Early Diagenetic Calcareous Coal Balls and Roof Shale Concretions from the Pennsylvanian (Allegheny Series)

The calcareous concretions studied formed in different depositional environments associated with the Pcnnsylvanian eyclothems of cast central Ohio. The late syngenetic to early diagenetie coal balls from Lower Frecport Coal in Jefferson County were formed by cellular permineralization of decaying terrestrial plants in a peat swamp. These coal balls, composed of N9.N% calcite, 7.0% pyrite, and 2.(3% organic material, preserve six identifiable plant genera, Sphenophyllum, Stigmaria, Medulosae, Taxospermum, Psaronius, and Myeloxylon, as well as fusain and spores. The early diagnetic nodules from roof shale overlying Middle Kittanning Coal in Tuscarawas County, Ohio were formed by authigenic cementation of marine muds that contained brachiopods, including Mesolobus, Lingula, and several productid species, bryozoan fronds, ostracodes, gastropods, crinoids, cephalopods, as well as coprolites, terrestrially-derived fusain, root casts, and megaspore coats. These nodules, composed of 84.5% calcite, 11.3% illite, 1.5% quartz, 0.9% pyrite, and 0.5% organic material, have calcite-filled septarian fissures. OHIO J. SCI. 77(3): 125, 1977 Coal balls, or concretions that formed in peat, and roof shale nodules preserve a portion of sediment that was not severely compressed before lithification. As such, they provide a key for deciphering the diagenetie history of the strata in which they formed and also for recognizing original depositional features. Although roof shale nodules, such as those found in the blue shale overlying the Middle Kittanning Coal (No. 6) in Tuscarawas County, are common in near shore shales of Pennsylvanian age rocks of Ohio, coal balls have been described from coals only in the Monongahela (Good and Taylor 1974) and Conemaugh Series (Rothwell 1976) in Ohio. My study compares the diagenetie concretions noted above and coal balls found near Wellsville, Ohio in the Lower Freeport Coal (No. 6a) of the Pennsylvanian Allegheny Series. Some coal balls show textural variations that indicate formation under a wide range of energy conditions (Perkins Manuscript received lanuary 10, 1977 and in revised form March 25, 1977 (#77-1). 1976) including large-scale marine inundations that carried marine organisms into a peat swamp environment (Mamay and Yochelson 1962). Most coal balls, however, including those so far described from Ohio, were formed in situ under relatively quiescent conditions in peat swamps. Roof shale nodules, such as those described in my study, were formed in marine muds that often transgressed over peat deposits (Stopes and Watson 1909). At the coal ball locality in Jefferson County, Ohio there is no known example of a marine limestone directly above the Lower Freeport Coal (Lamborn 1930). Instead, the coal commonly occurs below a sandstone that shows no indication of marine origin. Weller (1930) observed in Illinois that such sandstone deposits above coals signify a period of erosion in which sediments originally covering the coal were removed before the sandstone was deposited. The coal probably was represented at that time by compressed peat that resisted erosion. Marine deposits that may have occurred above the Lower Freeport Coal in the Wellsville area probably were removed