|
Dapingian
The Dapingian is the third stage of the Ordovician system and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The base of the Dapingian (and the top of the Floian) is defined as the first appearance of the conodont species '' Baltoniodus triangularis'' which happened about million years ago. The Dapingian lasted for about 1.9 million years until about million years ago. History The Ordovician was divided into three series and six global stages in 1995. Although at the time of 2005 GSSPs for the overlying Darriwilian and underlying " second stage" had already been ratified, definition of a GSSP for the first stage of the Middle Ordovician Series caused difficulties due to the deficiencies of the selected biohorizon and section. The Dapingian was the last Ordovician stage to be ratified, and was initially referred to as an informal and unnamed "third stage" corresponding to the early part of the Middle Ordovician. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Megaannum, Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era, and the second of twelve periods of the Phanerozoic Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Floian
The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician series. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from to million years ago. The lower boundary is defined as the first appearance of the graptolite species '' Tetragraptus approximatus''. History and naming The base of this stage was ratified by the International Commission on Stratigraphy (ICS) in 2002. The Floian Stage is named after Flo, a village in Västergötland, southern Sweden. The name "Floan" was proposed in 2004, but the ICS adapted Floian as the official name of the stage. GSSP The GSSP of the Floian is the lower Tøyen Shale in Diabasbrottet Quarry () which is an outcrop of a shale-dominated stratigraphic succession. The lower boundary of the Floian is defined as the first appearance of '' Tetragraptus approximatus'' which is about 2.1 above the Cambrian strata. Radiometric dating has set the Tremad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huanghuachang
Huanghuachang () is a village in Huanghua, Yiling, Yichang, Hubei, China. An outcrop of sedimentary rock from the Ordovician has made Huanghuachang famous in the earth science community. The "Huanghuachang section" () is an outcrop of the Dawan Formation in which the official base of the Dapingian The Dapingian is the third stage of the Ordovician system and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The base of the Dapingian (and the top of the Floian) is defined as t ... stage is defined. (Daping is a settlement near to Huanghuachang). References Geography of Yichang Village-level divisions of Hubei {{Hubei-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baltoniodus Triangularis
''Baltoniodus'' is an extinct genus of conodonts. Use in stratigraphy The base of the Dapingian, the first stage of the Middle Ordovician, is defined as the first appearance of ''Baltoniodus triangularis''. The Whiterock Stage refers mainly to the early Middle Ordovician in North America, it is often used in the older literature in a global sense. The Whiterock Stage is given a range from 471.8 (ca. 472) to 462 m.y.a., spanning close to 10 million years. Officially its start is defined by the potentially lowest occurrence of the conodont '' Protoprioniodus aranda'' or ''Baltoniodus triangularis''. ''B. gerdae'' has been found in the early Sandbian Bromide Formation The Bromide Formation is a formation (stratigraphy), geological formation in Oklahoma, USA. It is well known for its diverse echinoderm and trilobite fossil fauna. Location The Bromide Formation crops out in the Arbuckle Mountains, Arbuckle a ..., in Oklahoma, USA. References External links * Pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GSSP
A Global Boundary Stratotype Section and Point (GSSP), sometimes referred to as a golden spike, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. Most, but not all, GSSPs are based on paleontological changes. Hence GSSPs are usually described in terms of transitions between different faunal stages, though far more faunal stages have been described than GSSPs. The GSSP definition effort commenced in 1977. As of 2024, 79 of the 101 stages that need a GSSP have a ratified GSSP. Rules A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the ICS. The following list summarizes the criteria: * A GSSP has to define the lower boundary of a geologic stage. * The lower boundary has to be defined using a primary m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Darriwilian
The Darriwilian is the upper stage of the Middle Ordovician. It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species ''Undulograptus austrodentatus'' around million years ago. It lasted for about 10.8 million years until the beginning of the Sandbian around million years ago. This stage of the Ordovician was marked by the beginning of the Andean-Saharan glaciation. Naming The name Darriwilian is derived from Darriwil, a parish in County of Grant, Victoria (Australia). The name was proposed in 1899 by Thomas Sergeant Hall. GSSP The GSSP of the Darriwilian is the Huangnitang Section () near the village Huangnitang, 3.5 km southwest of Changshan County Town (Zhejiang, China). It is an outcrop of the Ningkuo Formation, consisting of mainly black shale. The lower boundary of the Darriwilian is defined as the first appearance datum of the graptolite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arenig
