Late Devonian mass extinctions attributed to extensive anoxia and/or euxinia of the oceans are associated with widespread deposition of organic-rich shales. Also in the epeiric waters of the Canning Basin (Western Australia), photic zone euxinia (PZE) prevailed during the Givetian–Frasnian, with geochemical evidence for PZE on the northern (Lennard Shelf)–, and southern (Barbwire Terrace) margins of the Fitzroy Trough. On the Lennard Shelf, shales record episodic pulses of PZE associated with high algal activity due to enhanced nutrient supply, whereas a restricted marine setting on the Barbwire Terrace is thought to be the main driver for the development of persistent PZE and associated bacterial predominance. Structural evidence indicates that the Fitzroy Trough was a confined basin during the Late Devonian with the possibility of limited ocean circulation. Widespread PZE is expected to have developed in the poorly mixed water column, if the basin received sufficient nutrient supply for enhanced primary production. Notwithstanding the presence of anoxia during deposition of potential source rocks, only two small Devonian-sourced oil fields and numerous oil shows have been found in the Canning Basin. Biomarker assemblages show that the oils produced from the Lennard Shelf fields (i.e. Blina-1, Blina-4 and Janpam North-1) have substantially different molecular compositions to the minor oil recovered from Mirbelia-1 on the Barbwire Terrace. A correlation was established between the Lennard Shelf oils and rock extracts from the Gogo Formation at Blina-1 and McWhae Ridge-1 based on their hopane, sterane and carotenoids abundances. A definitive source correlation was not obtained for the Mirbelia-1 oil, but it did show some genetic affinity to the Givetian–Frasnian extracts from the Barbwire Terrace, suggesting that local source rocks are developed in the region. <b>Citation:</b> Gemma Spaak, Dianne S. Edwards, Heidi J. Allen, Hendrik Grotheer, Roger E. Summons, Marco J.L. Coolen, Kliti Grice, Extent and persistence of photic zone euxinia in Middle–Late Devonian seas – Insights from the Canning Basin and implications for petroleum source rock formation, <i>Marine and Petroleum Geology</i>, Volume 93, 2018, Pages 33-56, ISSN 0264-8172, https://doi.org/10.1016/j.marpetgeo.2018.02.033.

<p>A geochemical study was conducted to establish oil-oil correlations and evaluate potential source rocks within the latest Devonian–earliest Carboniferous succession of the onshore Canning Basin, Western Australia. Aromatic hydrocarbons, together with the routinely used saturated biomarker ratios and stable carbon isotopes, demonstrate that the recently discovered Ungani oilfield located on the southern margin of the Fitzroy Trough are similar, but not identical, to the early Carboniferous Larapintine 4 (L4) oil family present to the north of the Fitzroy Trough on the Lennard Shelf. The L4 oil family has been correlated to a lower Carboniferous (Tournaisian) source rock core sample from the Laurel Formation at Blackstone-1 although its bulk geochemical properties signify that it could generate substantially more gas than liquid hydrocarbons. <p>The Ungani oils can be distinguished from the L4 oils by their higher concentrations of paleorenieratane and isorenieratane, coupled with more depleted &delta;¹³C values for n-alkanes, pristane and phytane compared with other components. Hopane isomerisation ratios show distinct grouping of the two oil families that reflect both source and maturity variations. The oil from Wattle-1 ST1 on the Lennard Shelf also has an unusual composition, exhibiting some molecular and isotopic features similar to both the L4 and Ungani oils. Source rocks for the Ungani and Wattle-1 ST1 oils are unknown since their geochemical signature does not match that of the Tournaisian Laurel Formation or the Middle−Upper (Givetian–Frasnian) Devonian Gogo Formation which sourced the Devonian-reservoired Larapintine 3 oils at Blina and Janpam North-1. It is postulated that such potential oil-prone source rocks could occur within the Famennian–Tournaisian succession. <b>Citation:</b> Gemma Spaak, Dianne S. Edwards, Clinton B. Foster, Andrew Murray, Neil Sherwood, Kliti Grice, Geochemical characteristics of early Carboniferous petroleum systems in Western Australia,<i> Marine and Petroleum Geology</i>, Volume 113, 2020, 104073, ISSN 0264-8172. https://doi.org/10.1016/j.marpetgeo.2019.104073

