assemblages with that from permineralized peats, in-situ coalified plants, and coal maceral and palynological analyses can assist in the interpretation of Australian Permian coal-forming environments and the structure of plant communities.

The Strzelecki Group incorporates Berriasian to Albian, fluvial sediments deposited in the Gippsland Basin during initial rifting between Australia and Antarctica. Neocomian strata of the lowermost Strzelecki Group are assigned to the Tyers River Subgroup (exposed in the Tyers area) and the Rhyll Arkose (exposed on Phillip Island and the Mornington Peninsula). The Tyers River Subgroup incorporates two formations: Tyers Conglomerate and Rintoul Creek Formation. The latter is subdivided into the Locmany and Exalt Members. Ten fluvial sedimentary facies are identified in the lowermost Strzelecki Group: two gravelly facies; four sandy facies; and four mudrock facies. Associations of these facies indicate: (i) prevalence of gravelly braided-river and alluvial-fan settings during deposition of the Tyers Conglomerate; (ii) more sluggish, sandy braided to meandering fluvial systems during Locmany Member sedimentation; and (iii) a return to active, sandy, braided-river settings for deposition of the Exalt Member. The Tyers Conglomerate and Rhyll Arkose rest on an irregular erosional surface incised into Palaeozoic rocks of the Lachlan Fold Belt. The overlying Rintoul Creek Formation incorporates more mature sediments where lithofacies associations varied according to base-level change, variations in subsidence rates, and/or tectonic uplift of the principal sediment source terranes to the northwest.

Anatomically preserved vegetative Glossopteris leaves in silicified peat deposits of Late Permian age are described from the Bowen Basin of Queensland and the Sydney Basin of New South Wales, Australia. Glossopteris homevalensis Pigg et McLoughlin, sp. nov., a distinctive new species from the Fort Cooper Coal Measures, Bowen Basin, is characterized by mesarch vascular bundles with parenchymatous bundle sheaths, a prominent midrib, the occasional presence of secondary vascular tissues, a differentiated mesophyll, an ad- and abaxial hypodermis of isodiametric cuboidal cells with abundant fibers, epidermal cells with sinuous anticlinal margins and simple, slightly sunken stomata. Anatomically preserved leaves similar to G. schopfii Pigg, originally described from the central Transantarctic Mountains of Antarctica are also documented from the Bowen and Sydney basins. Those from the Burngrove Formation (Bowen Basin) differ slightly from Antarctic G. schopfii in size, and possess more numerous bundle sheath fibers and sometimes a more pronounced palisade mesophyll. Those from Katoomba (Sydney Basin) are also similar but may differ in some cuticular details. Also occurring in the Katoomba and Burngrove floras are leaves resembling G. skaarensis Pigg, a second species originally described from Antarctica. The presence of G. schopfii and cf. G. skaarensis in Australia as well as in the Transantarctic Mountains demonstrates their widespread distribution in eastern Gondwana. In contrast, the apparent restriction of G. homevalensis to a single locality in the Bowen Basin may reflect a distinct, more local distribution of a floristic assemblage unlike those typical of other Australian and Antarctic floras.

An Early Cretaceous (Aptian or earliest Albian) impression flora is described from the upper part of the Maryborough Formation in the Maryborough Basin, southern Queensland. The flora is preserved in marine sediments hosting an abundant invertebrate fauna dominated by bivalve molluscs. The flora incorporates single species attributable to the Polypodiophyta, Pentoxylales and Bennettitales. Two cuneate leaves have affinities either with the Ginkgoales or seed-ferns. Four species of conifer foliage are represented together with araucarian ovulate cones. Fossils considered by previous workers to be plant roots are reinterpreted as invertebrate burrows, and forms attributed to equisetalean nodal diaphtragms may alternatively represent gastropod opercula. An Aptian or earliest Albian age based on past studies of the fossil fauna is supported by the presence of the stratigraphic index fossil Phyllopteroides serrata Cantrill & Webb.

