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Crinoids (Phylum Echinodermata) represent major components of fossil assemblages in the type Cincinnatian (Upper Ordovician: Katian) of the greater Cincinnati Arch region. However, certain shallow marine lithofacies are characterized by a nonexistent to depauperate crinoid fauna, being instead dominated by trilobites, bryozoans, mollusks, and in some layers solenoporid algae? and stromatoporoids. One such setting is represented by the Grant Lake Formation, equivalent to the upper Corryville and Mount Auburn members of the McMillan Formation of Ohio, as exposed south of Flemingsburg, Fleming County, northern Kentucky. Described herein is an articulated crinoid crown (Anomalocrinus?) from this otherwise crinoid-poor interval. This occurrence may reflect either (1) a brief interval where conditions were more amenable to occupation by crinoids, possibly corresponding to a minor flooding surface, or (2) transportation of skeletal remains from nearby, deeper offshore areas that contained crinoids in greater abundance. The second interpretation seems more likely given the absence of in situ attachment structures and rarity of disarticulated column material at the study site. This study illustrates the value of echinoderm remains in paleoenvironmental analysis, the significance of crinoidal material in taphonomic interpretation of Paleozoic argillaceous carbonate deposits, and the sensitivity of crinoid fossils as indicators of allochthony or autochthony., INTRODUCTION Crinoids (Phylum Echinodermata) represent one of the most common and widespread faunal groups in the richly fossiliferous type Cincinnatian (Upper Ordovician: Katian) strata of the greater Cincinnati Arch region [...]

The Upper Ordovician Bobcaygeon Formation of southern Ontario is a widespread unit that spans the Sandbian-Katian stage boundary and contains exceptionally preserved invertebrate fossil assemblages, including the famed 'Kirkfield echinoderm fauna.' However, the precise correlation of this interval remains poorly understood. This paper presents new data on high-resolution sequence and carbon isotope chemostratigraphy of the Bobcaygeon interval based on new quarry exposures and introduces refined definitions of unit boundaries based on allostratigraphic criteria. Sequence, chemo-, and biostratigraphic evidence indicate that the Bobcaygeon Formation represents a composite unit as it encompasses a major erosional unconformity. The Coboconk and Kirkfield formations, described in the early 20th century, were merged into a single unit, the Bobcaygeon, out of concern that the original lithostratigraphic divisions would be conflated with biostratigraphic zones of the same names. However, these biostratigraphic zones are no longer favoured, and the lower member of the Bobcaygeon is here elevated again to the status of formation (Coboconk Formation) and represents the uppermost portion of the Sandbian M4 sequence. The middle and upper members of the Bobcaygeon, herein reassigned to the Kirkfield Formation, represent the upper Sandbian to lower Katian M5A and M5B sequences recognized widely in the eastern and central United States. The term Bobcaygeon is retained and elevated to the rank of subgroup. The Kirkfield Formation is divided into three members and contacts are refined, placing a 1-2 m transgressive grainstone at the base of each sequence. These units are correlated with equivalent strata of New York and the Cincinnati Arch. Key words: Upper Ordovician, Kirkfield Formation, Bobcaygeon Formation, sequence stratigraphy, chemostratigraphy. La Formation de Bobcaygeon de l'Ordovicien superieur du sud de l'Ontario est une unite repandue qui chevauche la limite des etages Sandbiens et Katiens et renferme des assemblages de fossiles invertebres remarquablement bien preserves, dont la celebre << faune d'echinodermes de Kirkfield >>. La correlation precise de cet intervalle demeure toutefois mal comprise. L'article presente de nouvelles donnees de haute resolution sur la chimiostratigraphie sequentielle et des isotopes du carbone de l'intervalle de Bobcaygeon provenant de nouveaux affleurements en carriere et propose des definitions plus fines des limites d'unites basees sur des criteres allostratigraphiques. Les observations sequentielles, chimiostratigraphiques et biostratigraphiques indiquent que la Formation de Bobcaygeon represente une unite composite puisqu'elle renferme une importante discordance d'erosion. Les formations de Coboconk et Kirkfield, decrites au debut du [20.sup.e] siecle, avaient ete fusionnees en une seule unite, la Formation de Bobcaygeon, par peur que les divisions lithostratigraphiques originales ne soient confondues avec les zones biostratigraphiques portant les memes noms. L'usage de ces zones biostratigraphiques n'est toutefois plus preconise, et le membre inferieur de l'intervalle de Bobcaygeon est une fois de plus eleve au statut de formation (Formation de Coboconk) et represente la partie sommitale de la sequence sandbienne M4. Les membres intermediaire et superieur de l'intervalle de Bobcaygeon, reaffectes ici a la Formation de Kirkfield, representent les sequences M5A et M5B du Sandbien superieur au Katien inferieur reconnues largement dans l'est et le centre des Etats-Unis. Le terme Bobcaygeon est retenu et eleve au rang de sous-groupe. La Formation de Kirkfield est divisee en trois membres dont les contacts sont definis plus finement, en placant un grainstone transgressif de 1-2 m a la base de chaque sequence. Ces unites sont correlees a des strates equivalentes de l'Etat de New York et du bombement de Cincinnati. [Traduit par la Redaction] Mots-cles : Ordovicien superieur, Formation de Kirkfield, Formation de Bobcaygeon, stratigraphie sequentielle, chimiostratigraphie., Introduction Upper Ordovician sedimentary rocks in the Lake Simcoe area of southern Ontario, Canada (Fig. 1), dominated by shallow-water subtropical carbonates, provide key insights into paleoenvironments, sea level fluctuations, and [...]