<div>Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia, in partnership with state and Northern Territory governments, and aimed at stimulating exploration now to ensure a sustainable, long-term future for Australia through an improved understanding of the nation’s minerals, energy and groundwater resource potential. </div><div>The EFTF program is currently focused on eight interrelated projects, united in growing our understanding of subsurface geology. One of these projects, the Barkly–Isa–Georgetown project, will deliver new data and knowledge to assess the mineral and energy potential in undercover regions between Tennant Creek, Mount Isa and Georgetown. Building on the work completed in the first four years of the Exploring for the Future program (2016-2020), the project undertook stratigraphic drilling in the East Tennant and South Nicholson regions, in collaboration with MinEx CRC and the Northern Territory Geological Survey (NTGS). This work tests geological interpretations and the inferred mineral and energy potential of these covered regions. Geoscience Australia is undertaking a range of analyses on physical samples from these drill holes including geochemistry and geochronology. </div><div>The South Nicholson National Drilling Initiative (NDI) Carrara 1 drill hole is the first drillhole to intersect the Proterozoic rocks of the Carrara Sub-Basin, a depocentre newly discovered in the South Nicholson region based on interpretation from seismic surveys acquired as part of the EFTF. It is located on the western flanks of the Carrara Sub-basin on the South Nicholson Seismic line 17GA-SN1, reaching a total depth of 1751 m, intersecting ca. 630 m of Cambrian Georgina Basin overlying ca. 1100 m of Proterozoic carbonates, black shales and minor siliciclastics.</div><div>The NDI BK10 drill hole is the tenth drill hole drilled as part of the East Tennant project aimed to constrain the East Tennant basement geology and calibrate predictive mineral potential maps to further our understanding of the prospectivity of this region. NDI BK10 reached a depth of 766 m and intersected basement at 734 m. Overlying these basement metasediments of the Alroy Formation, the drillhole intersected about 440 m of Proterozoic rocks underlain by ca. 300 m rocks of Cambrian age from the Georgina Basin.</div><div>During coring of NDI Carrara 1 and NDI BK10, cores containing oil stains were identified and sent for geochemical analysis to Geoscience Australia. This report presents the geochemical data from these oil stains including biomarker and isotopic data.</div>

The Great Ordovician Biodiversification Event (GOBE) is regarded as one of the most significant evolutionary events in the history of Phanerozoic life. The present study integrates palynological, petrographic, molecular and stable isotopic (&delta;¹³C of biomarkers) analyses of cores from four boreholes that intersected the Goldwyer Formation, Canning Basin, Western Australia, to determine depositional environments and microbial diversity within a Middle Ordovician epicontinental, tropical sea. Data from this study indicate lateral and temporal variations in lipid biomarker assemblages extracted from Goldwyer Formation rock samples. These variations likely reflect changing redox conditions between the upper (Unit 4) and lower (Units 1 + 2) Goldwyer, which is largely consistent with existing depositional models for the Goldwyer Formation. Cryptospores were identified in Unit 4 in the Theia-1 well and are most likely derived from bryophyte-like plants, making this is the oldest record of land plants in Australian Middle Ordovician strata. Biomarkers in several samples from Unit 4 that also support derivation from terrestrial organic matter include benzonaphthofurans and δ¹³C-depleted mid-chain n-alkanes. Typical Ordovician marine organisms including acritarchs, chitinozoans, conodonts and graptolites were present in the lower and upper Goldwyer Formation, whereas the enigmatic organism <i>Gloeocapsomorpha prisca </i>(<i>G. prisca</i>) was only detected in Unit 4. The correlation of a strong <i>G. prisca</i> biosignature with high 3-methylhopane indices and ¹³C depleted <i>G. prisca</i>–derived chemical fossils (biomarkers) is interpreted to suggest an ecological relationship between methanotrophs and <i>G. prisca</i>. This research contributes to a greater understanding of Ordovician marine environments from a molecular perspective since few biomarker studies have been undertaken on age-equivalent sections. Furthermore, the identification of the oldest cryptospores in Australia and their corresponding terrestrial biomarkers provides further insight into the geographical distribution and evolution of early land plants. <b>Citation:</b> Gemma Spaak, Dianne S. Edwards, Clinton B. Foster, Anais Pagès, Roger E. Summons, Neil Sherwood, Kliti Grice, Environmental conditions and microbial community structure during the Great Ordovician Biodiversification Event; a multi-disciplinary study from the Canning Basin, Western Australia, <i>Global and Planetary Change</i>, Volume 159, 2017, Pages 93-112, ISSN 0921-8181 https://doi.org/10.1016/j.gloplacha.2017.10.010.

