New Data on the Famennian Conodonts from Esfahan Area
01 Jan 2005-
TL;DR: New investigations on a Late Devonian outcrop near Esfahan revealed new data about the Polygnathus bouckareti, PolygnATHus communis group and genus Clydagnathus, and feature differentiation related to the recovered species shows the exigency of a few changes in the age and variety of morphotypes.
Abstract: New investigations on a Late Devonian outcrop near Esfahan (Chahriseh section) revealed new data about the Polygnathus bouckareti, Polygnathus communis group and genus Clydagnathus. The feature differentiation related to the recovered species shows the exigency of a few changes in the age and variety of morphotypes of P. communis group. Some identified species in this paper are: Polygnathus communis communis, P. communis mugodzharicus, P. bouckaerti, P. pomeranicus, P. lanceolus, P. inconcinnus, Icriodus alternatus alternatus and I. cornutus. By considering the conodont associations, changes in the age of P. bouckaerti and P. communis mugodzharicus are the other results. In addition, two morphotypes of P. communis mugodzharicus and more detailed explanation of P. communis group are presented.
Citations
More filters
TL;DR: In this article, a rare outcrop at Jebel Ihrs West proved that Kalloclymenia and conodont faunas of the B. ultimus ultimus (= Upper expansa) Zone occur in a separate, overlying unit of the lower part of Famennian VI.
Abstract: The widely quarried and commercially exploited Gonioclymenia Limestone of the western and southern Tafilalt Platform (Anti-Atlas, SE Morocco) represents a transgressive but strongly condensed and shallowing upwards unit that overlies conformably or unconformably Famennian to Lower Devonian deposits. It is characterized by abundant, giant-sized Gonioclymenia speciosa, which characterizes the Famennian V-B, and rare Leviclymenia ramula sp. nov. Associated conodont faunas fall in the Bispathodus costatus Subzone of the B. aculeatus aculeatus (= Middle expansa) Zone. A rare outcrop at Jebel Ihrs West proved that Kalloclymenia and conodont faunas of the B. ultimus ultimus (= Upper expansa) Zone occur in a separate, overlying unit of the lower part of Famennian VI. Consequently, joint occurrences of Gonioclymenia and Kalloclymenia on large limestone slabs that are on offer in rock shops are artificial assemblages; there is no evidence for a regional co-occurrence of both genera. This is supported by correlation into thicker sections of the adjacent Maider and Tafilalt Basins. The Tafilalt Gonioclymenia Transgression may represent the regional expression of a eustatic pulse in the B. costatus Subzone that is known on the Ardennes Shelf as the transgressive Epinette Event. The conodont faunas yielded Neopolygnathus fibula sp. nov., Pseudopolygnathus primus tafilensis ssp. nov., new morphotypes of B. spinulicostatus and Pseudopolygnathus primus primus, the oldest Siphonodella (Eosiphonodella) and variable ‘siphonodelloids’ that are currently left in open nomenclature.
18 citations
Cites background from "New Data on the Famennian Conodonts..."
...In Neo. mugodzaricus (Gagiev, Kononova & Pazukhin, 1987), excluding stratigraphically older material (two morphotypes from Iran; Gholamalian, 2005), there are anterior rostra with few nodes and the unconstricted platform is smooth, with very deep adcarinal troughs....
[...]
TL;DR: The Bahram Formation is discontinuously underlain by the Lower Devonian Padeha Formation and disconformably overlain by the Permian Jamal Formation as mentioned in this paper, and conodont communities from the four sections in the Soh area (Najhaf and Neqeleh sections) and the Natanz area (Varcamar and North Tar sections) were investigated.
Abstract: Four sections of mainly Middle Devonian (Givetian) shallow-marine rocks at the northern margin of Gondwana (Central Iran) were investigated with a special focus on the Bahram Formation, as the stratigraphic range of the Bahram Formation is uncertain and still under discussion. Generally, the Bahram Formation is discontinuously underlain by the Lower Devonian Padeha Formation and disconformably overlain by the Permian Jamal Formation. Conodont communities from the four sections in the Soh area (Najhaf and Neqeleh sections) and the Natanz area (Varcamar and North Tar sections) were investigated. The most widely applied conodont standard zonation of the Upper Givetian contain taxa characteristic of deeper shelf facies whereas conodont fauna of the investigated sections mainly show affinities to shallow-marine environments. Shallow-water conodont associations corresponding to the expansus Zone and subterminus Zone are described from Central Iran for the first time, whereas the vast majority of icriodontid and polygnathid faunas were reported from shallow-marine carbonates around Laurussia (e.g. North America, and Europe). Thirty-six species and subspecies were assigned to five genera (Ancyrodella, Bipennatus, Icriodus, Polygnathus and Pandorinellina). The sedimentological record is characterised by remarkable lateral facies changes, but in the upper part of the Givetian, a general transgressive trend is obvious due to the dominance of limestones and small biostromes.
17 citations
TL;DR: The Zefreh section in central Iran represents a carbonate ramp succession with a general shallow-marine palaeoenvironment as discussed by the authors, where conodonts and brachiopods were used for establishing the biostratigraphical framework.
Abstract: The Zefreh section in central Iran represents a carbonate ramp succession with a general shallow-marine palaeoenvironment. This section represents most of the Bahram Formation (Givetian to at least Middle falsiovalis Zone) and consists of a very heterogeneous succession of medium- to coarse-grained sandstones, skeletal pack- to grainstones with local biostromes, massive or laminated dolostones, and shales. Microfacies analysis allowed the discrimination of 12 microfacies reflecting supratidal to open marine palaeoenvironments. The shallow-marine environment was investigated using facies analysis and geochemical proxies. Redox conditions in the Zefreh section appear to be primarily oxic and support the facies and sedimentological results. The provenance of the Zefreh sediments using La, Sc, Zr, and Th indicates that they are most likely derived from continental arc volcanics which is consistent with the preliminary tectonic interpretations. Conodonts and brachiopods were used for establishing the biostratigraphical framework. The lack of important zonal index taxa of the widely applied conodont standard zonation requires the application of an alternative shallow-marine conodont zonation. Based on conodont and brachiopod data, the Zefreh section covers sediments ranging from the upper Givetian to lower Frasnian.
