Early Osagean Research Articles

Mississippian (early Late Tournaisian; early Osagean) ammonoids from the Nancy Member of the Borden Formation, northeastern Kentucky

Mississippian (early Late Tournaisian; early Osagean) ammonoids from the Nancy Member of the Borden Formation, northeastern Kentucky

Camerate crinoids from the Nunn Member (Tournaisian, Osagean) of the Lower Mississippian Lake Valley Formation, New Mexico

The Nunn Member (early Osagean) of the Lake Valley Formation of New Mexico is known for its abundance and diversity of crinoids. Although crinoids were first reported in the late 1800s, no comprehensive study of the crinoids has been conducted and a complete list of the crinoid taxa does not exist. All subclasses of crinoids occur in the Lake Valley, but the camerates are by far the dominant group. Study of the Macurda collection from the University of Michigan, the Laudon collection from the University of New Mexico, and new collections provided more than 7000 specimens, 4,500 of which were identifiable camerates. Sixty-one species of camerates are recognized in the Nunn Member, including five new species: Blairocrinus macurdai, Iotacrinus novamexicanus, Agaricocrinus alamogordoensis, Uperocrinus kuesi, and Collicrinus laudoni. This camerate fauna is very similar to that of the lower Burlington Limestone of the Mississippi Valley. An update of the crinoid taxa in the Lake Valley Formation allows for a better understanding of the temporal and geographic relationships of crinoid faunas across North American during the Early Mississippian when camerates were at their global diversity maximum. The majority of the camerates come from the western New Mexico outcrops where the Nunn Member is thicker and the marine shelf was shallower, but several also occur in association with the deep-water Waulsortian mounds.

Sequence Stratigraphy and Depositional Dynamics of Carbonate Buildups and Associated Facies from the Lower Mississippian Fort Payne Formation of Southern Kentucky, U.S.A.

Abstract Carbonate buildups are a common feature in Mississippian sections worldwide. Yet despite intense study, questions remain about depositional processes that form such structures and their interrelations, if any, to each other. Carbonate buildups located in siliciclastic basins are particularly understudied and poorly understood. This study focuses on a new exposure of buildups in the siliciclastic-dominated Fort Payne basin (Osagean) of south central Kentucky. It represents a first attempt to combine field and petrographic descriptions of facies in the buildup interval of the Fort Payne with the concepts of sequence stratigraphy to gain better insight into their depositional histories. The buildup interval is composed of five distinct facies. Two of these, the fossiliferous green shale and the tabular crinoidal packstone-grainstone, represent the background sedimentation during buildup nucleation and growth. The remaining three facies make up the buildups themselves. The shaly packstone marks the inception of buildup growth, the massive wackestone represents the core of the buildups, and the crinoidal grainstone is a buildup-flank facies deposited near the end of buildup growth. The buildups of the Fort Payne Formation grew during the transgressive phase of one third-order sequence in the early Osagean. The time at which buildup growth ceased cannot be determined precisely with available data but likely occurred either at the maximum flooding surface or during the early highstand. Three commonly used depositional models, abbreviated as the lithoherm model, the baffling model, and the microbial model, are evaluated with respect to the Fort Payne buildups. None of the models is deemed adequate to explain all of the features of the buildups. Rather, a combination of all three seems to be required to account fully for all of the characteristics noted in this study. This multi-faceted depositional model compares favorably with other Carboniferous buildups worldwide, suggesting commonalities that transcend the properties of the basins in which they grew.

Organic Carbon Burial and Phosphogenesis in the Antler Foreland Basin: An Out-of-Phase Relationship During the Lower Mississippian