The Middle Devonian (lower–middle Givetian) Hamilton Group of New York State is an iconic unit in North America, which has contributed many key concepts in stratigraphy, sedimentary geology, paleoecology, and evolution. This interval comprises a 100- to 1200-m-thick clastic wedge, shed westward from the Acadian Mountains, with thin but persistent carbonates. Despite the rich and diverse invertebrate fauna that consists of more than 300 species of corals, bryozoans, brachiopods, mollusks, echinoderms, and trilobites, the age of the Hamilton Group is rather poorly constrained in terms of chronostratigraphy owing to the rarity of biostratigraphically useful conodonts and goniatites. The upper part of the Hamilton Group that is the focus of this paper apparently belongs to the Polygnathus timorensis to middle Polygnathus ansatus Conodont chronozones. The middle to upper Hamilton Group in New York State comprises three formations—the Skaneateles, Ludlowville, and Moscow—each defined as an interval delimited with a sharply based fossiliferous limestone-calcareous siltstone; these formations are interpreted as containing condensed transgressive deposits overlain by thicker highstand to falling-stage shales, mudstones/siltstones, and sandstones. The eastern equivalents of these formations are dominated by fine-grained sandstones and siltstones and include two formations: the Panther Mountain Formation, equivalent to the Skaneateles and Ludlowville formations combined, and the Cooperstown Formation, equivalent to the Moscow Formation. In the present paper, we review, revise and update a hierarchical framework of lithostratigraphic subdivisions of these formations, including 24 members (four new), 50 submembers (more than half newly proposed or redefined; 14 informal at this time), and more than 80 named beds, both formal and informal. This refined lithostratigraphy provides an excellent framework for studying high-resolution sequence stratigraphy. As defined herein, members and most submembers represent high-frequency depositional sequences with basal shell-rich carbonates and abrupt flooding surfaces that mark the bases of highstand deposits. Not only are most of the members and submembers traceable across western and central New York, but also to a lesser extent into adjacent regions that include southern Ontario, Ohio, the Michigan Basin, and northeastern Pennsylvania. Nevertheless, much work on correlation remains to be done in eastern New York and central Pennsylvania, where local progradation of siliciclastics and expansion of successions obscures many of the finer scale features. [ABSTRACT FROM AUTHOR]

Strata between the middle Givetian Moscow Formation and the newly recognized Givetian-Frasnian zonal stage boundary, at or near the top of the Lodi Member (Penn Yan Formation of the Genesee Group), include limestone-dominated strata of the Tully Formation and coeval siliciclastic deposits of the Gilboa Formation, overlain by progradational, siliciclastic deposits of the Geneseo Formation-Lodi Member succession. The Tully and Gilboa formations, the type expression of the North American provincial Taghanic Stage, correspond to the Polygnathus ansatus–“Ozarkodina” semialternans international conodont zones, and the Global Taghanic Biocrisis interval. The lower, pre-Frasnian part of the Genesee Group, corresponding to the successive hermanni (former hermanni-cristatus Zone), disparilis, and norrisi conodont zones, recorded the onset of a major Acadian tectophase (Tectophase 4; see Ver Straeten, 2023a [Vol. 1, Ch. 1]), timed with coincident deepening of the Devonian foreland basin and major global sea level-rise. The Tully Formation limestone in western and central New York State is an anomalous deposit of dominantly fine grained, medium to dark gray limestone that contrasts greatly with underlying Hamilton Group siliciclastic deposits and overlying progradational siliciclastic facies of the Genesee Group. Tully Formation deposits in western and central New York accumulated on a shallow platform. However, these deposits grade eastward and southward into the equivalent thicker siliciclastic Gilboa Formation, preserved within a structural trough or, possibly, a small-scale orogen-ward migrating basin, in eastern New York and central Pennsylvania that served as a “clastic trap” for siliciclastic sediments which failed to reach the platform. Diachronous basal Geneseo deposits record the westward regional onlap of basinal black mud deposits onto an east-sloping submarine ramp. The Geneseo Formation recorded geologically rapid subsidence and development of a shelf-slope break that imparted a strong control on sedimentary magnafacies. The Tully Formation largely displays distinctly clean carbonate deposits in central New York; the Gilboa Formation is herein applied to coeval eastern (shoreward) siliciclastic facies. Post-Gilboa, Geneseo-equivalent onshore divisions, which include the Unadilla Formation, Sherburne Formation, Otego Formation, and Otselic Formation, are, herein, delineated. Most member-scale units of the Tully- and Geneseo-correlative formations, described herein, correspond to divisions based on discontinuity-floored marine sequence and subsequence concepts. [ABSTRACT FROM AUTHOR]

