| Kendlbach Formation | |
|---|---|
| Stratigraphic range: | |
| Type | Formation |
| Sub-units | Tiefengraben Member, Breitenberg Member |
| Underlies | Adnet Formation |
| Overlies | Kössen Formation, Oberrhaet Limestone |
| Lithology | |
| Primary | marl, claystone |
| Other | shale, siltstone, limestone |
| Location | |
| Country | Austria Italy |
The Kendlbach Formation is a Late Triassic (latest Rhaetian) to Early Jurassic (Hettangian) geological formation in Austria and Italy. It contains the Global Boundary Stratotype Section and Point (GSSP) for the Hettangian stage (the first stage of the Jurassic period) at the Kuhjoch section in the Karwendel Mountains of Austria. [1] [2]
The Kendlbach Formation consists of clay-rich marls and other sediments deposited during and immediately after the Triassic-Jurassic extinction event at the end of the Rhaetian stage. It has two subunits: the thick Tiefengraben Member, which is deprived of limestone, and the succeeding Breitenberg Member, a thinner sequence which shows the return of limestone. Like the underlying Kössen Formation, sediments of the Kendlbach Formation were deposited within the Eiberg Basin, a seaway which developed along the northwest tip of the Neotethys Ocean in the region now occupied by the Northern Calcareous Alps. [2]
The boundary between the Kössen and Kendlbach formations is marked by a sharp transition from limestone to dark shales and marls. The boundary also shows a strong negative δ13C organic carbon isotope excursion as well as the extinction of many species of palynomorphs and marine invertebrates. The interval experiences an influx of freshwater palynomorphs, namely Classopollis pollen (from drought-tolerant Cheirolepidiaceae conifers) followed by spores and Cymatiosphaera (a type of prasinophyte algae). Some outcrops show a layer of reddish sediment, the Schattwald Beds, which follows the initial boundary interval. Above the Schattwald Beds occur the first fossils of Jurassic ammonites such as Psiloceras spelae , indicating the formal beginning of the Jurassic period. [1] [2]
The Triassic is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago (Mya), to the beginning of the Jurassic Period 201.4 Mya. The Triassic is the first and shortest period of the Mesozoic Era and the seventh period of the Phanerozoic Eon. Both the start and end of the period are marked by major extinction events. The Triassic Period is subdivided into three epochs: Early Triassic, Middle Triassic and Late Triassic.
The Triassic–Jurassic (Tr-J) extinction event (TJME), often called the end-Triassic extinction, marks the boundary between the Triassic and Jurassic periods, 201.4 million years ago. It is one of five major extinction events, profoundly affecting life on land and in the oceans. In the seas, about 23–34% of marine genera disappeared. On land, all archosauromorph reptiles other than crocodylomorphs, dinosaurs, and pterosaurs became extinct; some of the groups which died out were previously abundant, such as aetosaurs, phytosaurs, and rauisuchids. Plants, crocodylomorphs, dinosaurs, pterosaurs and mammals were left largely untouched, allowing the dinosaurs, pterosaurs, and crocodylomorphs to become the dominant land animals for the next 135 million years.
The Early Jurassic Epoch is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic–Jurassic extinction event, 201.3 Ma, and ends at the start of the Middle Jurassic 174.7 ±0.8 Ma.
The Rhaetian is the latest age of the Triassic Period or the uppermost stage of the Triassic System. It was preceded by the Norian and succeeded by the Hettangian. The base of the Rhaetian lacks a formal GSSP, though candidate sections include Steinbergkogel in Austria and Pignola-Abriola in Italy. The end of the Rhaetian is more well-defined. According to the current ICS system, the Rhaetian ended 201.4 ± 0.2 Ma.
The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma. The Hettangian follows the Rhaetian and is followed by the Sinemurian.
The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between 237 Ma and 201.4 Ma. It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. The corresponding series of rock beds is known as the Upper Triassic. The Late Triassic is divided into the Carnian, Norian and Rhaetian ages.
The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.9 Ma and 251.2 Ma. The Induan is sometimes divided into the Griesbachian and the Dienerian subages or substages. The Induan is preceded by the Changhsingian and is followed by the Olenekian.
The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between 242 Ma and ~237 Ma. The Ladinian was preceded by the Anisian and succeeded by the Carnian.
