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Sequence Boundaries and Chronostratigraphic Gaps in the Llandovery of Ohio and Kentucky: the Record of Early Silurian

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Sequence Boundaries and Chronostratigraphic Gaps in the Llandovery of Ohio and Kentucky: the Record of Early Silurian Research Paper GEOSPHERE Sequence boundaries and chronostratigraphic gaps in the Llandovery of Ohio and Kentucky: The record of early Silurian GEOSPHERE; v. 12, no. 6 paleoceanographic events in east-central North America doi:10.1130/GES01343.1 Nicholas B. Sullivan1, Patrick I. McLaughlin2, Carlton E. Brett3, Bradley D. Cramer4, Mark A. Kleffner5, James R. Thomka6, and Poul Emsbo7 1Chemostrat Inc., 3760 Westchase Drive, Houston, Texas 77042, USA 14 figures; 1 table 2Indiana Geological Survey, 611 N. Walnut Grove Street, Bloomington, Indiana 47405, USA 3Department of Geology, University of Cincinnati, 7148 Edwards One, Cincinnati, Ohio 45221, USA 4Department of Earth and Environmental Sciences, University of Iowa, 115 Trowbridge Hall, Iowa City, Iowa 52242, USA CORRESPONDENCE: nicksullivan@ chemostrat 5Division of Earth History, School of Earth Sciences, Ohio State University at Lima, 4240 Campus Drive, Lima, Ohio 45804, USA .com; nsullivan742@ gmail .com 6Department of Geosciences, Crouse Hall 114, University of Akron, Akron, Ohio 44325, USA 7U.S. Geological Survey, Federal Center, West 6th Avenue and Kipling Street, Lakewood, Colorado 80225, USA CITATION: Sullivan, N.B., McLaughlin, P.I., Brett, C.E., Cramer, B.D., Kleffner, M.A., Thomka, J.R., and Emsbo, P., 2016, Sequence boundaries and chrono­ ABSTRACT work has been hindered by a scarcity of index fossils, pervasive dolomitiza­ strati graphic gaps in the Llandovery of Ohio and Ken­ tion, and the lack of a uniformly applied nomenclature (see reviews of Berry tucky: The record of early Silurian paleoceano graphic events in east­central North America: Geosphere, New and published data are integrated herein to resolve the age and strati­ and Boucot, 1970; McLaughlin et al., 2008b; Brett et al., 2012). v. 12, no. 6, p. 1813–1832, doi: 10 .1130 /GES01343.1. graphic relationships for problematic strata of the Aeronian and Telychian This study integrates carbon isotope chemostratigraphy, facies analysis, (Llandovery; Silurian) in Ohio and Kentucky (USA). At least two major depo­ and sequence stratigraphy to resolve the depositional history of Llandovery Received 14 April 2016 sitional sequences were traced along the eastern flank of the Cincinnati Arch; units exposed in Ohio and Kentucky at the transition between the Appalachian Revision received 10 August 2016 these are separated by a regionally angular unconformity with complex topog­ foreland basin and Cincinnati Arch (Fig. 1). This new synthesis lays the ground­ Accepted 12 September 2016 Published online 25 October 2016 raphy. Underlying units are progressively truncated to the northwest while work for highly refined chronostratigraphic interpretations, a revised sequence overlying strata change facies, condense, and onlap in the same direction. stratigraphic framework, and a more complete understanding of the Silurian The basal unit of the upper sequence is the Waco Member of the Alger paleoenvironments and far­field tectonic activity in Laurentia. Shale Formation in Kentucky and southern Ohio and the Dayton Formation 13 in western Ohio. A persistent, positive carbonate carbon isotope (δ Ccarb) ex­ GEOLOGIC SETTING cursion associated with the mid­Telychian Valgu Event is recognized in the upper subunit of the Waco Member; the absence of a comparable signal in the Early Silurian Tectonics and Paleogeography Dayton Formation corroborates interpretations that it is significantly younger. The correlations proposed here can be used to understand the nuanced The study area is situated near the western margin of the