Lower Middle Devonian strata (Eifelian to lower Givetian stages) of New York are identified under the names Onondaga and Marcellus. As has been New York practice for over 80 years, they represent time-significant allostratigraphic units, which to some degree cut across lithologic boundaries. The Onondaga Formation is a relatively tabular, limestone-dominated unit throughout New York. Strata thin from both east and west into more basinward facies in the central part of the state. In contrast, the (revised) "Marcellus subgroup" forms an eastward-thickening and coarsening wedge of siliciclastic-dominated facies. Marcellus-equivalent strata range in thickness from less than seven meters in the western New York subsurface to an estimated maximum thickness of 580 meters in the Hudson Valley, eastern New York. Few stratigraphic revisions have been proposed for the Onondaga Formation since 1975, beyond minor revisions to two members associated with the abandonment of the informal, former Clarence member, chert-rich facies in western New York. In contrast, the term "Marcellus" has been raised in New York State from formation to subgroup status, with three formation-level units: a lower Union Springs and coeval upper Marcellus Oatka Creek and Mount Marion formations. The latter two represent correlative basinal dark shales and proximal dark shales to shoreface sandstones, respectively. Overall, following Cooper's classic 1930s stratigraphy of one formation with 11 members, 13 members are now recognized in the Marcellus subgroup; two in the Union Springs Formation and 11 in the upper Marcellus Oatka Creek and Mount Marion succession. Onondaga and Marcellus strata form three third-order depositional sequences, which feature three very distinct faunas. The sequences, termed Devonian Sequences Ic, Id, and Ie (alternatively Eif-1, Eif-2, and Eif-Giv) consist, respectively of 1) lower to middle Onondaga; 2) upper Onondaga and Union Springs; and 3) coeval Oatka Creek and Mount Marion formations, except where upper Mount Marion strata are not yet clearly distinguished form lower Skaneateles equivalents in eastern New York. The fossil assemblages of the Eifelian to lower Givetian have been subdivided into three "faunas" or ecological-evolutionary subunits. The oldest of the three faunas, the Onondaga Fauna, is succeeded by the Stony Hollow Fauna in shallow facies of the upper Union Springs and lowermost Mount Marion-Oatka Creek formations. The Stony Hollow Fauna is, in turn, succeeded by the classic Middle Devonian Hamilton Fauna throughout the remainder of upper Marcellus strata and Hamilton strata above. Numerous post-1970 studies have examined the stratigraphy, petrology, sedimentology, basin analyses, paleobiology, and geochemical characters of the Onondaga Formation and Marcellus subgroup. Overviews of these studies are presented herein. In the Appalachian Basin, the correlatives of these units across have been assigned the same names, Onondaga and Marcellus, in eastern Pennsylvania. More argillaceous Onondaga-correlative strata form the upper part of the Needmore Formation from central Pennsylvania to the vicinity of Highland and Pocahontas counties, in Virginia and West Virginia, respectively (Selinsgrove to the informal "calcareous shale and limestone" members). Continuing southwest along the Virginia-West Virginia border, Onondagacorrelative strata are replaced by chert and shale-dominated strata in the upper part of the Huntersville Formation. South of New York in the Appalachian Basin, the term "Marcellus" is applied lithostratigraphically, not allostratigraphically, so that lowest strata assigned the term Marcellus may variously range from lower Eifelian (middle Onondaga-equivalent, e.g., Frankstown, Pennsylvania) to correlative with the base of the Marcellus in New York. Similarly, youngest strata assigned to the Marcellus in Pennsylvania and southward may range from upper Eifelian Union Springs-equivalent (below proximal sandstones of the Turkey Ridge Member, central Pennsylvania) to lower Givetian, post-Marcellus black shales correlative with at least the Skaneateles Formation of New York in distal, basinward areas. From Highland County, Virginia, and adjacent West Virginia to the southwest, Marcellus strata are assigned to the lower part of the Millboro Shale, Finally, in southwestern Virginia and adjacent West Virginia, strata termed Marcellus in New York occur in lower parts of an interval sometimes termed "New Albany Shale" but shown by their correlation to be equivalent to upper Onondaga or lower Marcellus strata, based upon airfall volcanic tephras. [ABSTRACT FROM AUTHOR]