Stromatolite framework builders of a Cryogenian reef

The development of a carbonate reef on the eastern margin of the Adelaide Geosyncline in a period bracketed by two mid-Neoproterozoic (Cryogenian) global glaciations reflects the concurrence of extrinsic factors, including: low (~ 8°) palaeolatitudal position, palaeotopographic situation at a rift margin, relative sea level shallowing following prolonged basin wide post-glacial transgression, and likely reestablishment of seawater carbonate saturation following post-glacial carbonate sequestration as 'cap carbonate' immediately succeeding the earlier Sturtian glaciation. Conditions conducive to carbonate precipitation, deposition and preservation, therefore, facilitated initiation and sustained growth of an ~350 m thick carbonate reef with a framework dominated by a variety of stromatolite forms. Detailed field mapping along with cross-sectional exposure through the internal architecture of Arkaroola reef in the northern Flinders Ranges, South Australia, reveals a spatially and temporally variable stromatolite assemblage. The range of forms reflects ecological succession from microbial biostrome colonization through to a climax community of domal, columnar and digitate stromatolite forms. Growth of wrinkly-laminated, m-thick, microbial biostromes, 10s to 100s m in extent, initiated development of a stable carbonate substrate on underlyingthick muds. These biostromes mark the windward margin of anincipient reef, with spatial arrangements similar to spur and groove structures of modern windward reef margins. Once stabilised, a robust reef framework developed, first through growth of 1-3 m-scale domical and linked columnar stromatolites forming large stacked bioherms of many metres topographic relief at the reef front. This biological modification of local environmental conditions lead to an ecological succession of stromatolite forms in response to substrate stabilization, wave-energy bafflingand aggradationally driven shallowing. The spatial and stratigraphic distributionof a range of centimetre-to decimetre-scale columnar, domal and digitate stromatolites, in conjunction with intraclastic, peloidal and oolitic grainstone and packstone facies characterises development of a reef flat and leeward lagoon. Variability of stromatoliteforms across the reef morphology indicates ecological adaptation of function and structure responding to local differences in factors such as light, nutrient supply, hydrodynamics, water clarity and tidal exposure.Microbial (stromatolite) growth in a range of forms overwhelming controlled carbonate production resulting in both a biogenic framework and eroded and redistributed bioclast deposits across the reef. The range ofstromatolite forms and their facies distribution within the reef is consistent with biological control on ecosystem developmentand stabilisationas seen in Phanerozoic and modern reef ecosystems. The Arkaroola reef exhibits analogous ecological succession in a late Proterozoic stromatolite evolutionaryealm. Furthermore, Arkaroola reef records a period of relative climatic and sea level stability in a geological period notable for severe climatic upheaval

Future Understanding of Tectonics, Ores, Resources, Environment and Sustainability (FUTORES) II Conference: abstract volume

With the increasing world population and living standards the demand for mineral and energy resources continues to grow. Future exploration will need to target resources at increasing depths and in areas with cover, and will require an improved understanding of mineral and energy systems and advances in exploration methods and approaches. The Economic Geology Research Centre (EGRU) at James Cook University has organized the FUTORES II conference to summarise recent developments in the exploration and understanding of major types of mineral deposits, to examine the key issues and techniques critical to future minerals and energy exploration, and to discuss the way forward. The conference is being held in tropical Townsville, Queensland, Australia, on 4-7 June 2017. It is following on from the inaugural and highly successful FUTORES conference held in Townsville in 2013.FUTORES II will bring together researchers, explorers and government agencies to address issues related to the sustainable supply and utilisation of mineral and energy resources. The conference has three symposia: the David Groves Symposium - New Insights in Mineral Deposit Understanding, the New Technologies and Approaches in Mineral Exploration Symposium, and the Tectonics, Basins and Resources Symposium. The conference is convened by EGRU, an organisation that was established in 1982 to strengthen the links between research and exploration, to promote exploration-oriented research, and to facilitate knowledge transfer. EGRU has a track record of organising successful major conferences to facilitate the exchange of knowledge and ideas and to stimulate new ideas for cutting-edge research and exploration. The Hydrothermal Odyssey conference in 2001, and the STOMP (Structure, Tectonics and Ore Mineralization Processes) conference in 2005, both attracted over 200 participants. In 2009 EGRU collaborated with the SGA to host the tenth biennial SGA conference in Townsville - Smart Science for Exploration and Mining - which attracted over 480 delegates from around the world. In 2013 the first FUTORES conference attracted around 250 participants from 15 countries. FUTORES II is looking to be equally successful and has so far attracted around 265 registrants. This conference abstract volume contains 134 abstracts covering a wide range of topics related to mineral and energy resources, tectonics and metallogenesis. The abstracts have been reviewed and edited by the Editorial Committee and, in this volume, are organised in alphabetical order of the first author. We thank the delegates for their abstracts and the reviewers for ensuring the quality of the abstract volume

