Bowen Basin Research Articles

Novel ecosystems created by coal mines in central Queensland’s Bowen Basin

Open-cut coal mining began in central Queensland’s Bowen Basin approximately 50 years ago. Over this period of time, mine rehabilitators have used a variety of tree, shrub, and groundcover species to create ‘novel ecosystems’ to stabilise soils and provide vegetative cover for pre-supposed final end-land uses. We examine post-mining rehabilitation from multiple soil and vegetation monitoring activities in the Bowen Basin to assess the similarity of landforms, plant composition, and trends in plant diversity compared to unmined reference communities. Rehabilitated spoil dumps and reference sites were assessed using soil and vegetation data contained in compliance monitoring reports from Goonyella Riverside, Moura, Oaky Creek, Rolleston, and Blackwater mines. Slopes, soil chemistry, and plant species mixes of rehabilitation aged from 2 to 22 years were compared to selected reference communities. Mines in this region have generally proposed one of two post-rehabilitation end-land uses: either pasture for cattle grazing or reconstructed native communities which potentially provide native fauna habitat. Landform data from a selection of these mine sites suggest that when their rehabilitation was compared to nearby reference sites median slope values were between 2.5 and 7 times steeper and soil pH, electrical conductivity, and phosphorus levels were significantly higher. The steeply sloped landforms, poor soil characteristics, depauperate native species pool, and uniform presence of exotic pasture grasses in the rehabilitation indicate that most of these newly created ecosystems should not be used for cattle grazing and also have few natural values. Legislative and community expectations have changed progressively over time and, although much of the rehabilitation is currently dominated by an assemblage of exotic buffel grass (Cenchrus ciliaris) and Acacia spp., recent environmental authorities suggest these ‘novel ecosystems’ will be judged against native reference sites. Upon completion of mining activities the resilience of these new ecosystems to drought, fire, and grazing will need to be demonstrated prior to lease relinquishment.

New evidence of the reproductive organs of Glossopteris based on permineralized fossils from Queensland, Australia. II: pollen-bearing organ Ediea gen. nov

Ediea homevalensis H. Nishida, Kudo, Pigg & Rigby gen. et sp. nov. is proposed for permineralized pollen-bearing structures from the Late Permian Homevale Station locality of the Bowen Basin, Queensland, Australia. The taxon represents unisexual fertile shoots bearing helically arranged leaves on a central axis. The more apical leaves are fertile microsporophylls bearing a pair of multi-branched stalks on their adaxial surfaces that each supports a cluster of terminally borne pollen sacs. Proximal to the fertile leaves there are several rows of sterile scale-like leaves. The pollen sacs (microsporangia) have thickened and dark, striate walls that are typical of the Arberiella type found in most pollen organs presumed to be of glossopterid affinity. An examination of pollen organs at several developmental stages, including those containing in situ pollen of the Protohaploxypinus type, provides the basis for a detailed analysis of these types of structures, which bear similarities to both compression/impression Eretmonia-type glossopterid microsporangiate organs and permineralized Eretmonia macloughlinii from Antarctica. These fossils demonstrate that at least some Late Permian pollen organs were simple microsporophyll-bearing shoot systems and not borne directly on Glossopteris leaves.

Site-specific climate analysis elucidates revegetation challenges for post-mining landscapes in eastern Australia

