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Panjal Traps
The Panjal Traps or the Tethyan Plume is a large igneous province (LIP) that erupted during the Early–Middle Permian in what is now north-western India. The Panjal Traps are associated with the opening of the Neo-Tethys Ocean, which resulted in the dispersal of the Cimmerian continental blocks from the north-eastern margin of Gondwana and possibly the break-up of this old and large continent. In the Zanskar- Spliti-Lahaul area (in the north-western Himalayas and south-east Ladakh) the -thick basalts of the Panjal Traps are mostly exposed as massive (terrestrial) lava flows, but also as (marine) pillow lavas and hyaloclastites. The Panjal Traps were first documented in 1824 and were eventually named by British geologist Richard Lydekker in 1883, but their origin, age, and relationship with surrounding and underlying rocks remained elusive for more than a century. They remained one of the most understudied LIPs before being properly dated to 289 Ma in 2011. Geological sett ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Panjal Traps
The Panjal Traps or the Tethyan Plume is a large igneous province (LIP) that erupted during the Early–Middle Permian in what is now north-western India. The Panjal Traps are associated with the opening of the Neo-Tethys Ocean, which resulted in the dispersal of the Cimmerian continental blocks from the north-eastern margin of Gondwana and possibly the break-up of this old and large continent. In the Zanskar- Spliti-Lahaul area (in the north-western Himalayas and south-east Ladakh) the -thick basalts of the Panjal Traps are mostly exposed as massive (terrestrial) lava flows, but also as (marine) pillow lavas and hyaloclastites. The Panjal Traps were first documented in 1824 and were eventually named by British geologist Richard Lydekker in 1883, but their origin, age, and relationship with surrounding and underlying rocks remained elusive for more than a century. They remained one of the most understudied LIPs before being properly dated to 289 Ma in 2011. Geological sett ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abor Hills
The Abor Hills is a region of Arunachal Pradesh in the far northeast of India, near the border with China. The hills are bordered by the Mishmi Hills and Miri Hills, and drained by the Dibang River, a tributary of the Brahmaputra. During the British Raj, the hills had a reputation as a troublesome area, and military expeditions were sent against the residents in the 1890s. The region was administered as the Abor Hills District from 1948, with headquarters at Pasighat, but later reorganized into the Lower Dibang Valley and Lohit districts. Colonial history The Abor Hills are a tract of country on the north-east frontier of India, which was occupied by an independent tribe, the Adi people, formerly called the Abors. It lays north of Lakhimpur district, in the province of eastern Bengal and Assam, and is bounded on the east by the Mishmi Hills and on the west by the Miri Hills, the villages of the tribe extending to the Dibang river. The term Abor is an Assamese word, signifyin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syncline
In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed smaller folds. Synclines are typically a downward fold (synform), termed a synformal syncline (i.e. a trough), but synclines that point upwards can be found when strata have been overturned and folded (an antiformal syncline). Characteristics On a geologic map, synclines are recognized as a sequence of rock layers, with the youngest at the fold's center or ''hinge'' and with a reverse sequence of the same rock layers on the opposite side of the hinge. If the fold pattern is circular or elongate, the structure is a basin. Folds typically form during crustal deformation as the result of compression that accompanies orogenic mountain building. Notable examples * Powder River Basin, Wyoming, US * Sideling Hill roadcut along Interstate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleozoic Era; the following Triassic Period belongs to the Mesozoic Era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia. The Permian witnessed the diversification of the two groups of amniotes, the synapsids and the sauropsids ( reptiles). The world at the time was dominated by the supercontinent Pangaea, which had formed due to the collision of Euramerica and Gondwana during the Carboniferous. Pangaea was surrounded by the superocean Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artinskian
In the geologic timescale, the Artinskian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Artinskian likely lasted between and million years ago (Ma) according to the most recent revision of the International Commission on Stratigraphy (ICS) in 2022. It was preceded by the Sakmarian and followed by the Kungurian. Stratigraphy The Artinskian is named after the small Russian city of Arti (formerly ''Artinsk''), situated in the southern Ural mountains, about 200 km southwest of Yekaterinburg. The stage was introduced into scientific literature by Alexander Karpinsky in 1874. Base of the Artinskian The base of the Artinskian Stage is defined as the first appearance datum (FAD) of the conodont species '' Sweetognathus whitei'' and ''Mesogondolella bisselli''. In order to constrain this age, the ICS subcommission on Permian stratigraphy informally proposed a candidate GSSP in 2002, later followed by a formal proposal in 201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bhote Koshi
