Contrasting Siliciclastic-Evaporite Strata In Subsurface and Outcrop: An Example From the Permian Nippewalla Group of Kansas, U.S.A

Research Article| June 01, 2015 Contrasting Siliciclastic–Evaporite Strata In Subsurface and Outcrop: An Example From the Permian Nippewalla Group of Kansas, U.S.A Kathleen C. Benison; Kathleen C. Benison 1Department of Geology and Geography, West Virginia University, Morgantown, West Virginia 26506, U.S.A. e-mail: kcbenison@mail.wvu.edu Search for other works by this author on: GSW Google Scholar James J. Zambito, IV; James J. Zambito, IV 1Department of Geology and Geography, West Virginia University, Morgantown, West Virginia 26506, U.S.A. 2Wisconsin Geological and Natural History Survey, University of Wisconsin–Extension, Madison, Wisconsin 53705, U.S.A. Search for other works by this author on: GSW Google Scholar Jonathan Knapp Jonathan Knapp 1Department of Geology and Geography, West Virginia University, Morgantown, West Virginia 26506, U.S.A. Search for other works by this author on: GSW Google Scholar Author and Article Information Kathleen C. Benison 1Department of Geology and Geography, West Virginia University, Morgantown, West Virginia 26506, U.S.A. James J. Zambito, IV 1Department of Geology and Geography, West Virginia University, Morgantown, West Virginia 26506, U.S.A. 2Wisconsin Geological and Natural History Survey, University of Wisconsin–Extension, Madison, Wisconsin 53705, U.S.A. Jonathan Knapp 1Department of Geology and Geography, West Virginia University, Morgantown, West Virginia 26506, U.S.A. e-mail: kcbenison@mail.wvu.edu Publisher: SEPM Society for Sedimentary Geology Received: 01 Apr 2014 Accepted: 28 Feb 2015 First Online: 09 Mar 2017 Online ISSN: 1938-3681 Print ISSN: 1527-1404 Copyright © 2015, SEPM (Society for Sedimentary Geology) Journal of Sedimentary Research (2015) 85 (6): 626–645. https://doi.org/10.2110/jsr.2015.43 Article history Received: 01 Apr 2014 Accepted: 28 Feb 2015 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Kathleen C. Benison, James J. Zambito, Jonathan Knapp; Contrasting Siliciclastic–Evaporite Strata In Subsurface and Outcrop: An Example From the Permian Nippewalla Group of Kansas, U.S.A. Journal of Sedimentary Research 2015;; 85 (6): 626–645. doi: https://doi.org/10.2110/jsr.2015.43 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: Geologists tend to expect that rocks as they appear in outcrop are a very good approximation of the same strata in the subsurface. But this is not the case in mixed siliciclastic–evaporite units, strata that contain both a siliciclastic and an evaporite mineral component. Distinct differences in lithologic and stratigraphic descriptions of ancient siliciclastic–evaporite strata exist between outcrop and core. These differences present challenges in stratigraphic nomenclature, lithologic correlation, age determinations, and interpretations about past depositional environments, diagenetic history, and paleoclimate. An example of siliciclastic–evaporite strata is the middle Permian to early Triassic gypsum- and/or anhydrite- (hereby referred to as gypsum/anhydrite) and halite-bearing red beds throughout the midcontinent of North America and equivalent strata from other Pangean deposits. Here, we use core and field observations of the middle Permian Nippewalla Group in Kansas to show the range of similarities and differences in lithologies and thicknesses of specific lithofacies in outcrop and at various depths. For example, the displacive halite lithology, consisting of red mudstones dominated by randomly oriented halite crystals, is abundant in cores and interpreted as saline mudflat deposits. The outcrop counterpart is less common, friable, massive red mudstones with some gypsum/anhydrite pseudomorphs after displacive halite crystals. We interpret these lithologic differences of this saline mudflat lithofacies as the result of excellent preservation of buried displacive halite and late-stage dissolution of near-surface halite. Additionally, bedded halite and intergranular halite cements in siltstones and sandstones are also vulnerable to late-stage dissolution near the surface, further modifying lithologies and thicknesses. Thickness of the Nippewalla Group in the Amoco Rebecca K. Bounds core of western Kansas is 931 feet (∼ 284 meters) thick, but it is estimated to be only half as thick in the outcrop belt of south-central Kansas. To estimate amount of rock lost to late-stage dissolution, we conducted dissolution experiments on displacive halite units from cores, which resulted in 60–95% loss of rock thickness and mass due to dissolution of halite. The unconsolidated red sediment resulting from these dissolution experiments compares favorably with much of the fine massive red siliciclastics that make up the greater part of the Nippewalla Group outcrops. We propose that major lithologic differences resulting from near-surface diagenetic processes must be expected in any evaporite-bearing siliciclastic unit. Besides guiding correlation attempts between surface and subsurface, this knowledge is vital for making accurate interpretations of depositional and diagenetic history of siliciclastic–evaporite units. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.