The Aquitaine Basin is the second largest Mesozoic and Cenozoic sedimentary basin in France after the Paris Basin, occupying a large part of the country's southwestern quadrant. Its surface area covers 66,000 km2 onshore. It formed on Variscan basement which was peneplained during the Permian and then started subsiding in the early Triassic. The basement is covered in the Parentis Basin and in the Subpyrenean Basin—both sub-basins of the main Aquitaine Basin—by 11,000 m of sediment.
Psiloceras is an extinct genus of ammonite. Psiloceras is among the earliest known Jurassic ammonites, and the appearance of the earliest Psiloceras species form the definition for the base of the Jurassic. Unlike most earlier ammonites, which had complex shell shapes and ornamentation, Psiloceras had a smooth shell.
Waterloo Bay is an area of foreshore in Larne on the east coast of County Antrim, Northern Ireland. It is of particular interest to geologists because it provides a clear, complete and accessible example of the sequences from Upper Triassic to Lower Jurassic, when the rock types changed from land to marine.
The Gabbs Formation is a geologic formation in Nevada. It preserves fossils dating back to the Late Triassic and Early Jurassic periods, and is one of the few formations in the United States known to include the Triassic-Jurassic boundary. In 2007, an exposure of the Gabbs Formation at New York Canyon was proposed a candidate GSSP for the Hettangian stage, the first stage of the Jurassic. However, the New York Canyon section was ultimately not selected as Hettangian GSSP, which instead went to the Kuhjoch section of Austria in 2010.
The Kössen Formation is a Late Triassic (Rhaetian-age) geological formation in the Northern Calcareous Alps of Austria and Germany, in the Tiroler-Lech Nature Park. During the Late Triassic, the area now occupied by the Northern Calcareous Alps was instead a long, passive coastline at the western tip of the Neotethys Ocean. The environment was initially dominated by a wide and shallow carbonate platform within a lagoon between the shore and a string of reefs. This carbonate platform is nowadays preserved as the Carnian to Norian-age Hauptdolomit and Dachstein Formation. The Kössen Formation represents a period of increased siliciclastic clay input into the lagoon, covering up the carbonate platform with marls and marly limestones instead of pure limestone or dolomite. The Eiberg Member of the Kössen Formation was deposited in the Eiberg basin, a narrow strip of deeper water which developed between the carbonate platform and the shoreline in the later part of the Rhaetian.
The Oberrhaet Formation, also known as the Oberrhaet Limestone, is a Late Triassic (Rhaetian-age) geological formation in Austria. It is a unit of massive dark grey bioclastic limestones, found within the Northern Calcareous Alps. The Oberrhaet Limestone was originally a series of reefs which developed on the northwest edge of the Eiberg Basin, a narrow marine waterway extending along the northwestern tip of the Neotethys Ocean. The center of the Eiberg Basin is nowadays preserved as the Eiberg Member of the Kössen Formation, which was deposited southeast of the Oberrhaet Limestone and interfingers with it in many areas. The Oberrhaet Limestone was very similar to the Dachstein Limestone, which represented carbonate platforms and reefs on the southeast edge of the Eiberg Basin. The most prominent components of the reefs were giant frond-like colonies of Retiophyllia, a scleractinian coral.
Dracoraptor is a genus of coelophysoid dinosaur that lived during the Hettangian stage of the Early Jurassic Period of what is now Wales dated at 201.3 ± 0.2 million years old.
Misikella is an extinct genus of conodonts.
The Pignola-Abriola section is a ~63 m long stratigraphic sequence of cherty limestones deposited in the Lagonegro Basin during the latest Norian and the early Rhaetian Stages. The main outcrop is on the western side of Mount Crocetta along the SP5 road connecting the villages of Pignola and Abriola. A smaller outcrop, overlapping the central part of the main section, is located near a former railway tunnel, few meters below the road level. The Pignola-Abriola section has been recently proposed as GSSP of the Rhaetian Stage.
The geology of Tunisia is defined by the tectonics of North Africa, with large highlands like the Atlas Mountains as well as basins such as the Tunisian Trough. Geologists have identified rock units in the country as much as a quarter-billion years old, although most units date to the Mesozoic and Cenozoic, in the past 250 million years. Tunisia has a small but active mining industry and a significant oil and natural gas sector.
Oncodella is an extinct genus of Late Triassic conodont. The genus was given the type species Oncodella idiodentica by Mosher (1968), on the basis of fossils from the Late Triassic of Austria. However, Mosher (1969) later revised the species name to Oncodella paucidentata, since identical fossils from the same area were previously given the name Hindeodella paucidentata by Mostler (1967).
Palaeontology in Wales is palaeontological research occurring in Wales.
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