Siberian Traps

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Coordinates: 67°N 90°E / 67°N 90°E / 67; 90

The extent of the Siberian Traps (Map in German)

The Siberian Traps (Russian: Сибирские траппы, Sibirskiye trappy) is a large region of volcanic rock, known as a large igneous province, in Siberia, Russia. The massive eruptive event that formed the Traps is one of the largest-known volcanic events that has occurred in the last 500 million years.

The eruptions continued for roughly two million years and spanned the P–T boundary, or the Permian–Triassic boundary, which occurred between 251 to 250 million years ago.[1][2]

Large volumes of basaltic lava covered a large expanse of Siberia in a flood basalt event. Today, the area is covered by about seven million km2 of basaltic rock, with a volume of around 4 million km3.[3]

Formation[edit]

The source of the Siberian Traps basaltic rock has been attributed to a mantle plume, which rose until it impacted against the bottom of the Earth's crust, producing volcanic eruptions through the Siberian Craton.[4] It has been suggested that, as the Earth's lithospheric plates moved over the mantle plume (the Iceland plume), the plume produced the Siberian Traps in the Permian and Triassic periods, later going on to produce volcanic activity on the floor of the Arctic Ocean in the Jurassic and Cretaceous, and then generating volcanic activity in Iceland.[5] Other plate tectonic causes have also been suggested.[4] Another possible cause may be the impact that formed the Wilkes Land crater in Antarctica, which is estimated to have occurred around the same time and been nearly antipodal to the traps.[6]

The main source of rock in this formation is basalt, but both mafic and felsic rocks are present, so this formation is officially called a Flood Basalt Province. The inclusion of mafic and felsic rock indicates multiple other eruptions that occurred and coincided with the one-million-year-long eruption that created the majority of the basaltic layers. The traps are divided into sections based on their chemical, stratigraphical, and petrographical composition.[7]

One of the World Heritage Sites, the Putorana Plateau, is composed of Siberian Traps.

Impact on prehistoric life[edit]

One of the major questions is whether the Siberian Traps were directly responsible for the Permian–Triassic mass extinction event that occurred 250 million years ago,[8] or if they were themselves caused by some other, larger event, such as an asteroid impact. A recent hypothesis put forward is that the volcanism triggered the growth of Methanosarcina, a microbe that then spewed enormous amounts of methane into Earth's atmosphere,[9] ultimately altering the Earth's carbon cycle based on observations such as a significant increase of inorganic carbon reservoirs in marine environments.[9]

This extinction event, also called the Great Dying, affected all life on Earth, and is estimated to have killed about 95% of all species living at the time.[10][11][12] Some of the disastrous events that impacted the Earth continued to repeat themselves on Earth 5 to 6 million years after the initial extinction occurred.[13] Over time a small portion of the life that survived the extinction was able to repopulate and expand starting with low trophic levels (local communities) until the higher trophic levels (large habitats) were able to be re-established.[13] Calculations of sea water temperature from δ18O measurements indicate that at the peak of the extinction, the Earth underwent lethally hot global warming, in which equatorial ocean temperatures exceeded 40 °C (104 °F).[14] It took roughly 8 to 9 million years for any diverse ecosystem to be re-established; however, new classes of animals were established after the extinction that did not exist beforehand.[15]

Palaeontological evidence further indicates that the global distribution of tetrapods vanished, with very rare exceptions in the region of Pangaea that is today Utah, between latitudes bounded by approximately 40°S to 30°N. The tetrapod gap of equatorial Pangaea coincides with an end-Permian to Middle Triassic global "coal gap" that indicates the loss of peat swamps. Peat formation, a product of high plant productivity, was reestablished only in the Anisian stage of the Triassic, and even then only in high southern latitudes, although gymnosperm forests appeared earlier (in the Early Spathian), but again only in northern and southern higher latitudes.[16] In equatorial Pangaea, the establishment of conifer-dominated forests was not until the end of the Spathian, and the first coals at these latitudes did not appear until the Carnian, around 15 million years after their end-Permian disappearance. These signals suggest equatorial temperatures exceeded their thermal tolerance for many marine vertebrates at least during two thermal maxima, whereas terrestrial equatorial temperatures were sufficiently severe to suppress plant and animal abundance during most of the Early Triassic.[17]

