Clarence-Moreton Basin Research Articles

An Early Jurassic flora from the Clarence-Moreton Basin, Australia

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.

GEOLOGICAL CONTROLS ON EXPLOITABLE COAL SEAM GAS DISTRIBUTION IN QUEENSLAND

Methane is present in all coals, but a number of geological factors influence the potential economic concentration of gas. The key factors are (1) depositional environment, (2) tectonic and structural setting, (3) rank and gas generation, (4) gas content, (5) permeability, and (6) hydrogeology. Commercial coal seam gas production in Queensland has been entirely from the Permian coals of the Bowen Basin, but the Jurassic coals of the Surat and Clarence-Moreton basins are poised to deliver commercial gas volumes.Depositional environments range from fluvial to delta plain to paralic and marginal marine—coals in the Bowen Basin are laterally more continuous than those in the Surat and Clarence-Moreton basins. The tectonic and structural settings are important as they control the coal characteristics both in terms of deposition and burial history. The important coal seam gas seams were deposited in a foreland setting in the Bowen Basin and an intracratonic setting in the Surat and Clarence-Moreton basins. Both of these settings resulted in widespread coal deposition. The complex burial history of the Bowen Basin has resulted in a wide range of coal ranks and properties. Rank in the Bowen Basin coal seam gas fields varies from vitrinite reflectance of 0.55% to >1.1% Rv and from Rv 0.35-0.6% in the Surat and Clarence-Moreton basins in Queensland. High vitrinite coals provide optimal gas generation and cleat formation. The commercial gas fields and the prospective ones contain coals with >60% vitrinite.Gas generation in the Queensland basins is complex with isotopic studies indicating that biogenic gas, thermogenic gas and mixed gases are present. Biogenic processes occur at depths of up to a kilometre. Gas content is important, but lower gas contents can be economic if deliverability is good. Free gas is also present. Drilling and production techniques play an important role in making lower gas content coals viable. Since the Bowen and Surat basins are in a compressive regime, permeability becomes a defining parameter. Areas where the compression is offset by tensional forces provide the best chances for commercial coal seam gas production. Tensional setting such as anticline or structural hinges are important plays. Hydrodynamics control the production rate though water quality varies between the fields.

Towards GIS Mapping and Spatial Modelling of Archaeological Sites in the Southeast Queensland Bioregion

<p>In the early 1980s a strategic approach to the description, assessment and management of cultural heritage places using biogeographical boundaries was developed in Queensland. A recent refinement correlates sites on the Environmental Protection Agency's Indigenous Sites Database with environmental variables for the Moreton Basin Province of the Southeast Queensland Bioregion. Archaeological sites in the province are correlated with distance to water, elevation and particular geological and vegetation types. These correlations may reflect either real relationships or biases in the data. Preliminary correlative models developed are not considered substitutes for further inventory surveys and ongoing model refinement. The development of such models is considered useful in providing initial understanding of site distribution patterns.</p>

Crustal architecture across Phanerozoic Australia along the Eromanga-Brisbane Geoscience Transect: evolution and analogues

The crustal architecture across Phanerozoic Australia has been established from seismic data along an 1100-km-long east-west transect, the Eromanga-Brisbane Geoscience Transect. This has enabled a better understanding of deep structures and processes that have controlled the development of major sedimentary basin systems. It has shown that crustal dynamics throughout geological history have played an important role in the development of these sedimentary basins and that structures developed during the early Palaeozoic have influenced, and continue to influence, basin systems. The transect crosses three major basement provinces of the Tasman Orogenic System in eastern Australia - the Thomson, northern Lachlan, and New England Orogens. The basement geology in the transect region has, until now, been only poorly understood because it is largely obscured by the Mesozoic cover rocks of the Eromanga, Surat and Clarence-Moreton Basins. The transect interpretation has firmly identified crustal-scale ramp structures, multiple intra-crustal detachment surfaces, strike-slip fault architecture, lower-crustal magmatism/underplating, Mono remobilisation, and intra-crustal terranes in the geological reconstructions of southern Queensland. The boundaries between the orogens, the Foyleview and Burunga—Mooki Geosutures, have been identified as lithospheric-scale structures that have influenced the evolution of the Tasman Orogenic System as a whole.

