Cleveland Shale Research Articles

Geochemical and Hydrographic Evolution of the Late Devonian Appalachian Seaway: Linking Sedimentation, Redox, and Salinity Across Time and Space

AbstractContinental interiors were flooded by epeiric seas during many intervals of the geologic past. Few modern analogs exist for these environments, however, and basic variables such as redox, salinity, and restriction are difficult to reconstruct in deep time. Despite these challenges, constraining epeiric watermass properties is critical because much of our preserved and accessible sedimentary record was deposited in such settings. Here, we present a four‐dimensional reconstruction of watermass evolution in the Late Devonian Appalachian Seaway of North America. We use combined proxies for sediment supply, paleosalinity, paleoredox, and basin hydrography in six cores through the Upper Devonian Cleveland Shale deposited across a paleo‐depth transect. Cyclic, coupled changes in sedimentation, redox, and salinity are recorded in environments near the Catskill Delta. Additionally, a pronounced salinity gradient was present from low‐brackish conditions near the delta to fully marine conditions in the basin interior, with a lower‐salinity mixing zone recorded across the Cumberland Sill. We also identified two broad sequences—the lower and upper Cleveland Shale—each of which shows distinct watermass signatures. The lower Cleveland Shale records a redox gradient with euxinia only present along the Cumberland Sill, whereas the upper Cleveland Shale records intensification of euxinia (potentially in the photic zone) at all six sites, which may be coincident with the Hangenberg extinction event. Ultimately, this study identifies pronounced epeiric watermass gradients over short timescales (millennia) and distances (hundreds of km or less), highlighting the need for interpreting the geochemistry of epicontinental deposits in the context of basin hydrography and paleosalinity.

Reconstructing the paleoceanographic and redox conditions responsible for variations in uranium content in North American Devonian black shales

The uranium (U) content, and more recently, the ratio between 238 U and 235 U in black shales are commonly applied as a proxy to determine redox conditions and infer organic-richness. Uranium contents typically display a linear relationship with total organic carbon (TOC) in shales. This relationship is due to the processes and mechanisms responsible for the incorporation of U into the sediment during the deposition and remineralization of organic matter. This U/TOC relationship can vary, however, and some shales display uncharacteristically low U content despite having high TOC content, while others show large enrichments of U relative to TOC. Here we examine the U to TOC ratios and U-isotope compositions of three Upper Devonian-Lower Mississippian shales: the Woodford Shale, the Cleveland Shale, and the Bakken Shale, with two study sites in Oklahoma, one site in eastern Kentucky, and three sites in eastern Montana and western North Dakota, respectively. The U/TOC ratios of each shale are distinct from one another exhibiting average ratios ranging from 3 in the Cleveland Shale, to over 10 in the Bakken Shale. The distinct geochemical composition of the three shales suggests that, although lithologically similar, each study site represents a markedly different and dynamic depositional environment. The low average U/TOC (~3) along with the relatively high δ 238 U values (~0.03‰) of the Cleveland Shale core suggests deposition along the basin margin under normal marine conditions with periods of reduced bottom water oxygenation, likely due to fluctuations in the location of the pycnocline. The Woodford Shale on the other hand, shows higher U/TOC ratios (~4, George core, ~9, Poe core) and δ 238 U (~0.02‰ average, George core, ~0.06‰ average, Poe core), which suggests an unrestricted setting with intermittent euxinic conditions. In contrast, high U/TOC ratios (2–15), and very high δ 238 U values (up to 0.55‰) in the Bakken Shale cores indicate intense metal draw-down into sediments under sulfidic waters. The results show that when the U/TOC ratios and U-isotopic compositions of each studied shale are compared to modern anoxic basins and upwelling areas, it allows for an enhanced understanding of the paleoenvironmental conditions such as basin restriction and redox state of waters within the Late Devonian epicontinental seas of North America. • U/TOC ratios of Late Devonian shales vary due to basin restriction. • Bottom water euxinia does not require strong basin restriction. • δ 238 U values provide new insight into the paleogeography of N. American basins.

