Proceedings of the Iowa Academy of Science Volume 80 Number Article 3 1973 Mississippian Stratigraphy of North-Central Iowa Donald L. Koch Iowa Geological Survey Let us know how access to this document benefits ouy Copyright ©1973 Iowa Academy of Science, Inc. Follow this and additional works at: https://scholarworks.uni.edu/pias Recommended Citation Koch, Donald L. (1973) "Mississippian Stratigraphy of North-Central Iowa," Proceedings of the Iowa Academy of Science, 80(1), 1-3. Available at: https://scholarworks.uni.edu/pias/vol80/iss1/3 This Research is brought to you for free and open access by the Iowa Academy of Science at UNI ScholarWorks. It has been accepted for inclusion in Proceedings of the Iowa Academy of Science by an authorized editor of UNI ScholarWorks. For more information, please contact [email protected]. Koch: Mississippian Stratigraphy of North-Central Iowa 4 Mississippian Stratigraphy in Southeastern Iowa MARY C. PARKER1 PARKER, MARY C. Mississippian Stratigraphy in Southeastern Iowa. west portion of southeast Iowa and occur locally within the basal Proc. Ia. Acad. Sci., 80(1):4-7, 1973. Osage. Siltstone occurs within the lower portion of Kinderhook SYNOPSIS: All formational units of the Kinderhook, Osage and strata. The maximum thickness of the Mississippian System across Meramec Series are represented in Iowa. No rock units of the south-central Iowa represents the main axis of Mississippian de­ Chester Series are present in the state. The Mississippian sequence position. of rocks is dominated by cherty marine carbonates, but thin fossili­ INDEX DESCRIPTORS: Stratigraphy, Mississippian, Iowa, Meramec ferous shale units occur in the Osage and Meramec. Sandstone and Series, Osage Series, Kinderhook Series. sandy carbonate are dominant within the Meramec in the north- Mississippian formations constitute the bedrock in a diag­ outcrop belt in eastern Iowa. The general thinning to the onal belt twenty to forty miles wide from Lee and Des northwest reflects the transgressive conditions present in the Moines Counties in the southeast corner of the state north­ early Mississippian. westward to southern Cerro Gordo and Hancock Counties in The stratigraphic succession of the Mississippian rocks in north-central Iowa. southeastern Iowa is shown in Table 1. The thickness of The standard sections of Mississippian age rock units are the Mississippian sequence and the thickness of each series along the Mississippi Valley from southeastern Iowa into in southeastern Iowa is shown in Figure 1. southern Illinois and southeastern Missouri. All formational units of the Kinderhook, Osage and Meramec Series are rep­ resented in Iowa. Because the Kinderhook varies lithologi­ SERIES GROUP FORMATION MEMBER cally from place to place and many of the formations orig­ ;:,re. \.:7enev1eve inally correlated as Mississippian are now placed in the De­ Meramec ~r, LOUIS vonian, no standard section has been established for the ~pergen vvarsaw Kinderhook. The type sections of the Burlington and Keo­ i<.eOKUK kuk Formations are located near those cities in southeast Osage Cedar Fork Iowa. The Warsaw Formation derives its name from ex­ Burlington Haight Creek posures at Warsaw, Illinois, nearly opposite Keokuk, Iowa. Dolbee Creek The Spergen, St. Louis, and Ste. Genevieve Formations are I I I I I I I I I represented in Iowa by marginal facies of formations which are thicker and more uniform in composition farther south Hampton I 11 11 v assonv1 e in the Mississippi Valley. Kinderhook ~rarrs ._ave None of the Chester Formations are represented in the North Hill rrospec1 n111 state and it is probable that the Chester seas never extended McLraney this far north. The Mississippian-Devonian boundary is placed at the base Table 1. Stratigraphic succession of the Mississippian rocks in of the North Hill Group by the Iowa Geological Survey. A southeastern Iowa. discussion of the Mississippian-Devonian boundary in Iowa has been presented by Dorheim, Koch, and Parker (1969) . Along the eastern and northeastern edge of the outcrop STRATIGRAPHY-KINDERHOOK SERIES belt, Kinderhook strata occur above formations of the Yellow Spring Group (uppermost Devonian) . Along the northern The Kinderhook Series in southeastern Iowa includes the boundary in Hancock and Kossuth Counties, Kinderhook North Hill Group and the overlying Hampton Formation. strata occur above the Lime Creek Formation (lower Upper The Kinderhook is composed dominantly of carbonate rocks. Devonian). In western Iowa and eastern Nebraska, Kinder­ Siltstone occurs in the North Hill Group and chert in the hook strata occur above Middle Devonian rocks. For the Hampton. most part, the boundary is a transgressive, nonconformable The North Hill Group (Workman and Gillette, 1956) in­ contact. cludes in ascending order: McCraney Limestone, Prospect The Mississippian System is unconformably overlain by Hill Siltstone, and Starrs Cave Formation. The McCraney Lower Pennsylvanian (Cherokee Group) sediments in most Limestone is dominantly a very pale-orange to pale yellow­ of southeastern Iowa. Jurassic (?) (Fort Dodge Beds) and ish-brown, sublithographic limestone. Brown medium-grained Lower Cretaceous units were deposited upon the eroded dolomite occurs in irregular horizontally and vertically ori­ Mississippian surface in north-central and northwestern Iowa. ented planes. The McCraney is sparingly fossiliferous except Pleistocene deposits mantle the Mississippian rocks along the for the basal portion which consists of an oolitic, crinoidal limestone that locally contains a coarse brachiopod coquina composed almost entirely of Chonetes. The Prospect Hill 1 Iowa Geological Survey, 16 West Jefferson Street, Iowa City, Siltstone is dominantly a light greenish-gray, medium silt­ Iowa 52242. stone with discontinuous green shaley seams. The Prospect Published by UNI ScholarWorks, 1973 1 Proceedings of the Iowa Academy of Science, Vol. 80 [1973], No. 1, Art. 3 MISSISSIPPIAN SOUTHEASTERN low A 5 THICKNESS OF MISSISSIPPIAN ROCKS THICKNESS OF KINDERHOOK ROCKS IN SOUTHEASTERN IOWA IN SOUTHEASTERN IOWA contour interva I 100 feet contour interval 50 feet THICKNESS OF OSAGE ROCKS THICKNESS OF MERAMEC ROCKS IN SOUTHEASTERNIOWA IN SOUTHEASTERN IOWA contour interval 50 feet contour interval 50 feet Figure I. Thickness maps of Mississippian series in southeast Iowa. Hill contains fish teeth, brachiopods, and pelecypods. The tive of the Hampton Formation (Laudon, 1931) in south­ Starrs Cave Formation is a very pale orange to pale gray, eastern Iowa. The Wassonville consists of pale to dark yel­ oolitic limestone which contains fragmented brachiopods, lowish-orange, dolomitic limestone and pale yellowish-brown corals, and crinoids. dolomite. Over most of the area of its occurrence, the Was­ The Wassonville Limestone Member is the only representa- sonville contains appreciable amounts of light gray, fossilif- https://scholarworks.uni.edu/pias/vol80/iss1/3 2 Koch: Mississippian Stratigraphy of North-Central Iowa 6 PROC. lowA AcAD. Sc1. 80 ( 1973) erous chert. In the extreme southeastern counties the Was­ kuk. To the north an::l west it decreases in thickness and is sonville is relatively chert free and is dominantly a <lolomitic absent north of a line across southern Washington and Keo­ limestone. To the west and northwest the Wassonville be­ kuk Counties and west of a line from Hedrick to Centerville. comes more dolomitic and contains more chert. In Washington, Keokuk, and Louisa Counties a sandstone Little formational facies variation occurs in the Kinder­ occurs at the base of the Burlington which probably repre­ hook other than an increase of dolomite toward the west sents a shoreline deposit equivalent to the calcarenites of the and northwest in the carbonate units and an increase in shale Dolbee Creek. The Haight Creek Member (Laudon's Phys­ to the south in the Prospect Hill Siltstone. etocrinus zone) is highly cherty and contains dolomite as The thickness of the Kinderhook in southeastern Iowa well as limestone be::ls. The base of the Haight Creek is ranges from less than 50 feet near the outcrop area to over marked by a glauconitic dolomite. The glauconite occurs as 150 feet in parts of Van Buren, Davis, and Wapello Counties. greenish-black grains or pellets with roun::led or polished The variations in thickness and areal distribution of the surfaces. This zone extends beyond the limits of the under­ North Hill Group formations is more marked than that of the lying Dolbee Creek Member and rests on rocks of Kinder­ Wassonville Member of the Hampton Formation. The thick­ hook age to the north and west. The Haight Creek has a ness of the Wassonville averages 30 feet and varies from 8 rather uniform thickness ranging from 40 to 50 feet. The feet near Burlington to over 50 feet at Centerville in Appa­ Cedar Fork (Laudon's Dizygocrinus and Pentremites zones) noose County. In contrast, the North Hill Group varies from is relatively pure crystalline limestone. The Dizygocrinus approximately 25 feet at the type section near Burlington zone commonly contains abundant soft flakes of glauconite to over 100 feet in Davis County. The McCraney Lime­ which gives the limestone a green color, and the Pentre­ stone attains a thickness of 70 feet near Keokuk and 60 mites zone is cherty. The Cedar Fork ranges from 10 to 3(J feet at Ottumwa. It thins to the north and northwest from the feet in thickness. Burlington area and appears to be absent west of Davis The Burlington Limestone exhibits gradational changes in County. South of