Deposition and palaeogeography of a glacigenic Neoproterozoic succession in the east Kimberley, Australia

Facies, provenance and palaeocurrent analysis of the predominantly siliciclastic Neoproterozoic succession of the east Kimberley district of northwestern Australia indicates southwesterly-directed regional palaeoice-flow directions associated with continental glaciation. Facies relationships at three key study sites in the east Kimberley record glacial advance, retreat and marine transgression and the likely effects of ice dynamics on local basin depositional history. Ice-scour linked with provenance data indicate ice advance from the northeast. Additional ice-flow data from the west Kimberley and the Daly River area of Northern Territory are consistent and record a regional palaeoice-flow direction towards the southwest. Palaeocurrent data and facies relationships in the east Kimberley, however, suggest that sediment transport directions within the east Kimberley basin were influenced by a combination of ice-induced lithospheric flexure, pre-existing topography and modification of basin topography and sediment dispersal paths by ice-induced redistribution of debris. A basin evolution model incorporating these concepts within the framework of ice advance, retreat and marine inundation is proposed. Identification of regional ice-flow trends of this scale should ultimately prove a useful tool in testing possible palaeogeographic reconstructions of continent configurations in a post-Rodinian world

Assessment of geogenic contaminants in water co-produced with coal seam gas extraction in Queensland, Australia: implications for human health risk

Organic compounds in Australian coal seam gas produced water (CSG water) are poorly understood despite their environmental contamination potential. In this study, the presence of some organic substances is identified from government-held CSG water-quality data from the Bowen and Surat Basins, Queensland. These records revealed the presence of polycyclic aromatic hydrocarbons (PAHs) in 27% of samples of CSG water from the Walloon Coal Measures at concentrations <1 µg/L, and it is likely these compounds leached from in situ coals. PAHs identified from wells include naphthalene, phenanthrene, chrysene and dibenz[a,h]anthracene. In addition, the likelihood of coal-derived organic compounds leaching to groundwater is assessed by undertaking toxicity leaching experiments using coal rank and water chemistry as variables. These tests suggest higher molecular weight PAHs (including benzo[a]pyrene) leach from higher rank coals, whereas lower molecular weight PAHs leach at greater concentrations from lower rank coal. Some of the identified organic compounds have carcinogenic or health risk potential, but they are unlikely to be acutely toxic at the observed concentrations which are almost negligible (largely due to the hydrophobicity of such compounds). Hence, this study will be useful to practitioners assessing CSG water related environmental and health risk

Dryland salinity and vector-borne disease emergence in southwestern Australia

Broad-scale clearing of native vegetation for agriculture in southwestern Australia has resulted in severe ecosystem degradation, which has been compounded by the subsequent development of large areas of dryland salinity; decreased transevaporation allows the water table to rise, dissolving ancient aeolian salt deposits and creating saline surface pools. The mosquito-borne disease Ross River virus has been noted as a potential adverse human health outcome in salinity-affected regions because the principal vector, Aedes camptorhynchus, is salt tolerant and thrives preferentially in such systems. To understand the geology and ecology underlying the relationship between land clearing and disease emergence, we examine the relationship between dryland salinity processes that determine the dissolved solids profile of saline pools in affected areas, the mosquito vectors and interactions with the human population within the disease cycle. Aedes camptorhynchus is able to survive in a wide range of salinities in pools created by dryland salinity processes. The link with disease emergence is achieved where population distribution and activity overlaps with the convergence of environmental and ecological conditions that enhance disease transmission

Melioidosis case clusters in a tropical urban setting: association with soil type and geomorphology

Geospatial analysis of the distribution of clinical cases of melioidosis, an often fatal tropical disease, in the\ud Townsville region indicated case clustering in distinct geomorphic settings and characteristic soil associations. Two significant clusters were identified. Cluster 1 is associated with piedmont slopes adjacent to granitic hill and mountain slopes. The soils developed on colluvium are typically Kandosols with dark grey-brown loamy sand to silty loam A horizon, grading into dark red or yellow sandy clay loam to sandy clay subsoils. Cluster 2 is associated with Pleistocene floodplains, levees and channel-fill. The duplex soils typically grade from acidic to alkaline at depth. These soils are poorly draining due to a shallow\ud impermeable B horizon in Sodosols. It is postulated that the two geomorphic positions and soil types are predisposed to soil wetness following periods of intense rainfall. Cluster 1 is located where large amounts of runoff are received from the adjacent granitic hill, whereas Cluster 2 associates with poorly drained soils at the lower edges of poorly drained alluvial plains. This preliminary study has generated the hypothesis that melioidosis distribution in the Townsville region is controlled by environmental factors, specifically soil type, geomorphic position and drainage. A detailed multidisciplinary field-based study investigating soil physico-chemical features, field isolates of Burkholderia pseudomallei, and epidemiological considerations is now underway to test this hypothesis