A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry in the Clarence-Moreton Basin, eastern Australia, is dominated by Allocladus helgei Jansson sp. nov., a conifer with denticulate leaves tentatively attributed to Araucariaceae. The assemblage also includes Rintoulia variabilis and Caytoniales, (Caytonia cucullata McLoughlin sp. nov. and cf. Sagenopteris nilssoniana), reinforcing the wide distribution of this order in Early to Middle Jurassic floras of Gondwana. Ferns (Cladophlebis and Sphenopteris species) and isoetalean lycophytes (Isoetites sp.) constitute the herbaceous elements of the flora. The palynoflora is dominated by cheirolepidiacean (Classopollis) pollen and is attributable to the upper part of the Corollina (= Classopollis) torosa Zone of late Pliensbachianearly Toarcian age (180-185 Ma). The Inverleigh flora represents one of the few Australian assemblages dated between the major phases of floristic turnover at the end of the Triassic and the Toarcian. Sedimentological characteristics, cuticular features of the conifer leaves and the abundance of free-sporing plants indicate a relatively humid palaeoclimate for the Clarence-Moreton Basin Early Jurassic.

The northern Perth Basin lies between about 27° and 31°30'S adjacent to the Yilgarn Craton on the western margin of Western Australia. The basin contains up to 12 km of Ordovician and mid-Carboniferous to Cretaceous, primarily nonmarine to shallow-marine strata below extensive thin, mostly non-marine, Cenozoic cover. This guide describes 37 localities in the basin, from Kalbarri to Gingin, including access and land tenure, and emphasizes stratigraphy, sedimentology, and palaeontology. These localities constitute the key exposures of the pre-Cenozoic succession in the basin and include most of the type sections defi ned in outcrop.

Mineralogy of phosphatized and zeolitized hydrogenous cobalt-rich ferromanganese crusts from Dirck Hartog Ridge (DHR), the Perth Abyssal Plain (PAP), formed on an altered basaltic substrate, is described. Detail studies of crusts were conducted using optical transmitted light microscopy, X-ray Powder Diffraction (XRD) and Energy Dispersive X-ray Fluorescence (EDXRF), Differential Thermal Analysis (DTA) and Electron Probe Microanalysis (EPMA). The major Fe-Mn mineral phases that form DHR crusts are low-crystalline vernadite, asbolane and a feroxyhyte-ferrihydrite mixture. Accessory minerals are Ca-hydroxyapatite, zeolites (Na-phillipsite, chabazite, heulandite-clinoptilolite), glauconite and several clay minerals (Fe-smectite, nontronite, celadonite) are identified in the basalt-crust border zone. The highest Ni, Cu and Co contents are observed in asbolane and Mn-(Fe) vernadite. There is significant enrichment of Ti in feroxyhyte−ferrihydrite and vernadite. The highest rare earth ele...

Bergiopteris sp. cf. B. archangelskyi Rigby 1991 foliage is identified for the first time from late Early or early Late Permian strata of the Wagina Sandstone, Perth Basin, Western Australia. The pinnate frond impressions represent the youngest examples of this Gondwanan genus yet found. Bergiopteris sp. cf. B. archangelskyi has been previously recorded from the Sakmarian Nychum Volcanics, Queensland, and comparable forms occur in the roughly coeval Nueva Lubecka Formation, Argentina. Its extended stratigraphic range suggests caution should be applied to its use as a biostratigraphic marker.
Ottokaria bullatus sp. nov. and Arberia woolagaensis sp. nov., described from the Irwin River Coal Measures (Artinskian), Perth Basin, constitute the earliest Australian records of these genera and represent the first ovulate glossopterid fructifications identified from the Western Australian Permian. Reassessment of the morphology and generic relationships of Rigbya ranunculoides Melville 1983 comb. nov. supports its interpretation as a dorsiventral ovulate glossopterid fructification based on new material from Late Permian strata of the Bowen Basin, Queensland. Assessment of the stratigraphic ranges of known Gondwanan Arberia and Rigbya fructifications highlights their potential application to the recognition of Early and Late Permian strata respectively.

