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29-785: The Keuper together with the Muschelkalk and the Buntsandstein form the Germanic Trias Group , a characteristic sequence of rock strata that gave the Triassic its name. The Upper Triassic is well exposed in Swabia , Franconia , Alsace and Lorraine and Luxembourg ; it extends from Basel on the east side of the Rhine into Hanover , and through England into Scotland and north-east Ireland ; it appears flanking

58-423: A barrier. The results are presented as a correlation scheme (A). Practical correlation has a lot of difficulties: fuzzy borders of the layers, variations in composition and structure of the rocks in the layer, unconformities in the sequence of layers, etc. This is why errors in correlation schemes are not seldom. When the distances between available cross-sections are decreasing (for example, by drilling new wells)

87-471: A formation of sedimentary rock, then we can say that the igneous intrusion is younger than the sedimentary rock. The principle of superposition states that a sedimentary rock layer in a tectonically undisturbed stratum is younger than the one beneath and older than the one above it. The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds. The principles of lithostratigraphy were first established by

116-479: A lithostratigraphic unit includes a stratotype which is usually a type section . A type section is ideally a good exposure of the unit that shows its entire thickness. If the unit is nowhere entirely exposed, or if it shows considerably lateral variation, additional reference sections may be defined. Long-established lithostratigraphic units dating to before the modern codification of stratigraphy, or which lack tabular form (such as volcanic domes), may substitute

145-666: A major rise of the global ( eustatic ) sea level. A tropical sea filled the Germanic Basin then, stopping the deposition of the Buntsandstein and marking the beginning of the deposition of the Muschelkalk. The Buntsandstein belongs to the Changhsingian to Anisian stages , meaning it is between 252 and 246 million years old. In German lithostratigraphy, it is seen as a group, in the Netherlands and North Sea

174-574: A subdivision of the Triassic system. Among reasons to abandon this use was the discovery that its base lies actually in the latest Permian. The Buntsandstein was deposited in the Germanic Basin , a large sedimentary basin that was the successor of the smaller Permian Basin and spread across present day Poland , Germany, Denmark , the southern regions of the North Sea and Baltic Sea ,

203-450: A type locality for a type section as their stratotype. The geologist defining the unit is expected to describe the stratotype in sufficient detail that other geologists can unequivocally recognize the unit. Lithosome : Masses of rock of essentially uniform character and having interchanging relationships with adjacent masses of different lithology . e.g.: shale lithosome, limestone lithosome. The fundamental Lithostratigraphic unit

232-556: Is a sub-discipline of stratigraphy , the geological science associated with the study of strata or rock layers. Major focuses include geochronology , comparative geology, and petrology . In general, strata are primarily igneous or sedimentary relating to how the rock was formed. Sedimentary layers are laid down by deposition of sediment associated with weathering processes, decaying organic matter (biogenic) or through chemical precipitation. These layers are often distinguishable as having many fossils and are important for

261-449: Is called an unconformity . Four types of unconformity: To correlate lithostratigraphic units, geologists define facies, and look for key beds or key sequences that can be used as a datum. Geological correlation is the main tool for reconstructing the geometry of layering in sedimentary basins . The lithological correlation is a procedure, decisive what layers (strata) in geological cross-sections located in different places belong to

290-793: Is one of three characteristic Triassic units, together with the Muschelkalk and Keuper that form the Germanic Trias Supergroup . The Buntsandstein is similar in age, facies and lithology with the Bunter of the British Isles . It is normally lying on top of the Permian Zechstein and below the Muschelkalk. In the past the name Buntsandstein was in Europe also used in a chronostratigraphic sense, as

319-413: Is the formation . A formation is a lithologically distinctive stratigraphic unit that is large enough to be mappable and traceable. Formations may be subdivided into members and beds and aggregated with other formations into groups and supergroups. Two types of contact: conformable and unconformable . Conformable : unbroken deposition, no break or hiatus (break or interruption in the continuity of

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348-651: The Netherlands and south England. In the late Permian this region had an arid climate and it was covered by inland seas which deposited the Zechstein evaporites . At the end of the Permian a connection with the Paleo-Tethys Ocean to the south was formed in present-day southeast Poland, causing sea water to flow in periodically. This caused the inflow of more clastic material, which was deposited in

377-776: The 'Keuper' is no longer a formally recognised geological division. The one-time Keuper Marls are now redesignated as the Mercia Mudstone Group . The underlying Keuper Sandstone is now the Helsby Sandstone Formation at the top of the Sherwood Sandstone Group . Traditionally it contained the following subdivisions: The Keuper covers a large area in the Midlands and around the flanks of the Pennine range; it reaches southward to

406-523: The Danish naturalist, Nicolas Steno , in his 1669 Dissertationis prodromus . A lithostratigraphic unit conforms to the law of superposition , which in its modern form states that in any succession of strata , not disturbed or overturned since deposition , younger rocks lies above older rocks. The principle of lateral continuity states that a set of bed extends and can be traceable over a large area. Lithostratigraphic units are recognized and defined on

435-728: The Dutch subdivision, the upper two formations are part of the Upper Germanic Trias and the others part of the Lower Germanic Trias. Bunter sandstone often forms spectacular rock formations as a result of weathering: including isolated rocks several tens of metres high. Most of them are designated natural monuments , for example, the Devil's Table near Hinterweidenthal . In the Palatinate, near Eppenbrunn , are

