Journal articles on the topic 'Stratigraphic Devonian'
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Davlatov, Nodir Khairullaevich. "Stratigraphic Characteristic Devon System Of Mountain Kuldzhuktau (South Tian-Shan)." American Journal of Applied sciences 02, no. 12 (December 27, 2020): 100–112. http://dx.doi.org/10.37547/tajas/volume02issue12-16.
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This article presents the results of long-term stratigraphic studies on the territory of the Kuldzhuktau mountains. Schemes for the division and correlation of Devonian deposits have been created based on complete biostratigraphic data that most effectively reflect the geological age of local stratigraphic units and their reliable correlation with geological age. The tier units of the International Devonian Stratigraphic Scale are substantiated at the present stage of research. Due to the widespread use of conodonts, it was possible to clarify the physical and age volumes, as well as the sequence of Devonian deposits in the territory of Kuldzhuktau, and almost completely reconstruct the Devonian section.
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Anderson, Donna, and Mark Longman. "Subsurface Reinterpretation of Ordovician and Devonian Strata in Southwest Wyoming with Implications for Upwarping Across the Transcontinental Arch." Mountain Geologist 55, no. 3 (July 2018): 91–118. http://dx.doi.org/10.31582/rmag.mg.55.3.91.
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A new interpretation of the subsurface geometries of the Ordovician Bighorn Dolomite and overlying Devonian strata across southwestern Wyoming arises from revising the stratigraphy in a core from the Mountain Fuel Supply UPRR #11–19–104–4 well drilled on the crest of the Rock Springs Uplift in 1962. One of only a few wells to penetrate all or part of the Lower Paleozoic succession in the subsurface of southwestern Wyoming, the well was almost continuously cored through the Devonian–Cambrian succession. From a reinterpretation of the stratigraphy in the core, 22 ft of Bighorn Dolomite is recognized based on the characteristic Thalassinoides bioturbation fabric in skeletal dolowackestone typical of Late Ordovician subtidal carbonate facies ranging from Nevada to Greenland along the western margin of the Great American Carbonate Bank. This lithology is in complete contrast with the alternating dolomitic flat-pebble conglomerate and dolomudstone of the underlying Cambrian Gallatin Limestone and the cyclical units of brecciated anhydritic dolomudstone and quartzose sandstone of the overlying Devonian Lower Member of the Jefferson Formation. Stratigraphic re-interpretation yields insights regarding Ordovician–Devonian stratal geometries across southwestern Wyoming. More widespread than previously portrayed, the Bighorn Dolomite pinches out on the eastern flank of the Rock Springs Uplift. Similar to past interpretations, Devonian strata pinch out east of the Rock Springs Uplift at Table Rock Field. A true-geometry multi-datumed stratigraphic cross section yields insights not obtainable by mapping. Regionally, top truncation of stratigraphic units below the base-Madison Limestone unconformity normally progresses stratigraphically deeper eastward. However, in southwestern Wyoming, the Devonian Lower Member of the Jefferson Formation overlaps the older Bighorn Dolomite by marked onlap across the Rock Springs Uplift and then pinches out by top truncation/onlap near Table Rock Field, forming an “abnormal” overlap relationship along the northern margin of the Transcontinental Arch. The underlying Bighorn Dolomite shows little to no onlap onto the underlying Cambrian section, but is markedly top truncated below the Lower Member of the Jefferson Formation. Comparing proportions of onlap versus top truncation for the two formations constrains the timing of two successive upwarping episodes along the northern margin of the Transcontinental Arch across southwestern Wyoming. The first is arguably Middle Devonian, and the second spans the Devonian–Mississippian boundary. Two subtle and different angular unconformities created by these two episodes imply a persistent fold or tilt axis that sequentially was reactivated along the northern margin of the Transcontinental Arch in southwestern Wyoming.
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Leslie-Panek, Jennifer, Margot McMechan, and Fil Ferri. "Northeast British Columbia Liard Basin: A seismic stratigraphy study." Interpretation 8, no. 3 (June 13, 2020): T579—T588. http://dx.doi.org/10.1190/int-2019-0187.1.
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The Liard Basin is a highly prospective shale gas basin located in northeast British Columbia that is largely underrepresented in public literature. We used available-for-purchase 2D seismic data in the area to create a high-level, regional stratigraphic interpretation of the basin, providing the first seismically controlled overview of the basin structure and stratigraphy. The basin is characterized by two distinct, opposing wedges of sediment in the Mesozoic and Paleozoic sections: the Mesozoic with northeastward thinning and the Paleozoic with southwestward thinning. The wedging of the Upper Devonian-Lower Mississippian (Tournasian) section is dominated by multiple large packages of clinoforms, which progress into the basin from northeast to southwest and are predominantly seen in the seismic sequence stratigraphy. These distinct packages of clinoforms indicate changing sediment sources over time. In contrast, there are no clinoforms seen in the Mesozoic section, which may be a limitation of the orientation of the 2D seismic data that we used. Our result from the seismic interpretation is an updated interpretation of the Upper Devonian-Lower Mississippian stratigraphy of the Liard Basin, including an updated stratigraphic cross section for the area.
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URMANOVA, D., and D. D. HUMPHREY. "STRATIGRAPHIC DEVELOPMENT OF THE DEVONIAN-CARBONIFEROUS COMPLEX OF THE SOUTHERN SIDE OF THE CASPIAN DEEP." Neft i Gaz 131, no. 5 (October 30, 2022): 77–93. http://dx.doi.org/10.37878/2708-0080/2022-5.05.
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This article presents a study of the stratigraphic development of the Devonian-carboniferous complex of the southern side of the Caspian basin, in which a comprehensive study of sedimentary formations of the subsalt complex and the creation of a stratigraphic model of the Late Paleozoic stage of evolution of the southern Caspian sedimentary basin was carried out based on a refined correlation scheme by Abilkhasimov (2015), with the inclusion of generalized data on the structures of Ansagan and Maksat. The basis for the development of a stratigraphic model in the Late Paleozoic of the Coastal zone of carbonate structures in the south of the Caspian sedimentary basin is the classical structural and formation analysis, which reflects the main features: stratigraphy, tectonics, lithological composition, sedimentation conditions, sediment thickness.
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Sennikov, N. V., N. V. Novozhilova, O. T. Obut, and R. A. Khabibulina. "The Pridoli (Silurian) Lithostratigraphy and Biostratigraphy of Gorny Altai." Russian Geology and Geophysics 62, no. 11 (November 1, 2021): 1269–84. http://dx.doi.org/10.2113/rgg20204232.
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Abstract —The paper presents new data on the upper Silurian litho- and biostratigraphy of the Gorny Altai area. Sediments within this interval store a succession of taxonomically representative middle–upper Ludfordian, lower Pridoli, and Lower Devonian (Lochkovian–Pragian) conodont assemblages. The new fauna constraints made a basis for updated correlations of the local and regional stratigraphic units at the Silurian/Devonian boundary of Gorny Altai with the stages of the International Stratigraphic Chart. The correlation results reveal a mismatch between the boundaries of the local and regional Silurian units and the respective boundaries of stages in the International Stratigraphic Chart.
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Clark, David, Drew Derenthal, Bart Kowallis, and Scott Ritter. "The major pre-Mississippian unconformity in Rock Canyon, central Wasatch Range, Utah." Geology of the Intermountain West 1 (January 1, 2014): 1–5. http://dx.doi.org/10.31711/giw.v1.pp1-5.
