|
Guzhangian
The Guzhangian is an uppermost stage of the Miaolingian Series of the Cambrian. It follows the Drumian Stage and precedes the Paibian Stage of the Furongian Series. The base is defined as the first appearance of the trilobite ''Lejopyge laevigata'' around million years ago. The Guzhangian-Paibian boundary is marked by the first appearance of the trilobite ''Glyptagnostus reticulatus'' around million years ago. The name Guzhangian is derived from Guzhang County, Hunan Province, China. The GSSP is defined in the Huaqiao Formation in Hunan. The precise base of the Guzhangian is a limestone layer 121.3 m above the base Huaqiao Formation(花桥组) at the Louyixi section (), where ''Lejopyge laevigata ''Lejopyge laevigata'' is a species of agnostid trilobite belonging to the genus '' Lejopyge''. It existed during the Guzhangian to the Paibian Age (around to million years ago) of the Cambrian. It has a cosmopolitan distribution and is an ...'' has its first appearance. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guzhangian
The Guzhangian is an uppermost stage of the Miaolingian Series of the Cambrian. It follows the Drumian Stage and precedes the Paibian Stage of the Furongian Series. The base is defined as the first appearance of the trilobite ''Lejopyge laevigata'' around million years ago. The Guzhangian-Paibian boundary is marked by the first appearance of the trilobite ''Glyptagnostus reticulatus'' around million years ago. The name Guzhangian is derived from Guzhang County, Hunan Province, China. The GSSP is defined in the Huaqiao Formation in Hunan. The precise base of the Guzhangian is a limestone layer 121.3 m above the base Huaqiao Formation(花桥组) at the Louyixi section (), where ''Lejopyge laevigata ''Lejopyge laevigata'' is a species of agnostid trilobite belonging to the genus '' Lejopyge''. It existed during the Guzhangian to the Paibian Age (around to million years ago) of the Cambrian. It has a cosmopolitan distribution and is an ...'' has its first appearance. R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lejopyge Laevigata
''Lejopyge laevigata'' is a species of agnostid trilobite belonging to the genus '' Lejopyge''. It existed during the Guzhangian to the Paibian Age (around to million years ago) of the Cambrian. It has a cosmopolitan distribution and is an important index fossil in biostratigraphy. Description ''Lejopyge laevigata'' exhibits a cephalon and pygidium that are smooth and almost featureless ( effaced). Both possess axial furrows that gradually become shallower until they disappear distally. They surround the rear edges of the glabella (reaching about as far or a little past the basal glabellar lobes) and the anterior end of the central lobe of the pygidium. Basal furrows are also present. The genae ("cheeks") are usually smooth, but in extremely rare cases they may possess small pits (scrobicules) of moderate depth. The border around the pygidium is uniform in width at the back and narrows towards the front. Like all members of the suborder Agnostina, ''Lejopyge laeviga ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miaolingian
The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about to million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is preceded by the unnamed Cambrian Series 2 and succeeded by the Furongian series. Definition A number of proposals for fossils and type sections were made before it was formally ratified in 2018. The most promising fossil markers were seen to be the respective first appearances of either trilobite species ''Ovatoryctocara granulata'' or ''Oryctocephalus indicus'', which both have an age close to million years ago. After some deliberation, the FAD of ''Oryctocephalus indicus'' was chosen to be the lower boundary marker, and the GSSP was placed in Wuliu-Zengjiayan, Guizhou, China. The Miaolingian-Furongian boundary has the same definition as the Paibian Stage. It is defined as the first appearance of ''Glyptagnostus reticulatus ''Glyptagn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drumian
The Drumian is a stage of the Miaolingian Series of the Cambrian. It succeeds the Wuliuan and precedes the Guzhangian. The base is defined as the first appearance of the trilobite ''Ptychagnostus atavus'' around million years ago. The top is defined as the first appearance of another trilobite ''Lejopyge laevigata'' around million years ago. The GSSP is defined in the ''Drumian section'' () in the Drum Mountains, Millard County, Utah, United States. The stage was also named after the Drum Mountains. The section is an outcrop of the Wheeler Formation The Wheeler Shale (named by Charles Walcott) is a Cambrian ( 507 Ma) fossil locality world-famous for prolific agnostid and ''Elrathia kingii'' trilobite remains (even though many areas are barren of fossils) and represents a Konzent ..., a succession of calcareous shales. The precise base of the Drumian is a laminated limestone above the base of the Wheeler Formation. References Cambrian geochronology Geo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guzhang County
Guzhang County () is a county of Hunan Province, China. The county is the 2nd least populous administrative unit of the counties or county-level cities (after Shaoshan City) in the province, it is under the administration of Xiangxi Autonomous Prefecture. Located in the northwest of Hunan and in the east of Xiangxi Prefecture, the county is bordered to the north by Yongshun County, to the east by Yuanling County, to the south by Luxi County and Jishou City, to the west by Baojing County. Guzhang County covers , as of 2015, It had a registered population of 143,182 and a resident population of 131,900.about the population of Guzhang County in 2015, according to the Statistical Communiqué of Guzhang County on the 2015 National Economic and Social Development - ()guzhang.gov.cno/ref> The county has 7 towns under its jurisdiction, the county seat is Guyang ().the divisions of Guzhang County in 2015, according to the result on adjustment of township-level administrative divisions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Furongian