Abstract. In eastern Australia, the availability of water is critical for the successful rehabilitation of post-mining landscapes and climatic characteristics of this diverse geographical region are closely defined by factors such as erratic rainfall and periods of drought and flooding. Despite this, specific metrics of climate patterning are seldom incorporated into the initial design of current post-mining land rehabilitation strategies. Our study proposes that a few common rainfall parameters can be combined and rated using arbitrary rainfall thresholds to characterise bioregional climate sensitivity relevant to the rehabilitation these landscapes. This approach included assessments of annual rainfall depth, average recurrence interval of prolonged low intensity rainfall, average recurrence intervals of short or prolonged high intensity events, median period without rain (or water-deficit) and standard deviation for this period in order to address climatic factors such as total water availability, seasonality and intensity – which were selected as potential proxies of both short- and long-term biological sensitivity to climate within the context of post-disturbance ecological development and recovery. Following our survey of available climate data, we derived site "climate sensitivity" indexes and compared the performance of 9 ongoing mine sites: Weipa, Mt. Isa and Cloncurry, Eromanga, Kidston, the Bowen Basin (Curragh), Tarong, North Stradbroke Island, and the Newnes Plateau. The sites were then ranked from most-to-least sensitive and compared with natural bioregional patterns of vegetation density using mean NDVI. It was determined that regular rainfall and relatively short periods of water-deficit were key characteristics of sites having less sensitivity to climate – as found among the relatively more temperate inland mining locations. Whereas, high rainfall variability, frequently occurring high intensity events, and (or) prolonged seasonal drought were primary indicators of sites having greater sensitivity to climate – as found among the semi-arid central-inland sites. Overall, the manner in which these climatic factors are identified and ultimately addressed by land managers and rehabilitation practitioners could be a key determinant of achievable success at given locations at the planning stages of rehabilitation design.

Palynofacies changes and their reflection on preservation of peat accumulation stages in the Late Permian coal measures of the Bowen Basin, Australia: A new system for coal palynofacies characterisation

A high-resolution study (n=66) was conducted on Late Permian coal measures of the Bowen Basin, Australia, to observe palynofacies changes during peat accumulation over time. Palynofacies were determined using polytopic vector analysis (PVA) to derive end members with variable compositions that reflected fine scale environmental changes, within and between seams, of the Kaloola Member. Palynofacies reflect a three-stage succession within the palaeo- peat-forming environments from stable, anoxic conditions at the base, progressing to variable, oxic conditions toward the top of each seam. In cases where a seam was capped by tuff, rather than siliciclastic sediment, anoxic conditions similar to the bottom of each seam occurred. The results corroborate previous interpretations of palaeofloral communities and provide a new palynofacies model that integrates environmental progression within the coal seams in the Late Permian coal measures of the Bowen Basin. A complementary study of palynological assemblages recognised a shift from Dulhuntyspora sp., to Protohaploxypinus sp. in the lower Kaloola Member, indicating a change in pollen/spore source. Associations between dispersed palynomorphs and coal phyterals of parent flora remain tenuous beyond class rank, due to poor preservation and taxonomic bias inherent within the sample space. This is the first such palynofacies study to be conducted in the Bowen–Sydney–Gunnedah basin complex, thus opening the way for future work examining regional changes in palynofacies, expressed in both coal and siliciclastic sediments.

REHABILITATION CLOSURE CRITERIA ASSESSMENT USING HIGH RESOLUTION PHOTOGRAMMETRICALLY DERIVED SURFACE MODELS

Abstract. Relinquishment of mined land is unlikely to occur without compelling evidence that post mine landforms have a sustainable vegetation cover and represent a minimal liability to subsequent land users. Gully and rill erosion result in unstable landforms create unsafe landscapes for commonly targeted post mine land uses, such as grazing. The photogrammetric products of two small Unmanned Aerial Vehicle (UAV) platforms were compared as a means of delineating erosion gullies and comparing vegetation in rehabilitation at an open cut coal mine in the Bowen Basin, Queensland. Erosion gullies were clearly visible in both UAV products at 5 cm resolution; however, target illumination and photogrammetric processing methods largely determined the ability to identify erosion from surface models. Individual tree canopies were clearly visible in both products, as were phenological traits such as leaf flushing and flowering. The high spatial resolution resulted in unreliable detection of tree crowns in both processing methods.