First African thylacocephalans from the Famennian of Morocco and their role in Late Devonian food webs

Thylacocephalans are enigmatic arthropods with an erratic Palaeozoic and Mesozoic fossil record. In many of the few localities where they occur, they are quite abundant. This also holds true for the Famennian Thylacocephalan Layer in the Maider (eastern Anti-Atlas of Morocco), a small epicontinental basin hosting some strata with taphonomic properties of a conservation deposit yielding exceptionally preserved gnathostomes and non-vertebrates. In a thin argillaceous interval in the earliest middle Famennian, thylacocephalans occur in such great numbers that they became eponyms of this unit. Therein, we discovered a new taxon of thylacocephalans, Concavicaris submarinus sp. nov., which represent the oldest records of thylacocephalans from Africa. In the CT-imagery, the holotype of Concavicaris submarinus sp. nov. revealed anatomical details including its eyes, appendages and other soft parts. Sedimentary facies and faunal composition of the Thylacocephalan Layer suggest that these animals populated the water column above the low-oxygen sea floor. Thus, thylacocephalans likely represented an important component of the diet of chondrichthyans and placoderms, which are quite common as well. The abundance of thylacocephalans in other conservation deposits like the Cleveland Shale (USA) and the Gogo Formation (Australia) underline their pivotal role in Late Devonian pelagic food webs.

A stable and productive marine microbial community was sustained through the end-Devonian Hangenberg Crisis within the Cleveland Shale of the Appalachian Basin, United States.

The end-Devonian Hangenberg Crisis constituted one of the greatest ecological and environmental perturbations of the Paleozoic Era. To date, however, it has been difficult to precisely constrain the occurrence of the Hangenberg Crisis in the Appalachian Basin of the United States and thus to directly assess the effects of this crisis on marine microbial communities and paleoenvironmental conditions. Here, we integrate organic and inorganic chemostratigraphic records compiled from two discrete outcrop locations to characterize the onset and paleoenvironmental transitions associated with the Hangenberg Crisis within the Cleveland Shale member of the Ohio Shale. The upper Cleveland Shale records both positive carbon (δ13 Corg ) and nitrogen (δ15 Ntotal ) isotopic excursions, and replenished trace metal inventories with links to eustatic rise. These dual but apparently temporally offset isotope excursions may be useful for stratigraphic correlation with other productive end-Devonian epeiric marine locations. Deposition of the black shale succession occurred locally beneath a redox-stratified water column with euxinic zones, with signs of strengthening denitrification during the Hangenberg Crisis interval, but with an otherwise stable and algal-rich marine microbial community structure sustained in the surface mixed layer as ascertained by lipid biomarker assemblages. Discernible trace fossil signals in some horizons suggest, however, that bioturbation and seafloor oxygenation occurred episodically throughout this succession and highlight that geochemical proxies often fail to capture these rapid and sporadic redox fluctuations in ancient black shales. The paleoenvironmental conditions, source biota, and accumulations of black shale are consistent with expressions of the Hangenberg Crisis globally, suggesting this event is likely captured within the uppermost strata of the Cleveland Shale in North America.

New information on Titanichthys (Placodermi, Arthrodira) from the Cleveland Shale (Upper Devonian) of Ohio, USA

AbstractThe placoderm Titanichthys from the Late Devonian (Famennian) is based on incomplete and fragmentary specimens that have hindered understanding of its overall anatomy and phylogenetic relationships. A new, nearly complete, articulated specimen from the Upper Devonian Cleveland Shale provides new information about the previously undescribed rostral, postmarginal, postsuborbital, submarginal, posterior superognathal plates, and the nasal capsule. A revised diagnosis is provided for the genus. Three new diagnostic characters are identified, including a transversely elliptical rostral plate that does not contact adjacent plates, a reduced posterior superognathal, and a median dorsal plate that inserts into the posterior dorsal lateral plate. The first comprehensive phylogenetic analysis of Titanichthys indicates that the genus is a basal aspinothoracid arthrodire closely related to the enigmatic taxa Bungartius and Tafilalichthys.

