Perm (geology)

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< Carbon | P erm | Triassic >
298.9–251.9 million years ago
Atmospheric O 2 share
(average over period) 		approx. 23% by volume
(115% of today's level)
Atmospheric CO 2 share
(average over period) 		approx. 900 ppm
(2.25 times today's level)
Floor temperature (average over period) approx. 16 ° C
(1.5 ° C above today's level)
system series step ≈ age ( mya )
higher higher higher younger
Perm Lopingium Changhsingium 251.9
⬍
254.2
Wuchiapingium 254.2
⬍
259.9
Guadalupium Capitanium 259.9
⬍
265.1
Wordium 265.1
⬍
268.8
Roadium 268.8
⬍
272.3
Cisuralium Kungurium 272.3
⬍
279.3
Artinskium 279.3
⬍
290.1
Sacmarium 290.1
⬍
295.5
Asselium 295.5
⬍
298.9
deeper deeper deeper older

The Perm is on the geological time scale , the last system (or period in the Geochronologie ) in Paläozoikum . The Permian began about 298.9 million years ago and ended about 251.9 million years ago. The Permian follows the Carboniferous and is overlaid by the Triassic . The largest known mass extinction in geological history occurred at the Perm-Triassic border .

History and naming

The name Perm is derived from the former Russian Governorate of Perm (roughly equivalent to today's Perm region ) at the foot of the Ural Mountains . The rocks exposed here from this period served Roderick Murchison in 1841 as the basis for his scientific description. The Permian in Germany and Central Europe is essentially represented by the two lithostratigraphic groups of the Zechstein and the Rotliegend . After this dichotomy, this system was originally called Dyas in Germany , but it was not able to establish itself internationally. The term Dyas was primarily defined lithologically and is therefore also used today for a lithostratigraphic supergroup that includes Rotliegend and Zechstein.

Definition and GSSP

The beginning of the Permian (and the Asselium stage and the Cisuralium series) is defined by the first appearance of the conodont species Streptognathodus isolatus . The end of the Permian (and the beginning of the Triassic) is defined with the first appearance of the conodont species Hindeodus parvus and the end of the negative carbon anomaly of the Upper Permian . The type locality ( GSSP = Global Stratotype Section and Point) established by the IUGS for the base of the Permian (and the Asselium stage) is in the valley of the Aidaralash, near the city of Aqtöbe ( Russian Aktyubinsk ) in the southern Urals ( Kazakhstan ).

Subdivision of the Permian

The Perm was formerly mostly in Permian (299-270 million years ago) and Permian divided (270-251 million years ago), which would be called with today's terms as series. Today the Permian is divided into three series with a total of nine stages .

Paleogeography

The earth in the sacmarium, about 290 million years ago

After the collision of Sibiria with the major continents Gondwana and Laurussia , which were already united in the Carboniferous , the supercontinent Pangea reached its greatest extent in the Lower Permian with an area of ​​138 million km² (including the shelf bases ). A mountain building phase in which the Urals were unfolded was the result of this collision. In the equatorial area the Tethys opened like a wedge to the east . An arm of the sea in the west of the Tethys reached as far as the European land masses. Large rift systems and epicontinental basins formed in Europe, which were filled with rubble from the now largely eroded Variscan mountains and with volcanic rocks ( Rotliegend basin). The first signs of the incipient disintegration of Pangea can already be found from the Upper Permian.

Climate and environment

Permian Fossil Ripple Marks ( Lac du Salagou , France)

The permocarbone glaciation of the southern continents lasted well into the Permian and ended 265 to 260 million years ago in the Capitanium , with parts of what is now Australia apparently covered by ice caps the longest of all continental areas. In the temperate and cold zones of Gondwana, the Glossopteris flora, adapted to seasonal climatic fluctuations, grew up to high southern latitudes . During the Permian, many areas of the world had a dry and initially relatively cool climate , although temperatures often reached tropical values in the desert-like central areas of Pangea . The richest salt deposits in the history of the earth were formed during the Permian period.

After the end of the Permocarbon Ice Age , the trend towards a stable warm climate emerged , but this was interrupted by a major environmental change 260 million years ago. The decline in biodiversity in tropical waters, which has long been known in research and assessed differently in terms of extent, was, according to more recent findings, a global event that culminated in the mass extinction of Capitanium . A massive carbon dioxide and sulfur dioxide input into the oceans with the formation of anoxic zones and strong acidification of the sea water is assumed to be the cause. A direct connection with the simultaneously occurring flood basalts of the Emeishan Trapps in today's southern China is considered very likely in research. The differently pronounced activity cycles of the trap probably lasted almost two million years and during this time covered an area of ​​at least 250,000 km² with basaltic deposits. Although the extinction event primarily affected the marine fauna of all climatic zones, the biodiversity of terrestrial vertebrates also decreased significantly. It is believed that over 60 percent of the species and 33 to 35 percent of the genera died out during the Capitanium Crisis.

