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Home , Cuyahoga Formation, Logan Formation

Paleoenvironments of the Cuyahoga and Logan Formations () of central Ohio: Summary

ROBERT^ 'mALCUIT ^ Department of Geology and Geography, Denison University, Granville, Ohio 43023

INTRODUCTION REGIONAL SETTING AND STRATIGRAPHIC FRAMEWORK The Cuyahoga and Logan Formations of central Ohio are clastic units which record progradational and transgressional marine Mississippian strata in central Ohio strike generally north-south events during the Early Mississippian. This sequence of sediments is and dip gently to the east about 6 m/km. The outcrop belt of the characterized by: (1) the conglomeratic nature of some of the , the , and the members; (2) the facies relationships of the lobate and lies just to the west of the study area; farther to the shales of the ; (3) the sheetform nature of the southwest are the well-known exposures of rocks along members of the ; and (4) the faunal associations the Cincinnati Arch; and to the east are the and in both formations. In this paper, we synthesize information from strata of the Appalachian Basin. Lack of structural com- previous studies in the area, from our field and laboratory studies, plexity and relative abundance of outcrops in central Ohio facili- and from the current sedimentological literature in order to define a tates the recognition and interpretation of facies relationships. depositional model for the Cuyahoga and Logan Formations. The Cuyahoga and Logan Formations represent the upper part

The complete article, of which this is a summary, appears in Part II of the Bulletin, v. 90, p. 1782-1838.

Geological Society of America Bulletin, Part I, v. 90, p. 1091-1094, 2 figs., December 1979, Doc. no. S91202.

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thinning over the underlying lobes of Black Hand , but a MEMBER hallmark of the members in the Logan is their tabular form and re- LEGEND: gional continuity. LI THOLOGIES Boundaries between the sandstone lobes and the gray shales of SANDSTONE CONGLOMERATE the prodelta tend to be conformable. The erosional contact be- VINTON ooo tween the Cuyahoga Formation and the overlying Berne Member 0 0 0 (30-70 m) O ° »3 » of the Logan Formation is typically sharp in most outcrops. Boun- CONGLOMERATIC SANDSTONE daries between each of the four members of the Logan are generally well defined but conformable, in places transitional across several centimetres. A notable exception is the contact between the Byer and Allensville Members, which is commonly unconformable due m to erosion. SILTSTONE The composite stratigraphic column (Fig. 2) for the Cuyahoga BYER closely resembles the vertical profiles of sediments deposited along IBS prograding shorelines or in deltas (Coleman, 1976; Home and SANDSTONE SHALE (5-27 m) Ferm, 1978). Thick, gray, -poor siltstone and shale beds are overlain by sandstone and siltstone strata, which in turn are suc- BERNE ceeded by massive sandstones and conglomerates of the advancing CONGLOMERATE CONTACTS (0-5 m) nearshore environments. EROSION AL After the Cuyahoga complex had been deposited, Logan BLACK HAND sedimentation began with a major reworking of the coarse-grained SANDSTONE SHARP lobes, concomitant with transgression to the east. The thin, sheet- (0-100 m) form Berne Conglomerate was the first product of that episode. The