Maceral Characteristics and Vitrinite Reflectance Variation of The High Rank Coals, South Walker Creek, Bowen Basin, Australia

DOI: 10.17014/ijog.v8i2.156The Permian coals of the South Walker Creek area, with a vitrinite reflectance (Rvmax) of 1.7 to 1.95% (low-volatile bituminous to semi-anthracite), are one of the highest rank coals currently mined in the Bowen Basin for the pulverized coal injection (PCI) market. Studies of petrology of this coal seam have identified that the maceral composition of the coals are dominated by inertinite with lesser vitrinite, and only minor amounts of liptinite. Clay minerals, quartz, and carbonates can be seen under the optical microscope. The mineral matter occurs in association with vitrinite and inertinite macerals as syngenetic and epigenetic mineral phases. The irregular pattern of the vitrinite reflectance profile from the top to the bottom of the seam may represent a response in the organic matter to an uneven heat distribution from such hydrothermal influence. Examination of the maceral and vitrinite reflectance characteristics suggest that the mineralogical variation within the coal seam at South Walker Creek may have been controlled by various geological processes, including sediment input into the peat swamp during deposition, mineralogical changes associated with the rank advance process or metamorphism, and/or hydrothermal effects due to post depositional fluid migration through the coal seam.

Maceral Characteristics and Vitrinite Reflectance Variation of The High Rank Coals, South Walker Creek, Bowen Basin, Australia

Maceral Characteristics and Vitrinite Reflectance Variation of The High Rank Coals, South Walker Creek, Bowen Basin, Australia

Decoupling δ13C response to palaeoflora cycles and climatic variation in coal: A case study from the Late Permian Bowen Basin, Queensland, Australia

The Late Permian coal measures of the Bowen Basin, Australia express both environmental and climatic changes that occurred prior to the Permian Triassic (P–T) boundary. In order to decouple the influence of environmental factors (salinity, pH, base level and temperature) from depositional and climatic factors (atmospheric CO2) in organic δ13C, a high resolution study was performed on 24 coal seams (total 24.6m) in the Late Permian stratigraphy in the northern Bowen Basin. The Late Permian stratigraphy of the Bowen Basin records a transition from deltaic and lacustrine conditions within the Tinowan Formation and Black Alley Shale Formation, to fluvial deposition in the Kaloola and Bandanna Formations. Intermittent volcanism is recorded by tuff layers during periods of peat accumulation. Variations of coal lithotypes were recorded and formed the basis of sampling for petrography and isotope analysis. Coal samples were etched to expose cellular anatomy, and systematically identified to recognise palaeoflora assemblages. When observed within seam, δ13C of the coal varied cyclically (13C enriched-depleted-enriched) as a response to environmental changes expressed in palaeoflora communities. The total range of δ13C was −26.6‰ to −21.9‰. The overall trend of δ13C progresses to increasing 13C enrichment, corresponding with dull lithotypes (rich in inertinite) which indicate fluctuations in base level. The 13C enrichment peaks at −22.5‰ within the Kaloola Member and shifting rapidly toward a depletion (maximum −26.6‰) of 13C in the upper Bandanna Formation, prior to the P–T boundary. These changes are expressed in palaeoflora communities where ecosystems shifted from dominant Glossopteris flora, to climax community flora including Palaeosmunda, Cycadales and Ginkgo, suited to temperate, early Mesozoic climates. The results of this study represent an insight into the effects of environmental variables on 13C uptake of plants. The identification of flora within coal gives an insight into palaeowetland evolution, and can be partnered with classic petrographical techniques for integrated analysis in coals. Both the geochemistry and the anatomical aspects of coal represent an important tool for future palaeowetland research.

A collaborative approach to address the cumulative impacts of mine-water discharge: Negotiating a cross-sectoral waterway partnership in the Bowen Basin, Australia

The social and environmental impacts of rapidly expanding coal and gas industries have generated high levels of public concern and there is increasing evidence of cumulative impacts. In the Bowen Basin of Queensland (Australia) water quality issues have triggered a collaborative response to coordinate monitoring efforts, integrate data and information and undertake regional analysis to inform landscape-scale management. Collaborative governance is promoted as a response to complex environmental problems, such as cumulative impacts. However, application of this approach to the resources and energy sectors remains a significant research gap. This paper reports the results of action research in the 2 years taken to negotiate the establishment of collaborative governance arrangements to address mine-water discharge impacts in the Bowen Basin. The long establishment phase has been required to refine objectives, build trust, develop governance mechanisms and secure resourcing commitments. The partnership established involves more than 20 organisations including regulators, resources and energy companies, agricultural industries and research organisations. The breadth of participating sectors is a significant innovation, but also represents a major challenge in establishing this model of regional environmental governance. Promising strategies adopted to manage these tensions have included neutral brokerage, facilitative leadership, establishing legitimacy of the collaboration and credibility of its reports. The case study provides a cautionary tale of the pursuit of the promise of ‘everyone working together’ to address cumulative impacts. Policy implications include the need for extended commitment and integration of collaborative and other responses.