Southeast Queensland’s geomorphology is characterised by northwest – southeast-trending trunk drainage channels and highlands that strongly correlate with the distribution of geological units and major faults. Other geomorphological trends strongly coincide with subsidiary faults and geological domains. Australia is presently under compressional stress. Seismicity over the past 130 years records 56 earthquakes of 42 magnitude indicating continuing small-scale earth movements in the Moreton region. Highlands in this region are dominated by Paleozoic to Triassic metamorphic and igneous rocks, and are generally 20 – 80 km from the coastline. Coastal lowlands are largely dominated by Mesozoic sedimentary basins and a veneer of surficial sediments. The eastern coast of Australia represents a passive margin; crustal sag along this margin could be expected to produce relatively short, highenergy, eastward-flowing drainage systems. We performed a geomorphological analysis to characterise the drainage patterns in southeast Queensland and identify associations with geological features. Anomalous channel, valley and escarpment features were identified, which failed to match the anticipated drainage model and also lacked obvious geological control. Despite their proximity to the coast (base level), these features include areas where drainage channels flow consistently away from, or parallel to, the coastline. Although many channels do coincide with geological structures, the drainage anomalies cannot be directly related to known structural discontinuities. Anomalous drainage patterns are suggested to indicate previously unidentified structural features and in some cases relatively young tectonic control on the landscape. Recent seismicity data have also been analysed to assess spatial correlations between earthquakes and geomorphological features. Our results show that structure largely controls drainage patterns in this region, and we suggest that a presently unmapped and potentially active, deep-seated structure may exist parallel to the coast in the northern coastal region. We propose that this structure has been associated with uplift in the coastal region of southeast Queensland since mid-Cenozoic times.

A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry in the Clarence-Moreton Basin, eastern Australia, is dominated by Allocladus helgei Jansson sp. nov., a conifer with denticulate leaves tentatively attributed to Araucariaceae. The assemblage also includes Rintoulia variabilis and Caytoniales, (Caytonia cucullata McLoughlin sp. nov. and cf. Sagenopteris nilssoniana), reinforcing the wide distribution of this order in Early to Middle Jurassic floras of Gondwana. Ferns (Cladophlebis and Sphenopteris species) and isoetalean lycophytes (Isoetites sp.) constitute the herbaceous elements of the flora. The palynoflora is dominated by cheirolepidiacean (Classopollis) pollen and is attributable to the upper part of the Corollina (=Classopollis) torosa Zone of late Pliensbachian– early Toarcian age (180–185 Ma). The Inverleigh flora represents one of the few Australian assemblages dated between the major phases of floristic turnover at the end of the Triassic and the Toarcian. Sedimentological characteristics, cuticular features of the conifer leaves and the abundance of free-sporing plants indicate a relatively humid palaeoclimate for the Clarence-Moreton Basin Early Jurassic.

Jambadostrobus was established to accommodate fossils consisting of several multiovulate elliptical–ovate fructifications attached to the midline of glossopterid leaves. Two species have been assigned to the genus: J. pretiosus (the type species) and J. hillii from the Late Permian of India and Early Permian of Australia, respectively. Re-investigation of the original specimens reveals that only solitary fructifications are attached to the subtending leaf in J. pretiosus, hence the species is transferred to Plumsteadia, which was founded on equivalent characters. The putative reproductive organs constituting the single Australian specimen of J. hillii are reinterpreted to constitute a broad area of preservational damage on the leaf, hence Jambadostrobus is considered to be a nomen illegitimum.