Towards the end of the Permian, on the border with the Triassic , there was a rapid climate change in geological terms with far-reaching consequences for the terrestrial biosphere . The main possible cause are large-scale volcanic activities in the area of ​​today's Siberia ( Siberian Trapp ), which lasted several hundred thousand years and covered seven million square kilometers, sometimes several kilometers thick, with basalt . There are several hypotheses about the trigger (s) of these sudden eruptions, and the involvement of a large meteorite impact is occasionally discussed in this context . By the end of the epoch, around 96 percent of all marine life and around 75 percent of land life, including many species of insects, had died out. The vegetation cover of the continents also thinned out significantly. Thus, during the Permian Triassic Crisis, probably the largest mass extinction in the history of the earth occurred .

More recent isotope studies indicate that in an initial warming phase, the average temperatures of the atmosphere rose by 5 ° C within a few millennia due to the increasing concentration of volcanic carbon dioxide. At the same time, the oceans warmed up to a considerable extent, which led to the formation of oxygen-free sea zones and the large-scale release of methane hydrate . As a result of the additional methane input, the temperature increased by a further 5 ° C in the next phase, and the oxygen content of the air fell to 16 percent or was temporarily even lower. Another possible cause for the collapse of almost all ecosystems is the proliferation of certain marine protozoa, which released their metabolic products into the atmosphere in the form of halogenated hydrocarbons , hydrogen sulfide or methane. The total duration of the mass extinction has until recently been given as 1 million to 200,000 years, while more recent research initially postulated a period of around 60,000 years. According to a study published in 2018, the extinction event took place within a maximum of 30,000 years, possibly limited to a few millennia, and could be assigned to the lowest Triassic 251.94 million years ago using precise dating methods.

Development of the fauna

Reconstructed scene from the older Middle Perm of Russia: the carnivore Ivantosaurus (right) meets a resting group of Estemmenosuchus ( left), both Therapsids of the Otschor fauna

Terrestrial vertebrates

Among the terrestrial vertebrates there was a first major radiation of the groups that are grouped under the name amniotes , and the amphibian-like groups that still predominated in the Carboniferous have largely lost this dominance. Many species-rich groups of reptile-like amniotes that appeared during the Permian disappeared again during the Permian or at the end of this period, e.g. B. the mesosaurs or the pareiasaurs .

The first therapsids appear in the Middle Permian , more modern forerunners of today's mammals , but at that time they were still relatively reptile-like. "Primitive" Therapsids of the Permian are known in Eurasia mainly from the eastern part of the Russian tablet or the western Ural foothills ("Pri-Ural") in Russia and from the Xidagou formation in China, whereby these finds reflect the variety of forms at that time Reflect the northern hemisphere. Forms of the former southern hemisphere (subcontinent Gondwana ) can be found today in the deposits of the Beaufort group in the South African Karoo and in sedimentary rocks of the Paraná basin in southern Brazil .

Marine invertebrates

Among the unicellular foraminifera , the large fusulins are important key forms. They disappeared at the end of the Permian, as well as to the coelenterates counting taboo laten coral . The arm pods went through one last great radiation . In the Permian, for example, coral-like shapes (compare with the rudists ) and shapes with slotted dorsal valves (oldhaminides) that entered into a symbiosis with photosynthesis-inducing bacteria. These specialized groups and some other groups (Productiden, Davidsoniiden and Spiriferiden) died out completely or largely. Among the arthropods, the trilobites and the Eurypterids became extinct. A number of insect orders could first be detected in the Permian. Among the molluscs , the class of the beaked scarf (Rostroconchia) disappeared . Among the cephalopods, the bactrites and the goniatites died out; the Ceratites arose. From the trunk of the echinoderms (Echinodermata), the bud rays (Blastoidea) and the sea ​​lily groups of the Camerata and Flexibilia died out.

Development of flora

Representation of a typical tongue-shaped leaf of the genus Glossopteris

The change from the Paleophytic to the Mesophytic took place earlier than the change from the Paleozoic to the Mesozoic. The paleophytic ended about 256 Ma ago in the Wuchiapingium . The previously dominant groups of ferns have been replaced by the more drought-resistant naked-seed plants (gymnosperms). The Glossopteris flora developed on the Gondwana continent , the representatives of which were deciduous, cold-tolerant gymnosperms with the predominant order Glossopteridales .