16 citations
TL;DR: In this paper, the age of the Bahram Formation in central Iran has a stratigraphical range from the Givetian (hermanni Zone) to the late Famennian (Middle expansa Zone).
Abstract: Conodont fauna from the Kesheh and Dizlu sections in the North Isfahan province were investigated. Shallow-water and/or near-shore conodonts, mainly belonging to the icriodid–polygnathid biofacies, dominate the conodont fauna. Due to the depositional setting which is characterised by predominantly shallow-water palaeoenvironments and the lack of some important zonal index taxa (e.g. Palmatolepis species), a precise conodont biostratigraphy is difficult to establish. The Kesheh section covers sediments ranging from the Givetian hermanni Zone to disparilis Zone whereas in the Dizlu section, the ranges of Middle triangularis to Uppermost crepida, the marginifera to Upper trachytera, and the Lower and Middle expansa Zones indicate a Famennian age. The stratigraphic range of the Bahram Formation is discussed, and according to literature and new conodont data presented herein, it is likely that the age of the Bahram Formation in central Iran has a stratigraphical range from the Givetian (hermanni Zone) to the late Famennian (Middle expansa Zone).
11 citations
TL;DR: A bryozoan fauna from the Late Devonian (Frasnian) of the Bahram Formation of the Zefreh section in central Iran contains four species: three trepostomes and one rhabdomesine cryptostome as discussed by the authors.
Abstract: A bryozoan fauna from the Late Devonian (Frasnian) of the Bahram Formation of the Zefreh section in central Iran contains four species: three trepostomes and one rhabdomesine cryptostome. Two species are new: the trepostome Coeloclemis zefrehensis sp. nov. and the rhabdomesine cryptostome Euthyrhombopora tenuis sp. nov. The trepostome species Cyphotrypa definita Morozova, 1960 and Anomalotoechus ramosus Morozova, 1960 were recorded previously from the Upper Devonian (Frasnian) of the Kuznets Basin. The genera Coeloclemis and Euthyrhombo-pora are recorded from the Devonian for the first time. The fauna is dominated by the erect ramose Euthyrhombopora tenuis sp. nov., with rare occurrences of the massive Cyphotrypa definita Morozova, 1960. The bryozoans indicate low to moderate water energy environment of middle to outer ramp position.
6 citations
References
More filters
TL;DR: In this paper, a great variety of forms which I have collected within the last two years from several different formations in North America are described, and they will at least add something to our previous knowledge, and thus assist in reaching a decision on the subject.
Abstract: Soon after the publication by Dr. Pander, in 1856, of his wellknown monograph, in which he announced the discovery, in the lowest fossiliferous rocks of Russia, of small ‘teeth” named Conodonts, and referred by him to fishes, several discussions arose as to the character of these minute bodies, and various opinions were expressed as to their near relations, without, however, any satisfactory conclusion being arrived at. Since that date Conodonts have been found in several other places; and in this communication I propose to describe a great variety of forms which I have collected within the last two years from several different formations in North America. Though my specimens may not suffice to determine the true position of the organisms to which they were attached, they will at least add something to our previous knowledge, and thus assist in reaching a decision on the subject. The next account, after Dr. Pander9s, of the discovery of Conodonts is by Dr. J. Harley, in an article on the Ludlow bone-bed and its crustacean remains. Only two of the specimens described by this gentleman have any resemblance to the Conodonts of Pander; but a comparison of these with other very differently formed bodies in the same beds led him to express the opinion that all the forms were of crustacean origin, and that Conodonts were probably only spines similar to those attached to the margins of the carapace of Limulus and the caudal segment of Squilla. He therefore included all together under the provisional genus Astacoderma .
159 citations
01 Jan 1984
142 citations
21 Feb 1969
125 citations
21 May 1993
97 citations
TL;DR: A study of the conodont assemblages from the Maple Mill, Grassy Creek, and Louisiana formations was conducted by as discussed by the authors, who found that these assemblage are more closely related to conodons from unquestionably Devonian rocks than to an assemblaging from rocks of undoubted Mississippian age.
Abstract: A study of the conodont assemblages from the Maple Mill, Grassy Creek, and Louisiana formations discloses that these assemblages are closely related and also that these assemblages are more closely related to conodonts from unquestionably Devonian rocks than to an assemblage from rocks of undoubted Mississippian age. I have assigned the Maple Mill shale to the upper Devonian because of these reasons; therefore, the Maple Mill shale must be redefined to indicate its Devonian age. The Maple Mill and Grassy Creek shales, of Iowa and Missouri respectively, are time equivalents, because subsurface studies show that the 2 shales grade laterally into each other. The methods employed to determine the age and correlation of the Maple Mill shale were applied to the English River and Prospect Hill siltstones. These methods indicate that these siltstones are lower Mississippian, and that they are time equivalents of the Bushberg and Hannibal formations of Missouri. The Louisiana limestone of Missouri has been correlated with the McCraney limestone of Iowa because of similarity of a few macro-fossils and lithologic characteristics. Conodont studies suggest that the Louisiana is related to the Grassy Creek, whereas the McCraney is related to the Hannibal. This difference precludes the possibility of the two limestones being correlated as time equivalents.
61 citations