Mineralogy of phosphatized and zeolitized hydrogenous cobalt-rich ferromanganese crusts from Dirck Hartog Ridge (DHR), the Perth Abyssal Plain (PAP), formed on an altered basaltic substrate, is described. Detail studies of crusts were conducted using optical transmitted light microscopy, X-ray Powder Diffraction (XRD) and Energy Dispersive X-ray Fluorescence (EDXRF), Differential Thermal Analysis (DTA) and Electron Probe Microanalysis (EPMA). The major Fe-Mn mineral phases that form DHR crusts are low-crystalline vernadite, asbolane and a feroxyhyte-ferrihydrite mixture. Accessory minerals are Ca-hydroxyapatite, zeolites (Na-phillipsite, chabazite, heulandite-clinoptilolite), glauconite and several clay minerals (Fe-smectite, nontronite, celadonite) are identified in the basalt-crust border zone. The highest Ni, Cu and Co contents are observed in asbolane and Mn-(Fe) vernadite. There is significant enrichment of Ti in feroxyhyte−ferrihydrite and vernadite. The highest rare earth element (REE) content is measured in the phosphate minerals, less in phyllosilicates and Na-phillipsite. The geochemical composition of minerals in the DHR crusts supports the formation of crusts by initial alteration, phosphatization and zeolitization of the substrate basalts followed by oscillatory Fe-Mn oxyhydroxides precipitation of hydrogenous vernadite (oxic conditions) and diagenous asbolane (suboxic conditions).

A new leaf species of Nothofagaceae, Nothofagus plicata, from southern and southwestern continental Australia is described. N. plicata has plicate vernation and is therefore considered to be a deciduous species. This provides the first macrofossil evidence for deciduous elements on mainland Australia in the Eocene, as well as the previously missing macrofossil evidence for Nothofagus forests which palynologists have suggested existed in this region at that time.

A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry in the Clarence-Moreton Basin, eastern Australia, is dominated by Allocladus helgei Jansson sp. nov., a conifer with denticulate leaves tentatively attributed to Araucariaceae. The assemblage also includes Rintoulia variabilis and Caytoniales, (Caytonia cucullata McLoughlin sp. nov. and cf. Sagenopteris nilssoniana), reinforcing the wide distribution of this order in Early to Middle Jurassic floras of Gondwana. Ferns (Cladophlebis and Sphenopteris species) and isoetalean lycophytes (Isoetites sp.) constitute the herbaceous elements of the flora. The palynoflora is dominated by cheirolepidiacean (Classopollis) pollen and is attributable to the upper part of the Corollina (= Classopollis) torosa Zone of late Pliensbachianearly Toarcian age (180-185 Ma). The Inverleigh flora represents one of the few Australian assemblages dated between the major phases of floristic turnover at the end of the Triassic and the Toarcian. Sedimentological characteristics, cuticular features of the conifer leaves and the abundance of free-sporing plants indicate a relatively humid palaeoclimate for the Clarence-Moreton Basin Early Jurassic.

The Inglis Dome is an anticlinal structure located in the Denison Trough on the western side of the Bowen Basin, east central Queensland. Approximately 4000 m of Permian sediments accumulalcd in this area during several transgressive and regressive phases. In ascending order, the exposed Permian units comprise; the upper conglomerate member of the Aldebaran Sandstone. Freitag Formation, Ingclara Formation. Catherine Sandstone, Peawaddy Formation. Black Alley Shale and Bandanna Formation. Subsurface units include the Reids Dome beds, Cattlc Creek Formation and the lower sandstone member of the Aldebaran Sandstone. Sediments arc inferred to be largely derivcd from the Devonian - Carboniferous Drummond Basin and Cambrian-Ordovician Anakie Inlier to the west and northwest. The Inglis Dome initiated during Late Triassic regional deformation developed by up-arching of sedimcnts through reactivation and reversal of movement along normal dip-slip basement faults that dated from Early Permian times.
Palynological investigation of part of the Middle Permian sequence reveals that previous correlations of the Denison Trough formations with the Permian Upper 5b and Upper 5c palynostratigraphic interval zones require revision. Megafloral and palynofloral investigations rcveal that a Glossopteris-rich, cool temperate flora existed in the vicinity of the project area during the Middle Permian.

The northern Perth Basin lies between about 27 and 31 30'S adjacent to the Yilgarn Craton on the western margin of Western Australia. The basin contains up to 12 km of Ordovician and mid-Carboniferous to Cretaceous, primarily nonmarine to shallow-marine strata below extensive thin, mostly non-marine, Cenozoic cover. This guide describes 37 localities in the basin, from Kalbarri to Gingin, including access and land tenure, and emphasizes stratigraphy, sedimentology, and palaeontology. These localities constitute ...