ABSTRACT Stratigraphic analysis of Lower Mississippian successions at four localities in Utah and Wyoming establish the relative timing of a large carbon isotope excursion ( +7‰) and episode of regional phosphogenesis in the Antler foreland basin and adjacent shelf (Delle Phosphatic Member). The 13C excursion, which appears global in scope, is marked by peak values of +7.3‰ in western Wyoming, which are among the heaviest known from Phanerozoic successions. The isotope excursion is well dated to the late Kinderhookian S. isosticha and early Osagean lower G. typicus zones and precedes the Delle phosphorites of upper G. typicus Zone age. The Delle phosphatic event, which resulted in the demise of the shallow-water carbonate factory over a wide area, is marked by a heterogeneous succession of pelletal phosphatic crusts, phosphatic pisolites, and winnowed and reworked grain aggregates. The observed stratigraphic relationship between the positive 13C excursion and Delle Phosphatic Member is consistent with a scenario in which high organic-carbon burial and seawater phosphate enrichment under anoxic conditions took place in deeper water masses of the Antler foreland system. This period of high 13C in surface waters above the pycnocline was followed by an episode of persistent upwelling into a salinity-stratified water column and phosphogenesis that was triggered by regional uplift within the Antler foreland basin system in response to tectonic loading. Despite the high productivity associated with upwelling and the accumulation of organic matter on the seafloor, 13C values remained low during phosphogenesis. This is attributed to the counterbalancing effects of organic-matter oxidation during lowstands of sea level, which ventilated the water mass and resulted in sediment winnowing and condensation of phosphatic particles and the incorporation of light carbon from the upwelling water mass. A low in 13C coincident with phosphorite deposition suggests that upwelling, carbon oxidation efficiency, and phosphogenesis reached maxima at approximately the same time, a situation that may be analogous to several Precambrian-Cambrian intervals and the Middle Ordovician but is opposite to that observed for the Early Cretaceous.

Primitive cladid crinoids from the early Osagean Burlington Limestone and the phylogenetics of Mississippian species of Cyathocrinites

All 19 known species of the primitive cladid crinoid genera Atelestocrinus, Cyathocrinites, Goniocrinus, Parisocrinus, Pellecrinus, and Zygotocrinus from the early Osagean Burlington Limestone of the North American midcontinent are reviewed and redescribed or, where necessary, redefined. Nine of these species are illustrated for the first time herein. Sixteen are considered valid, including C. deroseari n. sp. Of the remaining three species, one is left in open nomenclature, and two are considered nomen dubia. Pellecrinus is recognized for the first time from the Burlington Limestone, although the specimens can not be identified to the species level and are left in open nomenclature.Cyathocrinites ranges from the Middle Silurian to at least the Middle Mississippian. During the Early Mississippian Cyathocrinites experienced an evolutionary radiation with a maximum diversity of nine species in the Burlington Limestone. Phylogenetic relationships were investigated in a parsimony-based phylogenetic analysis by combining morphologic data from the Burlington species with data from the four other species of Cyathocrinites from the late Osagean and early Meramecian of the east-central United States. The Kinderhookian C. chouteauensis (Miller and Gurley, 1896) served as the outgroup. A phylogenetic analysis of 14 species of Mississippian Cyathocrinites yielded a single most parsimonious tree with a length of 28 steps (C. I. = 0.607, H. I. = 0.392, R. I. = 0.718, R. C. = 0.436). Results of this analysis suggest that at least two major clades existed within Mississippian Cyathocrinites. One clade contains C. sampsoni (Miller, 1891b), C. gilesi (Wachsmuth and Springer, 1878), C. farleyi (Meek and Worthen, 1866), and C. barydactylus (Wachsmuth and Springer, 1878). The second clade contains C. iowensis, C. kelloggi (White, 1862), C. barrisi (Hall, 1861a), C. rigidus, C. deroseari n. sp., C. asperrimus (Springer, 1911), C. lamellosus (White, 1863), and C. harrodi (Wachsmuth and Springer, 1880). Cyathocrinites multibrachiatus forms a polytomy with these two clades. Members of the first clade exhibit a unique overall morphology present only during the Mississippian, suggesting the clade arose during this time. Members of the second clade, plus C. multibrachiatus, exhibit some characters present in Cyathocrinites species as old as the Middle Silurian and, thus, may have its roots among Silurian and Devonian species.