Modeling the impact of revegetation on regional water quality: A collective approach to manage the cumulative impacts of mining in the Bowen Basin, Australia

In this paper we quantify the additional water quality benefits that can be achieved through coordinated cumulative impact management. To do this we simulate coordinated and un-coordinated revegetation investments and compare their impact on achieving regional water quality goals. Our results show that coordination between multiple mining companies achieves additional benefits since prioritization is enabled across a broader range of investment opportunities. Additionally, when coordinated investment is permitted beyond the boundaries of coal mining leases, results show that additional benefits are greatly enhanced since these regions provide more rewarding investment opportunities. Results illustrate (a) how regional coordination may influence reputational benefits of investments, and (b) that coordination is beneficial when investment opportunities are unevenly distributed across the landscape. When additional benefits are achievable, we suggest that mining companies should develop collective investment projects with an understanding of how coordination influences project costs. Similarly, investment projects should be developed with an understanding of investment tradeoffs and how these may adversely impact on regional stakeholders and hence industry reputation. The mining industry has significant potential to contribute to regional wellbeing; however, land management policies must be flexible and promote incentives to enable companies to invest beyond compliance.

Distribution and origin of minerals in high-rank coals of the South Walker Creek area, Bowen Basin, Australia

The coals of the South Walker Creek area in the northern Bowen Basin, with a vitrinite reflectance (Rvmax) of 1.7 to 1.95%, are among the highest rank coals currently mined in Australia. X-ray diffraction studies have identified an unusual mineral variation through the vertical sequence, with kaolinite-rich assemblages typical of other Australian coals at the top and bottom of the seam section and an illite–chlorite assemblage resembling a metamorphic association in the middle. Calcite and ankerite are also abundant in parts of the vertical sequence. Diaspore is abundant in the middle section of the seam in some areas, and paragonite, dickite or nacrite occurs in some locations as well.The distribution of the non-carbonate mineral assemblages cross-cuts the seam stratigraphy, and appears to be primarily controlled by faults and other structural features. Integration of the mineral distribution with optical and electron microscope data on the coal and non-coal bands, chemical data from coal ash analysis, and information from X-ray micro-tomography, suggests that the illite–chlorite and diaspore-bearing assemblages resulted from hydrothermal effects associated with fluid migration through the middle part of the coal seam. This is further confirmed by the development of metamorphic textures in a tonstein band, also altered to illite and chlorite, in the illite-rich part of the seam section, in contrast to a tonstein with more normal sedimentary textures and a kaolinite composition in the kaolinite-rich upper part of the seam.Detailed studies of cleat mineralisation suggest that fluids rich in Ca, Mg and Al were introduced relatively early in the seam's post-depositional history, associated with heat flow sufficient to alter the minerals in the coal and tonstein in the affected part of the seam section. The relatively uniform vitrinite reflectance profile observed through the seam section may indicate that the coal was already of high rank before the fluids were introduced, or that any localised heat effects on the organic matter associated with the changes in clay mineralogy were overprinted by subsequent wider-ranging rank advance processes.

The First Four Wells: Unconventional Gas in Australia

The First Four Wells: Unconventional Gas in Australia

Classifying dragline swing dependencies using coincident limit graphs

Dragline productivity is strongly influenced by swing cycle times, comprising between 60–70% of all dragline operational time. The ability to classify and report on dragline swing cycles according to their limiting motion is essential for identifying performance losses and deriving continuous improvements. This paper presents an algorithm for the automatic classification of dragline cycle dependencies. The algorithm adopts a simple graphical approach, based on coincident limits defined by the locus of points where the swing and hoist motors work at full capacity for equivalent time periods. The algorithm is capable of distinguishing three cycle dependencies; swing, hoist, and drag limited cycles. The coincident limit algorithm was applied on a dragline at a coal mine in Queensland’s Bowen Basin. A data set of 200 000 cycles consisted of: 70% swing limited cycles; 27% hoist limited cycles and 3% drag limited cycles. The coincident limit algorithm permits an equivalent swing angle to be calculated for draglines in hoist limited situations. This facilitates the possibility of measuring dragline work as BCMs multiplied by the equivalent swing angle. This measure could potentially be applied to benchmark the performance of draglines in different operational contexts in which varied pit and block geometries influence the proportion of hoist limited cycles.