The relationship between geological fabric and drainage patterns in the 81.8 km2 Laceys Creek sub-catchment of the North Pine River catchment, southeast Queensland, Australia, is analysed using a new channel–ordination system. The Laceys Creek catchment is situated on the South D'Aguilar Block, which underwent metamorphism, faulting and uplift from the Late Carboniferous to Late Triassic. The catchment drains exposures of two main rock units, the Neranleigh–Fernvale Beds and the Bunya Phyllite. Both units are composed of metamorphosed deep-sea sediments that accumulated as an accretionary wedge during late Palaeozoic subduction of the palaeo-Pacific plate under the eastern margin of the Australian craton. The new channel ordination system used in this study allows improved classification of stream segments of equal prominence or rank in comparison to previous schemes. A 10 m contour digital elevation model (DEM) was produced within which drainage channels were digitised. Planar geological features, including bedding, faults, joints and cleavage, were mapped in the field and collated with data from previous geological mapping programs.
Regional and local trends of geological fabric are reflected in the variable orientation of channels of different rank in the catchment. Cleavage and fractures are the dominant planar features of the Bunya Phyllite and these correlate most closely with the orientation of middle-order incised stream segments. In contrast, middle-order channels on the Neranleigh–Fernvale Beds most closely correlate with bedding, which dominates the fabric of this unit. Although anthropogenic factors exert local influence and climatic processes exert broad influence on the catchment, this study focuses on structural and lithological fabrics, which are the apparent dominant controls on middleorder channel orientations. Identification of congruent patterns between bedrock fabric and channel ranks is variable, depending on the scale and number of channels included in the analysis. Many low-rank channels correspond closely to the orientation of fine-scale bedding and foliation and these influencesmay not be detected by coarse-scalemapping.Understanding the extent of geological controls on the morphology of a catchment may assist geo-hazard identification, land-use planning and civil-engineering projects.

A new species of fossil conifer foliage, Bellarinea richardsii, is described and illustrated from Neocomian (Early Cretaceous) sediments of the Tyers River Subgroup in south eastern Victoria. The specimens consist of intact seasonal shoots and isolated leaves, and their depositional setting in prominent leaf mats suggests a seasonal, deciduous habit. Individual leaves are spirally inserted on the shoot axis but the leaf bases are twisted to lie on a common plane giving the shoots plagiotropic symmetry. Although lacking attached reproductive structures the gross morphology and cuticular details of the shoots and leaves suggests assignment to either Podocarpaceae or Taxodiaceae. This species and a range of comparable forms represent a prominent component of Australian mid-Mesozoic floras.

Liknopetalon is an unusual fern-like taxon with fan-shaped pinnae that bear ovate sporangial bodies in a single series along the distal margin. Previously, Liknopetalon has been described from two Permian localities in South Africa, and a single pinna has been identified from the Perth Basin in Australia. The original material of the type species, Liknopetalon enigmata Smithies, lacks critical morphological characters and the species’ taxonomic affiliations have remained obscure. A re-evaluation of existing collections and additional information provided by material obtained from a third South African locality necessitated emendation of the generic diagnosis of Liknopetalon, and erection of an additional species, Liknopetalon gracilis Adendorff sp. nov. Detailed drawings and photographs of several important specimens are presented and these have contributed to the reconstruction of both species. Newly clarified features include the opposite arrangement of the pinnae on the rachis, the division of the distal margin of the lamina into a series of contiguous lobes that each bear a single sporangial body, and the absence of a longitudinal, medial cleft in the pinna. Without anatomical data, the nature of the marginal bodies could not be unequivocally elucidated, but based on gross morphology, they appear to represent synangia or particularly large sporangia. The new South African specimens extend the stratigraphic range of the plant from the Lower Permian into the Middle Permian.