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In central Utah, the major pre-Mississippian unconformity is fairly well understood at most of the localities where it is recognized. However, the unconformity is more enigmatic in Rock Canyon of the central Wasatch Range. At this locality, dolomitization of most pre-Mississippian rocks obscures stratigraphic identification of Devonian and older units. The absence of any identifiable angular relationship further complicates resolution. Because of this, both identification of the stratigraphic level of the unconformity and, consequently, its magnitude remain controversial. Large-size dolomite samples taken in Rock Canyon at closely spaced intervals for the 3.6-m directly below definite Upper Devonian rocks yield microfossils, including conodonts, in the uppermost 1.6-m of that interval that indicate no unconformity exists between the Cambrian Maxfield Limestone and the Upper Devonian-Lower Mississippian Fitchville Dolomite at the horizon previously identified as unconformable. Rather, an unknown thickness of dolomitized Upper Devonian Pinyon Peak Formation and probable older rock (possibly Bluebell Dolomite and Victoria Formation) occurs between the top of definite Maxfield and base of the Fitchville. The identification of the unconformity horizon remains unknown. Our preliminary work outlines a promising procedure for future understanding of the magnitude and stratigraphic level of the unconformity.
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Clark, David Leigh, Drew D. Derenthal, Bart J. Kowallis, and Scott M. Ritter. "The major pre-Mississippian unconformity in Rock Canyon, central Wasatch Range, Utah." Geology of the Intermountain West 1 (May 23, 2014): 1–5. http://dx.doi.org/10.31711/giw.v1i0.1.
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In central Utah, the major pre-Mississippian unconformity is fairly well understood at most of the localities where it is recognized. However, the unconformity is more enigmatic in Rock Canyon of the central Wasatch Range. At this locality, dolomitization of most pre-Mississippian rocks obscures stratigraphic identification of Devonian and older units. The absence of any identifiable angular relationship further complicates resolution. Because of this, both identification of the stratigraphic level of the unconformity and, consequently, its magnitude remain controversial. Large-size dolomite samples taken in Rock Canyon at closely spaced intervals for the 3.6-m directly below definite Upper Devonian rocks yield microfossils, including conodonts, in the uppermost 1.6-m of that interval that indicate no unconformity exists between the Cambrian Maxfield Limestone and the Upper Devonian-Lower Mississippian Fitchville Dolomite at the horizon previously identified as unconformable. Rather, an unknown thickness of dolomitized Upper Devonian Pinyon Peak Formation and probable older rock (possibly Bluebell Dolomite and Victoria Formation) occurs between the top of definite Maxfield and base of the Fitchville. The identification of the unconformity horizon remains unknown. Our preliminary work outlines a promising procedure for future understanding of the magnitude and stratigraphic level of the unconformity.
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Myszynski Junior, Lucinei José, Elvio Pinto Bosetti, Leonardo Borghi, Sandro Marcelo Scheffler, Daniel Sedorko, Paula Mendlowicz Mauller, and Gabrieli Goltz. "Taphofacies and Stratigraphic Correlation of Devonian Outcrops in Northwestern Region of State of Paraná, Brazil." Terr Plural 15 (2021): e2119466. http://dx.doi.org/10.5212/terraplural.v.15.2119466.031.
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The northeastern region of the state of Paraná, Brazil, is still little known in its paleontological and stratigraphic aspects. This work focused on Devonian outcrops located in Arapoti and Piraí do Sul and aimed at the recognition of sedimentary facies and the definition of taphofacies, with the intention of paleoenvironmental interpretation and stratigraphic correlation. Three different facies were identified, representing shoreface to offshore environments, and also three taphofacies were defined: T1 characterizes the most proximal and destructive environments, T2 represents lower shoreface environments and T3, originated offshore. The base of the section is correlated to the early Devonian, Ponta Grossa Formation, Siluro-Devonian Sequence (Neopraguian-Eoemsian) due to the visible contact with sandstones of the Furnas Formation, and the top, due to the presence of microfossils, is positioned in the São Domingos Formation, Devonian Sequence I (Neoemsian-Eoeifelian).
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THOMPSON, JEFFREY R., and TIMOTHY A. M. EWIN. "A new species of Hyattechinus (Echinoidea) from the type Devonian of the United Kingdom and implications for the distribution of Devonian proterocidarid echinoids." Geological Magazine 156, no. 5 (March 26, 2018): 801–10. http://dx.doi.org/10.1017/s0016756818000109.
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AbstractMany of the most diverse clades of Late Palaeozoic echinoids (sea urchins) originated in the Devonian period. Our understanding of diversity dynamics of these Late Palaeozoic clades are thus informed by new systematic descriptions of some of their earliest members. The Proterocidaridae are a diverse and morphologically distinct clade of stem group echinoids with flattened tests and enlarged adoral pore pairs, which are first known from the Upper Devonian. We herein report on a new species of Hyattechinus, Hyattechinus anglicus n. sp., from the Upper Devonian of the North Devon Basin, Devon, UK. This is the first Devonian Hyattechinus known from outside of the Appalachian Basin, USA, and provides novel information regarding the palaeogeographic and stratigraphic distribution of proterocidarids in Late Devonian times. We additionally update the stratigraphic distribution of Devonian Hyattechinus from the Appalachian Basin, following recent biostratigraphic resolution of their occurrences. Hyattechinus appears to have been present in the Rheic echinoderm fauna during Late Devonian times, and comparison of the palaeoenvironmental setting of Hyattechinus anglicus with that of other Hyattechinus from the Famennian of the Appalachian Basin suggests that the genus may have preferred siliciclastic settings. Furthermore, this new taxon increases the diversity of echinoids from the Upper Devonian of Devon to three species.
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Vacek, František, Jindřich Hladil, and Petr Schnabl. "Stratigraphic correlation potential of magnetic susceptibility and gamma-ray spectrometric variations in calciturbiditic facies (Silurian-Devonian boundary, Prague Synclinorium, Czech Republic)." Geologica Carpathica 61, no. 4 (August 1, 2010): 257–72. http://dx.doi.org/10.2478/v10096-010-0015-2.
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Stratigraphic correlation potential of magnetic susceptibility and gamma-ray spectrometric variations in calciturbiditic facies (Silurian-Devonian boundary, Prague Synclinorium, Czech Republic)Magnetic susceptibility (MS) and gamma-ray spectrometry (GRS) stratigraphy were used for correlation and characterization of eight Silurian-Devonian (S-D) sections in the Prague Synclinorium (Czech Republic). They represent two different facies developments: lower subtidal to upper slope deposits and slope-to-basin-floor distal calciturbidites. Sections from relatively shallow- and deep-water sections are easy to compare and correlate separately, although the detailed relationship between these two facies is still not entirely clear and correlations between the two settings are difficult. This may be due to sharp facies transitions and presence of stratigraphic gaps. The MS and GRS stratigraphic variations combined with sedimentologic data have been also used for reconstruction of the evolution of the sedimentary environment. The beds close above the S-D boundary show noticeably enhanced MS magnitudes but weak natural gamma-ray emissions. It may correspond to an increased amount of terrigenous magnetic material occurring with short-term shallowing (sedimentological evidence). In deep-water sections the uppermost Silurian is characterized by high MS and GRS values. It corresponds to a supply of recycled sediment to the lower wedge which occurred during the late Pridoli regression phase. The basal Devonian beds correspond to gradual deepening, but the overlying sequences reflect other shallowing episodes which are expressed in increasing MS and gamma ray activity of rocks. The MS and GRS fluctuations are interpreted as a result of local subsidence of the sea bottom along synsedimentary growth-faults and/or a biotic event rather than of eustatic sea-level changes.
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Evans, James E., Joshua T. Maurer, and Christopher S. Holm-Denoma. "Recognition and significance of Upper Devonian fluvial, estuarine, and mixed siliciclastic-carbonate nearshore marine facies in the San Juan Mountains (southwestern Colorado, USA): Multiple incised valleys backfilled by lowstand and transgressive systems tracts." Geosphere 15, no. 5 (August 9, 2019): 1479–507. http://dx.doi.org/10.1130/ges02085.1.