PRIMITIVE CLADID CRINOIDS FROM THE EARLY OSAGEAN BURLINGTON LIMESTONE AND THE PHYLOGENETICS OF MISSISSIPPIAN SPECIES OF CYATHOCRINITES

All 19 known species of the primitive cladid crinoid genera Atelestocrinus, Cyathocrinites, Goniocrinus, Parisocrinus, Pellecrinus, and Zygotocrinus from the early Osagean Burlington Limestone of the North American midcontinent are reviewed and redescribed or, where necessary, redefined. Nine of these species are illustrated for the first time herein. Sixteen are considered valid, including C. deroseari n. sp. Of the remaining three species, one is left in open nomenclature, and two are considered nomen dubia. Pellecrinus is recognized for the first time from the Burlington Limestone, although the specimens can not be identified to the species level and are left in open nomenclature.Cyathocrinites ranges from the Middle Silurian to at least the Middle Mississippian. During the Early Mississippian Cyathocrinites experienced an evolutionary radiation with a maximum diversity of nine species in the Burlington Limestone. Phylogenetic relationships were investigated in a parsimony-based phylogenetic analysis by combining morphologic data from the Burlington species with data from the four other species of Cyathocrinites from the late Osagean and early Meramecian of the east-central United States. The Kinderhookian C. chouteauensis (Miller and Gurley, 1896) served as the outgroup. A phylogenetic analysis of 14 species of Mississippian Cyathocrinites yielded a single most parsimonious tree with a length of 28 steps (C. I. = 0.607, H. I. = 0.392, R. I. = 0.718, R. C. = 0.436). Results of this analysis suggest that at least two major clades existed within Mississippian Cyathocrinites. One clade contains C. sampsoni (Miller, 1891b), C. gilesi (Wachsmuth and Springer, 1878), C. farleyi (Meek and Worthen, 1866), and C. barydactylus (Wachsmuth and Springer, 1878). The second clade contains C. iowensis, C. kelloggi (White, 1862), C. barrisi (Hall, 1861a), C. rigidus, C. deroseari n. sp., C. asperrimus (Springer, 1911), C. lamellosus (White, 1863), and C. harrodi (Wachsmuth and Springer, 1880). Cyathocrinites multibrachiatus forms a polytomy with these two clades. Members of the first clade exhibit a unique overall morphology present only during the Mississippian, suggesting the clade arose during this time. Members of the second clade, plus C. multibrachiatus, exhibit some characters present in Cyathocrinites species as old as the Middle Silurian and, thus, may have its roots among Silurian and Devonian species.

The cladid crinoid Barycrinus from the Burlington Limestone (early Osagean) and the phylogenetics of Mississippian botryocrinids

All species of Barycrinus from the early Osagean Burlington Limestone of the United States midcontinent are reviewed. Burlington Barycrinus species include: B. rhombiferus (Owen and Shumard, 1852); B. magister (Hall, 1858); B. spurius (Hall, 1858); B. crassibrachiatus (Hall, 1860); B. scitulus (Meek and Worthen, 1860) n. combination; and B. sampsoni Miller and Gurley, 1896. Cyathocrinus latus Hall, 1861a, is here considered a junior synonym of B. rhombiferus. The stratigraphic practice of dividing the Burlington into upper and lower parts, for purposes of reporting species ranges, is evaluated.Morphologic data from these Burlington species are combined with data from late Osagean and Meramecian botryocrinid species of Barycrinus and Meniscocrinus, plus four species of Devonian and Mississippian Costalocrinus in a parsimony-based phylogenetic analysis of Mississippian botryocrinids. Results of this analysis indicate that 1) species of Barycrinus form a monophyletic clade that radiated rapidly during the Osagean; 2) B. rhombiferus may have been ancestral to all other Barycrinus species; and 3) M. magnitubus forms a clade with the Mississippian C. cornutus (Owen and Shumard, 1850) and the Devonian C. rex McIntosh, 1984.

