气候变化领域集成服务门户(CCPortal): Microbial assemblage and palaeoenvironmental reconstruction of the 1.38 Ga Velkerri Formation, McArthur Basin, northern Australia

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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 conditions bacterium biomarker eukaryote euxinic environment hydrocarbon microbial community microfossil paleoenvironment photic zone Proterozoic reconstruction redox conditions reworking sediment-water interface species diversity trace metal Australia McArthur Basin Eukaryota environmental marker hydrocarbon environment fossil microbiology microflora Northern Territory sediment Environment Environmental Biomarkers Fossils Geologic Sediments Hydrocarbons Microbiota Northern 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).