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Abstract The Upper Devonian Ignacio Formation (as stratigraphically revised) comprises a transgressive, tide-dominated estuarine depositional system in the San Juan Mountains (Colorado, USA). The unit backfills at least three bedrock paleovalleys (10–30 km wide and ≥42 m deep) with a consistent stratigraphy of tidally influenced fluvial, bayhead-delta, central estuarine-basin, mixed tidal-flat, and estuarine-mouth tidal sandbar deposits. Paleovalleys were oriented northwest while longshore transport was to the north. The deposits represent Upper Devonian lowstand and transgressive systems tracts. The overlying Upper Devonian Elbert Formation (upper member) consists of geographically extensive tidal-flat deposits and is interpreted as mixed siliciclastic-carbonate bay-fill facies that represents an early highstand systems tract. Stratigraphic revision of the Ignacio Formation includes reassigning the basal conglomerate to the East Lime Creek Conglomerate, recognizing an unconformity separating these two units, and incorporating strata previously mapped as the McCracken Sandstone Member (Elbert Formation) into the Ignacio Formation. The Ignacio Formation was previously interpreted as Cambrian, but evidence that it is Devonian includes reexamined fossil data and detrital zircon U-Pb geochronology. The Ignacio Formation has a stratigraphic trend of detrital zircon ages shifting from a single ca. 1.7 Ga age peak to bimodal ca. 1.4 Ga and ca. 1.7 Ga age peaks, which represents local source-area unroofing history. Specifically, the upper plate of a Proterozoic thrust system (ca. 1.7 Ga Twilight Gneiss) was eroded prior to exposure of the lower plate (ca. 1.4 Ga Uncompahgre Formation). These results are a significant alternative interpretation of the geologic history of the southern Rocky Mountains.
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Johnson, Markes E., and D. L. Dineley. "Aspects of a Stratigraphic System: The Devonian." PALAIOS 1, no. 4 (August 1986): 424. http://dx.doi.org/10.2307/3514481.
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Crônier, Catherine, and Allart van Viersen. "Trilobite palaeobiodiversity during the Devonian in the Ardennes Massif." Bulletin de la Société Géologique de France 178, no. 6 (November 1, 2007): 473–83. http://dx.doi.org/10.2113/gssgfbull.178.6.473.
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Abstract Trilobite occurrences and biodiversity from Devonian sections of the Ardennes Massif are presented. Fluctuations in diversity reflect environmental changes and event-stratigraphic turnovers throughout the Devonian. Peak diversity is attained during the Eifelian (Middle Devonian) when the carbonate system is developed. Six trilobite associations have been delineated based on cluster analysis. Distribution of these associations is correlated with the deposition environments and age of the strata.
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Al-Hajri, Sa’id A., John Filatoff, Lawrence E. Wender, and A. Kent Norton. "Stratigraphy and Operational Palynology of the Devonian System in Saudi Arabia." GeoArabia 4, no. 1 (January 1, 1999): 53–68. http://dx.doi.org/10.2113/geoarabia040153.
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ABSTRACT Surface and subsurface Devonian rocks of Saudi Arabia are correlated using a combination of palynology and sequence stratigraphy. Recent exploratory drilling in eastern Saudi Arabia has confirmed that sweet gas and condensate-bearing Devonian strata are preserved on the flanks of high-relief Hercynian structures such as Ghawar field. This Devonian succession is composed of three homogeneous litho-stratigraphic units, the Tawil, Jauf and Jubah formations that cannot be imaged seismically nor readily discerned with conventional wireline logs. An operational palynological zonation was consequently devised based on first down-hole occurrences (i.e. extinctions) of encountered palynomorphs. This zonation was calibrated with the standard European spore zonations of Streel et al. (1987) and Richardson and McGregor (1986), and further controlled by mega-fossil data from outcrops in northwestern Saudi Arabia. Six palynozones, and four subzones, have been recognized. A particularly reliable late Early Devonian zone is based on the acme of an endemic Leiosphaeridia species. This palynosubzone coincides stratigraphically with the upper part of the gas-bearing Jauf Reservoir.
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Comniskey, Jeanninny Carla, Renato Pirani Ghilardi, Elvio Pinto Bosetti, Felipe Nascimento Sousa, Leonardo Fonseca Borghi de Almeida, and Victor Rodrigues Ribeiro. "Devonian Tentaculitoids from Brazil: extinction and stratigraphic distribution." Terr Plural 15 (2021): e2118019. http://dx.doi.org/10.5212/terraplural.v.15.2118019.028.
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The class Tentaculitoidea is an extinct group composed of small carbonate coniform-shaped invertebrates, distributed from Ordovician to Devonian. This group is more often recorded to the North Hemisphere, being less recorded to South Hemisphere deposits. This study aims (i) to analyze the species found in Brazilian Devonian outcrops, in addition (ii) to investigate their paleogeographic and stratigraphic distribution. The analyzed samples, which come from Paraná, Amazonas, and Parnaíba basins, are hosted in 9 Brazilian Research Centers. It was diagnosed 12 species of tentaculitoids: Tentaculites crotalinus, Tentaculites jaculus, Tentaculites kozlowskii, Tentaculites paranaensis, Tentaculites eldredgianus, Tentaculites trombetensis, Tentaculites stubeli, Tentaculites oseryi, Uniconus ciguelii, Homoctenus katzerii, Styliolina langenii, and Styliolina clavulus. The species from Paraná Basin are different from those recorded in Amazonas and Parnaíba basins, all present distinct stratigraphic ranges (Pragian to Givetian in Paraná Basin and Eifelian to Givetian in Amazonas and Parnaíba basins).
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Mizens, Anita G., and Larisa I. Mizens. "Stratigraphic significance of Devonian brachiopods of the Urals." LITOSFERA 17, no. 4 (August 2017): 62–72. http://dx.doi.org/10.24930/1681-9004-2017-4-062-072.
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LAMSDELL, JAMES C., JINZHUANG XUE, and PAUL A. SELDEN. "A horseshoe crab (Arthropoda: Chelicerata: Xiphosura) from the Lower Devonian (Lochkovian) of Yunnan, China." Geological Magazine 150, no. 2 (October 23, 2012): 367–70. http://dx.doi.org/10.1017/s0016756812000891.
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AbstractA single specimen of a new species of the synziphosurine Kasibelinurus Pickett, 1993 is described from the Lower Devonian (Lochkovian) Xiaxishancun Formation of Yunnan Province, China. The new species, K. yueya sp. nov., extends the geographic extent of the family Kasibelinuridae from the Australian palaeocontinent to the South China palaeocontinent, and the stratigraphic range back some 50 Ma from Late to Early Devonian.
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Fluegeman, Richard H., and R. William Orr. "Occurrence of Sievertsia (Echinodermata: Cyclocystoidea) from the Middle Devonian of northern Indiana." Journal of Paleontology 64, no. 3 (May 1990): 480–82. http://dx.doi.org/10.1017/s002233600001876x.
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Cyclocystoids (range: Ordovician–Devonian), particularly of Devonian age, are extremely rare fossils and stratigraphic ranges of most taxa are little known. For this reason, the discovery of a single fragmentary specimen referable to Sievertsia (Smith and Paul, 1982) from the Traverse Formation (Middle Devonian) in Cass County, northern Indiana, deserves mention. Furthermore, the precise stratigraphic position of the cyclocystoid occurrence is documented by a combination of significant conodont and brachiopod faunas. The specimen was collected in situ on a weathered surface from a position approximately 1.2 m above the base of the type section of the Miami Bend Lithofacies (Cooper and Phelan, 1966, p. 6, U.S. National Museum Locality 391a; Orr, 1969, p. 338, Locality 5) exposed at the top of the west wall of the old France Stone Company quarry (inactive) on the north side of U.S. Highway 24, 3.2 km east of Logansport, SW¼, NE¼, sec. 27, T27N, R2E, Cass County, Indiana (Logansport 7½′ quadrangle).
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Edgecombe, Gregory D., Norberto E. Vaccari, and Beatriz G. Waisfeld. "Lower Devonian calmoniid trilobites from the Argentine Precordillera: new taxa of the Bouleia Group, and remarks on the tempo of calmoniid radiation." Geological Magazine 131, no. 4 (July 1994): 449–64. http://dx.doi.org/10.1017/s0016756800012097.
