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Fossils of Dresbachian and Franconian (Cambrian) Age from the Subsurface of West-Central Indiana

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Fossils of Dresbachian and Franconian (Cambrian) Age from the Subsurface of West-Central Indiana - Fossils of Dresbachian and Franconian (Cambrian) Age from the Subsurface of West-Central Indiana By ALLISON R. PALMER DEPARTMENT OF NATURAL RESOURCES GEOLOGICAL SURVEY SPECIAL REPORT 29 PRINTED BY AUTHORITY OF THE STATE OF INDIANA BLOOMINGTON, INDIANA: 1982 STATE OF INDIANA r Robert D. Orr, Governor DEPARTMENT OF NATURAL RESOURCES James M. Ridenour, Director GEOLOGICAL SURVEY John B. Patton, State Geologist For sale by Geological Survey, Bloomington, Ind. 47405 Price $2.50 Contents Page r Abstract .... .1 Introduction .. .1 Acknowledgments .1 Stratigraphy ... .2 Paleontology . .3 Faunas of Franconian age .3 Faunas of Dresbachian age .7 Literature cited 11 Illustrations [Plates follow Literature Cited] Page Plate 1 Trilobites of Franconian age 2 Trilobites and gastropods of Dresbachian age Figure 1 Map of the eastern midcontinent region showing the general position of the lllinois Basin, subsurface datum points, and depositional facies of beds of the Crepicephalus Zone (middle Dresbachian age) ................. 2 2 Stratigraphic column showing the locations of paleontologic control (F) and the suggested stratigraphic nomenclature for the fossiliferous Cambrian part of Vermillion County well FMC No. WD-1 .................. 3 - Fossils of Dresbachian and Franconian (Cambrian) Age from the Subsurface of West-Central Indiana By ALLISON R. PALMER Abstract additional specimens not noted in my earlier Three fossiliferous levels in FMC No. WD-1, a report for Becker. Then publication of well in Vermillion County, Ind., have yielded descriptions of Franconian trilobites from Cambrian fossils. The highest level, in the southeastern Missouri (Kurtz, 1975) provided Davis Formation between depths of 4,497 a basis for reidentification of the trilobites and 4,546 feet, contains 17 distinct layers from the Davis Formation in the Vermillion with trilobites of the Elvinia Zone of early County well. The faunal identifications Franconian age. A single horizon, in an upper presented here reflect the new discoveries and oolite member of the Eau Claire Formation at the updating of identifications made since a depth of 4,698 feet, contains trilobites, completion of the 1970 report. gastropods, and other ·fossils of the Crepi­ Identifiable fossils, mostly trilobites, are cephalus Zone of middle Dresbachian age. present at three distinct levels in the Two lower horizons, in green shales of the Vermillion County well (fig. 2). The richest Eau Claire Formation at depths of 5,061 and interval is within the Davis Formation 5,083 feet, contain trilobites of the Cedaria between 4,497 and 4,546 feet. Seventeen silty Zone of early Dresbachian age. Characteristic to fine-sandy limestone layers in this 49-foot trilobites and gastropods are illustrated and interval yielded trilobites characteristic of the discussed. early Franconian Elvinia Zone (pI. 1). A single The upper oolite member is considered to collection from oolitic limestone at a depth of be a possible extension of part of the 4,698 feet yielded trilobites and other fossils Bonneterre Formation of Missouri. If this is (pI. 2, figs. 1-16) that represent the correct, the paleogeography of this interval in Crepicephalus Zone of middle Dresbachian the eastern midcontinent region suggests an age. Green to red micaceous shales at depths early presence of, or precursory conditions of 5,061 and 5,083 feet yielded trilobites (pI. for, the Illinois Basin. 2, figs. 17, 18) that represent a fauna of the Cedaria Zone of early Dresbachian age. Introduction This report confirms the record of fossils of Acknowledgments Dresbachian and early Franconian (Cambrian) Leroy E. Becker, then of the Indiana age from a deep well (FMC No. WD-l in the Geological Survey, and Alan S. Horowitz, NW1.4 sec. 9, T. 16 N., R. 9 W.) in Vermillion curator of paleontology, Department of County, west-central Indiana (figs. 1 and 2) Geology, Indiana University, sorted through (Becker and others, 1978). Fossils were first the Cambrian cores from Indiana and selected noted in cores 41,4 inches in diameter from the fossiliferous samples that were studied for this well by Becker in 1970 and were sent to this report. The photography was done by me for identification. Those preliminary Robert Eby, using facilities of the Depart­ identifications, made in August 1970, were ment of Earth and Space Sciences, State published in Becker and others (1978). In the University of New York, Stony Brook, N.Y. summer of 1977, I was asked to reexamine Partial funding was provided by NSF grant the faunas from this well and to prepare this EAR7825074. Final typing of the manuscript report. Permission was given for processing was done by Jean Davis of the Geological the samples for whatever could be recovered. Society of America. This resulted in the discovery of some 1 2 FOSSILS OF DRESBACHIAN AND FRANCONIAN (CAMBRIAN) AG - o 200 Miles I I I o 300 Km -----~- MO. EAU CLAIRE \ -.. ~I~ ) FORMATION I I ~r I .J WO-I l:weltfM9 I I . .