L'evolution sedimentaire et tectonique du bassin hercynien de Moravie-Haute-Silesie
7
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
Abstract The Moravia-Upper Silesia basin of southern Poland and northern Czechoslovakia is a good example of geosynclinal development. Geosynclinal sedimentation beginning in the Devonian passed gradually without tectonic break into late geosynclinal coal-producing sedimentation. After Asturian (upper Carboniferous) folding, upper Carboniferous and lower Permian sediments were laid down. The migration of subsidence and molasse-type sediments within the geosynclinal system is clearly shown.Keywords:
Devonian
Molasse
Late Devonian extinction
Abstract The Devonian Period occupied the central slice of a 250 Ma interval during which more than a dozen narrow, intercratonic oceans were undergoing closure, while an enormous northern hemisphere ocean was being widened by marginal subduction. The period was preceded, interrupted, terminated and followed by major orogenic events of differing types and affecting different belts of rock. The Devonian was consequently a period of remarkable geological variety, with early and late Devonian geologies quite different over most areas of Devonian deposition. The most important consequence from the viewpoint of the economic geologist was the division of Devonian rocks among three distinct tectofacies. In the Hercynian tectofacies the Devonian is essentially complete and continuous between the Silurian and the Carboniferous. In the Caledonian tectofacies some lower part of the system is missing below a sub-Devonian unconformity. In the Bretonian tectofacies the upper part of the system is missing above a post-Devonian unconformity (though the Bretonian must originally have been in one of the other tectofacies). The Hercynian tectofacies is confined to surprisingly narrow bands almost entirely restricted to the northern hemisphere. The other two tectofacies occupy huge areas within deformed belts and the whole of the Devonian coverage of the cratons. The relations between the tectofacies and the stages of the tectonic cycle are obvious. Their effects on Devonian mineral deposits are striking. Paleozoic mineral deposits of the separation and early closure stages of the cycle are nearly all pre-Devonian. Syngenetic deposits (especially of massive sulphides) are restricted to the Hercynian tectofacies; they are much commoner in the pre-Devonian, and even somewhat commoner in the Lower Carboniferous, than they are in the Devonian. Epigenetic deposits of Devonian origin occur wherever Devonian felsic igneous rocks occur, but they are very likely to be in pre-Devonian host rocks. Deposits in Devonian host rocks are almost certain to be of post-Devonian origin; the largest are of Mesozoic or Tertiary origin. Devonian of the Bretonian tectofacies is especially unlikely to be host to large epigenetic deposits. Only a handful of important deposits, like Murdochville in Quebec, represent the combination of circumstances permitting an epigenetic metalliferous deposit of Devonian origin to be in a Devonian host rock. Metallic deposits unrelated to the tectonic cycle, and nonmetallic and sedimentary deposits also possibly independent of it, illustrate the same apparent paradox. From Mississippi Valley-type lead-zinc to phosphorite deposits and from helium to building stone, the Devonian is endowed with less than its proper share of large deposits. Its compartmentalization by orogenies reduced it as a target for mineralization; it is the victim of its own variety. The exceptions are potash and petroleum, both reflecting great marine transgression over previously segmented basements. The Devonian is strikingly oil prone because it is superlatively endowed with rich source sediments. Surprisingly, of all the Paleozoic producing areas of the world, only seven basins have more than 50% of their recoverable oil in Devonian reservoir rocks. Of the approximately 12 × 109 m3 of reserves in these seven basins, 75% is in the Ural-Volga and Alberta basins. Conventional natural gas is almost foreign to the Devonian, but the black shales that provide some of its oil source sediments also represent a large potential future supply of unconventional natural gas.
Devonian
Late Devonian extinction
Cite
Citations (0)
Abstract The Daposhang section at Muhua, Changshun, Guizhou, is an excellent and attractive Devonian‐Carboniferous boundary section. The transitional beds between the Devonian and Carboniferous of the section are continuous and well exposed, belonging to the deep‐water basin facies. Abundant fossil groups have been discovered from this section: conodonts, ammonoids, trilobites, ostracods, vertebrate microfossils and so on. So far as known, it has the most continuous and complete conodont zonation for the Devonian‐Carboniferous boundary beds in the world. It is especially worth pointing out that both typical Siphonodella praesulcata and the transitional forms between S. praesulcata and S. sulcata have been found from the upper praesulcata Zone of the Daposhang section. Evidently, we can not only prove the actual existence of the evolutionary lineage from S. praesulcata to S. sulcata , but also exactly define the level of the Devonian‐Carboniferous boundary. In this paper, the development of the Devonian‐Carboniferous boundary beds at the Daposhang section is dealt with and the section is compared with the Muhua section and the Nanbiancun section which are the candidates for the Devonian‐Carboniferous boundary stratotype. In the authous' opinion the Daposhang section is obviously better than the Muhua and the Nanbiancun sections, hence it can be recommended as one of the candidates for the international Devonian‐Carboniferous boundary stratotype.