Shallow-Water Origin of a Devonian Black Shale, Cleveland Shale Member (Ohio Shale), Northeastern Ohio, USA

Black shales are usually interpreted to require anoxic bottom waters and deeper water sedimentation. There has long been a debate about whether the Devonian Cleveland Shale Member of the Ohio Shale (CSM) was deposited in shallow- or deep-water depositional environments. This study looked at the CSM at 3 stratigraphic sections and 5 well cores in northeastern Ohio. The CSM mostly consists of sapropelite (interbedded carbonaceous black mudstones and gray calcareous claystones). The black and gray “shales” are rhythmically bedded at micro- ( ≥35 km, while hyperpycnites are too thin ( ≤50 m depth).

Coprolite evidence for carnivorous predation in a Late Devonian pelagic environment of southern Laurussia

Small, light-brown and beige cylindrical structures found in the lower Famennian (Upper Devonian) shales and marls of the Holy Cross Mountains area, central Poland, have been investigated for the first time. Their compact, pellet-shaped morphology and the presence of various fossil fragments scattered within the phosphatic groundmass clearly indicate that they are coprolites. The coprolite inclusions are dominated by arthropod cuticle fragments followed by fish remains, one conodont, and one scolecodont. The arthropod cuticle fragments are represented by the crustacean-like thylacocephalan Concavicaris and three other different types of arthropods of uncertain affinity. The presence of some conical fragments resembling telsons from phyllocarid crustaceans suggests that some of the cuticle fragments may belong to that group of arthropods. The fish remains mainly consist of actinopterygian paleoniscoid scales and sarcopterygian teeth. Taking both fossil and facies characteristics into account, it is clear that the coprolites originated from a carnivorous pelagic fishes that hunted other fishes and swimming arthropods. Surprisingly, similar faunal contents consisting of paleoniscoid fishes, Concavicaris arthropods, and conodonts occur in situ within the body cavities of the Famennian cladoselachian sharks in the Cleveland Shale, Ohio. Such a coincidence suggests that at least some of the Famennian coprolites from Poland may have also been produced by pelagic carnivorous sharks. The preservation of defecated remains was influenced by an interplay between an oxygen-deficient benthic environment devoid of bioturbators and scavengers and rapid, microbially-driven phosphatization.

Late Devonian glacigenic and associated facies from the central Appalachian Basin, eastern United States

Late Devonian strata in the eastern United States are generally considered as having been deposited under warm tropical conditions. However, a stratigraphically restricted Late Devonian succession of diamictite-mudstone-sandstone within the Spechty Kopf and Rockwell Formations that extends for more than 400 km along depositional strike within the central Appalachian Basin may indicate otherwise. This lithologic association unconformably overlies the Catskill Formation, where a 3- to 5-m-thick interval of deformed strata occurs immediately below the diamictite strata. The diamictite facies consists of several subfacies that are interpreted to be subglacial, englacial, supraglacial meltout, and resedimented deposits. The mudstone facies that overlies the diamictite consists of subfacies of chaotically bedded, clast-poor mudstone, and laminated mudstone subfacies that represent subaqueous proximal debris flows and distal glaciolacustrine rhythmites or varvites, respectively. The pebbly sandstone facies is interpreted as proglacial braided outwash deposits that both preceded glacial advance and followed glacial retreat. Both the tectonic and depositional frameworks suggest that the facies were deposited in a terrestrial setting within the Appalachian foreland basin during a single glacial advance and retreat. Regionally, areas that were not covered by ice were subject to increased rainfall as indicated by wet-climate paleosols. River systems eroded deeper channels in response to sea-level drop during glacial advance. Marine facies to the west contain iceborne dropstone boulders preserved within contemporaneous units of the Cleveland Shale Member of the Ohio Shale. The stratigraphic interval correlative with sea-level drop, climate change, and glacigenic succession represents one of the Appalachian Basin's most prolific oil- and gas-producing intervals and is contemporaneous with a global episode of sea-level drop responsible for the deposition of the Hangenberg Shale/Sandstone of Europe. This interval records the Hangenberg biotic crisis near the Devonian-Carboniferous boundary.