POST-CARBONIFEROUS TECTONIC EVOLUTION OF EASTERN AUSTRALIA

Analysis of seismic data from the Bowen and Surat Basins has yielded valuable information on the Permian and Triassic evolution of eastern Australia. When combined with seismic data from the Clarence-Moreton and Maryborough Basins, a new understanding of the post-Triassic evolution of the region can be gained, with widespread implications for other eastern Australian basins.The Early Permian-Middle Triassic Bowen-Sydney Basin is a foreland basin system extending 2000 km in preserved section from Nowra in the south to Collinsville in the north. Permian outcrops as far north as Cape York were probably part of the same system prior to deformation and erosion. The basins in the Bowen-Sydney system were linked by similar structural and stratigraphic patterns controlled by a magmatic arc to the east. The Esk Trough and associated remnant basins east of the Taroom Trough were part of the Middle Triassic foreland sequence. The structural style in the system is dominated by thrusting from the east. An Early Triassic deformation is shown to be the most important, rather than the previously believed Middle Triassic event.The overlying Jurassic-Cretaceous foreland system, which included the Surat, Maryborough and Clarence-Moreton Basins, were once joined behind another magmatic arc, east of the Triassic arc position. A major mid-Cretaceous deformation is documented which fragmented the Jurassic-Cretaceous foreland basin into a number of remnant basins prior to the opening of the Tasman Sea in the Cenomanian. The dominant structural style is again thrusting from the east. Given the severity of the deformation, its effects are expected to be present in continental margin basins around Australia.

Continental rifting and drainage reversal: The clarence river of Eastern Australia

AbstractThe Clarence River on Australia's east coast has an anomalous drainage pattern. Its right‐bank tributaries are markedly barbed, suggesting reversal, whereas Tertiary volcanism has disrupted its left‐bank drainage. The southeast‐flowing Clarence is closely aligned with the northwest‐flowing Condamine River just across the Continental Divide. The Condamine‐Clarence alignment is continued by a large southern tributary, the Orara River, which flows northwest, away from the sea, to meet the southeast‐flowing Clarence. A broad river with a quite different character flows east from near the Orara‐Clarence junction to the sea. This is essentially an overflow channel.This series of aligned streams, the Condamine‐Clarence‐Orara, represents the remains of an earlier northwest‐flowing stream that extended the full length of the Clarence‐Moreton Basin, an eastern extension of the Great Artesian Basin. During the Jurassic, the Clarence‐Moreton Basin was filled with sediments from the surrounding highlands, including those to the east of the present coastline. Continental rifting from Late Cretaceous times onwards led to the opening of the Tasman Sea, causing the reversal and beheading of the original northwest‐flowing streams and the formation of the Great Escarpment.The evolution of the Clarence River does not fit into most conventional geomorphic paradigms such as cycles, climatic geomorphology or steady‐state landforms. It is the result of a succession of unique events on a very long timescale, and as such is a classic example of evolutionary geomorphology.

Apatite fission track thermochronology and tectonics in the Clarence-Moreton Basin of Eastern Australia

Apatite fission track thermochronology and tectonics in the Clarence-Moreton Basin of Eastern Australia

Development of Mesozoic transtensional basins in easternmost Australia

Seismic reflection profiles across Mesozoic basins in easternmost Australia show that the Esk Trough, Ipswich Basin and Clarence-Moreton Basin were initiated by transtensional events in the Late Permian or Early Triassic. The initial sediments in the basins are unexposed sequences below the Esk Trough and Ipswich Basin. In the Scythian, strike-slip faulting moved eastwards to the site of the present Ipswich Basin, and the Esk Trough subsided due to thermal relaxation. After oblique extension ceased in the Carnian, thermal relaxation subsidence led to deposition of sediments firstly in the Ipswich Basin and then in the more extensive Clarence-Moreton Basin. The structures and sediments of the extension and thermal relaxation phases show a pronounced asymmetry in cross-section, as expected during pure extension, but no low-angle detachment faults have been detected indicating strike-slip movement on the bounding fault of the Esk Trough (the West Ipswich Fault) during extension. Thus the basins developed dur...