Discriminating stromatolite formation modes using rare earth element geochemistry: Trapping and binding versus in situ precipitation of stromatolites from the Neoproterozoic Bitter Springs Formation, Northern Territory, Australia

Stromatolites consist primarily of trapped and bound ambient sediment and/or authigenic mineral precipitates, but discrimination of the two constituents is difficult where stromatolites have a fine texture. We used laser ablation-inductively coupled plasma-mass spectrometry to measure trace element (rare earth element – REE, Y and Th) concentrations in both stromatolites (domical and branched) and closely associated particulate carbonate sediment in interspaces (spaces between columns or branches) from bioherms within the Neoproterozoic Bitter Springs Formation, central Australia. Our high resolution sampling allows discrimination of shale-normalised REE patterns between carbonate in stromatolites and immediately adjacent, fine-grained ambient particulate carbonate sediment from interspaces. Whereas all samples show similar negative La and Ce anomalies, positive Gd anomalies and chondritic Y/Ho ratios, the stromatolites and non-stromatolite sediment are distinguishable on the basis of consistently elevated light REEs (LREEs) in the stromatolitic laminae and relatively depleted LREEs in the particulate sediment samples. Additionally, concentrations of the lithophile element Th are higher in ambient sediment samples than in stromatolites, consistent with accumulation of some fine siliciclastic detrital material in the ambient sediment but a near absence in the stromatolites. These findings are consistent with the stromatolites consisting dominantly of in situ carbonate precipitates rather than trapped and bound ambient sediment. Hence, high resolution trace element (REE + Y, Th) geochemistry can discriminate fine-grained carbonates in these stromatolites from coeval non-stromatolitic carbonate sediment and demonstrates that the sampled stromatolites formed primarily from in situ precipitation, presumably within microbial mats/biofilms, rather than by trapping and binding of ambient sediment. Identification of the source of fine carbonate in stromatolites is significant, because if it is not too heavily contaminated by trapped ambient sediment, it may contain geochemical biosignatures and/or direct evidence of the local water chemistry in which the precipitates formed

Survival, sublethal injury and recovery of environmental Burkholderia pseudomallei in soil subjected to desiccation

Environmental Burkholderia pseudomallei isolated from sandy soil at Castle Hill, Townsville, in the dry tropic region of Queensland, Australia, was inoculated into sterile-soil laboratory microcosms subjected to variable soil moisture. Survival and sublethal injury of the B. pseudomallei strain were monitored by recovery using culture-based methods. Soil extraction buffer yielded higher recoveries as an extraction agent than sterile distilled water. B. pseudomallei was not recoverable when inoculated into desiccated soil but remained recoverable from moist soil subjected to 91 days desiccation and showed a growth response to increased soil moisture over at least 113 days. Results indicate that endemic dry tropic soil may act as a reservoir during the dry season, with an increase in cell number and potential for mobilization from soil into water in the wet season

Seismic acquisition parameters to improve imaging beneath mafic igneous units: case study from Australia's Northwest Shelf

Mafic igneous units within sedimentary basins can be widespread and severely attenuate seismic reflection data. Attenuation obscures imaging of sub-igneous sedimentary units, impeding exploration in prospective and frontier basins. This study compared historical 2D seismic surveys and found two seismic acquisition parameters that have the greatest influence when imaging beneath mafic igneous rocks in offshore and onshore basins from Australia's Northwest Shelf. These parameters were found by using a 3D model developed with integrated 2D seismic and well data in the Browse, North Carnarvon, Onshore and Offshore Canning basins. Simultaneously comparing the 2D seismic lines in 3D space revealed that the surveys with the longest, streamer length and the most receivers are the most effective at imaging beneath igneous units. Additionally, we identified potential depocenters obscured by igneous horizons from a regional basement map. These depocenters correlate with older basins that are infilled by pre-rift, Paleozoic sediment and capped by mafic igneous rocks formed during late Permian-Mesozoic rifting events. Much of the Northwest Shelf maintains a frontier status, but exploration outcomes can be improved. Therefore, maximising streamer length and number of receivers to future seismic surveys can result in more effective exploration opportunities in basins with known igneous occurrences