A comparative study of the ocular skeleton of fossil and modern chondrichthyans

Many vertebrates have an ocular skeleton composed of cartilage and/or bone situated within the sclera of the eye. In this study we investigated whether modern and fossil sharks have an ocular skeleton, and whether it is conserved in morphology. We describe the scleral skeletal elements of three species of modern sharks and compare them to those found in fossil sharks from the Cleveland Shale (360 Mya). We also compare the elements to contemporaneous arthrodires from the same deposit. Surprisingly, the morphology of the skeletal support of the eye was found to differ significantly between modern and fossil sharks. All three modern shark species examined (spiny dogfish shark Squalus acanthias, porbeagle shark Lamna nasus and blue shark Prionace glauca) have a continuous skeletal element that encapsulates much of the eyeball; however, the tissue composition is different in each species. Histological and morphological examination revealed scleral cartilage with distinct tesserae in parts of the sclera of the porbeagle and blue shark, and more diffuse calcification in the dogfish. Strengthening of the scleral cartilage by means of tesserae has not been reported previously in the shark eye. In striking contrast, the ocular skeleton of fossil sharks comprises a series of individual elements that are arranged in a ring, similar to the arrangement in modern and fossil reptiles. Fossil arthrodires also have a multi-unit sclerotic ring but these are composed of fewer elements than in fossil sharks. The morphology of these elements has implications for the behaviour and visual capabilities of sharks that lived during the Devonian Period. This is the first time that such a dramatic variation in the morphology of scleral skeletal elements has been observed in a single lineage (Chondrichthyes), making this lineage important for broadening our understanding of the evolution of these elements within jawed vertebrates.

Biomechanics, functional patterns, and disparity in Late Devonian arthrodires

Studies of ecological structure and diversity over time in extinct groups have always been challenged by the inability to observe the behavior of fossil taxa directly. The only available evidence for function, behavior, and interactions between taxa is the morphological characteristics of the preserved fossils. Recent studies on modern groups have shown that morphological analyses may give misleading results in terms of ecological pattern and diversity. An alternative approach is to focus on functionally relevant aspects of morphology through a paleobiomechanical paradigm. The purpose of this research is to examine variation in the lower jaw morphology in Late Devonian arthrodire placoderms and develop biomechanical metrics that can be used to quantify functional diversity among this fossil group. Nine functionally relevant morphological characters were collected for 94 isolated arthrodire inferognathals from the Gogo Formation in Western Australia and the Cleveland Shale in Ohio. These data were used to address aspects of functional morphology, biomechanical disparity, and ecological structure in arthrodire placoderms from the Late Devonian. Results were compared with results from previous morphometric work on the same set of jaws.Statistical tests show a significant difference in functional characters between the two faunas. The differences may be related to phylogenetic differences between faunas, as the two major clades of arthrodire taxa included in this study are almost completely segregated between faunas. Average pairwise disparity analyses of the mechanical characters indicate that there is no significant difference in overall functional diversity between the Cleveland Shale and Gogo Reef arthrodire faunas. This result is at odds with previous results that show overall morphological disparity to be much higher in the Cleveland Shale. Clustering patterns within a multivariate function-space show tightly constrained functional groups of taxa independent of phylogenetic or shape-based morphological similarity. These functional groups illustrate a level of ecological diversity in Late Devonian arthrodires that is comparable to that in certain modern faunas.Further statistical analysis of the morphological and functional disparity of these Late Devonian taxa shows a disjoint between the two measures. Model I regression analysis of and Spearman rank-correlation analysis of average pairwise morphological and functional disparity measures indicate no significant relationship between morphological and functional disparity among the jaws used in this study. Although function is obviously derived from morphology, these results show that morphological shape analysis is not necessarily a good proxy for eco-functional diversity.