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AbstractNew calmoniids from the Lower Devonian Talacasto Formation in the Precordillera of San Juan, Argentina, extend the stratigraphic and geographic ranges of a clade including Bouleia Kozlowski, 1923 and Parabouleia Eldredge, 1972. The new genus Talacastops accommodates the Lochkovian T. zarelae sp.nov. from the Talacasto Formation and a closely related species from western Bolivia (Talacastops sp.nov. A). The diagnosis of Parabouleia is broadened to include P. eldredgei sp.nov., from Lochkovian strata in the lower part of the Talacasto Formation. Calmoniids from below the Scaphiocoelia Assemblage Zone display morphological disparity that rivals later occurrences, and do not conform to a model of gradual transformation of an acastomorph ancestor. Stratigraphic range extensions based on correction for ghost lineages imply a high diversity within Calmoniidae very early in the Devonian.
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Parmuzina, L. V., Yu A. Lagutina, and A. E. Smirnova. "SEUQENCE AND CORRELATION OF DEPOSITS OF IZHMA STEP UPPER DEVONIAN COMPLEX." Oil and Gas Studies, no. 2 (April 30, 2015): 17–25. http://dx.doi.org/10.31660/0445-0108-2015-2-17-25.
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It is shown that identification of regularities of hydrocarbon deposits occurrence in the Upper Devonian complex carbonate massifs in the Timan Pechora province is an actual problem. For prospecting and exploration of new oil and gas deposits in the Izhma step territory the development of a detailed correlation scheme is required. The article specifies the deposits structure and makes a correlation of stratigraphic units of the Izhma step Upper Devonian complex.
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Maxwell, W. Desmond, and Michael J. Benton. "Historical tests of the absolute completeness of the fossil record of tetrapods." Paleobiology 16, no. 3 (1990): 322–35. http://dx.doi.org/10.1017/s0094837300010022.
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Six compilations of fossil tetrapod families, spanning 100 years, each contain a broadly similar diversity pattern since the Upper Devonian. Comparison of four recent data bases, one of which is derived from a strict cladistic treatment, reveals widespread taxonomic and stratigraphic inaccuracies in three earlier data bases. Improvement of our interpretation of the tetrapod fossil record will come through continued taxonomic and stratigraphic revision as well as discovery of new fossils.
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Craigie, Neil W. "Definition of the Hercynian Unconformity in eastern Saudi Arabia using chemostratigraphy in conjunction with biostratigraphy, sedimentology and lithostratigraphy." Petroleum Geoscience 26, no. 4 (December 19, 2019): 568–88. http://dx.doi.org/10.1144/petgeo2019-116.
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The following chemostratigraphy study was conducted on Paleozoic sediments encountered in 14 wells in eastern Saudi Arabia. A total of 1500 samples were analysed by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS), with data acquired for 48 elements, ranging from Na to U in the periodic table. The aim was to utilize chemostratigraphy, in conjunction with existing biostratigraphic, lithostratigraphic and sedimentological data, to define the Hercynian Unconformity in each well and to recognize stratigraphic boundaries occurring above and below it. This was necessary as the unconformity eroded to different stratigraphic levels in each well, with Devonian, Silurian and Ordovician sediments found immediately below it in adjacent locations. In the absence of chemostratigraphic, biostratigraphic and sedimentological data, it is often very difficult to define this boundary and others using lithostratigraphy alone as many stratigraphic intervals yield similar gamma-ray (GR) log trends. For example, a low ‘blocky’ GR response is typical of both the Carboniferous Ghazal Member and the Ordovician Sarah Formation. Similarly, both the Silurian Sharawra Member and the Silurian–Devonian Tawil Formation produce a ‘ratty’ GR trend. Each stratigraphic member and formation was found to have distinctive chemostratigraphic, biostratigraphic, sedimentological and/or wireline log signatures.
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Yalçin, M., and Isak Yilmaz. "Devonian in Turkey — a review." Geologica Carpathica 61, no. 3 (June 1, 2010): 235–53. http://dx.doi.org/10.2478/v10096-010-0014-3.
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Devonian in Turkey — a reviewThe Devonian Period is represented in Turkey by almost complete non-metamorphic sections of more than 1000 meters, which exhibit varying lithofacial associations. They are parts of thick Paleozoic sedimentary successions in the Pontides, Taurides and Arabian Plate. The tectonic setting and the paleogeographical origin of these terranes is different. Therefore, the litho- and biostratigraphy and facies characteristics of these Devonian successions would enable a comparison and a paleogeographical assignment of these tectono-stratigraphic units. Devonian successions of the Arabian Plate and of the Taurides are represented by facies associations ranging from tidal flat to a deep shelf. Whereas, those of the Istanbul and Çamdağ-Zonguldak areas in the Pontides by a deepening upward sequence from a shallow shelf into a basin and a stable shelf, respectively. The Devonian of the Arabian Plate and the Taurides can surely be assigned to Gondwana. A Peri-Gondwanan (Avalonian) setting is suggested for the paleogeographic position of the Devonian of the Pontides.
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Plax, Dmitry P., and Michael J. Newman. "New Early Devonian (late Emsian) placoderms from Belarus." Journal of Paleontology 94, no. 4 (March 31, 2020): 773–87. http://dx.doi.org/10.1017/jpa.2020.6.
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AbstractFour placoderm fishes are described from the Lepel Beds of the Vitebsk Regional Stage of the Lower Devonian (upper Emsian) of Belarus. Two forms are new (Stipatosteus svidunovitchi new genus, new species and Actinolepis zaikai new species) and the other two taxa are left in open nomenclature (Coccosteidae gen. indet. sp. indet.; Placodermi indet. 1). Specimens of all four forms consist of disarticulated, mostly well-preserved plates (some are worn at the edges) originating from the cores of six boreholes. Additionally, the paper presents data on organic remains with the placoderms. A detailed lithological description of the enclosing rocks and a taphonomic description of the ichthyofauna are also provided. The 2010 Stratigraphic Chart of the Devonian deposits of Belarus was used as the stratigraphic basis. The presence of the genus Actinolepis Agassiz, 1844 in these deposits as well as in the Emsian of the Baltic region and Spitsbergen suggests a regional paleogeographic connection at this time.UUID: http://zoobank.org/368b44df-e9e9-417c-a0e0-f7e138b7f4ec
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Artushkova, O. V., and V. A. Maslov. "Devonian succession in the East-Zilair zone: conodont-based subdivision and paleontological verification." LITHOSPHERE (Russia) 22, no. 1 (March 2, 2022): 14–38. http://dx.doi.org/10.24930/1681-9004-2022-22-1-14-38.
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Research subject. Conodont-based biostratigraphic subdivision of the monotonous siliceous-terrigenous sequence stratigraphically underlying the Famennian Zilair Formation.Materials and methods. Conodont imprints on the bedding planes from our own collections along with the data from other researchers were used for dating and subdivision of siliceous formations.Results. Our study of conodonts from the deposits underlying the Zilair Formation at a number of intersections on the eastern side of the Zilair synclinorium showed that the stratigraphic scale of the straton, previously recognised as the “Betrinskaya Formation”, should be revised. Numerous collections from well-known and many new localities have proved that the terrigenous-siliceous deposits occurring stratigraphically below the graywackes of the Zilair Formation, in fact constitute the sequence of the entire Devonian section and include characterised by conodonts intervals of the upper Pragian and Emsian stages of the Lower Devonian, the Eifelian and Givetian stages of the Middle Devonian, and the Frasnian stage of the Upper Devonian. These deposits compose a lithologically homogeneous straton – the Novousmanovo succession with siliceous rocks prevailing in its section. The isolation of indicative siliceous members, in particular the Ibragimov horizon, is inexpedient due to the lithological uniformity of the succession as a whole, and its facies variability along the lateral. The limestone members included in it are dated by conodonts. They belong to different stratigraphic intervals and occur in situ in the section.Conclusions. The sediments stratigraphically underlying the Zilair Formation and fully comparable with the identified Novousmanovo succession are developed in the Kuragan-Sakmara zone (Akchura (D1), the remote facies of the Utyagulovo (D2 ef) and Sarbai (D2-D3f) Formations). In the West Magnitogorsk zone in the Voznesenka-Sakmara subzone below the Zilair Formation in a similar siliceous succession, a sequence in conodont zones of stratigraphic intervals of the Eifelian and Givetian stages (D2) and Frasnian stage (D3) united into the Aktau Formation are revealed.
