气候变化领域集成服务门户(CCPortal): Palaeoenvironments; flora; and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head; Australia

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DOI	10.1016/j.palaeo.2019.109292
	Palaeoenvironments; flora; and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head; Australia
	Mishra S.; Jha N.; Stebbins A.; Brookfield M.; Hannigan R.
发表日期	2019
ISSN	0031-0182
卷号	534
英文摘要	The Permian-Triassic boundary section at Wybung Head, eastern Australia shows a rapid change from humid coal-bearing lowland braided stream through a thin clay and coal breccia and paleosols to semi-arid silty floodplain deposits. Identifiable plant remains and total organic matter disappear above the coal and clay breccia. Three characteristic palynofacies accumulated in a range from oxic to sub-oxic to anoxic conditions. The dominance of opaque phytoclasts in the entire sequence reflects deposition under oxic conditions, especially in the sequence lying above the Birdie Coal, the result of fluctuating water tables, high energy and desiccating conditions. In the Birdie Coal, however, at certain horizons, a water-saturated environment favored the preservation of organic matter such as pollen, spores, and structured organic matter. This latest Permian paleovegetation was dominated by opportunistic understory spore-bearing plants, with a canopy of pollen-bearing glossopterids, conifers and cordaitales. Total organic carbon drops from >30% in the coal, through <5% in the breccia to <1% in the paleosols and silts. The organic δ13C values are constant at ~ −25.5‰ in the coal and coal breccia, but then decrease to less than −27‰ in the paleosols and silts. These results confirm the rapid sedimentary, floral and organic carbon isotope changes across the non-marine Permian-Triassic boundary in eastern Australia. Our δ13Corg values suggest a significant and sustained negative δ13Corg excursion, with a magnitude of about 3‰, above the Birdie Coal. Unlike δ13Corg, there is no clear trend in δ15Norg values. The low C/N ratios of 10 and less, of the samples above +55 cm, are only found in modern burned soils with low bacteria/fungi ratios or in decaying wood. There is no obvious fungal spike in the Wybung Head section, may have been destroyed during the formation of this soil B horizon, as elsewhere a global fungal spike layer marks an interval of decreased terrestrial biomass and decaying vegetation associated with the Permian-Triassic crisis and boundary. Two negative excursions in the uppermost Permian and lowest Triassic can be correlated throughout Gondwana. © 2019 Elsevier B.V.
英文关键词	Geochemistry; Paleosols; Paleovegetation; Palynology
语种	英语
scopus关键词	breccia; carbon isotope; flora; geochemistry; nitrogen isotope; organic carbon; paleobotany; paleoenvironment; paleosol; palynology; Permian-Triassic boundary; Coniferophyta; Cordaitales
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150794
作者单位	Department of Geology, University of Delhi, Delhi, 110007, India; Birbal Sahni Institute of Palaeosciences, Lucknow, 226007, India; School for the Environment, University of Massachusetts at Boston, Boston, MA 02125, United States
推荐引用方式 GB/T 7714	Mishra S.,Jha N.,Stebbins A.,et al. Palaeoenvironments; flora; and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head; Australia[J],2019,534.
APA	Mishra S.,Jha N.,Stebbins A.,Brookfield M.,&Hannigan R..(2019).Palaeoenvironments; flora; and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head; Australia.Palaeogeography, Palaeoclimatology, Palaeoecology,534.
MLA	Mishra S.,et al."Palaeoenvironments; flora; and organic carbon and nitrogen isotope changes across the non-marine Permian-Triassic boundary at Wybung Head; Australia".Palaeogeography, Palaeoclimatology, Palaeoecology 534(2019).