Lonchiphyllum aplospermum gen. et sp. nov.: An Anatomically Preserved Glossopterid Megasporophyll from the Upper Permian of Skaar Ridge, Transantarctic Mountains, Antarctica

A new anatomically preserved megasporophyll, Lonchiphyllum aplospermum, is described from permineralized peat collected on Skaar Ridge in the central Transantarctic Mountains. This new genus contains vascular features similar to those of the leaf genus Glossopteris schopfii, which is the exclusive leaf genus in the specimens in which the sporophylls were found. The vasculature of the sporophyll consists of a central vascular region with bordered pitting and anastomosing lateral bundles with helical-scalariform thickenings. Ovules are attached oppositely to suboppositely to lateral veins on the adaxial surface of the sporophyll. There is an abundance of bisaccate pollen of the Protohaploxypinus type at the base of the ovules. The ovules of Lonchiphyllum are small (1.1 mm × 0.97 mm) and ovate and have an unornamented integument. Comparison with anatomically known ovules from Skaar Ridge, i.e., Plectilospermum elliotii, Choanostoma verruculosum, and Lakkosia kerasata and Homevaleia gouldii from the Bowen Basin of Australia, supports the classification of Lonchiphyllum as a glossopterid. The differences in the sarcotesta and sclerotesta of all the Skaar Ridge ovules may indicate specialization for pollination or dispersal.

Carbon dioxide-rich coals of the Oaky Creek area, central Bowen Basin: a natural analogue for carbon sequestration in coal systems

High-CO2-containing coal seams in the Oaky Creek area of the Bowen Basin, eastern Australia provide natural analogues of the processes likely to occur as a result of CO2 injection and storage in coal systems. We conducted mineralogical, stable and radiogenic isotope and major element analyses of mudstones and sandstones adjacent to the coal seams and stable isotope and compositional studies of coal seam gas desorbed from the coals to establish the impact of the high CO2 levels and the mechanisms that keep the CO2 naturally sequestered. Siderite is the earliest carbonate phase present and occurs with kaolinite in mudstones and sandstones. It is interpreted to have formed under low-temperature, reducing conditions where methanogenesis has produced residual 13C-enriched CO2. Enhanced kaolinite concentrations adjacent to a low-CO2-containing coal seam reflect interaction with acidic fluids produced during the coalification of organic matter. Stable isotope data for carbonates and Rb–Sr isochron ages for illitic clays indicate that illitic clay–carbonate assemblages adjacent to both coal seams formed as a result of meteoric hydrothermal activity in the Upper Triassic with more intensive mineralogical reactions evident in the high-CO2 coals. The present-day CO2 in the high-CO2 coals at Oaky Creek was emplaced in the Upper Triassic based on dating of illitic clay minerals from the high-CO2 well and is magmatic or deep crustal in origin. Methane in the coals is of mixed origin, with secondary biogenic CH4 formed by microbial reduction of CO2 predominant in the high-CO2 coals. This suggests that methanogenesis may provide an additional sequestration mechanism for CO2 in coal seams.

Geostatistical drillhole spacing analysis for coal resource classification in the Bowen Basin, Queensland

Geostatistical drill hole spacing analysis (‘DHSA’) for resource classification using the global estimation variance technique has been used across BHP Billiton Mitsubishi Alliance (‘BMA’) Coal Operation's various mines and projects since 2004. Analysis of the results points to the emergence of possible patterns in the results for projects pertaining to specific coal measures being mined by BMA. This correlation may be a useful guide to assist in developing resource classifications for projects based on the coal measures in which they occur. Comparison of the results of classification using the Coal Guidelines versus classification using the geostatistical DHSA method for a selection of BMA's operating mines in Queensland's Bowen Basin indicates that the non-geostatistical approach leads to level of uncertainty that does not always agree with the complexity of the geology.