The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into three stages: the Paibian, Jiangshanian and the unnamed 10th stage of the Cambrian. Naming The Furongian was also known as the Cambrian Series 4, and the name replaced the older term Upper Cambrian and equivalent to the local term Hunanian. The present name was ratified by the International Commission on Stratigraphy in 2003. () means ' lotus' in Mandarin and refers to Hunan which is known as the "lotus state". Definition The lower boundary is defined in the same way as the GSSP of the Paibian Stage. Both begin with the first appearance of the trilobite ''Glyptagnostus reticulatus'' around million years ago. The upper boundary is the lower boundary and GSSP of the Tremadocian Stage which is the first appearance of the conodont ''Iapetognathus f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Ages
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardized international units of geologic time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precisely define gl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guzhang
Guzhang County () is a county of Hunan Province, China. The county is the 2nd least populous administrative unit of the counties or county-level cities (after Shaoshan City) in the province, it is under the administration of Xiangxi Autonomous Prefecture. Located in the northwest of Hunan and in the east of Xiangxi Prefecture, the county is bordered to the north by Yongshun County, to the east by Yuanling County, to the south by Luxi County and Jishou City, to the west by Baojing County. Guzhang County covers , as of 2015, It had a registered population of 143,182 and a resident population of 131,900.about the population of Guzhang County in 2015, according to the Statistical Communiqué of Guzhang County on the 2015 National Economic and Social Development - ()guzhang.gov.cno/ref> The county has 7 towns under its jurisdiction, the county seat is Guyang ().the divisions of Guzhang County in 2015, according to the result on adjustment of township-level administrative divisions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paibian
The Paibian is the lowest stage of Furongian series of the Cambrian. It follows the Guzhangian ( 3rd series of the Cambrian) and is succeeded by the Jiangshanian Stage. The base is defined as the first appearance of the trilobite ''Glyptagnostus reticulatus'' around million years ago. The top, or the base of the Jiangshanian is defined as the first appearance of the trilobite ''Agnostotes orientalis'' around million years ago. The name is derived from Paibi, a village in Hunan, China. The GSSP is defined in the "Paibi section" (Wuling Mountains, Huayuan County), an outcrop of the Huaqiao Formation(花桥组). The base is the first occurrence of ''Glyptagnostus reticulatus'' which is 396 m above the base of the Huaqiao Formation Huaqiao may refer to: *Overseas Chinese (华侨), or Huaqiao in pinyin *Huaqiao University (华侨大学), in Quanzhou, Fujian *Huaqiao railway station (花桥站), station of the Shanghai-Nanjing Intercity High-Speed Railway in Shanghai *Huaqiao s ... at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GSSP
A Global Boundary Stratotype Section and Point (GSSP) 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 2022, 77 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 marker (usually first appearance datum of a fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Louyixi
Luoyixi Town () is a Town in Guzhang County of China's Hunan Province. It is located on a bay of the Fengtan Reservoir (formerly, a southern tributary of the You River). As of the census of 2010, it has a total population of 10,000. Hongshilin (红石林, "Red Stone Forest") National Geopark is located on the reservoir's bank northeast of town (). The Luoyixi Global boundary Stratotype Section and Point is named after the town. The actual point is on the shore of the Fengtan Reservoir, some 4 km northwest (upstream) from Luoyixi Town, halfway to the neighboring Wangcun Town. Shanchi Peng, Loren E. Babcock Dr. Loren E. Babcock (born May 26, 1961) is an American geologist. He is professor of Earth Science at Ohio State University. Babcock has written over 125 scientific articles and the textbook, ''Visualizing Earth History''. He researches topics in ..., Jingxun Zuo1, Huanling Lin1, Xuejian Zhu1, Xianfeng Yang1, Richard A. Robison, Yuping Qi1, Gabriella Bagnoli, and Yon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glyptagnostus Reticulatus
''Glyptagnostus reticulatus'' is a species of agnostid trilobite belonging to the genus '' Glyptagnostus''. It existed during the Paibian Age ( million years ago) of the Cambrian. It has a cosmopolitan distribution and is an important index fossil in biostratigraphy. It was characterized by an unusual net-like pattern of furrows on both the cephalon and the pygidium. Description Like all members of the suborder Agnostida, ''Glyptagnostus reticulatus'' is completely blind and only has two thoracic segments. The cephalon and pygidium are more or less the same size and shape ( isopygous). The glabella of the cephalon has two lobes. The front lobe is roughly squarish in shape, while the rear lobe is elongated and split along the middle. The cephalon has a narrow well-defined border. The pygidium has a long tapering central axis which can be divided into three lobes. The axis is connected to the rear margin by a central furrow. At both sides of the axis are a row of four or more pi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.png "Click for more on -> Glyptagnostus Reticulatus")