In geology, the Arenig (or Arenigian) is a time interval during the Ordovician period and also the suite of rocks which were deposited during this interval. History The term was first used by Adam Sedgwick in 1847 with reference to the "Arenig Ashes and Porphyries" in the neighbourhood of Arenig Fawr, in Merioneth, North Wales. The rock-succession in the Arenig district has been recognized by W. G. Fearnsides (“On the Geology of Arenig Fawr and Moel Llanfnant", Q.J.G.S. vol. lxi., 1905, pp. 608–640, with maps). The above succession is divisible into: # A lower series of gritty and calcareous sediments, the "Arenig Series" as it is now understood; # A middle series, mainly volcanic, with shale, the "Llandeilo Series"; and # The shale and limestones of the Bala or Caradoc Stage. It was to the middle series (2) that Sedgwick first applied the term "Arenig". In the typical region and in North Wales generally the Arenig series appears to be unconformable upon the Camb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argentina
Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourth-largest country in the Americas, and the List of countries and dependencies by area, eighth-largest country in the world. Argentina shares the bulk of the Southern Cone with Chile to the west, and is also bordered by Bolivia and Paraguay to the north, Brazil to the northeast, Uruguay and the South Atlantic Ocean to the east, and the Drake Passage to the south. Argentina is a Federation, federal state subdivided into twenty-three Provinces of Argentina, provinces, and one autonomous city, which is the federal capital and List of cities in Argentina by population, largest city of the nation, Buenos Aires. The provinces and the capital have their own constitutions, but exist under a Federalism, federal system. Argentina claims sovereignty ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protoprioniodus
''Protoprioniodus'' is an extinct genus of conodont Conodonts, are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (''kōnos''), meaning " cone", and ὀδούς (''odoús''), meaning "tooth"). They are primarily known from their hard ...s. Use in stratigraphy The Whiterock Stage refers mainly to the early Middle Ordovician in North America. It is often used in the older literature in a global sense. The Whiterock Stage is given a range from 471.8 (ca. 472) to 462 m.y.a., spanning close to 10 million years. Officially its start is defined by the potentially lowest occurrence of the conodonts ''Protoprioniodus aranda'' or '' Baltoniodus triangularis''. References External links * * Prioniodontida genera Ordovician conodonts {{conodont-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
International Commission On Stratigraphy
The International Commission on Stratigraphy (ICS), sometimes unofficially referred to as the International Stratigraphic Commission, is a daughter or major subcommittee grade scientific organization that concerns itself with stratigraphy, stratigraphical, geology, geological, and chronology, geochronological matters, worldwide. It is the largest subordinate body of the International Union of Geological Sciences (IUGS). The ICS is essentially a permanent working committee, working subcommittee, which meets far more regularly than the quadrennial meetings scheduled by the IUGS, when it meets as a congress or committee, membership of the whole. Aims One of its main aims, a project begun in 1974, is to establish a multidisciplinary standard and global geologic time scale that will ease paleontology, paleontological and geobiology, geobiological comparisons region to region by benchmarks with stringent and rigorous strata criteria called Global Boundary Stratotype Section and Points ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chitinozoan
Chitinozoa (singular: chitinozoan, plural: chitinozoans) are a group of flask-shaped, organic walled marine microfossils produced by an as yet unknown organism. Common from the Ordovician to Devonian periods (i.e. the mid-Paleozoic), the millimetre-scale organisms are abundant in almost all types of marine sediment across the globe. This wide distribution, and their rapid pace of evolution, makes them valuable biostratigraphic markers. Their bizarre form has made classification and ecological reconstruction difficult. Since their discovery in 1931, suggestions of protist, plant, and fungal affinities have all been entertained. The organisms have been better understood as improvements in microscopy facilitated the study of their fine structure, and it has been suggested that they represent either the eggs or juvenile stage of a marine animal. However, recent research has alternatively suggested that they represent the test of a group of protists with uncertain affinities. Chitin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