Dynamic Models of CO2 Injection in the Surat and Bowen Basins, Queensland, Australia

In three radial models (typical of the Trelinga-1, Overston-1 and Moonie-39 wells) with boundaries placed at different distances, injection rates of 2 million tonnes per annum (Mt/a) cannot be sustained. In larger sector models, (with parameters typical of these three wells) injection of 2Mt/a is sustained in the Precipice Sandstone (Surat Basin), but reduces to 1.2Mt/a in the Showgrounds Sandstone (Bowen Basin). Plume footprints and overpressures range 10- 15km and 35-75bar, respectively. Baffles cause maximum overpressure and CO2 accumulation to occur underneath the seal at different times. Critical techno-economic areas of uncertainty for storage performance are revealed and thus inform exploration data acquisition strategy.

First South Australian Labyrinthodont: A Possible Chigutisaurid Stereospondyl Amphibian from the Late Triassic at Leigh Creek

Labyrinthodont fossils are recorded from most Australian states (Warren 2006), most particularly from Queensland (Bowen Basin; Warren idem), Western Australia (Canning Basin; Cosgriff 1965) and the Tasmanian Basin (Cosgriff 1974). The oldest is Metaxygnathus from the Devonian of New South Wales, and most have been of early to middle Triassic age, but some have been younger: Siderops kehli (Warren & Hutchinson 1983) is from the early Jurassic of Queensland, and Koolasuchus cleelandi (Warren et al. 1997) is from the early Cretaceous of Victoria. Few species are known in Australia between the early Triassic and the early Jurassic, so any Late Triassic find is noteworthy.This note records the presence of an unidentified, possible chugutisaurid, stereospondyl from the upper Triassic coal measures at Leigh Creek, Northern Flinders Ranges, noted in passing by Warren (2006:233). The specimen comprises the compressed anterior torso of an individual estimated to be roughly 2 m. long, preserved in a block of carbonaceous oil-shale. Extremities were not found.

An investigation of statics correction methods for 3D PS-wave seismic reflection

In the last decade converted-wave (PS-wave) seismic reflection studies have successfully demonstrated that a more complete geological interpretation can be obtained by integrated interpretation of P-wave and S-wave information, at both the petroleum and coal scales. Full 3D implementation of PS reflection presents particular challenges at the coal scale, because relative offsets and dominant frequencies are both large compared to petroleum-scale reflection. One of the most difficult steps in the PS processing sequence is estimation of the S-wave receiver statics. Statics are time delays caused by variations in the weathering layer, and changes in source and receiver elevation. These time errors can significantly degrade CMP stack quality, and the final geological interpretation of seismic images. Static errors tend to be much more significant in PS surveys since the S wave travels more slowly through the weathering layer and is therefore more likely to be affected by variations within this layer. In this presentation we evaluate of a number of different approaches for estimating 3D PS statics solutions. These include a surface-consistent inversion algorithm (analogous to the residual-statics method used in conventional P-wave processing), a so-called 'robust-statistical' method, and PPS refraction analysis. The methods are evaluated using a coal-scale 3D-3C survey acquired in the Bowen Basin. This has been used to examine the comparative performance, and the influence of various algorithmic and geological factors. The results indicate that the surface-consistent inversion method can fail under some weathering conditions. When this occurs the refraction based method or a robust statistical method are preferred.

Interburden mapping using 3D seismic attributes at an underground coal mine, Bowen Basin, Queensland

SUMMARY Six high resolution 3D seismic surveys comprising approximately 31 km 2 were recorded for an underground coal mine in the Permian aged Bowen Basin Central Queensland. The colliery had previously interpreted the data with view to identifying hazards at the mined seam level. The seismic data and an extensive set of borehole data were made available for a Masters Project at the Queensland University of technology with the focus being to study the geology of the interburden. This paper discusses the background to the seismic surveys and the work flow used for the interburden mapping. Conclusions and recommendations are drawn