GRADATIONAL sedimentary petrology of the Logan Formation was quantified by RACCOON SHALE Pinker (1970); Bork (1970) used bivariate comparisons, prob- (FAIRFIELD SH.) ability-curve analysis, and discriminant functions in order to (WOOSTER SH.) INTERCALATED reach conclusions about the environment of deposition of the Berne (70-140 m) Conglomerate. Recent comments by Amaral and Pryor (1977) and others have argued that bivariate analysis and parameter compari- Figure 1. Generalized columnar section of Cuyahoga and Logan sons can produce misleading interpretations. Reconsidering the Formations in south-central Ohio. C = coarse-grained, F = fine- Berne data in light of such caveats led us to conclude that several grained. ambiguities of the Berne grain-size distribution — for example, the large percentage of fines, the similarity of Berne sediments to of the , a designation classically used for the Mis- modern fluvial deposits, and the occurrence of marine in sed- sissippian clastic rocks above the Ohio Shale of Devonian age and iments which plot in the fluvial field of parameter-comparison below the rocks of Pennsylvanian age. Basal Pennsylvanian sedi- graphs — are resolved by invoking the storm process model of ments, notably the Sharon Conglomerate, lie with erosional discon- Kumar and Sanders (1976). Log-probability plots of grain-size formity on the Logan Formation. Figure 1 summarizes the strati- data, internal structure, unit distribution and thickness, and graphic relations, thicknesses, lithologies, and boundary types for configuration of the bottom contact also suggest that storm the members of the Cuyahoga and Logan Formations. mechanisms played a significant role in deposition of the Berne Conglomerate. PHYSICAL ASPECTS OF THE Continued transgression led to deposition of the fine quartzose DEPOSITIONAL MODEL sand and silt of the Byer Member on a shallow marine shelf. Bed- ding is dominantly horizontal with some small-scale tabular cross- Following Potter (1967), Shelton (1973), Pettijohn (1975), and beds. The fauna is dominated by (rhipidomellids, Selley (1978), a general model of deposition for the units in the syringothyrids, chonetids, camarotoechids, and dictyoclostids), and study area has been developed. By analysis of several key features, normal marine diversity is represented by pelmatozoans, pectina- the paleoenvironmental conditions have been determined. These cean bivalves, fenestrate bryozoans, assorted pelecypods, and features include the geometry of units, boundary relations, vertical trilobites. Influx of the relatively coarse sediments of the Allensville sequences of lithology, fossil types, and grain-size distribution. Member probably resulted from a slight lowering of sea level which Lobes of sandstone and conglomerate have long been recognized reactivated erosion of coarse clastics in the source region to the in the Cuyahoga (Hyde, 1915, 1953; Holden, 1942; Ver Steeg, east. Logan sedimentation continued with a sea-level rise of several 1947). These lobes typically trend to the northwest, have a length metres which caused a return to Byer-like conditions and a re- of 40 to 60 km, are as much as 16 km wide, and have a maximum sumption of deposition of extensive silt or fine sand, with some thickness of 90 m. In cross section, the lobes are biconvex (Barclay, mud, on a marine shelf. These uppermost Logan sediments make 1968). Facies transitions, from the conglomeratic core to interdigi- up the Vinton Member. tated sandstone and siltstone on the margins, to sequences of gray shale, can be traced along an east-west line in the study area. PALEOBIOLOGY AND THE DEPOSITIONAL MODEL Geometry of the Logan Formation is quite simple in that its four members are extensive sheets of terrigenous sediments. Thicknesses Properly interpreted, analysis of fossil communities can aid in the vary only slightly within a given member, primarily as a function of understanding of paleoenvironments. Fossils from the Cuyahoga

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DESCRIPTION LITHOLOGY INTERPRETATION

CONGLOMERATIC SANDSTONE; LOW-ANGLE CROSS-BEDDING AND HORIZONTAL BEDDING; MARINE FOSSILS MARINE BAR OR SHOAL

CONGLOMERATIC SANDSTONE; TROUGH CROSS- BEDDING PREDOMINANT) SOME CONGLOMERATE LAYERS AND LENSES; GRADED BEDDING DISTRIBUTARY MOUTH BAR COMMON; SOME PLANT DEBRIS; NO MARINE FOSSILS Figure 2. Composite vertical profile of Cuyahoga Formation in vicinity of Licking County, Ohio.

