The Geological Society of/(meric^ Inc. Microform Pubficati^n 3
Pennsylvanian Conodont Biost^tigraphy and Paieoecolbgy of NorthwesternHIIinbis
cai ' Glen'K. Merrill V Department of Geology f College of Charleston Charleston, South Carolina
&3&f *"-*:. **
Published by Jhe G^ologicaLSociety of America,,Inc. \ . 3300 Penrose Place * Boulder, Colorado 80301
1975
Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 CONTENTS Page Card/Row Acknowledgments v. j index Abstract...... T...... ^j^...... 1 1, A6" Introduction...... i ...... ,- , . . . . 2 1 , A7 _ Purpose and Scope...... J...... 2 1 , A7 Geologic Setting...... /...... 2 "i, r A7 Paleoecology...... v...... J...... 6 l^All ' General Environmental Analysis ...... ;...... rv*C. '. . 6 . 1 / :A1 1 ' Depth...... :...... J...... i* . 6 . 1, All Substrate...... ,...'...... '...... 7 -*' 1, A12~ Conodont Abundance...... v *...... 8 .lv, A13 Conodont Biof acies Analysis ...... *.. 8 1 , A13 Idtogruztfodiis-Biof acies ...... ^. . 10 1, Bl Cavu8gnathu8 -Biof acies ...... 10 1 , Bl Streptognathodus-Eiof acies...... 10 1, Bl Aethotaxis-Xiof acies...... 11 lj B2 Idiopriontodus-'Biof acies ...... 1 1 1 > B2 Condole lla-*Bio fades-'...... ".. . . . 11 I , B2 -Biof acies ...... 13. 1 , B4 Environmental Significance of Black Shales ...... 13 1 , B4 Summary Model...... 17 1 , B8 Descriptions of Individual Stratigraphic Units...... '...... 19 1, BIO Cramer Member...... 19 1, BIO Exline Member...... 19 1, BIO Desmoinesian-Missourian Boundary ...... 20 1, B12 Lonsdale Member ..:...... ^...... 20 1 / B12 Sparland Member:...... 26 1, C4 .Pokeberry Member...... 27 1, C5 Brereton Limestone...... ,...... '...... ,...... '...... 28 1 , C6 St. David Member...... ,....'...... 30 1, CJO Hanover Member...... 32 T, C12 Oak Grove Member......
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Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 Gondolella pulchra n. sp...... 57 1, E10 Gondolella bella Stauffer and ; Plummer...... '. 58 1, EH Gondolella.magna. Stauffer and Plummer...... '..,...... 61 1, E14 Genus Idiognathodus Gunnell...... 61 1, EI4 _..._ - Idiognathodus claviformis Gunnell...... ,...-...;.....,,...., 63 1, F2 «v Idiognathodus delicatus Gunnell. ...,.....'...... ,. 63 1, F2 Genus, Neognathodus Dunn...... '...... ;.'...... 64 - 1, F3 Neognathodus bassleri bassleri (Harris-and Hollingsworth)..... 67 1-,- F6 - ' Neognathodus bothrops Merrill...... ^ ...... 69 I/F8 . \ Neognathodus medadultimus Merrill...... v ...... 69 1, -F8 Neognathodus medexultimus Merrill...... >...... , 69 1, F8 Intermediate Neognathodids...... '...... 71 1, F10 Neognathbdus roundyi (Gunnell)...... ^ 71 1, F10 t Neognathodus dilatus (Stauffer and Plummer)...... 71 * 1, F10 Neognathodus metanodosus n. sp.. T...... ; ..,.«...... 71 1, F10 \ Neognathodus polynodosus n. sp. ... .^...... r ...... 72 1, Fl1 Neognathodus oligonodosus n. sp. ...^...... -73. _ 1, F12 Neognathodus anodosus n. sp...... ??...... 73 1, F12 Genus Streptognathodus Stauffer and Plummer...... 74 1, F13 Streptognathodus excelsus Staaffer and Plummer...... 75 1, F14 * Streptognathodus gracilis Stauffer and Plummer... J...... 76 1, Gl Streptognathodus elegantulus Stauffer and Plummer...... 76 1, Gl Streptognathodus caneellosus (Gunnell)...... 77 1, G2 Streptognathodus oppletus Ellison..-...... 77 1, G2 Multielement Taxonomy...... '...... 78 1, G3 Appendix 1. Distribution of Specimens...... 97 2, Bl Appendix 2. Register or Collecting Localities.../....-.,...... 117" 2, Dl References. Cited...... :v...... 124 2, El J * Reprint of article from Geology...... v...... 128 2, F2 t ILLUSTRATIONS >i^_ Note. Most illustrations are repeated in the next frame following every callout in the text.
