气候变化领域集成服务门户(CCPortal): Changes in terrestrial ecosystems across the Cretaceous-Paleogene boundary in western Canada inferred from plant wax lipid distributions and isotopic measurements

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DOI	10.1016/j.palaeo.2020.110081
	Changes in terrestrial ecosystems across the Cretaceous-Paleogene boundary in western Canada inferred from plant wax lipid distributions and isotopic measurements
	Bourque R.D.; Douglas P.M.J.; Larsson H.C.E.
发表日期	2020
ISSN	0031-0182
英文摘要	Changes in terrestrial environments across the Cretaceous-Paleogene boundary, including plant ecology and carbon and water-cycling, remain poorly defined. Fluvial sediments spanning the Cretaceous-Paleogene (K-Pg) boundary of southern Saskatchewan, Canada contain well preserved plant wax n-alkanes that provide a means of reconstructing changes to plant ecology and carbon and water cycling during this mass extinction event. We measured n-alkane carbon (δ13C) and hydrogen (δ2H) isotope ratios in two sedimentary sections and applied established fractionation factors to estimate the isotopic compositions of precipitation and bulk sedimentary organic matter sources. We also analyzed the distribution of n-alkanes as an indicator of the relative abundance of aquatic and terrestrial plants. We find a consistent shift towards a greater relative abundance of longer-chain n-alkanes across the boundary, implying a persistent increase in the relative abundance of terrestrial plants in the sedimentary basin. This is consistent with an increase in birch and elm palynomorphs immediately above the boundary. We hypothesize the extinction of all large herbivores at the boundary may have facilitated this transition to a terrestrial angiosperm dominated flora immediately after the boundary. We also find that the region was characterized by isotopically light precipitation, with δ2H values between −95‰ to −160‰, but do not observe evidence for major millennial-scale changes in regional precipitation isotopic composition spanning the boundary. n-Alkanes derived from both aquatic and terrestrial plants at one site display an upward trend in δ13C values of approximately 2‰ across the K-Pg boundary. This suggests millennial-scale local or global carbon-cycle variability altering either plant carbon isotope fractionation or the carbon isotope composition of dissolved inorganic carbon and atmospheric CO2. Overall our results suggest that carbon and water cycle changes associated with the K-Pg impact in terrestrial environments in western Canada were short-lived, but ecological shifts in plant communities were longer-lasting. © 2020
英文关键词	Carbon isotopes; Compound specific isotope analysis; Hydrogen isotopes; Mass extinction; Paleohydrology; Plant wax lipids
语种	英语
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/150700
作者单位	Department of Earth and Planetary Sciences, Geotop Research Centre, McGill University, 3450 University Street H3A 0E8, Montreal, QC, Canada; Redpath Museum, McGill University, 859 Sherbrooke Street West H3A 0C4, Montreal, QC, Canada
推荐引用方式 GB/T 7714	Bourque R.D.,Douglas P.M.J.,Larsson H.C.E.. Changes in terrestrial ecosystems across the Cretaceous-Paleogene boundary in western Canada inferred from plant wax lipid distributions and isotopic measurements[J],2020.
APA	Bourque R.D.,Douglas P.M.J.,&Larsson H.C.E..(2020).Changes in terrestrial ecosystems across the Cretaceous-Paleogene boundary in western Canada inferred from plant wax lipid distributions and isotopic measurements.Palaeogeography, Palaeoclimatology, Palaeoecology.
MLA	Bourque R.D.,et al."Changes in terrestrial ecosystems across the Cretaceous-Paleogene boundary in western Canada inferred from plant wax lipid distributions and isotopic measurements".Palaeogeography, Palaeoclimatology, Palaeoecology (2020).