Appalachian depositional history and chronostratigraphic completeness of the lower Basin, which was located at ~lat 20°S–30°S during the early Silurian (Cocks Silurian in eastern North America. This framework can be used to characterize and Scotese, 1991). Starting in the Late Ordovician, accretion of island arcs sea­level history and local conditions that prevailed during global paleoenvi­ onto the eastern margin of Laurentia produced several episodes of moun­ ronmental events. tain building called the Taconian orogeny (Ettensohn and Brett, 2002). This produced structural loading and subsidence in the Appalachian Basin, which INTRODUCTION was rapidly filled with clastics flushed off the newly formed Taconic high­ lands (Beaumont et al., 1988; Ettensohn and Brett, 1998; Ettensohn, 2008). This The Aeronian and Telychian Stages of the Silurian record the transition event also created a structural arch on the western margin of the basin, pro­ from the Late Ordovician mass extinction and early Silurian recovery (Raup duced by flexure of the crust in response to the strain of accretion, and facili­ and Sepkoski, 1982; Sheehan, 2001; Krug and Patzkowsky, 2007) to the eco logi­ tated by deep­seated basement faults (Quinlan and Beaumont, 1984; Root and cal upheaval of the early Sheinwoodian Ireviken Event (Jeppsson et al., 1995; Onasch, 1999). Munnecke et al., 2003; Lehnert et al., 2010). The richly fossiliferous successions Toward the middle of the Rhuddanian, orogenic activity had begun to ta­ of eastern North America provide an important venue for study of this transi­ per, but renewed tectonism and uplift (the Salinic orogeny) is recorded by the tion (Zaffos and Holland, 2012), being represented by extensive exposures that thick packages of strata spanning the Llandovery to Ludlow Series (Goodman For permission to copy, contact Copyright have a long history of investigation (Hall, 1852; Orton, 1870; Foerste, 1906). and Brett, 1994; Ettensohn and Brett, 1998; Brett et al., 1998; van Staal et al., Permissions, GSA, or [email protected]. However, the temporal and stratigraphic resolution of this depositional frame­ 2009; Ettensohn et al., 2013). © 2016 Geological Society of America GEOSPHERE | Volume 12 | Number 6 Sullivan et al. | Llandovery stratigraphy in Ohio and Kentucky Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/6/1813/1000625/1813.pdf 1813 by guest on 29 September 2021 Research Paper Miami Columbus Madison 70 Franklin Silurian absent Silurian bedrock at the surface PLT CN JB CS Preble Dayton CV Silurian bedrock in the subsurface Greene Fig. 12 PNT Pickaway Fayette 75 MN 71 Clinton MMNE MMSE Michigan MMSW NRF Basin Cincinnati Highland CCD SS Brown ESQ Adams BC Illinois Appalachian Basin 71 WU Basin Fig. 9 75 64 Bath 64 Lexington OVM DCW IN Madison 0 mi 50 mi WJYW DCE Estill Fig. 11 0 km 50 km Figure 1. Map showing the precise locations of studied outcrops and cores. Base maps were modified from GoogleEarth composite, Barry and Boucot (1970), Noger (1988), and 13 Slucher (2006). Black dots represent outcrops studied here; white dots represent cores. A label in bold indicates a succession for which new carbonate carbon isotope (δ Ccarb) 13 data were produced; a label in bold and italics indicates a succession with δ Ccarb data published in prior studies. Red lines denote the path of correlation cross sections in subsequent figures. These correlations are shown perpendicular to depositional strike. Abbreviations are shown in Table 1. The study area is within a transitional zone between deep­water, mud­ Chronostratigraphy domi nated depositional environments of the central Appalachian Basin and the shallower, carbonate­dominated systems in the northwest (Fig. 2; Hunter, Conodonts are widely used for biostratigraphy in the calcareous lower 1970; Brett et al., 1990, 1998). The bathymetric high occupied by this bank Silurian rock units found in eastern North