Shape variation between arthrodire morphotypes indicates possible feeding niches

ABSTRACT Examining morphological patterns is key to understanding mechanics and function in biological systems. In extinct taxa, there is a lack of observational or behavioral data to use to understand function, and groups without descendants limit the use of modern homologues. The only available evidence for function is the morphological characteristics of the preserved fossils. The purpose of this research is to analyze the functional consequences of variation in the lower jaw morphology in Late Devonian arthrodire placoderms. Landmark-based morphometric data were collected for 94 isolated arthrodire inferognathals (lower jaws) from the Gogo Formation in Western Australia and the Cleveland Shale in Ohio. These data were used to define the morphological differences and variation between two phylogenetically distinct morphotypes. Statistical results indicate fundamental shape differences between the two arthrodire morphotypes (coccosteomorphs and pachyosteomorphs). Differences in the shape of the blade portion of the jaws imply that the extreme coccosteomorph form (determined by Canonical Variate Analysis, CVA) had stiffer jaws with occlusion patterns similar to modern mammalian carnivores, while the extreme pachyosteomorphs (also determined by CVA) had higher mechanical advantage (force transfer) with occlusion patterns similar to modern herbivorous mammals and bamboo sharks. Arthrodires possibly filled a number of diverse feeding niches. Based on morphological disparity analyses, the mostly open basin pachyosteomorphs had greater overall morphological diversity than the reef-dwelling coccosteomorphs. Lower disparity in reef dwelling arthrodires may be due to sampling bias, environmental factors, or competition from other fish groups present in Devonian reef faunas.

Trace-element budgets in the Ohio/Sunbury shales of Kentucky: Constraints on ocean circulation and primary productivity in the Devonian–Mississippian Appalachian Basin

The hydrography of the Appalachian Basin in late Devonian–early Mississippian time is modeled based on the geochemistry of black shales and constrained by others' paleogeographic reconstructions. The model supports a robust exchange of basin bottom water with the open ocean, with residence times of less than forty years during deposition of the Cleveland Shale Member of the Ohio Shale. This is counter to previous interpretations of these carbon-rich units having accumulated under a stratified and stagnant water column, i.e., with a strongly restricted bottom bottom-water circulation. A robust circulation of bottom waters is further consistent with the palaeoclimatology, whereby eastern trade-winds drove upwelling and arid conditions limited terrestrial inputs of siliciclastic sediment, fresh waters, and riverine nutrients. The model suggests that primary productivity was high (~ 2 g C m − 2 d − 1 ), although no higher than in select locations in the ocean today. The flux of organic carbon settling through the water column and its deposition on the sea floor was similar to fluxes found in modern marine environments. Calculations based on the average accumulation rate of the marine fraction of Ni suggest the flux of organic carbon settling out of the water column was approximately 9% of primary productivity, versus an accumulation rate (burial) of organic carbon of 0.5% of primary productivity. Trace-element ratios of V:Mo and Cr:Mo in the marine sediment fraction indicate that bottom waters shifted from predominantly anoxic (sulfate reducing) during deposition of the Huron Shale Member of the Ohio Shale to predominantly suboxic (nitrate reducing) during deposition of the Cleveland Shale Member and the Sunbury Shale, but with anoxic conditions occurring intermittently throughout this period.

Can marine anoxic events draw down the trace element inventory of seawater?

The trace element inventory of seawater is likely to have varied in the past owing to changes in the proportion of oxic-suboxic versus anoxic marine facies. Because only ∼0.3% of the modern global seafloor is subject to benthic anoxia, removal of redox- sensitive trace elements from seawater is largely mediated by oxic-suboxic facies. This results in higher concentrations and longer residence times for such elements in seawater compared with strongly anoxic paleoseas such as those of the Late Devonian. Reservoir modeling of Mo in Late Devonian seawater suggests that its concentration could have been reduced to ∼30%–50% of the present-day value. Chemostratigraphic data from Upper Devonian black shales of the Central Appalachian Basin provide empirical evidence of such depletion: sedimentary Mo concentrations decline within the Cleveland Shale despite intensified benthic anoxia, as proxied by degree of pyritization. Mo may have been depleted in penecontemporaneous seawater as a consequence of elevated burial fluxes associated with black shale deposition at time scales of 105 to >106 yr.

