| 词条 | Darriwilian | ||||||||||||||||||||||||||||||||
| 释义 |
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 {{Period start|Darriwilian}} million years ago. It lasted for about 8.9 million years until the beginning of the Sandbian around {{Period start|Sandbian}} million years ago.[1] NamingThe name Darriwilian is derived from Darriwil, a parish in County of Grant, Victoria (Australia). The name was proposed in 1899 by Thomas Sergeant Hall.[2] GSSP{{Location map | China | width = | float = | border = | caption = Map of China showing the GSSP location.| alt = | relief = China edcp relief location map.jpg| AlternativeMap = | label = Huangnitang Section| label_size = | position = | background = | mark = | marksize = | link = | lat_deg = 28.8539| lon_deg = 118.4897}}The GSSP of the Darriwilian is the Huangnitang Section ({{Coord|28.8539|N|118.4897|E|display=inline}}) 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 species Undulograptus austrodentatus in that section.[3] A Secondary fossil marker is the graptolite Arienigraptus zhejiangensis.[3] BiostratigraphyThe base of the Darriwilian is also the base of the Undulograptus austrodentatus graptolite zone. This zone lies just above the North Atlantic Microzarkodina parva conodont zone. The base also lies in the upper part of the North American Histiodella altifrons conodont zone.[3] The Undulograptus austrodentatus graptolite zone is known from outcrops around the world, making the base of the Darriwilian easily correlatable.[4] Regional stagesThe Darriwilian overlaps with the upper Arenig and the Llanvirn.[5] The base of the Darriwilian can be correlated with a level in the Fennian stage of the Arenig.[3] PalaeontologyAgnathans
MolluscsCephalopodsEndocerids
References1. ^{{cite web|title=GSSP Table - Paleozoic Era|url=https://engineering.purdue.edu/Stratigraphy/gssp/index.php?parentid=77|publisher=Geologic Timescale Foundation|accessdate=30 November 2012}} {{Geological history|p|p|state=collapsed}}2. ^[https://www.mindat.org/geotime.php?t=129 Mindat.org] 3. ^1 2 3 {{cite web|title=GSSP for Darriwilian Stage|url=https://engineering.purdue.edu/Stratigraphy/gssp/detail.php?periodid=137&top_parentid=77|publisher=Geologic Timescale Foundation|accessdate=30 November 2012}} 4. ^{{cite journal|last=Mitchell|first=C. E.|author2=Chen Xu|author3=S. M. Bergström|author4=Zhang Yuan-dong|author5=Wang Zhi-hao|author6=B. D. Webby|author7=S. C. Finney|title=Definition of a global boundary stratotype for the Darriwilian Stage of the Ordovician System|journal=Episodes|year=1997|volume=20|issue=3|pages=158–166|url=http://www.stratigraphy.org/GSSP/file39.pdf|accessdate=20 September 2012}}{{dead link|date=September 2017 |bot=InternetArchiveBot |fix-attempted=yes }} 5. ^{{cite book|title=The Geologic Time Scale 2012|year=2012|publisher=Elsevier Science Ltd|isbn=978-0444594259|pages=1176|url=https://books.google.com/books?hl=en&id=usoqlA8AVDUC&q=504#v=snippet&q=504&f=false|editor=Gradstein, F. M.|accessdate=30 November 2012}} 3 : Darriwilian|Middle Ordovician|Ordovician geochronology |
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