Our research provides new tools to take into account for further applications in fluid-source rock correlation studies which represent the main challenge in assessing petroleum systems in the sub-Basin. delta-plain/front-deltaic from estuarine/lagoonal in a dominantly fluvial deltaic record. The δ¹☼ of PAHs in combination with their distributions can be used to establish the facies type i.e. A similar separation for the samples was obtained with phenanthrene and other PAHs. samples from the Mungaroo Formation - North Rankin-5, Goodwyn-9 and Goodwyn-5 wells) whereas the positive region for Δ¹☼ (Combustion Marker-1,3,6,7 TeMN) is assigned to transitional facies deposited under an estuarine/lagoonal environment with a high sapropelic contribution (Brigadier Formation) and marginal marine environment (Legendre Formation). We demonstrated here that samples plotting below 0 for Δ¹☼ (Combustion Marker-1,3,6,7 TeMN) are related to delta-plain/front-deltaic facies or coaly fluvial deltaic facies (e.g. The relative abundance of the PAHs was plotted against the difference between δ¹☼ values of 1,3,6,7-tetramethylnaphthalene (TeMN) and each PAH.
These sequences correspond to fluvial deltaic systems which integrate the Mungaroo, Brigadier and Legendre Formations, and the organic matter has been assigned as mixed terrigenous/marine material.
SEAFALL POWER OF THE ANCIENTS SERIES
The δ¹☼ of polycyclic aromatic hydrocarbons (PAHs) was measured in a series of Triassic and Jurassic source rocks from the Dampier sub-Basin, Carnarvon Basin, North West Shelf of Australia. If the precursors of perylene are destroyed during transportation and early sedimentation, no perylene will be formed during diagenesis, no matter how strong the reducing conditions are. It is proposed that the preservation of the precursors of perylene is critical, as these are sensitive to destruction by oxidation. Terrigenous-sourced organic matter was detected at all four sites, but perylene is only concentrated at the site closest to Tasmania. The concentrations of perylene are positively correlated to pristane/phytane ratios, implying that perylene is probably formed under dysoxic rather than highly reducing conditions. Detailed examination of the relationship between the concentrations of perylene and organic matter input and depositional conditions illustrate that both factors are important but not essential. Contributions from autochthonous organic matter and combustion cannot be validated. Other molecular compositions, including land-plant-derived aromatic hydrocarbons, pyrogenic-related aromatic hydrocarbons and n-alkanes, indicate that the origin of perylene can be attributed to allochthonous organic material associated with terrigenous plants. The concentrations of perylene increase with burial depth, suggesting its formation from diagenetic processes. However, only trace amounts of perylene (< 5 ng/g dws) are present in samples from the other three sites, except for two deep samples from Site 1171, which is furthest from Tasmania, with perylene concentrations of 15 ng/g dws and 95 ng/g dws. Perylene is enriched in samples from Site 1168, which is located closest to Tasmania, accounting for up to 53.4% of the total quantified aromatic hydrocarbons, with concentrations ranging from 15 ng/g dry weight sediment (dws) to 1700 ng/g dws. Fungi are proposed to be the major precursor carriers for perylene in sediments based on the facts that (1) perylenequinone structures have been previously suggested to be the natural precursors for perylene (2) perylenequinone pigments exist in many fungal bodies (3) fungi have played an important role during geological processes.Įocene to Lower Oligocene sediments were collected by Ocean Drilling Program Leg 189 at four sites in the Tasmanian Gateway, Australia, and geochemically characterised to investigate the occurrence and controlling factors of perylene.
Its carbon isotope composition is slightly heavier than higher-plant derived PAHs, but still in the range of the terrestrially sourced PAHs including higher-plant PAHs and combustion-derived PAHs as suggested previously. The concentration of perylene in the sediments is proportional to the amount of terrestrial input, decreasing with distance from the source of land sediments. This suggests a diagenetic origin for perylene. Its depth/age profiles are not related to the combustion-derived PAHs that have been believed to be produced during ancient vegetation fires before deposition.
Perylene was found to be a major PAH component in the top Lower to base Middle Jurassic sediments that are immature or at low maturity. The distributions of polycyclic aromatic hydrocarbons (PAHs) in sediments of three Upper Triassic to Middle Jurassic sedimentary sequences from the Northern Carnarvon Basin, Australia have been investigated.
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