Ten fluvial sedimentary facies are identified in the lowermost Strzelecki Group: two gravelly facies; four sandy facies; and four mudrock facies. Associations of these facies indicate: (i) prevalence of gravelly braided-river and alluvial-fan settings during deposition of the Tyers Conglomerate; (ii) more sluggish, sandy braided to meandering fluvial systems during Locmany Member sedimentation; and (iii) a return to active, sandy, braided-river settings for deposition of the Exalt Member. The Tyers Conglomerate and Rhyll Arkose rest on an irregular erosional surface incised into Palaeozoic rocks of the Lachlan Fold Belt. The overlying Rintoul Creek Formation incorporates more mature sediments where lithofacies associations varied according to base-level change, variations in subsidence rates, and/or tectonic uplift of the principal sedimentsource terranes to the northwest.

The Cretaceous saw dramatic changes in the tectonic setting, landscape and biodiversity of Australasia. Continental fragmentation, marine transgression, the rise of ‘modern’ faunas and floras, and the Cretaceous–Paleogene mass extinction represent key events that set the stage for future evolution of this region’s insular Cenozoic biotas. Australasia’s rich but scattered Cretaceous fossil record also provides a rare glimpse into austral high-latitude life and environments throughout the breakup phase of southeastern Gondwana.

A small assemblage of clitellate annelid cocoons (egg cases) is described from the Early Jurassic Marburg Subgroup, Clarence-Moreton Basin, eastern Australia. Two complete specimens are preserved on bedding planes, and numerous fragments were recovered from organic residues prepared for mesofossil analysis. The complete specimens are assigned to Burejospermum Krassilov emend. Manum, Bose & Sawyer, 1991, having a well-developed mesh-like hapsine and a solid layer of underlying alytine. The fragments include a form assigned to Dictyothylakos Horst, 1954 emend. Manum, Bose & Sawyer, 1991 having a mesh-like hapsine but lacking an alytine layer. The cocoons are preserved in floodbasin facies represented by leaf-rich, dark shales. Palynological data indicate a Pliensbachian to earliest Toarcian age for the assemblage. Similarities between the new specimens, congeneric material from the Triassic to Neogene of other continents, and modern egg cases highlight the long-term morphological conservatism of clitellate cocoons. The new material extends the distribution of such fossils, which generally have a poor macrofossil record.

Three new glossopterid fructifications and a new Glossopteris leaf are described from Late Permian sediments of the southwest and central Bowen Basin, Queensland, Australia. Glossopteris bucklandensis sp. nov. and the female fructification Ottokaria inglisensis sp. nov. are described from the Black Alley Shale, Denison Trough. Cometia biloba gen. et sp. nov. and Senotheca kingii sp. nov. are instituted for new female fructifications from the Burngrove and Fair Hill Formations respectively on the Comet Platform. A collection of female fructifications from the Rangal Coal Measures, Comet Platform, is assigned to Dictyopteridium walkornii (Rigby) comb. nov. Numerous specimens of O. inglisensis and D. walkomii show that receptacle dimension ratios and tubercle (ovule attachment point) densities are useful taxonomic features, whereas wing and stalk vs. receptacle dimension ratios are less consistent. Exceptionally high tubercle densities on some small fructifications possibly reflect limitation of receptacle growth induced by local ecological conditions.

Two new species of the gymnospermous leaf form-genus Rochipteris Herbst, Troncoso and Gnaedinger are described. Leaves belonging to this genus are apetiolate, flabellate, with an entire to variably dissected apex, a truncate to slightly flaring base, and sparsely anastomosing venation. Rochipteris etheridgei (Arber) comb. nov. is documented from Carnian sediments of the Leigh Creek Coal Measures, South Australia. Rochipteris ginkgoides sp. nov. is described from the Ipswich Coal Measures (Carnian) Queensland, Australia. A single additional incomplete leaf from the Triassic Springfield Basin, South Australia is assigned to Rochipteris sp. These fossil leaves have previously been assigned to a range of genera based on leaf shape and apparent dichotomous venation. Rochipteris species represented a sub-dominant component of the Dicroidium-rich lowland vegetation across Gondwana during the Late Triassic.