A Comparison of Magnetotelluric Analysis Methods Based on Data from a Site in the Moreton Basin

A magnetotelluric (MT) system with sampling frequencies in decade steps from 1 kHz to .01 Hz was operated at a site in the Moreton Basin, near Peaks Crossing, Queensland. The data were analysed by both the conventional rotated impedance and the Spitz eigenvalue methods, then resistivity?depth profiles were calculated using a Molochnov/Bostick inversion technique. The magnitude of the resistivity information derived from the two methods was found to differ substantially, presumably due to the three-dimensional nature of some of the underlying geological structures. The finer structural features were similar between methods, though the depth of these features varied due to the differing apparent resistivities. The variation of the principle directions in the Spitz method was much smoother. Comparison between the resulting profiles and geological and geophysical information in the area showed reasonable agreement with expected geological structures.

THE PETROLEUM PROSPECTIVITY OF THE CLARENCE-MORETON BASIN IN NEW SOUTH WALES

The Clarence-Moreton Basin covers an area of some 28 000 km2 in north-eastern New South Wales and south-eastern Queensland. The basin is relatively unexplored, with a well density in New South Wales of one per 1600 km2. Since 1980, Endeavour Resources and its co-venturers have pursued an active exploration programme which has resulted in the recognition of significant petroleum potential in the New South Wales portion of the basin.Previous studies indicated that the Upper Triassic to Lower Cretaceous Clarence-Moreton Basin sequence in general, lacked suitable reservoirs and had poor source- rock potential. While exinite rich, oil-prone source rocks were recognised in the Middle Jurassic Walloon Coal Measures, they were considered immature for oil generation. Moreover, during the 1960's the basin acquired a reputation as an area where seismic records were of poor quality.These ideas are now challenged following the results of a new round of exploration which commenced in the New South Wales portion of the basin in 1980. This exploration has involved the acquisition of over 1000 km of multifold seismic data, the reprocessing of some 200 km of existing single fold data, and the drilling of one wildcat well. Over twenty large structural leads have been identified, involving trapping mechanisms ranging from simple drape to antithetic and synthetic fault blocks associated with normal and reverse fault dependent and independent closures.The primary exploration targets in the Clarence- Moreton Basin sequence are Lower Jurassic sediments comprising a thick, porous and permeable sandstone unit in the Bundamba Group, and channel and point-bar sands in the Marburg Formation. Source rocks in these and the underlying Triassic coal measures are gas-prone and lie at maturity levels compatible with gas generation. In contrast, it was established from the results of Shannon 1 that the Walloon Coal Measures are mature for oil generation and this maturity regime is now considered to be applicable to most of the basin in New South Wales.A consideration of reservoir and source rock distribution, together with structural trends across the basin in Petroleum Exploration Licences 258 and 259, has led to the identification of three prospective fairways, two of which involve shallow oil plays. Exploration of these fairways is currently the focus of an ongoing programme of further seismic data acquisition and drilling.

Geology of Principal Australia Coals and Coal Basins: A Review: ABSTRACT

Bituminous or subbituminous coals are known from nearly all parts of Australia. Those of greatest economic importance today are found in the Permian and Triassic Bowen and Galilee basins of Queensland and the Sydney-Bowen basin of New South Wales, with some coalfields of lesser significance in the Clarence-Moreton basin in Queensland and New South Wales. The lesser known fields also include the Permian Collie coalfield and Perth (Permian-Cretaceous) and Canning (Permian-Triassic) basins of Western Australia; the Bonaparte basin (Permian), mostly offshore in the Darwin area of Northern Territory and Western Australia; the shallow Permian coals of the large Arckaringa basin, and the smaller Triassic-Jurassic Leigh Creek basin in South Australia; the Early Cretaceous of the ippsland basin, Victoria; and the Permian and Triassic coals of the Tasmania basin, particularly the Fingal area. Structural, sedimentary, and paleobiologic features of the coal-bearing strata and regional trends of various coal characteristics of some of the principal economic or geologically interesting basins and coals are reviewed and illustrated. These include the Hail Creek syncline, Goonyella, Peak Downs, German Creek, Blackwater, Baralaba, Tolmeis and Moura Mines of the Bowen basin of Queensland and the unique Blair Athol mine at the far western edge of Bowen basin. In New South Wales these include the Hunter Valley area Singleton Coal Measures represented by the Foyebrook-Liddell Seam and Ravensworth mines; the Newcastle area; the Ulan Seam of the Goulburn Valley area; the weste n shelf area and Sydney-Wollongong region represented by the Illawarra (Permian) Coal Measures which are overlain by the thick Triassic Narrabean Series, Hawksbury Sandstone, and Wianamatta Group. A paleobiologic analysis of the thick brown coal sequences in the Yallourn, Latrobe Valley, and Bacchus Marsh areas of Victoria, and the significance of tectonics in the development of these great coal swamps will be reviewed. End_of_Article - Last_Page 1454------------