The Permian in Central Europe

In Germany, the traditional division of the Permian into Rotliegend and Zechstein results from the striking change that has taken place on the border between the two formations. After a long continental period, which began in the Carboniferous, about 257.3 million years ago a tropical shallow sea penetrated into northern and central Germany in what was probably a very brief transgression , which marked the beginning of the Zechstein Age. Only southern Germany initially remained mainland. The economically important copper shale was deposited at the base of the marine deposits . This geological mark is one of the most distinctive guiding horizons in Germany.

For the entire duration of the Permian, today's Central and Western Europe was part of the supercontinent Pangea in the tropical climate zone, i.e. in the immediate vicinity of the equator and thus in the area of ​​a seasonally occurring, very strong monsoon current . At the beginning of the epoch at about 5 ° south latitude, these areas shifted in the course of almost 50 million years in the course of continental movement towards the 10th north latitude. During this time there was a relatively frequent change between humid (damp) and arid (dry) phases. The pronounced monsoon system between latitudes 30 ° north and 30 ° south also determined the weather over the course of the year. In the summer months the monsoon wind transported humid air masses from the tropical Tethys to the European regions of the time, while in winter dry continental air flowed in from the north.

literature

  • Wolfgang Oschmann: Evolution of the Earth. History of the earth and life. Haupt Verlag, Bern 2016 (UTB basics; 4401), ISBN 978-3-8252-4401-9 , pp. 191-210.
  • Werner Vasicek : 280 million year old traces of the hard coal forests of Zöbing . Catalog series of the Krahuletz Museum 4, Eggenburg 1983.
  • Werner Vasicek : Young Palaeozoic von Zöbing , series of publications by the Waldviertler Heimatbund 38, 1999, p. 63ff. (in cooperation with Fritz F. Steininger )
  • Ronny Rößler: Fern forests, glowing clouds and salt deserts: The Permian . In: Biology in our time , 33 (4), 2003, pp. 244-251, ISSN  0045-205X
  • Wolfgang Frey and Rainer Lösch : Textbook of Geobotany. Gustav Fischer, Stuttgart 1998, ISBN 3-437-25940-7 , 436 pp.
  • Jörg W. Schneider , Frank Körner, Marco Roscher, Uwe Kroner: Permian climate development in the northern peri-Tethys area - The Lodève basin, French Massif Central, compared in a European and global context . In: Palaeogeography, Palaeoclimatology, Palaeoecology , 240 (1-2), Amsterdam 2006, pp. 161-183, ISSN  0031-0182

Web links

Wiktionary: Perm  - explanations of meanings, word origins, synonyms, translations
Commons : Perm  - collection of images, videos and audio files

