Wikipedia

Darriwilian

(Redirected from Llanvirnian)

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 467.3 million years ago. It lasted for about 8.9 million years until the beginning of the Sandbian around 458.4 million years ago.[7] This stage of the Ordovician was marked by the beginning of the Andean-Saharan glaciation.[8]

Darriwilian
467.3 ± 1.1 – 458.4 ± 0.9 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionFAD of the Graptolite Undulograptus austrodentatus
Lower boundary GSSPHuangnitang Section, Huangnitang Village, Changshan, Zhejiang, China
28°51′14″N 118°29′23″E / 28.8539°N 118.4897°E / 28.8539; 118.4897
Lower GSSP ratified1997[5]
Upper boundary definitionFAD of the Graptolite Nemagraptus gracilis
Upper boundary GSSPFågelsång section, Sularp Brook, Skåne, Sweden
55°42′49″N 13°19′32″E / 55.7137°N 13.3255°E / 55.7137; 13.3255
Upper GSSP ratified2002[6]

Naming

edit

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.[9][10]

GSSP

edit
 
 
Huangnitang Section
class=notpageimage|
Map of China showing the GSSP location.

The GSSP of the Darriwilian is the Huangnitang Section (28°51′14″N 118°29′23″E / 28.8539°N 118.4897°E / 28.8539; 118.4897)[11] 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.[12]

A secondary fossil marker is the graptolite Arienigraptus zhejiangensis.[12]

Biostratigraphy

edit

The 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.[12]

The Undulograptus austrodentatus graptolite zone is known from outcrops around the world, making the base of the Darriwilian easily correlatable.[10]

Regional stages

edit

The Darriwilian overlaps with the upper Arenig and the Llanvirn.[13] The base of the Darriwilian can be correlated with a level in the Fennian stage of the Arenig.[12]

References

edit
  1. ^ Wellman, C.H.; Gray, J. (2000). "The microfossil record of early land plants". Phil. Trans. R. Soc. B. 355 (1398): 717–732. doi:10.1098/rstb.2000.0612. PMC 1692785. PMID 10905606.
  2. ^ Korochantseva, Ekaterina; Trieloff, Mario; Lorenz, Cyrill; Buykin, Alexey; Ivanova, Marina; Schwarz, Winfried; Hopp, Jens; Jessberger, Elmar (2007). "L-chondrite asteroid breakup tied to Ordovician meteorite shower by multiple isochron 40 Ar- 39 Ar dating". Meteoritics & Planetary Science. 42 (1): 113–130. Bibcode:2007M&PS...42..113K. doi:10.1111/j.1945-5100.2007.tb00221.x.
  3. ^ Lindskog, A.; Costa, M. M.; Rasmussen, C.M.Ø.; Connelly, J. N.; Eriksson, M. E. (2017-01-24). "Refined Ordovician timescale reveals no link between asteroid breakup and biodiversification". Nature Communications. 8: 14066. doi:10.1038/ncomms14066. ISSN 2041-1723. PMC 5286199. PMID 28117834. It has been suggested that the Middle Ordovician meteorite bombardment played a crucial role in the Great Ordovician Biodiversification Event, but this study shows that the two phenomena were unrelated
  4. ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. September 2023. Retrieved November 10, 2024.
  5. ^ Mitchell, C.; Xu, Chen; Yuan-dong, Zhang; ZhI-hao, Wang; Webby, B.; Finney, S. (September 1997). "Definition of a global boundary stratotype for the Darriwilian Stage of the Ordovician System". Episodes. 20 (3): 158–166. doi:10.18814/epiiugs/1997/v20i3/003. Retrieved 13 December 2020.
  6. ^ Bergström, Stig; Finney, S.; Xu, Chen; Pålsson, Christian; Zhi-hao, Wang; Grahn, Yngve (June 2000). "A proposed global boundary stratotype for the base of the Upper Series of the Ordovician System: The Fågelsång section, Scania, southern Sweden". Episodes. 23 (2): 102–109. doi:10.18814/epiiugs/2000/v23i2/003. Retrieved 13 December 2020.
  7. ^ "GSSP Table - Paleozoic Era". Geologic Timescale Foundation. Retrieved 30 November 2012.
  8. ^ Pohl, Alexandre; Donnadieu, Yannick; Le Hir, Guillaume; Ladant, Jean-Baptiste; Dumas, Christophe; Alvarez-Solas, Jorge; Vandenbroucke, Thijs R. A. (28 May 2016). "Glacial onset predated Late Ordovician climate cooling". Paleoceanography and Paleoclimatology. 31 (6): 800–821. doi:10.1002/2016PA002928. hdl:1854/LU-8057556. S2CID 133243759.
  9. ^ "Darriwilian". Mindat.org. Archived from the original on 2020-11-06.
  10. ^ a b Mitchell, C. E.; Chen Xu; S. M. Bergström; Zhang Yuan-dong; Wang Zhi-hao; B. D. Webby; S. C. Finney (1997). "Definition of a global boundary stratotype for the Darriwilian Stage of the Ordovician System". Episodes. 20 (3): 158–166. doi:10.18814/epiiugs/1997/v20i3/003.
  11. ^ David A. T. Harper; Tõnu Meidla; Thomas Servais (May 10, 2023). "A short history of the Ordovician System: from overlapping unit stratotypes to global stratotype sections and points". Geological Society, London, Special Publications. 532 (1). The Geological Society of London: 13–30. Bibcode:2023GSLSP.532..285H. doi:10.1144/SP532-2022-285. Archived from the original on 2024-05-18.
  12. ^ a b c d "GSSP for Darriwilian Stage". Geologic Timescale Foundation. Retrieved 30 November 2012.
  13. ^ Gradstein, F. M., ed. (2012). The Geologic Time Scale 2012. Elsevier Science Ltd. p. 1176. ISBN 978-0444594259. Retrieved 30 November 2012.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Darriwilian&oldid=1231821181"