<p>Geoscience Australia's Oracle organic geochemical database comprises analytical results for samples relevant to petroleum exploration, including source rocks, crude oils and natural gases collected across the Australian continent. The data comprises organic chemical analyses of hydrocarbon-bearing earth materials as well as including connectivity to some inorganic analyses. These data enable petroleum fluids to be typed into families and correlated to their source rock, from which depositional environment, age, and migration distances can be determined, and hence the extent of the total petroleum system can be mapped. This comprehensive data set is useful to government for evidence-based decision making on natural resources and the petroleum industry for de-risking conventional and unconventional petroleum exploration programs. <p>The data are produced by a wide range of analytical techniques. For example, source rocks are evaluated for their bulk compositional characteristics by programmed pyrolysis, pyrolysis-gas chromatography and organic petrology. Natural gases are analysed for their molecular and isotopic content by gas chromatography (GC) and gas chromatography-temperature conversion-mass spectrometry (GC-TC-IRMS). Crude oils and the extracts of source rocks are analysed for their bulk properties (API gravity; elemental analysis) and their molecular (biomarkers) and isotopic (carbon and hydrogen) content by GC, gas chromatography-mass spectrometry (GCMS) and GC-TC-IRMS. <p>The sample data originate from physical samples, well completion reports, and destructive analysis reports provided by the petroleum industry under the Offshore Petroleum and Greenhouse Gas Storage Act (OPGGSA) 2006 and previous Petroleum (submerged Lands) Act (PSLA) 1967. The sample data are also sourced from geological sampling programs in Australia by Geoscience Australia and its predecessor organisation's Australian Geological Survey Organisation (AGSO) and Bureau of Mineral Resources (BMR), and from the state and territory geological organisations. Geoscience Australia generates data from its own laboratories. Other open file data from publications, university theses and books are also included <b>Value:</b> The organic geochemistry database enables digital discoverability and accessibility to key petroleum geochemical datasets. It delivers open file, raw petroleum-related analytical results to web map services and web feature services in Geoscience Australia’s portal. Derived datasets and value-add products are created based on calculated values and geological interpretations to provide information on the subsurface petroleum prospectivity of the Australian continent. For example, the ‘Oils of Australia’ series and the ‘characterisation of natural gas’ reports document the location, source and maturity of Australia’s petroleum resources. Details of the total petroleum systems of selected basins studied under the Exploring for the Future project can be found in the Petroleum Systems Summaries Tool in Geoscience Australia’s portal. Related Geoscience Australia Records and published papers can be obtained from eCat. <b>Scope:</b> The collection initially comprised organic geochemical and petrological data on organic-rich sedimentary rocks, crude oils and natural gas from petroleum wells drilled in the onshore and offshore Australian continent. Over time, other sample types (ground water, fluid inclusions, mineral veins, bitumen) from other borehole types (minerals, stratigraphic – including the Integrated Ocean Drilling Program), marine dredge samples and field sites (outcrop, mines, surface seepage samples) have been analysed for their hydrocarbon content and are captured in the database. Results for many of the oil and gas samples held in the Australian National Offshore Wells Data Collection are included in this database.

The unexpected discovery of oil in Triassic sedimentary rocks of the Phoenix South 1 well on Australia’s North West Shelf (NWS) has catalysed exploration interest in pre-Jurassic plays in the region. Subsequent neighbouring wells Roc 1–2, Phoenix South 2–3 and Dorado 1–3 drilled between 2015 and 2019 penetrated gas and/or oil columns, with the Dorado field containing one of the largest oil resources found in Australia in three decades. This study aims to understand the source of the oils and gases of the greater Phoenix area, Bedout Sub-basin using a multiparameter geochemical approach. Isotopic analyses combined with biomarker data confirm that these fluids represent a new Triassic petroleum system on the NWS unrelated to the Lower Triassic Hovea Member petroleum system of the Perth Basin. The Bedout Sub-basin fluids were generated from source rocks deposited in paralic environments with mixed type II/III kerogen, with lagoonal organofacies exhibiting excellent liquids potential. The Roc 1–2 gases and the Phoenix South 1 oil are likely sourced proximally by Lower–Middle Triassic TR10–TR15 sequences. Loss of gas within the Phoenix South 1 fluid due to potential trap breach has resulted in the formation of in-place oil. These discoveries are testament to new hydrocarbon plays within the Lower–Middle Triassic succession on the NWS.