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CRÔNIER, CATHERINE, FATIMA ZOHARA MALTI, ANGELA FRANÇOIS, MADANI BENYOUCEF, and DENISE BRICE. "First occurrence of a phacopid trilobite faunule from the Upper Devonian of Saoura Valley, Algeria and biodiversity fluctuations." Geological Magazine 150, no. 6 (May 16, 2013): 1002–21. http://dx.doi.org/10.1017/s0016756813000277.
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AbstractPhacopid trilobites are relatively widespread in Devonian deposits of north Gondwana and some have been collected from several sections of the Saoura Valley in SW Algeria. New occurrences of phacopids assigned to Trimerocephalus, Dianops and Phacops sensu lato are described from this area and comparisons are made with closely allied species from Morocco and Europe. The trilobite assemblages of the ‘Argiles de Marhouma’ Formation are considered to be Frasnian–Famennian in age. These new occurrences have been integrated into an analysis of Upper Devonian phacopid biodiversity. Diversity fluctuations reflect environmental changes, bioevents and stratigraphic turnovers throughout the Upper Devonian. Peak diversity was attained after the post-Kellwasser event.
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Rodygin, Sergei. "The role of conodonts in the global stratigraphic correlation on example of southern Siberia (Russia) and eastern Serbia." Annales g?ologiques de la Peninsule balkanique, no. 76 (2015): 11–17. http://dx.doi.org/10.2298/gabp1576011r.
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Conodonts are very precise tools for global stratigraphic correlation of Devonian deposits. They can be correlated at the level of standard conodont zones even for basins having very different geological structure. In this paper Devonian conodont correlations between north-western margin of the Kuznetsk Basin (Siberia) and eastern Serbia are demonstrated. The geology of both regions is quite different. East Serbian zone is the southern tip of the Carpathian folded area (Carpatho-Balkanides). Middle Paleozoic carbonate and terrigenous deposits (Silurian, Devonian and Lower Carboniferous) are replaced by Hercynian molasse, and sedimentation continued throughout the Mesozoic and Cenozoic Eras. Rocks were exposed to repeatedly tectonic effects, olistoliths, olistostromes are widespread. Middle Paleozoic sediments, including Devonian, are localized within separate small tectonic blocks, often shifted from its place and form allochthons. In the western part of the Altai-Sayan folded area the Middle Paleozoic sediments have undergone folding and orogeny during the Hercynian phase of tectonic and magmatic activity, but since that time the continental conditions have been dominant in this region. The Devonian deposits are well represented in the marginal parts of the Kuznetsk Basin. In both regions the Devonian rocks have been well studied and the standard conodont zones varcus, gigas (rhenana) - linguiformis, crepida, expansa and praesulcata were established.
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Hassan, Meor Hakif Amir. "The Devonian-Carboniferous Boundary At Guar Sanai, Kampung Guar Jentik, Perlis: An Updated Map And Stratigraphic Section." Bulletin of the Geological Society of Malaysia 71 (May 31, 2021): 57–69. http://dx.doi.org/10.7186/bgsm71202105.
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The Sanai Hill B outcrop, exposed at Kampung Guar Jentik, Beseri district, Perlis, exposes one of the best-preserved Devonian-Carboniferous boundary successions in Malaysia. A new geologic map for the locality is presented, which is based on better exposure of the outcrop due to active quarrying, and was constructed using a combination of aerial drone imagery, three-dimensional photogrammetry, Google Earth satellite imagery and traditional field methods. The sedimentary strata include the Silurian Mempelam Limestone, the Lower Devonian Timah Tasoh Formation, the Upper Devonian Sanai Limestone, the Lower Carboniferous Telaga Jatoh Formation and the Lower Carboniferous Chepor Member of the Kubang Pasu Formation. The Devonian-Carboniferous boundary is marked by the contact between the Sanai Limestone and the Telaga Jatoh Formation. It shows an abrupt change from carbonate to siliceous (chert) deposition, with the contact represented by a paraconformity. This unconformity can be correlated to the Devonian-Carboniferous unconformity in the Kanthan Limestone of Perak. It can also be identified in many sections throughout the Western Belt, including in southern Thailand, Langkawi, Kedah, Perak and the Selangor-Kuala Lumpur area. The unconformity can be linked to a eustatic sea level fall at the end of the Devonian. N-S trending imbricate reverse faults and repeated sections have been interpreted as evidence for collisional tectonics associated with the Late Triassic Indosinian Orogeny. E-W trending normal faults mark a Tertiary extensional phase.
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Jackson, M. J., L. J. Diekman, J. M. Kennard, P. N. Southgate, P. E. O'Brien, and M. J. Sexton. "SEQUENCE STRATIGRAPHY, BASIN-FLOOR FANS AND PETROLEUM PLAYS IN THE DEVONIAN – CARBONIFEROUS OF THE NORTHERN CANNING BASIN." APPEA Journal 32, no. 1 (1992): 214. http://dx.doi.org/10.1071/aj91017.
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A sequence stratigraphic study of 4 000 kilometres of seismic data and fifty wells from the northern part of the Canning Basin has improved vasdy our knowledge of the evolution of the basin succession and has identified new petroleum play concepts. The Devonian to Lower Carboniferous succession can be subdivided into at least sixteen 'Vail type' sequences. This shows two contrasting phases of development; a reef complex in the Frasnian—Early Famennian, and a ramp in the Late Famennian-Tournaisian. The reef complex was characterised by reciprocal sedimentation with thick clastic lowstand wedges deposited in the Fitzroy Trough and thinner transgressive and highstand carbonate sediments deposited on the Lennard Shelf. The reef complex shows an early phase of backstepping, related to rapid drowning of the platform, and a later phase of marked progradadon when relative subsidence was lower. The ramp, in contrast, has only poorly developed lowstand wedges. Early ramp sequences are lenticular and successively offlap basinward; later sequences are more tabular and progressively onlap landward.Sequence stratigraphy has provided a new perspective on the setting and evolution of the traditional Devonian reef play. It emphasises the attractiveness of the Frasnian cycle of reef growth where source, seal and reservoir potential appear to be better than in the younger, much more extensively drilled Famennian cycle.New and untested stratigraphic targets have been identified in Famennian-Tournaisian highstand ramps and in lowstand fans. These new stradgraphic targets are generally basinward of the more traditional target areas and need to be assessed by either wildcat or stratigraphic drilling. The lowstand fans, especially, are large and extensive and favourably located to trap migrating hydrocarbons. Several prospects, each with the potential to contain in excess of 100 million barrels of recoverable oil, have already been identified on seismic data recorded basinward of the Lennard Shelf.
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Martel, A. Thomas, D. Colin McGregor, and John Utting. "Stratigraphic significance of Upper Devonian and Lower Carboniferous miospores from the type area of the Horton Group, Nova Scotia." Canadian Journal of Earth Sciences 30, no. 5 (May 1, 1993): 1091–98. http://dx.doi.org/10.1139/e93-092.
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Late Devonian (late Famennian) miospores have been found in the lowermost 7.3 m of the Horton Group on Harding Brook in the type area, Windsor Subbasin, Nova Scotia, below Tournaisian miospores of the Emphanisporites rotatus – Indotriradites explanatus Zone. Extending the age of the Horton Group in the type area down into the latest Devonian shows that the lowest beds of the ~ 1000 m thick group are coeval with latest Devonian rocks elsewhere in the Maritimes Basin that have been excluded from the Horton Group by some authors. Evidence presented here favours the argument that Late Devonian rocks lithologically similar to the Horton Group, deposited on the Acadian unconformity, should be included in that group. Miospore evidence indicates a minimum age of about 355 Ma for exhumation of the northeastern part of the South Mountain Batholith.