Figure 1. Locality Map...... 3 1, A8 Figure 2. Generalized Stratigraphic Column...... ,...;...... ,..... 4 1, A9 Figure 3. The Flotant Model...;...... '...... 15 1, 36 Figure 4. Summary Model of Depositional Environments...... 18 1, B9 Figure 5. Lonsdale Depositional Environments..,.....^...... 22 1, B14 Figure 6. Lonsdale Columnar Sections ...... y ...... 25 1, C3 Figure 7. Summary of'Hanover Depositional Environments...... 34 1, C14 Figure 8. Summary of Oak Grove. Sediment Distribution...... 36 1, D2 Figure 9. Cavusgnathus , Range and Phylogeny...... 45 1, D12 Figure 10. Diplognathodua Morphologyv^«$4...... 47 1, D14 Figure 11. Diplognothodus , Range and Phy logeny...... 49 1, E2 Figure 12. Gondolella, Range and Phylogeny...... /... 53 1, E6 Figure 13. Neognathodus , Range and Phylogeny...... /... 68 1, F7 . Conodont Figures (photographic prints are also included) N* Figure 14. McLeansboro (Modesto) Conodonts...... 90 ,2, A2 Figure 15. Kewanee (Upper Carbondale) Conodonts...... 92 2, A4 Figure 16. Kewanee (Middle Carbondale) Conodonts...... 94 2, A6
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Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 Figure 17. Kewanee (Spoon and Lower Carbondale) Conodonts...... '...... 95 2, A8 Table 1. Transgressive/Regressive Mechanisms in Perideltaic Environments. 9 I, A14 Table 2.'Distribution of All Conodonts from This Study...... 9 1, A14D7' *" Table 3. Conodont Zonation .of Northeastern Illinois...... 40 1, Table 4. Internal_CJironostratigraphic Correlations, Northwestern Illinois 1 42 D9 Table 5. Interregional Correlations and Comparison Between Neognathodid and Fusulinid Zonation...... 42 li D9 Table 6. Distribution of Gondole'lla in Northwestern Illinois...... 52 1, E5 TabT.e 7. Features of Middle and Late Desmoinesian Gondolellids...... 60 1, E13 Table 8. Ratio of Neognathodids to Other Platforms...... '...... 66 1, F5 Table 9. Distribution of Species of Neognathodus by Stratigraphic Unit in Northwestern Illinois...... 70 1, F9 Table 10. Taxonomic Libretto...... 81 G6
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iv Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 ACKNOWLEDGMENTS
'During the six years this work was in preparation a great many persons assisted in a variety of ways. Field and laboratory facilities for the bulk of the, work were provided by .'the Geology Department at Monmouth College, Mofamoj|th, Illinois. Two Students from that department, Miss Susan M. Bahnick and^lr. Michael J. Hochsteih, devoted many hours in the field, in the processing laboratory, and at the microscope during the early stages of this study. Their contribution cannot be overemphasized. The personnel of the Illinois State Geological Survey, particularly the Coal Section, and especially Dr. M', E. Hopkins and Mr. William H. Smith, kindly provided a wealth of locality information that greatly facilitated site selection for sampling. Computer programs for tabulating the large numbers of specimens,' samples, units, and taxa, arid for calculating Fagej: Coefficients for these occurrences were written by Mr, Ted H. Heithecker, the Computer Center, The University of Texas at Arlington. Photographic facilities were kindly made available to me by Dr. John W. Huddle, U. S. .Geological Survey, Washington, D. C. Additionally, Dr. and Mrs. Huddle extended me the hospitality of their home while I was perf orming ^the photography of these conodonts . Miss Bernice Fox, Classics-Department, Monmouth College, assisted in the formation of Linnean names. Several persons and agencies at Frostb'urg State College, Frostburg, Md., provided services and .facilities that supported this study: Dr. Melvin L. Brown of the Biology Department permitted the use of microscope facilities, darkroom use was provided by the Audio-Visual Section, and some subsidiary use was made of computer facilities (key punch) at the college. Most of all, my wife Stina, without whose constant help, nothing would be possible. - .y. Each of these persons and agencies has my sincere thanks as" diy-some long-suffering colleagues, especially Dr. Peter H. von Bitter, Rofal Ontario Museum, who read portions of the manuscript. Assistance from many sources made completion of th'is work possible; in the final analysis j however, the conclusions expressed herein are mine alone. . ,
Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 ABSTRACT A" ' "'— T- •—-—-- - PennsyIvanian rocks .^xposetl in Knox, Peoria*', Fulton, and Counties in northwesterly/Illinois include 11 major marine units. . The oldest marine unites late Ajx&an and the youngest is early Missourian; the remainder are Desmoinesian in age. Each unit has produ'ced^at least some conodonts, and the/more, than 300 samples produced an aggregate total in. excess of 160,00^/conadont specimens. These can be grouped into not fewer than 78 kinds, considered specJLes in disjunct-element taxontftny. At least f 10 .multielement genera and 40 multielement species are represented. £>ix ptew ^pecies: Dipl'ognathodus illinoisensis , Neognatho^dus metanodosu$ , N. polij/- nodDsus , N. oligonoclosus, N.' anodosus , and G'ondolelta pulchrg. are described. Although all marine beds were formed in shallow water, 'general!^' near shore, they represent the products of highly diverse environments,. .-Conodont biofacies are sharply differentiated and mirror this diversity.*'Ectdogic controls that effected conodont distribution are believed to have "been sal- iflELty, energy, pH, and possibly biologic antagonism. Neognathodus is the most useful conodont ~genus for biostratigraphy in these rocks. Four zones and subzones are based on spacies of-this genus and it has permitted relatively precise interregional correlations. Secondary zonations can be based on other genera that supplement the Neognathodus zonation and assist in identifying units, In decreasing importance these ,are Gondolella, the Idiognathodus-Streptognathodus plexus, and Dtplognathodus, Keywords: PennsyIvanian> conodonts 3 biostratigraphy 3 paleoeoology 3 Illinois. * *
Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 V . ' : INTRODUCTION
Purpose and Scope ' 4 ' ' . \.
Pennsylvanian rocks form the bedrock surface beneath' approximately 75 percent of Illinois. The study area £Fig* i next'frame) is generally that northwest of the Illinois River, northeast of the LaMoine River, but excludes Henry,'Bureau, Stark, and LaSalle Counties. Included therefore are Rock Island, Mercer, Warren, and Knox Couplties (.the lower units of which were studied by Merrill and King, 1971), plus the present coverage of the entire stratigraphic column in Knox, Peoria, Fulton,.and Schuyler Counties. This study area includes the area covered by Wanless' definitive works (1957, 1958) on the Beardstown, Glasford, Havana, and Vermont quadrangles. Also included is much of the area covered by the.Avon-Canton quadrangle report (Savage, 1922) and, the Peoria quadrangle report (Udden, 1912). Knowledge about this area is therefore relatively detailed. The large surface area covered ( roughly 2,650 square miles or 7,000 sq km) presents a great many possible sample sites for the several marine units. The studied marine units that produced conodonts, in descending order (Fig. 2) are the Cramer (Trivoli of literature), Exline, Lonsdale, "Sparland", Pokeberry, "Sheffield", Brereton, St. David, Hanover, Oak Grove, Seahorne, "Seville", and Seville Members. Reasons for the quotations will be explained in the'discussions of the units. This study is both a geographic and stratigraphic extension of the work of Merrill and King (1971). Data from that study have been incorporated into the present conclusions, but except for recollection of one locality and the figuring of a few of their specimens, there,is no duplication between this study and the 1971 work. . n '
Geologic Setting.
