气候变化领域集成服务门户(CCPortal): High-precision Re–Os dating of Lower Jurassic shale packages from the Western Canadian Sedimentary Basin

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DOI	10.1016/j.palaeo.2020.110010
	High-precision Re–Os dating of Lower Jurassic shale packages from the Western Canadian Sedimentary Basin
	Toma J.; Creaser R.A.; Pană D.I.
发表日期	2020
ISSN	0031-0182
卷号	560
英文摘要	The Lower Jurassic rock record contains abundant organic-rich mudrocks suitable for refining Early Jurassic time using Re–Os organic-rich shale (ORS) geochronometry, such as those associated with the Sinemurian–Pliensbachian boundary event or the Toarcian Ocean Anoxic Event (T-OAE). Despite this, most studies to date have failed to obtain high precision, geologically meaningful, ages for such Lower Jurassic rocks. The cause of imprecision in Re–Os ORS age dates, at least for the Toarcian, has been linked to subtle chemostratigraphic variations in 187Os/188Osi values. Here, we report the first high-precision Re–Os ages of organic-rich shale packages of the Gordondale and basal Poker Chip Members of the Lower Jurassic Fernie Formation of Northwestern Alberta, Canada from the Western Canadian Sedimentary Basin (WCSB). Our Re–Os age results bracket sediment deposition between the late Sinemurian-early Pliensbachian (192.11 ± 0.77 Ma [2σ] and 193.83 ± 1.34 Ma [2σ]) and late Toarcian (180.10 ± 2.68 Ma [2σ]). When coupled with chemo- (87Sr/86Sr and 187Os/188Os isotopes) and bio-stratigraphy (ammonite and coccolith), our Re–Os ages correlate with regional and global stratigraphic tie points corresponding to pivotal points of Early Jurassic time, such as the Sinemurian–Pliensbachian boundary event, T-OAE, and late Toarcian, that are otherwise weakly constrained by isotopic methods. This integrative approach helps to place these events in a more robust temporal framework. Based on seawater Os isotope data, we also speculate that a previously unidentified positive Os isotope excursion exists at the Sinemurian–Pliensbachian boundary - perhaps triggered by late-stage Central Atlantic Magmatic Province (CAMP) volcanism. © 2020 Elsevier B.V.
英文关键词	Gordondale Member; Organic-rich shales; Osmium isotopes; Pliensbachian–Toarcian boundary; Sinemurian–Pliensbachian boundary; Strontium isotopes
语种	英语
scopus关键词	chemostat; chemostratigraphy; dating method; isotopic analysis; Jurassic; mudstone; oil shale; precision; shale; Toarcian; Alberta; Canada; Western Canada Sedimentary Basin; Ammonoidea
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/150291
作者单位	Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada; Alberta Geological Survey/Alberta Energy Regulator, Edmonton, AB, Canada
推荐引用方式 GB/T 7714	Toma J.,Creaser R.A.,Pană D.I.. High-precision Re–Os dating of Lower Jurassic shale packages from the Western Canadian Sedimentary Basin[J],2020,560.
APA	Toma J.,Creaser R.A.,&Pană D.I..(2020).High-precision Re–Os dating of Lower Jurassic shale packages from the Western Canadian Sedimentary Basin.Palaeogeography, Palaeoclimatology, Palaeoecology,560.
MLA	Toma J.,et al."High-precision Re–Os dating of Lower Jurassic shale packages from the Western Canadian Sedimentary Basin".Palaeogeography, Palaeoclimatology, Palaeoecology 560(2020).