Permineralized Callixylon woods from the Late Devonian Cleveland Shale of Ohio, U.S.A. and that of Kettle Point, Ontario, Canada

Two permineralized woods are described in this paper, one from the Late Devonian Cleveland Shale of Ohio, USA and the other from the Late Devonian Huron Shale of Kettle Point, Ontario, Canada. Both samples of wood are satisfactorily preserved with primary and secondary xylem but without cortex and bark. Both are identified as Callixylon. They differ in specific characters from each other and from other described species. Hence two new species are designated, Callixylon beckii and Callixylon huronensis, respectively, to accommodate them in the class Progymnospermopsida (Progymnospermophyta) under the group Archaeopteridales.

A new specimen of Tamiobatis vetustus (Chondrichthyes, Ctenacanthoidea) from the Late Devonian Cleveland Shale of Ohio

ABSTRACT Tamiobatis vetustus is a very rare Paleozoic shark, originally based on a well-preserved, isolated brain-case of somewhat doubtful provenance from Eastern Powell Co., Kentucky. A second much larger braincase has been referred to the genus but, like the holotype, is completely isolated. The latest specimen, found on a bedding plane in the Late Devonian Cleveland Shale, is associated with partial jaws, teeth, scales, and a spine impression which demonstrates that it is a ctenacanthoid shark, herein assigned to the family Tamiobatidae Hay, 1902. The well-preserved basicranial region reveals details of the blood circulation pattern not previously seen.

Evolutionary significance of the Late Devonian lycopsids of the northcentral America

The paper focusses on the evolutionary characters revealed by the lycopsid axes and cones of North America. Highlighted especially are the specimens collected from the Late Devonian greyish-black shale of Greater Cleveland, Ohio and from the Late Devonian silty shale of Venango Formation in Erie County and Pennsylvania. Axes and cones are very large in dimensions comparable to those of Carboniferous. Dominance of many different kinds of lycopsids in the collection suggests that the coastal marshes of Late Devonian sea had forests of respectable size lycopsid trees. Clevelandodendron ohioensis, a slender, unbranched plant with an apical heterosporous cone and short, basal appendages, shows isotalean growth habit similar to a few Carboniferous genera and Triassic Pleuromeia-like forms. This, coupled with presence of Skilliostrobus-like cones from the Triassic of Australia and Tasmania, suggest lineage of Triassic lycopsids from the Late Devonian forms of the Cleveland Shale.

Clevelandodendron ohioensis, gen. et sp. nov., a slender upright lycopsid from the late Devonian Cleveland Shale of Ohio

Clevelandodendron ohioensis Chitaley & Pigg gen. et sp. nov. is an almost entire lycopsid plant known from a single compressed specimen from the Cleveland Shale member of the Upper Devonian Ohio Shale. This unique specimen is 125 cm long, consisting of an unbranched, slender, monopodial axis with a partially preserved plant base bearing thick appendages at one end, and a compact, terminal ovoid bisporangiate strobilus at the other. The stem is 2 cm wide for most of its length. Visible on the decorticated stem surface are helically arranged, elongate leaf traces and laterally compressed, slender leaves along the stem margin. The plant base bears 4‐6 thick appendages. The terminal strobilus is compact, ovoid, 9 cm long and up to 6 cm wide, morphologically similar to those of some Lepidodendrales, and bears helically arranged sporophyll/sporangium complexes with narrow bases and distal laminae up to 18 mm long, turned upward. Megaspores are 320‐360 μm, trilete and laevigate, lacking a gula; microspores are 30‐42 μm, trilete, indistinctly punctate and possibly assignable to Calamospora or Punctatisporites. Clevelandodendron demonstrates that slender unbranched lycopsids with an isoetalean plant habit similar to the Carboniferous genera Chaloneria and Sporangiostrobus and Triassic Pleuromeia‐like forms were present as early as the Late Devonian. The early occurrence of this unique habit suggests that diversification within the isoetalean clade sensu Rothwell and Erwin (including both Isoetales and Lepidodendrales) was well established prior to the Carboniferous.