THE CLADID CRINOID BARYCRINUS FROM THE BURLINGTON LIMESTONE (EARLY OSAGEAN) AND THE PHYLOGENETICS OF MISSISSIPPIAN BOTRYOCRINIDS

All species of Barycrinus from the early Osagean Burlington Limestone of the United States midcontinent are reviewed. Burlington Barycrinus species include: B. rhombiferus (Owen and Shumard, 1852); B. magister (Hall, 1858); B. spurius (Hall, 1858); B. crassibrachiatus (Hall, 1860); B. scitulus (Meek and Worthen, 1860) n. combination; and B. sampsoni Miller and Gurley, 1896. Cyathocrinus latus Hall, 1861a, is here considered a junior synonym of B. rhombiferus. The stratigraphic practice of dividing the Burlington into upper and lower parts, for purposes of reporting species ranges, is evaluated.Morphologic data from these Burlington species are combined with data from late Osagean and Meramecian botryocrinid species of Barycrinus and Meniscocrinus, plus four species of Devonian and Mississippian Costalocrinus in a parsimony-based phylogenetic analysis of Mississippian botryocrinids. Results of this analysis indicate that 1) species of Barycrinus form a monophyletic clade that radiated rapidly during the Osagean; 2) B. rhombiferus may have been ancestral to all other Barycrinus species; and 3) M. magnitubus forms a clade with the Mississippian C. cornutus (Owen and Shumard, 1850) and the Devonian C. rex McIntosh, 1984.

Tournaisian (Early Osagean) brachiopods from a bioherm in the St. Joe Formation near Kenwood, Oklahoma

Tournaisian (Early Osagean) brachiopods from a bioherm in the St. Joe Formation near Kenwood, Oklahoma

Calcareous Foraminifers from the Humboldt Oolite of Iowa: Key to Early Osagean (Mississippian) Correlations between Eastern and Western North America

Tuberculate foraminifers dominate the calcareous microfauna of the early Osagean Humboldt Oolite in north-central Iowa. This assemblage, previously unknown east of the Transcontinental Arch, occurs commonly in western North America, thus facilitating foraminiferal correlations between that area and the Midcontinent. Analysis of early Osagean microfossil occurrences within the Cordillera permits definition of an informal Zone of Tuberculate Foraminifers (ZTF) composed, in ascending order, of the subzones (1) Tuberendothyra tuberculata, (2) Spinoendothyra spp., (3) Inflatoendothyra spp., and (4) Eoforschia moelleri group-Paradainella spp. Comparison of the Humboldt microfauna to this succession indicates that an hiatus probably separates the oolite from the underlying Gilmore City Limestone, which contains a pre-ZTF assemblage. This break, which lies at the Kinderhookian-Osagean boundary, can be recognized widely in the western-shelf seaway where ZTF assemblages generally have been misinterpreted as late rather than early Osagean. Faunal gaps higher in the ZTF suggest that shelf sedimentation at some localities in the Cordillera may have been interrupted again later in the early Osagean. In Eurasia, the Humboldt assemblage best correlates to the late Tournaisian Kizel horizon and equivalent beds of the Russian Platform, Urals, and Ukraine. Newly named taxa include the alga Cylindrofolia glenisteri and the problematic Asphaltina? macadami.

Devonian and Mississippian Stratigraphy and Depositional Environments in Big Hatchet Mountains of Southwestern New Mexico: ABSTRACT

In the Big Hatchet Mountains the Upper Devonian Percha Shale rests unconformably on the Upper Ordovician Montoya Formation and is overlain by strata referred to the upper part of Sabin's Portal Formation. To date, this is the farthest east the Portal has been observed. Devonian rocks record a shallowing-up sequence from the lower Percha (Ready Pay-Box Members) deposited in quiet water to the Portal grainstone deposited at or above wave base. The Portal contains Upper Devonian (Famennian) conodonts indicative of Sandberg's shallow-water polygnathid-icriodid biofacies. Mississippian strata, represented by the Escabrosa Group, contain Early Mississippian (Osagean) conodonts at the base. Lower Mississippian strata record 2 Osagean cycles of submergence and emergence. Encroachment began in the early Osagean (isosticha-upper crenulata Zone) when the basal oolitic grainstones of the Bugle member of the Keating Formation were deposited. A shallowing-up sequence followed, culminating in the deposition of high-energy grainstones of the upper Bugle. The end of Bugle deposition is marked by a second submergence (lower typicus-Anchoralis latus Zone) when argillaceous wackestones were deposited. This deepening continued during deposition of the basal Witch member. Regression began during deposition of the Witch, as suggested by the vertical sequence from fine-g ained mudstones to high-energy grainstones. This shallowing sequence continues into the lower Hatchita Formation. End_of_Article - Last_Page 509------------