Bhote Koshi in Nepal and Poiqu in Tibet, both names roughly mean "Tibetan river," is the name given to the upper course (main tributary) of the Sun Kosi river. It is part of the Koshi River system in Nepal.Shrestha, A. B., Eriksson, M., Mool, P., Ghimire, P., Mishra, B., & Khanal, N. R. (2010). Glacial lake outburst flood risk assessment of Sun Koshi basin, Nepal. Geomatics, Natural Hazards and Risk 1(2): 157–169. Names and etymology ''Bhotekoshi'' is the Nepalese name ( ne, भोटे कोशी, translit=Bhōṭē kōśī). In Nepali language, the word "bhoṭe" or "bhoṭiyā" means Tibetan; and the word "kosi" means river. As such the name is not unique, the western tributary of the upper Dudh Koshi is also called Bhote Koshi. ''Poiqu'' () is the common name for the river on the Chinese side. It is also transliterated as Boqu via Chinese (). and as Po Chu by early 1990s Everest expeditions. This name means "River of Tibet." This is not a unique name, as it is also a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spilite
Spilite (from el, σπιλάς) is a fine-grained igneous rock, resulting particularly from alteration of oceanic basalt. The term was introduced into the geological literature by Alexandre Brongniart in 1827.Manfred Schidlowski: ''Spilite and the basal tables volcanism''. Natural sciences, Bd. 56, No. 10, P. 488-493, Springer publishing house, Berlin/Heidelberg 1969, ISSN 0028-1042 Spilite is formed when basaltic lava reacts with seawater, or from hydrothermal alteration when seawater circulates through hot volcanic rocks.Monica Price, Kevin Walsh, ''Pocket Nature, Rocks and Minerals'', page 63. Dorling Kindersley. It is a metasomatic rock with a microscopic or very-fine grain size produced by hydrothermal alteration of basalt, and composed of albite or oligoclase, together with chlorite, epidote, calcite, and actinolite.''McGraw-Hill encyclopedia of the geological sciences'', page 793 Spilite is veined by calcite or chalcedony, and vesicle Vesicle may refer to: ; In cellu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tholeiitic Basalt
The tholeiitic magma series is one of two main magma series in subalkaline igneous rocks, the other being the calc-alkaline series. A magma series is a chemically distinct range of magma compositions that describes the evolution of a mafic magma into a more evolved, silica rich end member. Rock types of the tholeiitic magma series include tholeiitic basalt, ferro-basalt, tholeiitic basaltic andesite, tholeiitic andesite, dacite and rhyolite. The variety of basalt in the series was originally called ''tholeiite'' but the International Union of Geological Sciences recommends that ''tholeiitic basalt'' be used in preference to that term.Le Maitre ''et al.'' 2002 Tholeiitic rock types tend to be more enriched in iron and less enriched in aluminium than calc-alkaline rock types. They are thought to form in a less oxidized environment than calc-alkaline rocks. Tholeiitic basalt is formed at mid-ocean ridges and makes up much of the oceanic crust. Almost all the basalt found on the Moon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Roadian
In the geologic timescale, the Roadian is an age or stage of the Permian. It is the earliest or lower of three subdivisions of the Guadalupian Epoch or Series. The Roadian lasted between and million years ago (Ma). It was preceded by the Kungurian and followed by the Wordian. Stratigraphy In 1961, the regional timescale used for the southeastern US had the Wordian and Capitanian as subdivisions of the Guadalupian. Efforts to correlate the Permian stratigraphy of the southeastern US with that of Russia led to the conclusion that between the Wordian stage and the Russian Artinskian stage, another stage needed to be introduced. This stage, the Roadian Stage, was established in 1968 and took its name from the Road Canyon Formation in Brewster County, Texas, formerly considered the lower (oldest) part of the Word Formation. The stage was added to the internationally used IUGS timescale in 2001.; 1999: ''Proposal of Guadalupian and Component Roadian, Wordian and Capitanian Stages a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sakmarian
In the geologic timescale, the Sakmarian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Sakmarian lasted between 293.52 and million years ago (Ma). It was preceded by the Asselian and followed by the Artinskian.; 2004: ''A Geologic Time Scale 2004'', Cambridge University Press Stratigraphy The Sakmarian Stage is named after the Sakmara River in the Ural Mountains, a tributary to the Ural River. The stage was introduced into scientific literature by Alexander Karpinsky in 1874. In Russian stratigraphy, it originally formed a substage of the Artinskian Stage. Currently, the ICS uses it as an independent stage in its international geologic timescale. The base of the Sakmarian Stage is laid with the first appearance of conodont species ''Streptognathodus postfusus'' in the fossil record. A global reference profile for the base (a GSSP), located in the southern Ural Mountains, Russia, was ratified in 2018. The top of the Sakmarian (the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lopingian
The Lopingian is the uppermost series/last epoch of the Permian. It is the last epoch of the Paleozoic. The Lopingian was preceded by the Guadalupian and followed by the Early Triassic. The Lopingian is often synonymous with the informal terms late Permian or upper Permian. The name was introduced by Amadeus William Grabau in 1931 and derives from Leping, Jiangxi in China. It consists of two stages/ ages. The earlier is the Wuchiapingian and the later is the Changhsingian. The International Chronostratigraphic Chart (v2018/07) provides a numerical age of 259.1 ±0.5 Ma. If a Global Boundary Stratotype Section and Point (GSSP) has been approved, the lower boundary of the earliest stage determines numerical age of an epoch. The GSSP for the Wuchiapingian has a numerical age of 259.8 ± 0.4 Ma. Evidence from Milankovitch cycles suggests that the length of an Earth day during this epoch was approximately 22 hours. The Lopingian ended with the Permian–Triassic extinction event. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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