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Mineral and aqueous geochemical data are combined with a conceptual groundwater flow model, to establish the origin and fate of iron, aluminium and manganese in the groundwater system of a small backbarrier island. The flow model domain consists of an unconfined island fresh groundwater lens overlying a semi-confined hypersaline aquifer. The two aquifers are separated by a discontinuous, clay-rich aquitard and both contain diffusion governed variable density flow fields. High concentrations of dissolved iron and manganese are associated with brackish to hypersaline groundwater, although there is no systematic relationship with salinity. Calculation of S 2− /SO 4 2− and Fe 2+ /Fe 3+ redox couples and the results of thermodynamic modelling show that redox disequilibrium in the groundwater is widespread. Groundwater samples containing aqueous sulphide and ferric iron complexes are supersaturated with respect to pyrite, goethite and haematite but the prevailing state of redox disequilibrium controls mineral dissolution and precipitation. Aqueous iron in the deeper regions of both aquifers is derived from the dissolution of iron oxide-hydroxides in lateritic palaeosols controlled by seasonal fluctuations in groundwater redox state. Aqueous manganese is potentially derived from the dissolution of ilmenite and amorphous oxidehydroxides. The oxidation of iron sulphides contributes to the aqueous iron concentration and sulphuric acid production in the shallow groundwater. The solubility of aluminium is also limited by this process, governed by acidity regulation. A significant proportion of aqueous iron is transmitted from the semi-confined to the overlying unconfined aquifer through discontinuities in the aquitard layer. Movement of metals in solution outside the island groundwater system is restricted by the presence of diffusion boundaries within variable density transition zones.

Jurassic plant remains in Western Australia are sparse but small assemblages of impression fossils have been deposited in the collections of the Australian Museum, Sydney, over the past century. They reveal the presence of ?Matoniaceae and Cladophlebis sp. from the Cockleshell Gully Formation (Toarcian–Aalenian), Zamites sp. from the Dingo Claystone (Middle to Upper Jurassic), and Elatocladus confertus (Oldham & Morris) Halle, Pagiophyllum amanguanus sp. nov., ?microsporangiate cones, Otozamites bengalensis Oldham & Morris, Otozamites linearis Halle, Otozamites sp. and Ptilophyllum cutchense Morris from the Yarragadee Formation (Late Jurassic). The assemblages show links to eastern Australian, Indian and Antarctic floras of Early Jurassic to Early Cretaceous age. The macrofloras generally support previous palynological dating of the host units, but also indicate broad (generic-level) similarities between Jurassic and Early Cretaceous floras across Gondwana. The macrofloras have no strong taxonomic or morphological signatures indicative of either aridity or humidity but the bennettitaleans have leaves intermediate in size between low and high latitude mid-Mesozoic assemblages, which favours previous palaeogeographic placements of Western Australia in the mesothermal middle-latitude province in the Jurassic.

Western Australian, Lower Cretaceous, macrofloras from the Broome Sandstone• and Callawa Formation (Canning Basin), Nanutarra Formation and Birdrong Sandstone (Carnarvon Basin), Cronin Sandstone (Officer Basin), and Leederville and Bullsbrook Formations (Perth Basin) incorporate a range of lycophytes, ferns, pteridosperms, bennettitaleans, and conifers. The new monotypic genus Roebuckia is established for spatulate fern fronds (R. spatulata) of possible vittariacean alliance. Other newly establish species include Phyllopteroides westralensis, Elatocladus ginginensis,
and Carpolithes bullsbrookensis. Although the Western Australian fossil suites reveal some specific differences from other Australian late Mesozoic assemblages, several shared index taxa and the high proportion of bennettitaleans support correlation with the Victorian Neocomian Ptilophyllum-Pachypteris austropapillosa Zone (Zone B). Some Western Australian taxa are shared with Indian assemblages but fewer similarities exist with other Gondwanan Early Cretaceous floras. The representation of several hydrophilous fern, lycophyte, and pteridosperm groups together with growth indices from fossil woods implies a seasonal humid mesothermal climate for the Western Australian cratonic margin during the Neocomian-Barremian. Minor differences between the Western Australian assemblages are attributable to local depositional and preservational factors.