Rock-eval pyrolysis and vitrinite reflectance trends in the Cleveland Shale Member of the Ohio Shale, eastern Kentucky

Within eastern Kentucky, organic petrographic and geochemical data indicate a southeastwards increase in maturation of the Cleveland Shale Member of the Ohio Shale (Devonian-Mississippian). Reflectance levels of dispersed organic material in the Cleveland Shale increase from 0.5% in the outcrop belt in central Kentucky, to slightly over 1.0% in Pike County, eastern Kentucky. A decrease in fluorescence intensity of liptinitic components, such as Tasmanites, accompanies this reflectance increase, as does a shift in fluorescence color of the alginite towards the red. In the highest rank areas, fluorescence is almost absent. Groundmass fluorescence is observed also, and follows trends similar to those shown by the alginite. Kerogen in the Cleveland Shale is primarily Type II, as indicated by petrographic observations and Rock-Eval data. Total organic carbon contents of this shale decrease from over 12% in the outcrop belt, to less than 2% in the eastern-most part of the study area. Source rock potential ranges from good to very good, with the highest potentials occurring in the outcrop belt. T max values for this unit increase from under 430°C in the outcrop belt to over 450°C in the southeast, confirming the increase in maturation trends indicated by vitrinite reflectance data. Both petrographic and geochemical maturation parameters place the Cleveland Shale of eastern Kentucky within the oil window. Comparison with maturation data for Pennsylvanian-age coals upsection suggests that maturation indices are retarded, or suppressed, in the Devonian shales. The level of maturation indicated for the Cleveland may be problematical considering that the Ohio Shale is a major gas-producer in this area.

On the occurrence of Prototaxites in the Cleveland Black Shale of Ohio, USA

A permineralized specimen of Prototaxites Dawson collected from the Upper Devonian Cleveland Shale in Cuyahoga County, Ohio, is grayish black, resembling decorticated, petrified wood. Cellulose acetate peels and ground sections show only the medullary region, consisting of wide and narrow, densely crowded tubes, almost all running parallel, and some oblique, to the long axis of the specimen. The tubes are thick-walled, two-layered, with longitudinal furrowa on the inner surface, septate, showing successive branching, some branches anastomosing. Thin-walled septate branched filaments are present in the intertubal spaces and also cover the tubes; small areas of disintegrated tubes are present all over. Structural details of the tube wall observed with SEM, coupled with other characters, when compared with the structurally known species of Prototaxites, warrant a new name for the Cleveland specimen: P. clevelandensis sp. nov.

Organic petrography of Mississippian and Devonian shales in east-central Kentucky

The Devonian and Mississippian oil shales of east-central Kentucky are classified as marinites. The petrographic composition of the kerogen in the shales is complex, and significant amounts of macerals from all of the major groups are present. Unfigured alginite (lamalginite) and bituminite are the most abundant macerals present, followed by vitrinite and inertinite (fusinite and semifusinite). Figured alginite (telalginite) includes Leosphoridia and Tasmanites; a minor amount of sporinite (~1% or less) is also present. The maceral composition of the Cleveland and Sunbury Shale interval from a core taken in Fleming County, Kentucky was determined quantitatively. The liptinite suite in the Sunbury interval was dominated by bituminite, while the Cleveland contained higher proportions of alginite. The total amount of inertinite plus vitrinite was found to be relatively constant. Variations in maceral composition affect the scatter of Fischer assay oil yield versus organic carbon relations for Eastern US oil shale. The kerogen macerals were found to correlate selectively with certain trace elements (e.g. Cr, Cu, V and Zn), suggesting that the maceral composition may be related to shale provenance. Bituminite:alginite ratio was found to correlate selectively with trace element concentration and supports the concept that the organic precursors for this maceral were bacterial decay products.