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Bezgodova, D. V. "A new species of Theodossia Nalivkin (Brachiopoda: Spiriferida) from the Frasnian of Novaya Zemlya." Proceedings of the Zoological Institute RAS 319, no. 4 (December 25, 2015): 465–79. http://dx.doi.org/10.31610/trudyzin/2015.319.4.465.
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Descriptions of three new species of Devonian brachiopods Theodossia kagarmanovi sp. nov., Th. novosemelica sp. nov. и Th. tcherkesovae sp. nov. are given. Species belong to the order Spiriferida, suborder Spiriferidina, superfamily Theodossioidea, family Theodossiidae. Brachiopods are collected from the Middle and Upper Frasnian sections of the Southern Novaya Zemlya, Karskie Vorota strait area (Zhandrov and Menshikov subregional Horizons). Besides the description of the shell morphology and interior structure the article contains data about new species stratigraphic distribution and a history of Devonian brachiopods from Novaya Zemlya study.
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Fernandes, Antonio Carlos Sequeira, Sandro Marcelo Scheffler, and Roberto Videira-Santos. "WYATT EARP, DE HERÓI DO FAROESTE NORTE-AMERICANO A NOME DE FORMAÇÃO DEVONIANA NO TERRITÓRIO ANTÁRTICO." PALEONTOLOGIA EM DESTAQUE - Boletim Informativo da Sociedade Brasileira de Paleontologia 36, no. 75 (December 31, 2021): 05–13. http://dx.doi.org/10.4072/paleodest.2021.36.75.01.
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Wyatt Earp, from Hero of the American Western to the Name of Devonian Formation in Antarctic Territory.In science, it is common to name new taxa, geographic points or stratigraphic units with the names of important researchers, pioneer explorers or simply people important to the author who is describing these novelties. This paper presents a curious case of an Antarctic Devonian formation whose name is a tribute to Wyatt Earp, an illustrious character from the American Western. The story began with the American explorer Lincoln Ellsworth, who was a fan of Wyatt Earp and named one of the boats used by him during his expedition to Antarctica after his hero. Later, the name of the boat served as an inspiration to baptize a mount in Antarctica and its name served as a reference to name the Devonian age formation that outcrops in the region of that mount. Wyatt Earp died about four years before Ellworth’s explorations to Antarctica began, and he certainly never imagined that he would become immortalized with the name of a geographic point and a stratigraphic unit as far away as the South Pole. The nomenclature of novelties in the natural sciences encompasses several possibilities and reasons. Keywords: Nomenclature, Mount Wyatt Earp Formation, West Antarctica.
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McCracken, Alexander D., Derek K. Armstrong, and Thomas E. Bolton. "Conodonts and corals in kimberlite xenoliths confirm a Devonian seaway in central Ontario and Quebec." Canadian Journal of Earth Sciences 37, no. 12 (December 1, 2000): 1651–63. http://dx.doi.org/10.1139/e00-055.
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Eighteen samples containing sedimentary rock xenoliths were obtained from cores drilled into eight Mesozoic kimberlite pipes in the Kirkland Lake area, Ontario, and in Ontario and Quebec near Lake Timiskaming. Nine samples from five pipes contained fossils that were used for age determinations. These fossils are Middle or Late Ordovician graptolites, inarticulate brachiopods, and conodonts; Silurian and (or) Devonian conodonts; Early Devonian colonial corals; a Devonian stromatoporoid; and Early to Middle Devonian conodonts. Regionally, conodonts are unaltered (conodont colour alteration index, CAI 1). Conodont CAI values from the xenoliths are elevated (CAI 2), and a few conodonts have surface colour changes, suggesting hydrothermal alteration. Age determinations allow stratigraphic correlation between xenoliths and Paleozoic outcrops. For the Ordovician and Silurian samples, correlations are made to exposures in the nearby Lake Timiskaming outlier. For the Devonian samples, the closest possible correlative outcrops are about 300 km away. These fossils provide the first physical evidence of a connection between a Lake Timiskaming "basin" and other Ontario basins during at least part of the Devonian. These strata persisted at least until the Mesozoic before they were removed by erosion.
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Barrett, Stephen F. "Aspects of a Stratigraphic System: The Devonian. D. L. Dineley." Journal of Geology 94, no. 4 (July 1986): 633. http://dx.doi.org/10.1086/629068.
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POTY, EDOUARD, FRANCOIS-XAVIER DEVUYST, and LUC HANCE. "Upper Devonian and Mississippian foraminiferal and rugose coral zonations of Belgium and northern France: a tool for Eurasian correlations." Geological Magazine 143, no. 6 (September 4, 2006): 829–57. http://dx.doi.org/10.1017/s0016756806002457.
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The radiation of early Carboniferous foraminifers and rugose corals following the Devonian–Carboniferous crisis offers the best tool for high-resolution correlations in the Mississippian, together with the conodonts in the Tournaisian, notably in the Namur–Dinant Basin. However, some of the guides are facies-controlled and an integrated approach combining biostratigraphy, sedimentology and sequence stratigraphy is critical to identify delayed entries, potential stratigraphic gaps and to avoid diachronous correlations. The main difficulty is in correlating shallow and deeper water facies at any given time. In existing zonations, the Viséan part of the scheme is always more detailed, reflecting the widespread development of shallow-water platforms in the early Viséan which created conditions more suitable for foraminifers and rugose corals over large areas. In contrast, the Tournaisian zones, less well documented, reflect unfavourable environmental conditions in the lower ramp (Dinant Sedimentation Area) and pervasive dolomitization of the inner ramp (Condroz and Namur Sedimentation Areas). Recent progress in understanding the Belgian early Carboniferous sequence stratigraphy and lithostratigraphy, and revision of the biostratigraphy of the key sections, strongly modify former biostratigraphic interpretations. Improvements mainly concern the latest Devonian, the late Tournaisian and the early Viséan. The late Devonian and the Tournaisian are equated with foraminifer zones DFZ1 to DFZ8 and MFZ1 to MFZ8 respectively. The Viséan correlates with zones MFZ9 to MFZ14. Zone MFZ15 straddles the Viséan–Namurian boundary and Zone MFZ16 is the youngest Mississippian zone. The rugose corals allow the recognition of ten zones, RC0 to RC9, covering the Strunian (late Famennian) to Serpukhovian interval. Discrepancies with former zonations are discussed. The Moliniacian Stage is emended to restore the coincidence between its base and that of the Viséan.
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Korn, Dieter, Konrad Bartzsch, Stella Zora Buchwald, Volker Ebbighausen, and Dieter Weyer. "The Late Devonian ammonoid subfamily Paratornoceratinae." Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen 297, no. 3 (September 1, 2020): 245–85. http://dx.doi.org/10.1127/njgpa/2020/0924.
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Ammonoids of the subfamily Paratornoceratinae are characterised by disc-shaped adult conchs; furthermore they display a wide range of ontogenetic pathways leading to a similar adult conch morphology. The subfamily Paratornoceratinae occurs in the late early Famennian shelf sediments of various regions from the Anti-Atlas of Morocco to the Canning Basin of Western Australia; where endemic species of the genera Paratornoceras and Acrimeroceras appear in stratigraphic succession. We revise the species Paratornoceras lentiforme (Sandberger, 1857) and describe the new species Paratornoceras thuringense Korn, Bartzsch & Weyer n. sp., P. harounense Korn & Ebbighausen n. sp., P. ayense Korn & Buchwald n. sp., P. peterseni Korn & Buchwald n. sp., Acri meroceras hoppeckense Korn & Buchwald n. sp., A. ropicense Korn, Bartzsch & Weyer n. sp. and A. saalense Korn, Bartzsch & Weyer n. sp.