The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the Offshore Energy Studies section. This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and facilitate exploration investment in Australia. The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018), Dorado 1 (2018), Dorado 2 (2019) and Dorado 3 (2019) wells in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata (Thompson, 2020; Thompson et al., 2015 and 2018). The current study aims to better understand this new petroleum system and establish its extent. As part of this program, a range of organic geochemical analyses were acquired on source rocks from the Roc 2 well with these data released in this report.

A regional hydrocarbon prospectivity study was undertaken in the onshore Canning Basin in Western Australia as part of the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to driving investment in resource exploration. As part of this program, significant work has been carried out to deliver new pre-competitive data including new seismic acquisition, drilling of a stratigraphic well, and the geochemical analysis of geological samples recovered from exploration wells. A regional, 872 km long 2D seismic line (18GA-KB1) acquired in 2018 by Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), images the Kidson Sub-basin of the Canning Basin. In order to provide a test of geological interpretations made from the Kidson seismic survey, a deep stratigraphic well, Barnicarndy 1, was drilled in 2019 in a partnership between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) in the Barnicarndy Graben, 67 km west of Telfer, in the southwest Canning Basin. Drilling recovered about 2100 m of continuous core from 580 mRT to the driller’s total depth (TD) of 2680.53 mRT. An extensive analytical program was carried out to characterise the lithology, age and depositional environment of these sediments. This data release presents organic geochemical analyses undertaken on rock extracts obtained from cores selected from the Barnicarndy 1 well. The molecular and stable isotope data carbon and hydrogen will be used to understand the type of organic matter being preserved, the depositional facies and thermal maturity of the Lower Ordovician sedimentary rocks penetrated in this well. This information provides complementary information to other datasets including organic petrological and palynological studies.

