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DOI | 10.1111/gbi.12331 |
Microbial assemblage and palaeoenvironmental reconstruction of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia | |
Jarrett A.J.M.; Cox G.M.; Brocks J.J.; Grosjean E.; Boreham C.J.; Edwards D.S. | |
发表日期 | 2019 |
ISSN | 14724677 |
起始页码 | 360 |
结束页码 | 380 |
卷号 | 17期号:4 |
英文摘要 | The ca. 1.38 billion years (Ga) old Roper Group of the McArthur Basin, northern Australia, is one of the most extensive Proterozoic hydrocarbon-bearing units. Organic-rich black siltstones from the Velkerri Formation were deposited in a deep-water sequence and were analysed to determine their organic geochemical (biomarker) signatures, which were used to interpret the microbial diversity and palaeoenvironment of the Roper Seaway. The indigenous hydrocarbon biomarker assemblages describe a water column dominated by bacteria with large-scale heterotrophic reworking of the organic matter in the water column or bottom sediment. Possible evidence for microbial reworking includes a large unresolved complex mixture (UCM), high ratios of mid-chained and terminally branched monomethyl alkanes relative to n-alkanes—features characteristic of indigenous Proterozoic bitumen. Steranes, biomarkers for single-celled and multicellular eukaryotes, were below detection limits in all extracts analysed, despite eukaryotic microfossils having been previously identified in the Roper Group, albeit largely in organically lean shallower water facies. These data suggest that eukaryotes, while present in the Roper Seaway, were ecologically restricted and contributed little to export production. The 2,3,4- and 2,3,6-trimethyl aryl isoprenoids (TMAI) were absent or in very low concentration in the Velkerri Formation. The low abundance is primary and not caused by thermal destruction. The combination of increased dibenzothiophene in the Amungee Member of the Velkerri Formation and trace metal redox geochemistry suggests that degradation of carotenoids occurred during intermittent oxygen exposure at the sediment–water interface and/or the water column was rarely euxinic in the photic zone and likely only transiently euxinic at depth. A comparison of this work with recently published biomarker and trace elemental studies from other mid-Proterozoic basins demonstrates that microbial environments, water column geochemistry and basin redox were heterogeneous. © 2019 Commonwealth of Australia. Geobiology © 2019 John Wiley & Sons Ltd |
关键词 | anoxic conditionsbacteriumbiomarkereukaryoteeuxinic environmenthydrocarbonmicrobial communitymicrofossilpaleoenvironmentphotic zoneProterozoicreconstructionredox conditionsreworkingsediment-water interfacespecies diversitytrace metalAustraliaMcArthur BasinEukaryotaenvironmental markerhydrocarbonenvironmentfossilmicrobiologymicrofloraNorthern TerritorysedimentEnvironmentEnvironmental BiomarkersFossilsGeologic SedimentsHydrocarbonsMicrobiotaNorthern Territory |
语种 | 英语 |
来源机构 | Geobiology |
文献类型 | 期刊论文 |
条目标识符 | http://gcip.llas.ac.cn/handle/2XKMVOVA/133229 |
推荐引用方式 GB/T 7714 | Jarrett A.J.M.,Cox G.M.,Brocks J.J.,et al. Microbial assemblage and palaeoenvironmental reconstruction of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia[J]. Geobiology,2019,17(4). |
APA | Jarrett A.J.M.,Cox G.M.,Brocks J.J.,Grosjean E.,Boreham C.J.,&Edwards D.S..(2019).Microbial assemblage and palaeoenvironmental reconstruction of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia.,17(4). |
MLA | Jarrett A.J.M.,et al."Microbial assemblage and palaeoenvironmental reconstruction of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia".17.4(2019). |
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