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Adrain, Jonathan M., and Gerald J. Kloc. "Lower Devonian aulacopleuroidean trilobites from Oklahoma." Journal of Paleontology 71, no. 4 (July 1997): 703–12. http://dx.doi.org/10.1017/s0022336000040154.
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New aulacopleuroidean trilobites from the Lochkovian of Oklahoma include the otarionine Cyphaspis carrolli new species from the Haragan Formation, and the brachymetopid Cordania wessmani new species from the overlying Bois d'Arc Formation. Cyphaspis carrolli is the first record of the genus from the North American Devonian. It is a highly plesiomorphic species, dissimilar to contemporaries from Europe, but closely related to Silurian species from Northern Laurentia and England. Cordania wessmani had previously been interpreted as a possible sexual dimorph of Cordania falcata Whittington, 1960, but new material and information shows that the forms occur separately with no stratigraphic overlap. New information on trilobite occurrence in the Haragan and Bois d'Arc Formations does not support previous hypotheses of trilobite sexual dimorphism, but rather indicates the presence of distinct, stratigraphically successive faunas.
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Horowitz, Alan Stanley, and Joseph F. Pachut. "Specific, generic, and familial diversity of Devonian bryozoans." Journal of Paleontology 67, no. 1 (January 1993): 42–52. http://dx.doi.org/10.1017/s0022336000021156.
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Lack of an adequately calibrated Devonian time scale precludes satisfactory comparisons of Recent and Devonian bryozoan diversities. Nevertheless, Devonian bryozoans apparently are 3–100 times less diverse than Recent bryozoans. This variation is a function of how Devonian time is divided (whole period, stages, per million years) as well as the diverse skeletal architecture of cheilostome bryozoans, the most abundant Recent bryozoan order.The Givetian has the largest specific, generic, and familial diversity of any Devonian stage and the drop in bryozoan diversity from the Givetian to the Frasnian is greater than the rise or fall of diversity between any other adjacent stages. Diversity hardly changes among bryozoans across the Frasnian–Famennian boundary. Among bryozoans the Givetian–Frasnian extinction was a major event.Devonian taxonomic diversity is less than nomenclatorial diversity, although both exhibit the same trends from stage to stage during the Devonian. The amount of difference between the two measures of diversity is probably a reflection of the intensity of research on Devonian Bryozoa, especially revisionary studies of previously described faunas. Monographic bursts in diversity are present and are a measure of the episodic character of taxonomic studies on less popular phyla. Examination of the literature commonly provides a finer stratigraphic resolution than indicated in compilations such as the Zoological Record.Although some significant areas of the exposed continents have not received adequate study, Devonian bryozoans show marked geographic changes in diversity that can not be ascribed entirely to lack of study.
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West Jr, David P., Charles V. Guidotti, and Daniel R. Lux. "Silurian orogenesis in the western Penobscot Bay region, Maine." Canadian Journal of Earth Sciences 32, no. 11 (November 1, 1995): 1845–58. http://dx.doi.org/10.1139/e95-142.
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New 40Ar/39Ar mineral ages from rocks collected west of Penobscot Bay, Maine, indicate this region was regionally deformed, metamorphosed to amphibolite facies conditions, and intruded by plutons in Silurian times rather than in the Devonian as previously assumed. Disturbed hornblende age spectra, along with the presence of some Devonian felsic plutons and extensive retrograde metamorphic textures do suggest, however, that these rocks were subsequently affected by low-grade Devonian thermal events. In sharp contrast, rocks west of the Sennebec Pond thrust fault, a major tectono-stratigraphic boundary in this region, lack a significant Silurian tectono-thermal signature, and instead record the effects of intense Devonian deformation and high-grade regional metamorphism. The data suggest the two regions experienced very different pre-Devonian histories and were most likely juxtaposed by the Sennebec Pond thrust fault in latest Silurian to Early Devonian time. Rocks now exposed east of the Sennebec Pond fault probably occupied much higher structural levels during Devonian orogenesis and were not subjected to the same intense Devonian deformation and metamorphism as those rocks now found to the west of this structure. The Silurian tectonism now recognized in this region bears striking resemblance to events of similar age recorded along the northwest margin of the Avalon composite terrane throughout much of Atlantic Canada. This greatly extends the zone of Silurian orogenesis in the northern Appalachians and requires that previous models of New England middle Paleozoic tectonism be significantly revised.
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Zhang, Jing, and Roger Slatt. "The significance of karst unconformities on overlying resource shales: Lessons learned from the Devonian Woodford Formation applied to the Permian Wolfcamp Shale." Interpretation 7, no. 4 (November 1, 2019): SK33—SK43. http://dx.doi.org/10.1190/int-2019-0042.1.
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We have summarized the threefold significance of karst unconformity boundary: (1) The development of a sequence stratigraphic model for the Devonian Woodford Shale Formation is transferable to the Upper Wolfcamp in the Permian Basin, (2) demonstration of the more general application of that model beyond the Woodford to other resource shales, and (3) illustration of a modification of common sequence stratigraphy models specifically to unconventional resource shales. During early transgression, marine encroachment into the paleolows created anoxic, hypersaline marine “pockets” conducive to the preservation of organic matter. The result is deposition of thick, laterally discontinuous, organic-rich strata stratigraphically at or near the unconformity surface. This pattern of deposition and distribution of the organic-rich shale has been well-documented in the Devonian Woodford Shale and is applicable to other resource shales, in this case to the Permian Upper Wolfcamp Formation in the Central Basin Platform of the Permian Basin. The stratigraphy of the distribution of the Upper Wolfcamp on top of the Upper/Middle Wolfcamp Unconformity is similar to that of the Woodford, suggesting a similar origin and distribution. The resulting stratigraphy in both cases resembles that of the classical Exxon sea slug model except that rather than a single organic-rich deposit defining the condensed section and maximum flooding surface, a second organic-rich deposit occurs stratigraphically lower, at or near the unconformity surface. This theoretical summary can support the discovery of potential drillable target zones in the Woodford Shale and the Wolfcamp Shale.
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Brown, Derek A., James M. Logan, Michael H. Gunning, Michael J. Orchard, and Wayne E. Bamber. "Stratigraphic evolution of the Paleozoic Stikine assemblage in the Stikine and Iskut rivers area, northwestern British Columbia." Canadian Journal of Earth Sciences 28, no. 6 (June 1, 1991): 958–72. http://dx.doi.org/10.1139/e91-087.
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The Stikine assemblage, the "basement" of Stikinia, extends 500 km along the western flank of the Intermontane Belt, east of younger Coast Belt plutons. Four different stratigraphic successions are characteristic of Lower to Middle Devonian, Carboniferous and Permian rocks in the Stikine and Iskut rivers area. West of Forrest Kerr Creek are penetratively deformed Lower to Middle Devonian island-arc volcaniclastic rocks, coralline limestone, and felsic tuff. Fringing carbonate buildups in an arc setting are best illustrated in the sequence at Round Lake where Lower Carboniferous mafic-dominated, bimodal submarine volcanic rocks grade upward into two distinctive coarse echinoderm limestone units and medial siliceous siltstone and limestone conglomerate. Conodont colour alteration indices for Lower Carboniferous rocks near Newmont Lake indicate an anomalously low-temperature thermal history. Upper Carboniferous–Permian polymictic volcanic conglomerate and Lower Permian limestone overlie these strata there. The Scud River sequence is distinguished by subgreenschist- to greenschist-grade Carboniferous(?) volcanic and sedimentary rocks overlain by a structurally thickened package (greater than 1000 m) of Lower Permian limestone. Local calcalkaline pyroclastic rocks interfinger with limestone near the top of the Scud River sequence. Basinal, shelf, and shallow-water carbonate facies developed in the Early Permian, giving way to calcalkaline volcanism in Late Permian followed by deposition of deep-water chert and argillite.The tectonic setting during the Devonian and Carboniferous is comparable with modern Pacific volcanic arcs and atolls, but there is no modern analogue for the shelf-carbonate accumulation during the Early Permian which characterizes the Stikine assemblage and permits Cordilleran-scale correlations. Permian fusulinid and coral species have very close affinity to those of the McCloud Limestone of the eastern Klamath Mountains, California. Other geologic events common to both Stikinia and the Eastern Klamath terrane are Devonian limestone breccia deposition, Lower Permian limestone accumulation with McCloud faunal affinity, Carboniferous and Permian calcalkaline volcanism, and Upper Permian tuffaceous limestone. Stratigraphic differences include the absence of quartz detritus in Devonian strata and lack of thick Upper Permian volcanic rocks in the Stikine River area.