<p>The Early Paleozoic, specifically the Middle Ordovician, marks a significant period in Earth's history due to the appearance and diversification of life on land. Plant megafossil records indicate vascular plants first appeared in the Early Silurian and by Devonian times had diversified rapidly (e.g. Wellman and Gray, 2000; Steemans et al., 2009; Kenrick et al., 2012; Strother, 2016). However non-vascular plants (bryophytes) predating vascular plants are rarely preserved as body fossils and the bryophyte microfossil record in the lowermost Palaeozoic is scarce. This lack of fossil data severely limits our understanding of life in the earliest non-marine environments and the origin of land plants. <p>In comparison to microfossils, molecular fossils (biomarkers) are more ubiquitous in the sedimentary record and have a higher preservation potential, thus providing a powerful tool to track terrestrial signals when microfossils are either scarce or absent. Molecular proxies such as long chain n-alkanes have been used extensively in both modern and ancient environments to identify terrestrial contributions to the organic matter (e.g. Eglinton and Hamilton, 1967; Ficken et al., 2000; Hautevelle et al., 2006). Furthermore, the isotopic composition of these molecules can be used to further distinguish between sources (e.g. Bird et al., 1995; Sikes et al., 2009; Rouillard et al., 2016). That being said, only relatively few studies have combined palynological evidence with geochemical proxies to assess geochemical signatures of early land plants. <p>This work presents biomarker and palynological data of the Middle Ordovicianupper Goldwyer Formation which records the earliest occurrence of land plant microfossils (cryptospores) in Australia. The higher-molecular-weight n-alkane distributions and their isotopic compositions recorded in the upper Goldwyer show high resemblances to modern day bryophytes and aquatic macrophytes. Retene, a biomarker conventionally used as a proxy for gymnosperms, was also identified in some extracts. The presence of retene in Middle Ordovician (this work) and Silurian (Romero-Sarmiento et al., 2010) rocks indicates conifers are not the sole source of this compound. <p>Linking biomarkers and palynology has shown to beuseful in the study of early land plants where fossil records are sparse. Molecular and isotopic proxies distinctive of these plants can provide a more complete record of the geographical distribution of early land plants, providing useful information to understand their early evolution. <p>Bird, M.I., Summons, R.E., Gagan, M.K., Roksandic, Z., Dowling, L., Head, J., Fifield, L.K., Cresswell, R.G., Johnson, D.P., 1995. Terrestrial vegetation change inferred from n-alkane δ13C analysis in the marine environment. Geochimica et Cosmochimica Acta 59, 2853-2857. <p>Eglinton, G., Hamilton, R.J., 1967. Leaf epicuticular waxes. Science 156, 1322-1335. <p>Ficken, K.J., Li, B., Swain, D.L., Eglinton, G., 2000. An n-alkane proxy for the sedimentary input of submerged/floating freshwater aquatic macrophytes. Organic Geochemistry 31, 745-749. <p>Hautevelle, Y., Michels, R., Malartre, F., Trouiller, A., 2006. Vascular plant biomarkers as proxies for palaeoflora and palaeoclimatic changes at the Dogger/Malm transition of the Paris Basin (France). Organic Geochemistry 37, 610-625. <p>Kenrick, P., Wellman, C.H., Schneider, H., Edgecombe, G.D., 2012. A timeline for terrestrialization : consequences for the carbon cycle in the Palaeozoic. Philosophical Transactions of the Royal Society B: Biological Sciences 367, 519-536. <p>Romero-Sarmiento, M.F., Riboulleau, A., Vecoli, M., Versteegh, G.J.M., 2010. Occurrence of retene in upper Silurian-lower Devonian sediments from North Africa: origin and implications. Organic Geochemistry 41, 302-306. <p>Rouillard, A., Greenwood, P.F., Grice, K., Skrzypek, G., Dogramaci, S., Turney, C., Grierson, P.F., 2016. Interpreting vegetation change in tropical arid ecosystems from sediment molecular fossils and their stable isotope compositions: a baseline study from the Pilbara region of northwest Australia. Palaeogeography, Palaeoclimatology, Palaeoecology 459, 495-507. <p>Sikes, E.L., Uhle, M.E., Nodder, S.D., Howard, M.E., 2009. Sources of organic matter in a coastal marine environment: Evidence from n-alkanes and their delta13C distributions in the Hauraki Gulf, New Zealand. Marine Chemistry 113, 149-163. <p>Steemans, P., Herisse, A. Le, Melvin, J., Miller, M. a, Paris, F., Verniers, J., Wellman, C.H., 2009. Origin and radiation of the earliest vascular land plants. Science (New York, N.Y.) 324, 353. <p>Strother, P.K., 2016. Systematics and evolutionary significance of some new cryptospores from the Cambrian of eastern Tennessee, USA. Review of Palaeobotany and Palynology 227, 28-41. <p>Wellman, C.H., Gray, J., 2000. The microfossil record of early land plants. Philosophical Transactions of the Royal Society B: Biological Sciences 355, 717-732.

<div>The Gas Chromatography-Mass Spectrometry (GC-MS) biomarker database table contains publicly available results from Geoscience Australia's organic geochemistry (ORGCHEM) schema and supporting oracle databases for the molecular (biomarker) compositions of source rock extracts and petroleum liquids (e.g., condensate, crude oil, bitumen) sampled from boreholes and field sites. These analyses are undertaken by various laboratories in service and exploration companies, Australian government institutions and universities using either gas chromatography-mass spectrometry (GC-MS) or gas chromatography-mass spectrometry-mass spectrometry (GC-MS-MS). Data includes the borehole or field site location, sample depth, shows and tests, stratigraphy, analytical methods, other relevant metadata, and the molecular composition of aliphatic hydrocarbons, aromatic hydrocarbons and heterocyclic compounds, which contain either nitrogen, oxygen or sulfur.</div><div><br></div><div>These data provide information about the molecular composition of the source rock and its generated petroleum, enabling the determination of the type of organic matter and depositional environment of the source rock and its thermal maturity. Interpretation of these data enable the determination of oil-source and oil-oil correlations, migration pathways, and any secondary alteration of the generated fluids. This information is useful for mapping total petroleum systems, and the assessment of sediment-hosted resources. Some data are generated in Geoscience Australia’s laboratory and released in Geoscience Australia records. Data are also collated from destructive analysis reports (DARs), well completion reports (WCRs), and literature. The biomarker data for crude oils and source rocks are delivered in the Petroleum and Rock Composition – Biomarker web services on the Geoscience Australia Data Discovery Portal at https://portal.ga.gov.au which will be periodically updated.</div>