Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA
Limestone and shale facies of the Upper Ordovician Grant Lake Formation (Katian: Cincinnatian, Maysvillian) are well exposed in the Cincinnati Arch region of southern Ohio and north-central Kentucky, USA. These rocks record a gradual change in lithofacies and biofacies along a gently northward-slopi...
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| Format: | Article |
| Language: | English |
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Estonian Academy Publishers
2015-02-01
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| Series: | Estonian Journal of Earth Sciences |
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| Online Access: | http://www.kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2015/issue_1/earth-2015-1-19-23.pdf |
| _version_ | 1818180547748298752 |
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| author | Carlton E. Brett Thomas J. Malgieri James R. Thomka Christopher D. Aucoin Benjamin F. Dattilo Cameron E. Schwalbach |
| author_facet | Carlton E. Brett Thomas J. Malgieri James R. Thomka Christopher D. Aucoin Benjamin F. Dattilo Cameron E. Schwalbach |
| author_sort | Carlton E. Brett |
| collection | DOAJ |
| description | Limestone and shale facies of the Upper Ordovician Grant Lake Formation (Katian: Cincinnatian, Maysvillian) are well exposed in the Cincinnati Arch region of southern Ohio and north-central Kentucky, USA. These rocks record a gradual change in lithofacies and biofacies along a gently northward-sloping ramp. This gradient spans very shallow, olive-gray, platy, laminated dolostones with sparse ostracodes in the south to offshore, nodular, phosphatic, brachiopod-rich limestones and marls in the north. This study uses facies analysis in outcrop to determine paleoenvironmental parameters, particularly those related to water depth (e.g., position of the photic zone and shoreline, relative degree of environmental energy). Within a tightly correlated stratigraphic interval (the Mount Auburn and Straight Creek members of the Grant Lake Formation and the Terrill Member of the Ashlock Formation), we document the occurrence of paleoenvironmental indicators, including desiccation cracks and light-depth indicators, such as red and green algal fossils and oncolites. This permitted recognition of a ramp with an average gradient of 10–20 cm water depth per horizontal kilometer. Thus, shallow subtidal (“lagoonal”) deposits in the upramp portion fall within the 1.5–6 m depth range, cross-bedded grainstones representing shoal-type environments fall within the 6–18 m depth range and subtidal, shell-rich deposits in the downramp portion fall within the 20–30 m depth range. These estimates match interpretations of depth independently derived from faunal and sedimentologic evidence that previously suggested a gentle ramp gradient and contribute to ongoing and future high-resolution paleontologic and stratigraphic studies of the Cincinnati Arch region. |
| first_indexed | 2024-12-11T21:21:30Z |
| format | Article |
| id | doaj.art-69400f2f066947af9f5e87cd5ef692a6 |
| institution | Directory Open Access Journal |
| issn | 1736-4728 1736-7557 |
| language | English |
| last_indexed | 2024-12-11T21:21:30Z |
| publishDate | 2015-02-01 |
| publisher | Estonian Academy Publishers |
| record_format | Article |
| series | Estonian Journal of Earth Sciences |
| spelling | doaj.art-69400f2f066947af9f5e87cd5ef692a62022-12-22T00:50:28ZengEstonian Academy PublishersEstonian Journal of Earth Sciences1736-47281736-75572015-02-01641192310.3176/earth.2015.0410.3176/earth.2015.04Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USACarlton E. Brett0Thomas J. Malgieri1James R. Thomka2Christopher D. Aucoin3Benjamin F. Dattilo4Cameron E. Schwalbach5Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA; brettce@ucmail.uc.eduDepartment of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA; malgietj@mail.uc.eduDepartment of Geosciences, University of Akron, Akron, Ohio 44325, USA; jthomka@uakron.eduDepartment of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA; aucoincd@mail.uc.eduDepartment of Geoscience, Indiana University-Purdue University-Fort Wayne, Fort Wayne, Indiana 46805, USA; dattilob@ipfw.eduDepartment of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA; schwalce@mail.uc.eduLimestone and shale facies of the Upper Ordovician Grant Lake Formation (Katian: Cincinnatian, Maysvillian) are well exposed in the Cincinnati Arch region of southern Ohio and north-central Kentucky, USA. These rocks record a gradual change in lithofacies and biofacies along a gently northward-sloping ramp. This gradient spans very shallow, olive-gray, platy, laminated dolostones with sparse ostracodes in the south to offshore, nodular, phosphatic, brachiopod-rich limestones and marls in the north. This study uses facies analysis in outcrop to determine paleoenvironmental parameters, particularly those related to water depth (e.g., position of the photic zone and shoreline, relative degree of environmental energy). Within a tightly correlated stratigraphic interval (the Mount Auburn and Straight Creek members of the Grant Lake Formation and the Terrill Member of the Ashlock Formation), we document the occurrence of paleoenvironmental indicators, including desiccation cracks and light-depth indicators, such as red and green algal fossils and oncolites. This permitted recognition of a ramp with an average gradient of 10–20 cm water depth per horizontal kilometer. Thus, shallow subtidal (“lagoonal”) deposits in the upramp portion fall within the 1.5–6 m depth range, cross-bedded grainstones representing shoal-type environments fall within the 6–18 m depth range and subtidal, shell-rich deposits in the downramp portion fall within the 20–30 m depth range. These estimates match interpretations of depth independently derived from faunal and sedimentologic evidence that previously suggested a gentle ramp gradient and contribute to ongoing and future high-resolution paleontologic and stratigraphic studies of the Cincinnati Arch region.http://www.kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2015/issue_1/earth-2015-1-19-23.pdfpaleobathymetryCincinnatianfaunal gradientsmicroendolithswater depth. |
| spellingShingle | Carlton E. Brett Thomas J. Malgieri James R. Thomka Christopher D. Aucoin Benjamin F. Dattilo Cameron E. Schwalbach Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA Estonian Journal of Earth Sciences paleobathymetry Cincinnatian faunal gradients microendoliths water depth. |
| title | Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA |
| title_full | Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA |
| title_fullStr | Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA |
| title_full_unstemmed | Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA |
| title_short | Calibrating water depths of Ordovician communities: lithological and ecological controls on depositional gradients in Upper Ordovician strata of southern Ohio and north-central Kentucky, USA |
| title_sort | calibrating water depths of ordovician communities lithological and ecological controls on depositional gradients in upper ordovician strata of southern ohio and north central kentucky usa |
| topic | paleobathymetry Cincinnatian faunal gradients microendoliths water depth. |
| url | http://www.kirj.ee/public/Estonian_Journal_of_Earth_Sciences/2015/issue_1/earth-2015-1-19-23.pdf |
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