A Triassic Upwelling Zone: The Shublik Formation, Arctic Alaska, U.S.A.

Abstract

Research Article| March 01, 2001 A Triassic Upwelling Zone: The Shublik Formation, Arctic Alaska, U.S.A. Judith Totman Parrish; Judith Totman Parrish 1Dept. of Geosciences, P.O. Box 210077, University of Arizona, Tucson Arizona 85721, U.S.A.; [e-mail] Search for other works by this author on: GSW Google Scholar Mary L. Droser; Mary L. Droser 2Dept. of Earth Sciences, University of California, Riverside, California 92521, U.S.A. Search for other works by this author on: GSW Google Scholar David J. Bottjer David J. Bottjer 3Department of Geological Sciences, University of Southern California, Los Angeles, California 90089-0740, U.S.A. Search for other works by this author on: GSW Google Scholar Author and Article Information Judith Totman Parrish 1Dept. of Geosciences, P.O. Box 210077, University of Arizona, Tucson Arizona 85721, U.S.A.; [e-mail] Mary L. Droser 2Dept. of Earth Sciences, University of California, Riverside, California 92521, U.S.A. David J. Bottjer 3Department of Geological Sciences, University of Southern California, Los Angeles, California 90089-0740, U.S.A. Publisher: SEPM Society for Sedimentary Geology Received: 18 May 1999 Accepted: 26 May 2000 First Online: 03 Mar 2017 Online ISSN: 1938-3681 Print ISSN: 1527-1404 Copyright © 2001, SEPM (Society for Sedimentary Geology) Journal of Sedimentary Research (2001) 71 (2): 272–285. https://doi.org/10.1306/052600710272 Article history Received: 18 May 1999 Accepted: 26 May 2000 First Online: 03 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Judith Totman Parrish, Mary L. Droser, David J. Bottjer; A Triassic Upwelling Zone: The Shublik Formation, Arctic Alaska, U.S.A.. Journal of Sedimentary Research 2001;; 71 (2): 272–285. doi: https://doi.org/10.1306/052600710272 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyJournal of Sedimentary Research Search Advanced Search Abstract The Shublik Formation (Triassic, North Slope, Alaska) is an organic-, phosphate-, and glauconite-rich unit with abundant fossils of marine vertebrates and mollusks. Four lithofacies are identified in the Shublik Formation:nonglauconitic sandstone—thin- to medium-bedded, fine, quartzose, calcareous to noncalcareous sandstone or silty to muddy sandstone, fossiliferous in places; glauconitic—thin- to medium-bedded, fine, quartzose sandstone, muddy sandstone, or siltstone containing 10% to > 50% glauconite grains phosphatic—thin- to medium-bedded siltstone or sandstone or laminated, black silty limestone or limestone containing phosphate nodules; and organic-rich—laminated, black limestone, marl, and mudstone.The organic carbon content of the organic-rich facies is as high as 5.45 wt %, despite the fact that the rocks are overmature and have generated oil. The mean P content of the phosphatic facies is as high as 14 wt % elemental P. Ichnofabrics are related to lithofacies and consistent with interpreted oxygen levels. Ichnofabrics also provide evidence of fluctuating oxygen levels within the facies, especially the nonglauconitic sandstone and glauconitic facies. The organic-rich facies and, to a lesser extent, the phosphatic facies contain abundant, pristine, disarticulated shells of the clam Halobia. The facies, geochemistry, ichnofabrics, and taphonomy are interpreted to be related to onshore-offshore gradients in biologic productivity and redox conditions. The facies array in the Shublik Formation is more similar to that in modern upwelling zones than facies arrays in other well-studied upwelling deposits. The Shublik Formation is interpreted as an upwelling-zone deposit and can serve as an archetype of such deposits. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.