Devonian
Stratotype
Section (typography)
Conodont
Late Devonian extinction
Tournaisian
Cite
Citations (3)
Devonian
Late Devonian extinction
plant evolution
Stele
Vascular plant
Cite
Citations (49)
Regionally, the number of large and “gigantic” accumulations of oil (>50 million tons and >100 million tons of proved economic reserve, respectively) decreases progressively with decreasing age of their Paleozoic host. The apparent exceptions, in the Lower Carboniferous, are due to migrations of the Devonian pools into the Carboniferous traps. However, large accumulations of oil may develop also in several complexes, at intersections of the Devonian domes with the Lower Carboniferous Kama-Kinel trough. – IGR Staff.
Devonian
Trough (economics)
Late Devonian extinction
Cite
Citations (0)
Devonian
Late Devonian extinction
Cite
Citations (4)
A single specimen of a shrimp-like crustacean, Devonostenopus pennsylvaniensis , new genus and species is described from the Huntley Mountain Formation, which is Devonian–Carboniferous (Mississippian) in age. The specimen was collected in north-central Pennsylvania. Devonostenopus pennsylvaniensis is attributed to Stenopodidae. Co-occurrence of the specimen with pinnules of Archaeopteris halliana Goeppert, 1852, suggests that it is Devonian in age. Occurrence of a stenopodidean in the Devonian of North America is significant, as only three definitive decapods have been previously described from the Paleozoic and only two have been described from the Devonian. The earliest stenopodideans described to date are Cretaceous (Cenomanian and Santonian) in age. As such, Devonostenopus pennsylvaniensis extends the geologic range of Stenopodidea from Cretaceous to Late Devonian. Occurrence of a stenopodidean in the Devonian of North America, as well as the occurrence of the only two other known Devonian decapods in North America, suggests that Laurentia might have been a major area of endemism for Devonian decapods.
Devonian
Late Devonian extinction
Cenomanian
Cite
Citations (17)
Brachiopods from the Devonian-Carboniferous passage beds in the Babilon 1 column (Western Pomerania) (Preliminary Report) 42 brachiopod species belonging to 29 genera have been determined from the higher members of the Famennian and the Devonian-Carboniferous passage beds of the Babilon 1 column. Their distribution in the profile is shown and two assemblages distinguished, namely assemblage A - of the Devonian brachiopods and B – containing Devonian, Strunian and Carboniferous forms. Three subassemblages have been distinguished within the B” assemblage.
Devonian
Assemblage (archaeology)
Late Devonian extinction
Cite
Citations (0)
Devonian
Late Devonian extinction
Tetrapod (structure)
Laurasia
Cite
Citations (60)
The transition between the Devonian and Carboniferous is important for tetrapod vertebrates. By the end of the Devonian the first limbs are present in aquatic animals, and by the mid Carboniferous fully terrestrial tetrapods have diversified. Knowledge of the fin-to-limb transition is sparse because few fossils from the earliest Carboniferous (Tournaisian) are known. Blue Beach Nova Scotia, in addition to a small number of sites in Scotland and Australia, is an exception to this global trend. Previous reports from Blue Beach identified fossils from a variety of Devonian-like and Carboniferous-like tetrapod body forms, making it a valuable site for studying the fin-to-limb transition. Here we report on a new left fibula from Blue Beach, which we attribute to the later occurring Visean-aged (early Carboniferous) Crassigyrinidae. Recent investigations of deposits in Scotland, similar in age to the Tournaisian exposed at Blue Beach, have found Crassigyrinus-like elements as well, reinforcing this 20-million-year lineage extension.
Tournaisian
Devonian
Viséan
Tetrapod (structure)
Late Devonian extinction
Cite
Citations (5)