Individual evidence

  1. ↑ Oxygen content-1000mj
  2. ↑ Phanerozoic Carbon Dioxide
  3. ↑ All palaeotemps
  4. ↑ Spencer G. Lucas, Joerg W. Schneider, Giuseppe Cassinis: Non-marine Permian biostratigraphy and biochronology: an introduction. In: Spencer G. Lucas, Giuseppe Cassinis, Joerg W. Schneider (Eds.): Non-Marine Permian Biostratigraphy and Biochronology. Geological Society, London, Special Publications, 265, London 2006, pp. 1-14, PDF
  5. ↑ Isabel P. Montañez, Neil J. Tabor, Deb Niemeier, William A. DiMichele, Tracy D. Frank, Christopher R. Fielding, John L. Isbell, Lauren P. Birgenheier, Michael C. Rygel: CO 2 -Forced Climate and Vegetation Instability During Late Paleozoic Deglaciation . In: Science . 315, No. 5808, January 2007, pp. 87-91. doi : 10.1126 / science.1134207 . Alternative full text access : UNL .
  6. ↑ John L. Isbell, Lindsey C. Henry, Erik L. Gulbranson, Carlos O. Limarino, Margaret L. Fraiser, Zelenda J. Koch, Patricia L. Ciccioli, Ashley A. Dineen: Glacial paradoxes during the late Paleozoic ice age: Evaluating the equilibrium line altitude as a control on glaciation . (PDF) In: Gondwana Research . 22, No. 1, July 2012, pp. 1-19. doi : 10.1016 / j.gr.2011.11.005 .
  7. ^ Neil J. Tabor: Wastelands of tropical Pangea: High heat in the Permian . In: Geology . tape 41 , no. 5 , 2013, p. 623–624 , doi : 10.1130 / focus052013.1 .
  8. ↑ David PG Bond, Paul B. Wignall, Michael M. Joachimski, Yadong Sun, Ivan Savov, Stephen E. Grasby, Benoit Beauchamp, Dierk PG Blomeier: An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification . (PDF) In: GSA Bulletin (Geological Society of America) . 127, No. 9-10, September 2015, pp. 1411-1421. doi : 10.1130 / B31216.1 .
  9. ↑ He Bin, Yi-Gang Xu, Xiao-Long Huang, Zhen-Yu Luo, Yu-Ruo Shi, Qi-Jun Yang, Song-Yue Yu: Age and duration of the Emeishan flood volcanism, SW China: Geochemistry and SHRIMP zircon U-Pb dating of silicic ignimbrites, post-volcanic Xuanwei Formation and clay tuff at the Chaotian section . (PDF) In: Earth and Planetary Science Letters . 255, March 2007, pp. 306-323. doi : 10.1016 / j.epsl.2006.12.021 .
  10. ↑ J. Gregory Shellnutt: The Emeishan large igneous province: A synthesis . In: Geoscience Frontiers (Elsevier) . 5, No. 3, August 2016, pp. 369-394. doi : 10.1016 / j.gsf.2013.07.003 .
  11. ↑ David PG Bond, Stephen E. Grasby: On the causes of mass extinctions . (PDF) In: Palaeogeography, Palaeoclimatology, Palaeoecology . 478, No. 15, July 2017, pp. 3–29. doi : 10.1016 / j.palaeo.2016.11.005 .
  12. ↑ Adrian P. Jones; David G. Price; Paul S. DeCarli; Richard Clegg: Impact Decompression Melting: A Possible Trigger for Impact Induced Volcanism and Mantle Hotspots? In: C. Koeberl and F. Martinez-Ruiz (eds.): Impact markers in the Stratigraphic Record . Springer Verlag, Berlin 2003, ISBN 3-540-00630-3 , pp. 91-120 ( mantleplumes.org [PDF]).
  13. ↑ Borja Cascales-Miñana and Christopher J. Cleal: The plant fossil record reflects just two great extinction events . In: Terra Nova . 26, No. 3, 2013, pp. 195-200. doi : 10.1111 / ter.12086 .
  14. ↑ Michael M. Joachimski, Xulong Lai, Shuzhong Shen, Haishui Jiang, Genming Luo, Bo Chen, Jun Chen and Yadong Sun: Climate warming in the latest Permian and the Permian – Triassic mass extinction . In: Geology . 40, No. 3, January 2012, pp. 195-198. doi : 10.1130 / G32707.1 .
  15. ^ Yadong Sun, Michael M. Joachimski, Paul B. Wignall, Chunbo Yan, Yanlong Chen, Haishui Jiang, Lina Wang, Xulong Lai: Lethally Hot Temperatures During the Early Triassic Greenhouse . In: Science . No. 366, October 2012. doi : 10.1126 / science.1224126 .
  16. ^ Mass extinctions: Peter Ward : The microbes strike back, New Scientist Feb. 9, 2008; Spiegel, 2009 .
  17. ^ Daniel H. Rothman, Gregory P. Fournier, Katherine L. French, Eric J. Alm, Edward A. Boyle, Changqun Cao, Roger E. Summons: Methanogenic burst in the end-Permian carbon cycle. In: PNAS. 2014, doi: 10.1073 / pnas.1318106111 .
  18. ↑ Shu-Zhong Shen, Jahandar Ramezani, Jun Chen, Chang-Qun Cao, Douglas H. Erwin, Hua Zhang, Lei Xiang, Shane D. Schoepfer, Charles M. Henderson, Quan-Feng Zheng, Samuel A. Bowring, Yue Wang , Xian-Hua Li, Xiang-Dong Wang, Dong-Xun Yuan, Yi-Chun Zhang, Lin Mu, Jun Wang, Ya-Sheng Wu: A sudden end-Permian mass extinction in South China . In: GSA Bulletin (The Geological Society of America) . September 2018. doi : 10.1130 / B31909.1 .
  19. ^ Seth D. Burgess, Samuel A. Bowring, Shuzong Shen: High-precision timeline for Earth's most severe extinction . In: PNAS . 111, No. 9, 2014. doi : 10.1073 / pnas.1317692111 .
  20. ↑ Frey and Lösch, p. 94
  21. ↑ Frank Körnerː Climate and sedimentation patterns of the peri-tethyalen, continental Permian - interdisciplinary studies on red beds of the Lodève basin (S-France). Faculty of Geosciences, Geotechnics and Mining of the Technical University Bergakademie Freiberg, 2005. (PDF)