MEDIUM TO FINE-GRAINED SANDSTONE, SILTSTONE AND SHALE; CROSS AND DELTA FRONT HORIZONTAL LAMINATIONS; MARINE FOSSILS) SOME PLANT DEBRIS

DARK SHALE AND SILTSTONE; CARBONATE CONCRETIONS; PYRITIZED MARINE FOSSILS; SIDERITE LAYERS; TRACE FOSSILS COMMON; MARINE FOSSILS PRESENT BUT NOT ABUNDANT; SOME PLANT DEBRIS

and Logan Formations were identified, analyzed for recurrent as- sandstone of the Black Hand Member of the Cuyahoga represents sociations (in the sense defined by Kauffman and Scott, 1976), and distributary mouth bar deposits. compared with the associations reported for Upper Devonian strata 3. The coarse clastic sediments of the Black Hand Member by Bowen and others (1974), McGhee (1976), and Thayer (1974). which contain horizontal bedding and laminations, low-angle It is concluded that the mollusc-rich fauna from shale in the cross-beds, and scattered marine fossils near the top of the unit are Cuyahoga is comparable to the Bellerophon community of Bowen marine shoreface or barrier-bar deposits. and others (1974) and is representative of a nearshore zone adja- 4. All four members of the Logan Formation contain marine cent to where a prograding clastic lobe was being deposited. The fossils and were deposited, except for the Allensville Member, Black Hand Sandstone Member of the Cuyahoga Formation has a under conditions of rising sea level. fauna that is more like the sheetsand faunas of the 5. Thickness, regional distribution, petrologic affinities with the Logan than the shale biota of the Cuyahoga, thereby demonstrating underlying Black Hand, nature of the contacts, and grain-size dis- the importance of environment and substrate. Thayer's (1974) tribution suggest that much of the Berne Conglomerate Member of Rhipidomella-Leiorhynchus association suggests a rapid progra- the Logan was deposited during major storm activity. dation environment, and is partly correlated with the brachiopod 6. Transgression to the east created the requisite shallow-marine fauna of the Black Hand Member. Faunal associations of the Logan conditions for deposition of the Byer Sandstone Member. Lack of Formation have affinity with the Rhipidomella community of coarse material is attributed to a shift of the sediment feeder system Bowen and others (1974) and the Rhipidomella-Leiorhynchus as- to the south of the study area, as well as to increased water depth sociation of Thayer (1974), considered to be characteristic of a and distance from the shoreline. shallow-marine, mid-shelf environment. 7. Temporary lowering of sea level, by perhaps 5 m, caused the influx and distribution, by longshore current, of coarser materials CONCLUSIONS that now form the Allensville Member. The coarse sand and small pebbles could have been derived from downcutting of the alluvial The Lower Mississippian Cuyahoga and Logan Formations of plain to the east and need not have required a tectonic pulse in the central Ohio represent deltaic and shallow-marine deposits. Re- source region. gional distribution of facies, , vertical var- 8. With the rise in sea level of several metres, conditions re- iations in lithology and grain size, and faunal content have been turned during deposition of the Vinton Member which were similar used to depict specific subenvironments in the shoreline complex. to those during deposition of the Byer Sandstone Member. The Eustatic changes in sea level and shifts in the feeder systems which Vinton Member is characterized by fine-grained sandstone similar brought clastic material from the source region to the east played a to that in the Byer, but it also contains significant amounts of role in the evolution of the paleoenvironments. Among the conclu- siltstone and shale. sions reached are the following. Paleocological analysis of the faunas in the Cuyahoga and Logan 1. The gray, fossil-poor siltstone and shale in the Cuyahoga Formations supports conclusions reached through investigation of Formation exposed in the western part of the outcrop area are pro- the physical nature of the units. Comparison with the faunas from delta deposits. clastic rocks of Late Devonian age aided in the interpretation of 2. The nonfossiliferous, cross-bedded, quartzose conglomeratic paleogeographic settings for the Cuyahoga and Logan Formations.