America (e.g., Rexroad et al., 1965; (the proto–Cincinnati Arch) approximates the axis of the modern Cincinnati-­ Rexroad, 1967; Rexroad and Nicoll, 1972; Cooper, 1975; Kleffner, 1987, 1994). Findlay­ Algonquin arch system (Root and Onasch, 1999). However, most of this work was conducted prior to recent advances in the field GEOSPHERE | Volume 12 | Number 6 Sullivan et al. | Llandovery stratigraphy in Ohio and Kentucky Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/6/1813/1000625/1813.pdf 1814 by guest on 29 September 2021 Research Paper 13 A δ Ccarb ‰ (VPDB) Ma –2.0 0.0 2.0 4.0 6.0 Kockelella ortus ortus 431.0 Kockelella walliseri Michigan Basin Ireviken 432.0 Ozarkodina sagitta rhenana woodian enlock bonate Kockelella ranuliformis Car Shale W estrial Shein Pterospathodus procerus Terr 433.0 tz Sand Quar Upper Pseudooneotodus bicornis Lower Pseudooneotodus bicornis Basin Axis Illinois 434.0 Basin Pterospathodus amorphognathoides amorphognathoides 0 100 200 mi 435.0 0 100 200 300 km Pterospathodus amorphognathoides lithuanicus Pterospathodus amorphognathoides lennarti 436.0 Pterospathodus amorphognathoides Silurian Outcrop Subsurface Silurian angulatus ry elychian Pterospathodus eopennatus ssp. n. 2 Figure 2. Distribution of Silurian strata in the east­central United States; major structural and T depositional provinces are labeled (modified from Berry and Boucot, 1970; Beaumont et al., 437.0 1987). The area that forms the central focus of this study is outlined on this map. Prevailing facies Pterospathodus eopennatus ssp. n. 1 Valgu belts are overlain on the outcrop pattern (modified from Hunter, 1970; McLaughlin et al., 2012). 438.0 Distomodus staurognathoides of conodont biostratigraphy, most notably the development of highly refined conodont biozonations (Fig. 3; Jeppsson, 1997; Jeppsson et al., 2006; Männik, Llandove 2007a, 2007b). Earlier reports of Llandovery conodonts from the eastern flank 439.0 Late Aeronian of the Cincinnati Arch employed a comparatively low resolution zonation that was
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  • 159571755.Pdf
    ·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-·-· STATE at OHIO MICH.Ul. V. DISALLE. C:O- DEPAll'IMENT at NATUkAL RESOUllCES HERBERT I. EAGON, D1rec11or DIVISION OF GEOLOGICAL SURVEY RALl'H J. IERNHAGDf1 Chief Information Circular No. 26 THE AMERICAN UPPER ORDOVICIAN STANDARD Development of I II. STRATIGRAPHIC CLASSIFICATION OF ORDOVICIAN ROCKS ,in the I Cincinnati 'Region By Malcolm P. Weiss I and Carl E. Norman COLUMIUS 1960 ~--·~·~·-·-·-·-·-·-·~·-·-·-·-·-·-·-·~·-·-·-·-·-·-·~ STATE OF OHIO Michael V. DiSalle Governor DEPARTMENT OF NATURAL RESOURCES Herbert B. Eagon Director NATUR.AL RESOURCES C~ISSic;>N c. D. Blubaugh Joseph E. Hurst Herbert B. Eagon L. L. Rummell Byron Frederick Demas L. Sears Forrest G. Hall Myron T. Stllrgeon William Hoyne DMSION OF GEOLOGICAL SURVEY Ralph J. Bernhagen Chief ·~ The F. J. Heer Printing Company Columbus 16, Ohio 1960 Bound by the State of Ohio THE AMERICAN UPPER ORDOVICIAN STANDARD II. DEVELOPMENT OF STRATIGRAPHIC CLASSIFICATION OF ORDOVICIAN ROCKS IN THE CINCINNATI REGION Malcolm P. Weiss 1 and Carl E. Norman2 ABSTRACT The development of the classification of the rocks in the region about Cincinnati, Ohio is shown in tabular form. The successive columns of stratigraphic names that make up the chart have been correlated in order that the history of the nomenclature of even the smallest stratigraphic units may be traced. The text accompanying the table supplements it in certain respects and includes an historical analysis of the stratigraphic unit called Madison or Saluda. INTRODUCTION A number of authors, particularly of theses and dissertations, have found it help- ful to trace the complicated development of the classification and nomenclature of the beds in the Cincinnati region.
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