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DOI	10.1016/j.palaeo.2020.110025
	Redox and paleoenvironmental conditions of the Devonian-Carboniferous Sappington Formation; southwestern Montana; and comparison to the Bakken Formation; Williston Basin
	Browne T.N.; Hofmann M.H.; Malkowski M.A.; Wei J.; Sperling E.A.
发表日期	2020
ISSN	0031-0182
卷号	560
英文摘要	The Sappington Formation outcrops in southwestern Montana and spans the Upper Devonian—Lower Mississippian transition. It consists of two carbonaceous shale intervals, one upper and one lower, and a middle dolomitic siltstone and silty sandstone. It was deposited in a relatively small basin, with the Central Montana Uplift separating the Sappington Basin from the Williston Basin to the east, which contains the economically important Bakken Formation. Previous biostratigraphic and lithostratigraphic comparisons have identified the Sappington and Bakken Formations as depositionally contemporaneous, and, due to the subsurface nature of the Bakken, the Sappington has emerged as a useful outcrop analogue. This study presents new geochemical data from the Sappington Formation, providing a comparison to the Bakken and insight into paleo-redox conditions during the Devonian-Carboniferous on the western Laurentian margin. Geochemical signals in the Sappington Formation outcrop samples are partially obscured by oxidative weathering, but similar to the Lower Bakken Shale, the Lower Sappington Shale appears to record dominantly euxinic conditions, albeit with intervals when the water column was suboxic to ferruginous and with an absence of organic or inorganic geochemical evidence for photic-zone euxinia. The Upper Sappington Shale appears to have been deposited in ferruginous to dysoxic conditions. Thus, the Sappington appears to be an excellent analogue to the Bakken on a lithostratigraphic level, but the geochemical environment for black shales/source rock deposition appears less reducing. Closer proximity to the open ocean and consequent lower levels of restriction may have been responsible for these redox differences; however, Sappington core samples and an increased focus on integrating geochemical data into the regional stratigraphic record will be necessary to further understand paleoceanographic and biogeochemical drivers. © 2020 Elsevier B.V.
英文关键词	Biomarker; Fammenian; Iron speciation; Source rock; Tournaisian; Trace metal
语种	英语
scopus关键词	Devonian-Carboniferous boundary; geochemical survey; geological record; lithostratigraphy; Mississippian; open ocean; outcrop; paleoenvironment; redox potential; shale; siltstone; water column; Montana; United States; Williston Basin
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/150278
作者单位	Department of Geological Sciences, Stanford University, 450 Jane Stanford Way, Bldg 320, Stanford, CA 94301, United States; Department of Geosciences, The University of Montana, Missoula, MT 59812, United States; AIM GeoAnalytics, Missoula, MT 59801, United States; Department of Earth System Science, Stanford University, 473 Via Ortega, Stanford, CA 94301, United States
推荐引用方式 GB/T 7714	Browne T.N.,Hofmann M.H.,Malkowski M.A.,et al. Redox and paleoenvironmental conditions of the Devonian-Carboniferous Sappington Formation; southwestern Montana; and comparison to the Bakken Formation; Williston Basin[J],2020,560.
APA	Browne T.N.,Hofmann M.H.,Malkowski M.A.,Wei J.,&Sperling E.A..(2020).Redox and paleoenvironmental conditions of the Devonian-Carboniferous Sappington Formation; southwestern Montana; and comparison to the Bakken Formation; Williston Basin.Palaeogeography, Palaeoclimatology, Palaeoecology,560.
MLA	Browne T.N.,et al."Redox and paleoenvironmental conditions of the Devonian-Carboniferous Sappington Formation; southwestern Montana; and comparison to the Bakken Formation; Williston Basin".Palaeogeography, Palaeoclimatology, Palaeoecology 560(2020).