Cambrian Stage 10 | ||||||||||||||||||||||||||||||||||||||
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Chronology | ||||||||||||||||||||||||||||||||||||||
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Etymology | ||||||||||||||||||||||||||||||||||||||
Name formality | Informal | |||||||||||||||||||||||||||||||||||||
Usage information | ||||||||||||||||||||||||||||||||||||||
Celestial body | Earth | |||||||||||||||||||||||||||||||||||||
Regional usage | Global (ICS) | |||||||||||||||||||||||||||||||||||||
Time scale(s) used | ICS Time Scale | |||||||||||||||||||||||||||||||||||||
Definition | ||||||||||||||||||||||||||||||||||||||
Chronological unit | Age | |||||||||||||||||||||||||||||||||||||
Stratigraphic unit | Stage | |||||||||||||||||||||||||||||||||||||
Time span formality | Formal | |||||||||||||||||||||||||||||||||||||
Lower boundary definition | Not formally defined | |||||||||||||||||||||||||||||||||||||
Lower boundary definition candidates | FAD of the Trilobite Lotagnostus americanus | |||||||||||||||||||||||||||||||||||||
Lower boundary GSSP candidate section(s) | Duibian, Zhejiang, China | |||||||||||||||||||||||||||||||||||||
Upper boundary definition | FAD of the Conodont Iapetognathus fluctivagus . | |||||||||||||||||||||||||||||||||||||
Upper boundary GSSP | Greenpoint section, Green Point, Newfoundland, Canada 49°40′58″N57°57′55″W / 49.6829°N 57.9653°W | |||||||||||||||||||||||||||||||||||||
Upper GSSP ratified | 2000 [2] |
Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. [3] It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. [4] The proposed lower boundary is the first appearance of the trilobite Lotagnostus americanus around 489.5 million years ago, but other fossils are also being discussed (see below). The upper boundary is defined as the appearance of the conodont Iapetognathus fluctivagus which marks the beginning of the Tremadocian and is radiometrically dated as 485.4 million years ago. [5]
The 10th stage of the Cambrian has not been formally named by the ICS yet, [3] although a number of local names exist. Several authors favor the name "Lawsonian" after Lawson Cove, in the Wah Wah Mountains of Utah. [6] [7] The lower part of the North American Skullrockian Stage corresponds roughly to the Cambrian Stage 10. [8] The name "Nelegerian", after the Neleger River in Yakutia, was also proposed in 2011. [9]
The ICS is still discussing which geological section and biostratigraphic marker will be used to define the base of the 10th Cambrian stage. [10] [11]
Likely candidates for the section are still investigated. A first proposal was a section near Duibian, Zhejiang province (China). Note recent publications favor Steamboat Pass in the House Range of Utah. If a conodont is used for the base the stage then many more sections would be likely candidates for the GSSP, e.g. in Australia, Kazakhstan and Canada. [6]
Candidates for the biostratigraphic marker are the first appearance of a trilobite or conodont species. The trilobite Lotagnostus americanus was first suggested by the ICS, but has proven to be problematic. [6] [12] In 2006 another working group proposed the first appearance of Cordylodus andresi . [13] The first appearance of Eoconodontus notchpeakensis is favored by many authors because it is globally widespread and is independent of facies (known from continental rise to peritidal environments). [6]
The Eoconodontus notchpeakensis proposal would also incorporate a non-biostratigraphic marker to correlate the beginning of stage 10 globally. A carbon isotope excursion (the HERB-event) occurs in the lower part of the E. notchpeakensis range. [6]
Cambrian Stage 10 can be subdivided using different biostratigraphic zones. Several conodont zone and subzones can be distinguished. The same is true for trilobites. [6]
The Early Ordovician is the first epoch of the Ordovician period, corresponding to the Lower Ordovician series of the Ordovician system. It began after the Age 10 of the Furongian epoch of the Cambrian and lasted from 485.4 ± 1.9 to 470 ± 1.4 million years ago, until the Dapingian age of the Middle Ordovician. It includes Tremadocian and Floian ages.
First appearance datum (FAD) is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. FADs are determined by identifying the geologically oldest fossil discovered, to date, of a particular species. A related term is last appearance datum (LAD), the last appearance of a species in the geologic record.
The Tremadocian is the lowest stage of Ordovician. Together with the later Floian Stage it forms the Lower Ordovician Epoch. The Tremadocian lasted from 485.4 to 477.7 million years ago. The base of the Tremadocian is defined as the first appearance of the conodont species Iapetognathus fluctivagus at the Global Boundary Stratotype Section and Point (GSSP) section on Newfoundland.