t It is especially fitting that conodonts from this^part of Illino^E should be used' in an attempt to enhance Pennsylvanian biostratigraphy 9Qd paledecology. The column for this four-county region has become, more or less a standard for the entire Illinois basin, and in some respects, for the North American Pennsylvanian as a whole. Moreover, several important concepts were developed here, and the area figured particularly strongly in the development of the Weller-Wanless model of Pennsylvanian cyclic sedimentation. In recent years the resulting^cyclothem model has cpme under Increased scrutiny and is held in greater skepticism in many^quarters than was previously the case./ Valuable"evidence is available from northwestern . Illinois that speaks to" this question; indeed, this is the birthplace of the concept. x The four counties studied possess some of the best natural an*d man-made exposures of Pennsylvanian rodks in the state. Man-made exposures, . mostly the!by-products of strip (surface;sxmining, provide unexcelled
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LOCATION OF
KHOME7ERS CONODONT SAMPLES
"igure I.- Locality map s/.sving the district!en- of all samples in this study and those of Merrill and King (1971) that arV located in the* four- county area. Unproductive localities are indicatedVv cresses placed ever the unit symbols and include Seville 22, Seahcrne 7 an& il, Hancver 12 and 13. Br'erexco. 19 and 23, Sparland 5. and Exline i and 3, All ^ther-localities had" at least-one productive sarple. Some localities that axe nuir.b'ered vithin the serial sequence for each stratigraphic unit are off/?map and net included in this report. These and the Merrill and King localities are not listed in Appendix 2. Seville localities 1-1- are off map ; th^^re listed in Merrill and King (1971,_ p. .o61,662) as are 15 and 16 shown here. Seville localities 18-20 are also off nap. Seahcrne localities l-~ are listed in Merrill and King, and 1 is off map as well. Oak Grove localities 1-19 are listed in Merrill and King and of these 1,2,6,7,15, and 16 are off ~ap. Also off ~ap is Oak Grove locality 25. Hanover localities off nap are ^-6. ^ Locality 7 in the St. David is an omitted number and 12,13, and 18-20 are off map.. Brereton locality 6 is*off map, and the only other locality off map is Crarr.er 2.
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"~X - Merrill Figure 2 Figure 2.- Generalized stracigraphic Column of the Pennsylvanian rocks cropping out in Knox, Peoria, Fulton, and Schuyler Counties, northwestern Illinois. Intervals are based on Wanless (1958, Fig. 2) and tfce * Desmoinesian-Missourian boundary (M/D) is based on Illinois State Geological Survey practice (Kosanke and others, 1960, PI. 1) rather^ than the opinion expressed herein about the placement of this boundary. X Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3743718/9780813759036_frontmatter.pdf by guest on 02 October 2021 opportunities to examine and physically trace individual lithosomes in detail. The transient nature of these exposures can hardly be overemphasized, however;- and several of the outcrops sttfdied'and sampled for this report no longer are accessible. Unfortunately, surface -mining, while aiding some investigations, has adversely ^effected other studies of regional stratigraphy t Square kilometre after square kilometre of'the rocks used ?y Wel$eV-and Wanless in their synthesis literally are no longer- in existence, -uToo often they have been successively, exposed and destroyed faster than they could be studied. During deposition of the rocks studied,, this part of Illinois was influenced most importantly by one or more deltaic complexes. The bulk of the stratigraphic column can be called "SjUbaerial deltaic",'and nearshore marine 'sediments compose the remainder. Delta switching of considerable magnitude resembled older Carboniferous deltas in the same general area (Swann, 1963) except that for the younger deltas, progradation was dominantly from the south and southeast and open water lay to the noiEth, northwest, and west. Evidence for this is derived mostly 'from deeper water and shallower water directions observed for several units (Figs, 5,7,8) as well as\align• ment of such structures as algal banks parallel to the ancient shoreline. The delta model is now generally accepted to explain the repetitive character of Pennsylvanian rocks in Illinois (Rao and Gluskoter, 1973). Numerou^ alternations between marine and nonmarine deposition prevailed in vthe 4rea for a considerable length of geologic time. These repeated changes in \ relative sea level have prompted several workers (Wanless-,ahd Shepard, 1.936; Weller, 1956) to search for either a tectonic or eustatic mechanism to explain these transgressions and regressions. In point of fact, any causitive mechanism related to repeated eustatic or te^onic changes would probably have adversely affected the patterns /pf delofic sedimentatioji reflected yy these rocks. Granted an ongoing, bui^gentle, subsidence of tha basin, tie normal processes of deltaic progradation, avulsion, compaction, and repeated progradation would suffice to produce,the preserved sedimentary record,
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