( uppel: \ \ >()oH.te l i ILLINOIS·;memner ~j -- -- T~~N.- - -­ Figure 1. Map of the eastern midcontinent region showing the general position of the minois Basin, subsurfac datum points, and depositional facies of beds of the Crepicephalus Zone (middle Dresbachian age). Well FM No. WD-l yielded the fossils described in this report. Stratigraphy most part of the Bonneterre Formation i The description of the lithologic succession several areas includes an oolitic interval ( that was assigned to the Eau Claire Formation comparable thickness (Howe and other in the Vermillion County well by Becker and 1972, pI. 1; Kurtz and others, 1975, pI. 1 others (1978) suggests that perhaps an that has also yielded faunas of the Crep alternative stratigraphic nomenclature might cephalu8 Zone (Lochman, 1968). Thereforl be appropriate for this interval. The upper the upper oolitic member of the Eau Claire i 18S-foot unit of the Eau Claire Formation is Indiana is considered to correlate with, an the upper of two distinct oolitic limestone perhaps to be an extension of, the UpPE members within the predominantly shaly and Bonneterre of Missouri. silty dolomitic Eau Claire Formation, and it is Buschbach (1964) described the Lombar this member that yields the faunas of the Dolomite Member of the Eau Claire Forml Crepicephalus Zone. In Missouri, the upper­ tion in northeastern lliinois as a sand PALEONTOLOGY 3 is no precise faunal control on the age of these rocks, the Lombard Dolomite Member D~EpLiH STRATIGRAPHIC FAUNAL DATA AND AGE (FT) NOMENCLATURE INTERPRETATION may also be a tongue of the upper part of the Bonneterre Formation. As better control on the ages and lithologic correlations of r KNOX DOLOMITE Z 4400-+----------1 subsurface units in the eastern midcontinent <t region is developed, the lithostratigraphic Z o nomenclature should be reviewed and revised to reflect more clearly the regional distribu­ DAVIS u 4500 z tion of distinctive bodies of rock. Figure 1 FORMATION Elvinia <t assumes that the correlations discussed above Zone c::: u... are correct and gives some indication of the distribution of lithofacies of probable Crepi­ ? cephalus Zone age in the eastern midconti­ 4600 nent region on the basis of data from upper Grohskopf (1955), Buschbach (1964), Howe and others (1972), Kurtz and others (1975), oolite CrepicephallJs and Becker and others (1978). 4700 member F Zone z The area of probable carbonate sedimenta­ tion of middle Dresbachian age covers the site <t of much of the present Illinois Basin and changes southward into a deeper water 4800 :r: black-shale facies with agnostid trilobites u (Glyptagnostus) typical of ocean-facing sites <t (Grohskopf, 1955; Palmer, 1962). This 4900 OJ suggests that tectonic conditions controlling sedimentation patterns in Cambrian time were EAU CLAIRE en perhaps precursors to the formation of the w illinois Basin. c::: Some comments on the biostratigraphic 5000 o and biogeographic significance of the fossils found in the Vermillion County well are FORMATION F Cedaria presented below. 5100 F Zone Paleontology FAUNAS OF FRANCONIAN AGE A 51-foot interval within the Davis Forma­ Figure 2. Stratigraphic column showing the locations tion, between depths of 4,497 and 4,546 feet of paleontologic control (F) and the suggested stra­ in the Vermillion County well, includes a tigraphic nomenclature for the fossiliferous Cam· brian part of Vermillion County well FMC No. fauna dominated by disarticulated remains of WD-l. Datum is 5 feet above ground level and 647 trilobites, with rare fragments of linguloid feet above sea level. brachiopods. Thirteen species of trilobites, representing 10 genera, are present. Almost all of them represent genera characteristic of the dolomite with rare limestone interbeds. This Elvinia Zone of early Franconian age. The member ranges from 100 to 150 feet in definitive species for biostratigraphic dating thickness, which is not too much less than the are Eluinia roemeri (Shumard), Eluinia granu­ thickness of the Bonneterre equivalent (upper lata Resser, Pterocephalia sanctisabae Roe­ oolite member) in the Vermillion County mer, Bynumina caelata Resser, and Calo­ well. Although Buschbach included other cephalites cf. C. vulgaris Kurtz. The abun­ clastics above this dolomite in the Eau Claire dance of specimens of Calocephalites and the Formation of northeastern Illinois and there presence of Bynumina caeiata, both previous­ 4 FOSSILS OF DRESBACHIAN AND FRANCONIAN (CAMBRIAN) AG ly known only from the Davis Formation of material will be required to adequatel: Missouri (Kurtz, 1975), suggest similar condi­ characterize the new taxa that they rna: tions of deposition for the Davis Formation in represent. - Indiana and Missouri and emphasize the general faunal similarity of the two regions. Occurrence: Vermillion County well FMC N( Most other elements in the fauna are found in WD-1 at depths of 4,518, 4,518.5, 4,52( the Elvinia Zone throughout the central and 4,520.8, 4,530, 4,531, 4,531.5, 4,533, an, western United States.
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