The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from 497 to 485.4 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.
The Famennian is the later of two faunal stages in the Late Devonian epoch. The most recent estimate for its duration is that it lasted from around 371.1 to 359.3 million years ago. An earlier 2012 estimate, still used by the International Commission on Stratigraphy, is that it lasted from 372.2 million years ago to 358.9 million years ago. It was preceded by the Frasnian stage and followed by the Tournaisian stage.
Paibi, a village in Paibi Township, Huayuan County, Xiangxi Tujia and Miao Autonomous Prefecture Hunan, China, is the location of the Global Boundary Stratotype Section and Point (GSSP) which marks the boundary between the third and Furongian epochs of the Cambrian Period on the geologic time scale. Paibi was selected over the Kyrshabakty River section, Malyi Karatau, Kazakhstan, and the GSSP was ratified by the International Union of Geological Sciences in late 2003. It established the first formally agreed upon subdivision of the Cambrian. The village gives its name to the Paibian Age in the Cambrian Period.
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 477.7 to 470 million years ago. The lower boundary is defined as the first appearance of the graptolite species Tetragraptus approximatus.
The Dapingian is the third stage of the Ordovician period 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 is defined as the first appearance of the conodont species Baltoniodus triangularis which happened about 470 million years ago. The Dapingian lasted for about 2.7 million years until about 467.3 million years ago.
Lotagnostus is a genus of very small trilobites in the order Agnostida, which lived on the outer continental shelves worldwide, during the late Upper Cambrian. It was described by Whitehouse in 1936, and the type species is Lotagnostus trisectus, which was originally described as a species of Agnostus by Salter in 1864.
The Terreneuvian is the lowermost and oldest series of the Cambrian geological system. Its base is defined by the first appearance datum of the trace fossil Treptichnus pedum around 538.8 million years ago. Its top is defined as the first appearance of trilobites in the stratigraphic record around 521 million years ago. This series' name was formally accepted by the International Commission on Stratigraphy in 2007.
The Jiangshanian is the middle stage of the Furongian series. It follows the Paibian Stage and is succeeded by the still unnamed Stage 10 of the Cambrian. The base is defined as the first appearance of the trilobite Agnostotes orientalis which is estimated to be 494 million years ago. The Jiangshanian lasted until approximately 489.5 million years ago.
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 500.5 million years ago. The Guzhangian-Paibian boundary is marked by the first appearance of the trilobite Glyptagnostus reticulatus around 497 million years ago.
The Wuliuan stage is the fifth stage of the Cambrian, and the first stage of the Miaolingian Series of the Cambrian. It was formally defined by the International Commission on Stratigraphy in 2018. Its base is defined by the first appearance of the trilobite species Oryctocephalus indicus; it ends with the beginning of the Drumian Stage, marked by the first appearance of the trilobite Ptychagnostus atavus around 504.5 million years ago.
Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commission on Stratigraphy. One proposal is the first appearance of two trilobite genera, Olenellus or Redlichia. Another proposal is the first appearance of the trilobite species Arthricocephalus chauveaui. Both proposals will set the lower boundary close to 514 million years ago. The upper boundary corresponds to the beginning of the Wuliuan.
Cambrian Series 2 is the unnamed 2nd series of the Cambrian. It lies above the Terreneuvian series and below the Miaolingian. Series 2 has not been formally defined by the International Commission on Stratigraphy, lacking a precise lower boundary and subdivision into stages. The proposed lower boundary is the first appearance of trilobites which is estimated to be around 521 million years ago.
Iapetognathus fluctivagus is a species of denticulate cordylodan conodonts belonging to the genus Iapetognathus. It existed during the Tremadocian Age of the Ordovician. It is an important index fossil in biostratigraphy.
Westergaardodina is a species-rich genus of spine, U or W-shaped paraconodont known from Middle Cambrian to Lower Ordovician strata.
Eoconodontus is an extinct genus of conodonts of the Late Cambrian. It is a two-elements genus from the Proconodontus lineage.
Conodonts are an extinct class of animals whose feeding apparatuses called teeth or elements are common microfossils found in strata dating from the Stage 10 of the Furongian, the fourth and final series of the Cambrian, to the Rhaetian stage of the Late Triassic. These elements can be used alternatively to or in correlation with other types of fossils in the subfield of the stratigraphy named biostratigraphy.
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