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Blodgett, Robert B., and J. G. Johnson. "First recognition of the genus Verneuilia Hall and Clarke (Brachiopoda, Spiriferida) from North America (west-central Alaska)." Journal of Paleontology 68, no. 6 (November 1994): 1240–42. http://dx.doi.org/10.1017/s0022336000034235.
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The brachiopod genus Verneuilia Hall and Clarke, 1893, is recognized for the first time in North America, where it is represented by a new species described here, V. langenstrasseni. This occurrence not only extends the geographic range of the genus, but also the lower age and stratigraphic limit into the Eifelian (early Middle Devonian). Previously, the oldest known species was the type, V. cheiropteryx d'Archiac and de Verneuil, 1842, from the Givetian (late Middle Devonian) of Germany. Internal structures of V. langenstrasseni n. sp. are similar to those of genera in the ambocoeliid subfamily Rhynchospiriferinae, providing the first good evidence of a systematic relationship.
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Prosh, Eric C. "The Devonian ammonoid Agoniatites from Hungry Hollow, southwestern Ontario." Canadian Journal of Earth Sciences 27, no. 7 (July 1, 1990): 999–1001. http://dx.doi.org/10.1139/e90-102.
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A new specimen of the locally rare ammonoid Agoniatites has been recovered from the Middle Devonian Hamilton Group at Hungry Hollow, southwestern Ontario. Although immature, the specimen displays close affinity to Agoniatites vanuxemi Hall, with which it may be conspecific. An earlier and long-since discredited record of Agoniatites from Ontario is therefore reconfirmed. Despite continued uncertainty as to its precise stratigraphic provenance, the Ontario Agoniatites may prove important for regional correlation.
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Lavoie, Denis. "Carbonate sedimentation in an extensional tectonic regime: the Lower Devonian Upper Gaspé Limestones, Quebec Appalachians." Canadian Journal of Earth Sciences 29, no. 1 (January 1, 1992): 118–28. http://dx.doi.org/10.1139/e92-012.
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Carbonate sedimentation occurred over most of eastern Gaspé Peninsula in Early Devonian time. The resulting succession, known as the Upper Gaspé Limestones, is a 500–1800 m thick unit outcropping in the Connecticut Valley – Gaspé Synclinorium. Detailed stratigraphic and sedimentologic work allows recognition of important thickness and lithofacies variations in a north–south-oriented transect in the eastern part of the peninsula. Variations are spatially associated with Acadian (Middle Devonian) dextral strike-slip faults. Three lithotectonic domains are proposed and interpreted; they are, from north to south, (1) a proximal outer shelf, (2) a distal, gently sloping outer shelf, and (3) a slope or slope toe. Field mapping and reinterpretation of seismic profiles from this area have shown that the faults bounding the three domains are reactivated normal listric faults. Early Devonian vertical movement along these faults caused accelerated subsidence of the central and southern segments of the sedimentary basin and is thought to be responsible for the observed Lower Devonian thickness and megafacies variations in eastern Gaspé.
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Oliver, William A., and A. E. H. Pedder. "Crises in the Devonian history of the rugose corals." Paleobiology 20, no. 2 (1994): 178–90. http://dx.doi.org/10.1017/s0094837300012665.
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Detailed analysis of the stratigraphic ranges of Devonian rugose coral genera within the Old World and Eastern Americas Realms gives new information on faunal extinctions and other bioevents in both realms. Various origination and extinction metrics are calculated from tabulations of occurrences in each stage. The most significant faunal changes were near or at the ends of the Lochkovian and Frasnian stages. The former marks the gradual transition from dominance by Silurian families and genera to the characteristic Devonian coral assemblages; the latter marks the virtual extinction of the Devonian families and genera. Other coral events are related to the two major changes.The data provide new bases for comparing the histories of the two realms. Most of the events are recorded in both, giving support to previous suggestions that the causes were worldwide. The coral record shows an increase (probably episodic) in environmental deterioration persisting through the Middle Devonian and culminating in extinction at the end of the Frasnian. Eustatic sea level fluctuations may have caused the precursor events and a bolide impact may have caused the end-Frasnian extinction.
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Bultynck, Pierre, and Léon Dejonghe. "Preface." Geologica Belgica 4, no. 1-2 (April 15, 2002): 3–4. http://dx.doi.org/10.20341/gb.2014.041.
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The lithostratigraphic guide of Belgium is subdivided into ten chapters dealing respectively with Cambriam-Ordovician-Silurian formations, Devonian formations, Lower Carboniferous formations, Upper Carboniferous formations, Permian formations, Triassic and Jurassic formations, Cretaceous formations, Paleogene and Neogene formations, Quaternary formations. The different chapters have been prepared by the respective national stratigraphic subcommissions set up by the Belgian National Committee for Geological Sciences.
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Kotliar, O. "THE DEVONIAN STRATIGRAPHIC SCALE OF THE VOLHYN-PODOLIA. STEP TOWARDS MODERNIZATION." Tectonics and Stratigraphy, no. 38 (December 8, 2011): 51–66. http://dx.doi.org/10.30836/igs.0375-7773.2011.92237.
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Yiming, GONG, LI Baohua, and WU Yi. "Devonian Frasnian-Famennian Transitional Milankovitch Cycles and High-Resolution Stratigraphic Correlation." Acta Geologica Sinica - English Edition 75, no. 4 (September 7, 2010): 354–63. http://dx.doi.org/10.1111/j.1755-6724.2001.tb00053.x.
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McKie, T., and I. R. Garden. "Hierarchical stratigraphic cycles in the non-marine Clair Group (Devonian) UKCS." Geological Society, London, Special Publications 104, no. 1 (1996): 139–57. http://dx.doi.org/10.1144/gsl.sp.1996.104.01.10.
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Barr, Sandra M., and Rebecca A. Jamieson. "Tectonic setting and regional correlation of Ordovician–Silurian rocks of the Aspy terrane, Cape Breton Island, Nova Scotia." Canadian Journal of Earth Sciences 28, no. 11 (November 1, 1991): 1769–79. http://dx.doi.org/10.1139/e91-158.
Full textAbstract:
Interlayered mafic and felsic metavolcanic rocks and metasedimentary rocks of Ordovician to Silurian age are characteristic of the Aspy terrane of northwestern Cape Breton Island. These rocks were affected by medium- to high-grade metamorphism and were intruded by synkinematic granitoid orthogneisses during Late Silurian to Early Devonian times. They were intruded by posttectonic Devonian granitic plutons and experienced rapid Devonian decompression and cooling. The chemical characteristics of the mafic metavolcanic rocks indicate that they are tholeiites formed in a volcanic-arc setting. The volcanic rocks of the Aspy terrane differ from many other Silurian and Silurian–Devonian successions in Atlantic Canada, which have chemical and stratigraphic characteristics of volcanic rocks formed in extensional within-plate settings, and are somewhat younger than the Aspy terrane sequences. Aspy terrane units are most similar to Ordovician–Silurian volcanic and metamorphic units in southwestern Newfoundland, including the La Poile Group and the Port aux Basques gneiss. Together with other occurrences of Late Ordovician to Early Silurian volcanic-arc units, they indicate that subduction-related compressional tectonics continued into the Silurian in parts of the northern Appalachian Orogen. The complex Late Silurian – Devonian tectonic history of the Aspy terrane may reflect collision with the southeastern edge of a Grenvillian crustal promentory.