GEOLOGY, SOURCE ROCKS AND HYDROCARBON GENERATION IN THE CLARENCE-MORETON BASIN

The geology and exploration history of the Triassic-Cretaceous Clarence-Moreton Basin are reviewed. Consideration of new geochemical data ('Rock-Eval', vitrinite reflectance, gas chromatography of extracts, organic carbon and elemental analysis of coals and kerogens) gives further insights into the hydrocarbon potential of the basin. Although organic-rich rocks are relatively abundant, most source rocks that have achieved the levels of maturation necessary for hydrocarbon generation are gas-prone. The exinite-rich oil-prone Walloon Coal Measures are in most parts relatively immature. Some restraints on migration pathways are evident and igneous and tectonic events may have disturbed potentially well-sealed traps. Further exploration is warranted, even though the basin appears gas-prone and the overall prospects for hydrocarbons are only fair. The most promising areas seem to be west of Toowoomba for oil and the Clarence Syncline for gas.

DEEP STRATIGRAPHIC CORE-DRILLING AS AN AID TO PETROLEUM EXPLORATION

The Queensland Department of Mines has undertaken stratigraphic drilling to assist petroleum exploration since 1965. The primary purpose was to obtain core for palynological and petrological study, in order to facilitate correlation of strata met in deep exploratory wells with the type sections of outcrop.To the end of October, 1970, 61 bores have been completed for a total of 50,473 feet (15,394 metres), an average depth of 827 feet (252 metres).Average drilling cost ranged from about $5 per foot at shallow depths to about $15 per foot towards the current maximum capacity of 4,000 feet (1,220 metres), total cost was of the order of $400,000.All holes were fully cored from about 50 feet (about 15 metres) to total depth. With minor exceptions, all drilling has been with NX equipment, giving a core approximately 1.7 inches (4.3 centimetres) in diameter. The core barrel is 10 feet (3 metres) long; it is recovered by the wireline method. On completion, most holes have been logged electrically and radiometrically (spontaneous potential, single-point resistivity and gamma-ray).Drilling lias been undertaken in sediments of the Surat, Bowen, Moreton and Ipswich Basins, and the Esk Rift. In the Surat Basin, complete sections of the Jurassic have been obtained on both the western and eastern flanks, and the Cretaceous has been sampled completely near the middle of the basin; in addition, the Injune Creek Group (Jurassic) is being investigated in some detail. In the Bowen Basin, representative material has been obtained from the Triassic units (Rewan, Clematis and Moolayember); the Permian on the eastern flank has been sampled completely in a Departmental coal-exploration project. In the Moreton Basin, a series of regional lines was drilled, partly in order to establish the relationship of the Bundamba Group to the Jurassic of the Surat Basin.One hole was drilled in the Ipswich Basin, to sample the upper part of the Triassic succession there.The program has been especially effective in providing material for palynological studies, both descriptive and stratigraphic, particularly in sandstone units. By this means, several important stratigraphic problems were resolved. For example, the type Wandoan Formation of Union-Kern-A.O.G. Wandoan 1 well was shown to be equivalent in age to the lower and middle Clematis Sandstone of outcrop, whereas the so-called Wandoan elsewhere in the basin was shown to be equivalent to the uppermost Clematis and lower Moolayember Formation of outcrop. Again, the drilling has confirmed the lithological correlation of the Precipice Sandstone of the Surat Basin with the Helidon Sandstone of the Moreton Basin, and the Evergreen Formation and Hutton Sandstone (which overlie the Precipice) with the Marburg Sandstone (which overlies the Helidon); the remarkably persistent oolite marker in the Evergreen and Marburg has been shown to be of essentially the same age throughout.Extension of the project widely through the sedimentary basins of Queensland is warranted.Proposed work for 1971 includes drilling of the Permian on the western flank of the Bowen Basin, and of the Tertiary in the Hillsborough Basin.