Organic-rich black shale geochemistry and their association with lead-zinc ores: Mid-continent United States

PreviousNext No AccessSecond International Meeting for Applied Geoscience & EnergyOrganic-rich black shale geochemistry and their association with lead-zinc ores: Mid-continent United StatesAuthors: Noah S. MorrisAdriana PotraJohn R. SamuelsenNoah S. MorrisUniversity of ArkansasSearch for more papers by this author, Adriana PotraUniversity of ArkansasSearch for more papers by this author, and John R. SamuelsenArkansas Archeological Survey and University of ArkansasSearch for more papers by this authorhttps://doi.org/10.1190/image2022-3748347.1 SectionsSupplemental MaterialAboutPDF/ePub ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinked InRedditEmail AbstractThe source(s) of the metal ions in carbonate-hosted Mississippi Valley-type (MVT) lead-zinc (Pb-Zn) ore deposits remain unclear. To constrain the source(s) and assess any potential relationship to the MVT ores, geochemical analyses of organic-rich black shales of the Mid-continent US were examined. These ores are thought to have formed during the Pennsylvanian due, at least in part, to the migration of warm, subsurface fluids away from the Ouachita orogeny. Many black shales have significant concentrations of U and Th, which decay into radiogenic Pb. The Pb isotope signatures can be used as a proxy to indicate the potential of shales as possible source(s) of ore metals. However, it is not clear if the Pb was transported from distal or proximal sources, or in-situ. Shales sampled from across the mid-continent include Cambrian (Eau Claire, Mt. Simon, Tunnel City), Cambrian-Ordovician (Collier), Ordovician (Mazarn, Polk Creek, Womble), Devonian-Mississippian (Chattanooga, New Albany), Mississippian (Fayetteville, Stanley), and Pennsylvanian (Atoka, Eudora, Excello, Heebner, Hushpuckney, Jackfork, Little Osage, Muncie Creek, Stark, Vilas) units. This study incorporates total organic carbon (TOC), X-ray diffraction (XRD), radiogenic Pb isotopes, and redox-sensitive trace element analyses. The results indicate that these shales formed in a range of depositional environments (e.g., oxic to euxinic). Lead, Zn, and U concentrations vary, but many Pennsylvanian shales exhibit higher concentrations of these elements, as well as higher TOC values and anoxic depositional indicators. Isotopic signatures indicate that a highly radiogenic Pb source was a major contributor to the MVT ores.Keywords: lead, geochemistry, ore deposit, shale, isotopePermalink: https://doi.org/10.1190/image2022-3748347.1FiguresReferencesRelatedDetails Second International Meeting for Applied Geoscience & EnergyISSN (print):1052-3812 ISSN (online):1949-4645Copyright: 2022 Pages: 3694 publication data© 2022 Published in electronic format with permission by the Society of Exploration Geophysicists and the American Association of Petroleum GeologistsPublisher:Society of Exploration Geophysicists HistoryPublished Online: 15 Aug 2022 CITATION INFORMATION Noah S. Morris, Adriana Potra, and John R. Samuelsen, (2022), "Organic-rich black shale geochemistry and their association with lead-zinc ores: Mid-continent United States," SEG Technical Program Expanded Abstracts : 1984-1988. https://doi.org/10.1190/image2022-3748347.1 Plain-Language Summary Keywordsleadgeochemistryore depositshaleisotopePDF DownloadLoading ...