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9. Trace fossils of the Zoophycos association suggest that the South Carolina, University of South Carolina, Department of Geol- gray shale units of the Cuyahoga were deposited well offshore. ogy, 151 p. Vertical burrows imply that some sandstone units in the Logan rep- Hyde, J. E., 1915, of the Waverly Formations of central and southern Ohio: Journal of Geology, v. 23, p. 655-682. resent shallow-marine nearshore deposits. 1953, The Mississippian formations of central and southern Ohio: 10. The mollusc-rich fauna in siltstone in the Cuyahoga indi- Ohio Geological Survey Bulletin 51, 355 p. cates the calmer marine conditions that preceded the onset of pro- Kauffman, E. G., and Scott, R. W., 1976, Basic concepts of community gradation of clastic lobes from the east. Nearshore marine ecology and paleoecology, in Scott, R. W., and West, R. R., eds., Structure and classification of paleocommunities: Stroudsburg, brachiopods dominated the upper barrier sands that formed the Pennsylvania, Dowden, Hutchinson, and Ross, p. 1—28. Black Hand Sandstone Member. Kumar, N., and Sanders, J. E., 1976, Characteristics of shoreface storm de- 11. A diverse normal-marine fauna characterizes most of the posits: Modern and ancient examples: Journal of Sedimentary Petrol- Logan Formation and indicates deposition on a shallow shelf. ogy, v. 46, p. 145-162. McGhee, G. R., Jr., 1976, Late Devonian benthic marine communities of the central Appalachian Allegheny Front: Lethaia, v. 9, p. 111-136. REFERENCES CITED Pettijohn, F. J., 1975, Sedimentary rocks (3rd edition): New York, Harper and Row, 628 p. Amaral, E. J., and Pryor, W. A., 1977, Depositional environment of the St. Pinker, R. W., 1970, The sedimentary petrology of the Logan Formation in Peter Sandstone deduced by textural analysis: Journal of Sedimentary Licking County, Ohio [M.S. thesis]: Columbus, Ohio, Ohio State Uni- Petrology, v. 47, no. 1, p. 32-52. versity, 85 p. Barclay, C. C., 1968, Sedimentary structures and depositional history of the Potter, P. E., 1967, Sand bodies and sedimentary environments — A review: coarse-clastic rocks of the Cuyahoga Formation in northern Ohio American Association of Petroleum Geologists Bulletin, v. 51, p. [M.S. thesis]: Kent, Ohio, Kent State University, 108 p. 337-365. Bork, K. B., 1970, Use of textural parameters in evaluating the genesis of Selley, R. C., 1978, Ancient sedimentary environments (2nd edition): the Berne Conglomerate (Mississippian) in central Ohio: Journal of Ithaca, New York, Cornell University Press, 287 p. Sedimentary Petrology, v. 40, p. 1007-1017. Shelton, J. W., 1973, Models of sand and sandstone deposits: A methodol- Bowen, Z. P., Rhoads, D. C., and McAlester, A. L., 1974, Marine benthic ogy for determining sand genesis and trend: Oklahoma Geological communities in the Upper Devonian of New York: Lethaia, v. 7, p. Survey, Bulletin 118, 122 p. 93-120. Thayer, C. W., 1974, Marine paleoecology in the Upper Devonian of New Coleman, J. M., 1976, Deltas: Processes of deposition and models for ex- York: Lethaia, v. 7, p. 121-155. ploration: Champaign, Illinois, Continuing Education Publication Ver Steeg, Karl, 1947, Black Hand Sandstone and Conglomerate in Ohio: Company, Inc., 102 p. Geological Society of America Bulletin, v. 58, p. 703-728. Holden, F. T., 1942, Lower and middle Mississippian stratigraphy of Ohio: Journal of Geology, v. 50, p. 34—67. MANUSCRIPT RECEIVED BY THE SOCIETY JANUARY 18, 1979 Home, J. C., and Ferm, J. C., 1978, depositional environ- REVISED MANUSCRIPT RECEIVED JULY 16, 1979 ments: Eastern Kentucky and southern West Virginia: Columbia, MANUSCRIPT ACCEPTED JULY 20, 1979

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