464-840: The Keuper unit is divided into three groups: The salt , which is associated with gypsum, is exploited in south Germany at Dreuze, Pettoncourt, as well as in Vie in the Lorraine region of France. A 4-metre (13 ft) coal is found on this horizon in the Ore Mountains on the border between Germany and the Czech Republic , and another, 2 metres thick (7 ft), has been mined in Upper Silesia , now in Poland . In Great Britain

493-510: The basis of observable physical rock characteristics. The lithology of a unit includes characteristics such as chemical and mineralogical composition, texture, color, primary depositional structures , fossils regarded as rock-forming particles, or other organic materials such as coal or kerogen . The taxonomy of fossils is not a valid lithological basis for defining a lithostratigraphic unit. The descriptions of strata based on physical appearance define facies . The formal description of

522-876: The central plateau of France and in the Pyrenees and Sardinia . The Keuper sequence is linked by name to the Keuper Uplands area of southern Germany. In south Sweden , the lower portion contains coal -bearing strata, as in the Himalayas , Japan , Tibet , Burma , eastern Siberia and in Spitsbergen . The upper portion of the Karoo Supergroup of South Africa and part of the Otapiri stage of New Zealand are probably of Rhaetian age. In Germany and adjacent parts of western and central Europe,

551-557: The early beetle Triamyxa is also known from the Keuper. Buntsandstein The Buntsandstein (German for coloured or colourful sandstone ) or Bunter sandstone is a lithostratigraphic and allostratigraphic unit (a sequence of rock strata ) in the subsurface of large parts of west and central Europe. The Buntsandstein predominantly consists of sandstone layers of the Lower Triassic series and

580-511: The east Devon coast, northeastward into Yorkshire and northwestward into Northern Ireland and southernmost Scotland. The Keuper is not rich in fossils ; the principal plants are cypresslike conifers ( Walchia , Voltzia ) and a few calamites with such forms as Equisetum arenaceum and Pterophyllum jaegeri . Avicula contorta , Protocardium rhaeticum , Terebratula gregaria , Myophoria costata , M. goldfassi , Lingula tenuessima , and Anoplophoria lettica may be mentioned among

609-499: The form of large alluvial fans . The same process happened in the Triassic for the Basque-Cantabrian Basin , in the axis of the future Pyrenees . Deposition took place in an arid, continental environment ( playa facies), so that there was little chemical weathering . Therefore, the Buntsandstein deposits are typical red beds , mainly sandstones and conglomerates with little clay . The late Anisian saw

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638-410: The formal terms lithodeme , which is comparable to a formation; a suite , which is analogous to a group, and a supersuite , similar to a supergroup. A lithodeme is the fundamental unit and should possess distinctive and consistent lithological features, comprising a single rock type or a mixture of two or more types that distinguishes the unit from those around it. As with formations, a lithodemic unit

667-407: The geological record). The surface strata resulting is called a conformity . Two types of contact between conformable strata: abrupt contacts (directly separate beds of distinctly different lithology, minor depositional break, called diastems ) and gradational contact (gradual change in deposition, mixing zone). Unconformable : period of erosion/non-deposition. The surface stratum resulting

696-438: The invertebrates. The fish include Ceratodus , Hybodus and Lepidotus . Labyrinthodonts represented by the footprints of Cheirotherium and the bones of Mastodonsaurus (originally called Labyrinthodon ) and Capitosaurus . Among the reptiles are Hyperodapedon , Palaeosaurus , Zanclodon , Nothosaurus , Henodus and Belodon . The first fossil mammals also make their appearance at this time and

725-692: The name has no official status (though that does not keep geologists from using it). In the official Dutch lithostratigraphy, the Buntsandstein is divided into the Lower and Upper Germanic Trias Groups . The British Bunter Formation is basically a continuation of the same unit. In Germany the Buntsandstein is subdivided into three subgroups with seven formations (from top to base): Upper Buntsandstein Middle Buntsandstein Lower Buntsandstein All of these are reasonably good reservoir rocks for oil and gas. In

754-457: The quality of correlation is improving, but meanwhile the wrong geological decisions could be made that increases the expenses of geological projects. The law of superposition is inapplicable to intrusive, highly deformed, or metamorphic bodies of rock lacking discernible stratification. Such bodies of rock are described as lithodemic and are determined and delimited based on rock characteristics. The 1983 North American Stratigraphic Code adopted

783-474: The same geological body now (or belonged in the past). The identification is based on comparison of physical and mineralogical characteristics of the rocks, and on general assumptions known as the Steno's principles: 1. The sedimentary strata occurred sequentially in time: the youngest at the top. 2. The strata are originally horizontal. 3. The stratum extends in all directions until it thins out or encounters

812-515: The so-called Altschlossfelsen ("Old Castle Rocks"). The massif has a length of around 1.5 km and a height of up to 25 metres, easily the largest bunter sandstone massif in the Palatinate. On the island of Heligoland , the 47-metre-high Lange Anna ("Tall Anna"), is the best-known landmark on the island and was declared a natural monument in 1969. The Buntsandstein contains a few small saurians, tracks like Chirotherium and plant remnants. Lithostratigraphy Lithostratigraphy

841-549: The study of biostratigraphy . Igneous layers occur as stacks of lava flows, layers of lava fragments (called tephra ) both erupted onto the Earth's surface by volcanoes, and in layered intrusions formed deep underground. Igneous layers are generally devoid of fossils and represent magmatic or volcanic activity that occurred during the geologic history of an area. There are a number of principles that are used to explain relationships between strata. When an igneous rock cuts across

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