Dating[edit]

The volcanism that occurred in the Siberian Traps resulted in copious amounts of magma being ejected from the Earth's crust—leaving permanent traces of rock from the same time period of the mass extinction that is able to be examined today.[18] More specifically, zircon is found in some of the volcanic rocks. To further the accuracy of the age of the zircon, several varying aged pieces of zircon were organized into a timeline based on when they crystallized.[19] The CA-TIMS technique, a chemical abrasion age-dating technique that eliminates variability in accuracy due to lead depletion in zircon over time,[20] was then used to accurately determine the age of the zircons found in the Siberian Traps. Eliminating the variability due to lead, the CA-TIMS age-dating technique allowed uranium within the zircon to be the centre focus in linking the volcanism in the Siberian Traps that resulted in high amounts of magmatic material with the Permian–Triassic mass extinction.[19]

To further the connection between the Permian–Triassic extinction event, other disastrous events occurred around the same time period, such as sea level changes, meteor impacts and volcanism.[21] Specifically focusing on volcanism, rock samples from the Siberian Traps and other southern regions were obtained and compared.[22] Basalts and gabbro samples from several southern regions close to and from the Siberian Traps were dated based on argon isotope 40 and argon isotope 39 age-dating methods.[22] Feldspar and biotite was specifically used to focus on the samples age and duration of the presence magma from the volcanic event in the Siberian Traps.[22] The majority of the basalt and gabbro samples dated to 250 million years ago, covered a surface area of five million square kilometres on the Siberian Traps[22] and occurred within a short period of time with rapid rock solidification/cooling.[23] Studies confirmed that samples of gabbro and basalt from the same time period of the Permian–Triassic event from the other southern regions also matched the age of samples within the Siberian Traps. This confirms the assumption of the linkage between the age of volcanic rocks within the Siberian Traps, along with rock samples from other southern regions to the Permian–Triassic mass extinction event.[23]

Mineral deposits[edit]

A sample of Siberian Traps basalt (dark) containing native iron

The giant Norilsk-Talnakh nickelcopperpalladium deposit formed within the magma conduits in the most complete part of the Siberian Traps.[24] It has been linked to the Permian–Triassic extinction event, which occurred approximately 251.4 million years ago,[25] based on large amounts of nickel and other elements found in rock beds that were laid down after the extinction occurred.[26] The method used to correlate the extinction event with the surplus amount of nickel located in the Siberian Traps, is by comparing the timeline of the magmatism within the traps and the timeline of the extinction itself.[27] Before the linkage between magmatism and the extinction event was discovered, it was hypothesized that the mass extinction and volcanism occurred at the same time due to the linkages in rock composition.[28]

See also[edit]

References[edit]

  1. ^ Sun, Yadong; Joachimski,Wignall,Yan,Chen,Jiang,Wang,La (October 27, 2013). "Lethally Hot Temperatures During the Early Triassic Greenhouse". Science. 338: 366–70. Bibcode:2012Sci...338..366S. doi:10.1126/science.1224126. PMID 23087244.
  2. ^ "New Studies of Permian Extinction Shed Light On the Great Dying", New York Times, April 30, 2012. Retrieved on May 2, 2012.
  3. ^ Ivanov, Alexei V.; He, Huayiu; Yan, Liekun; Ryabov, Viktor V.; Shevko, Artem Y.; Palesskii, Stanislav V.; Nikolaeva, Irina V. "Siberian Traps large igneous province: Evidence for two flood basalt pulses around the Permo-Triassic boundary and in the Middle Triassic, and contemporaneous granitic magmatism". Earth-Science Reviews. 122: 58–76. Bibcode:2013ESRv..122...58I. doi:10.1016/j.earscirev.2013.04.001.
  4. ^ a b Foulger, G.R. (2010). Plates vs. Plumes: A Geological Controversy. Wiley-Blackwell. ISBN 978-1-4051-6148-0.
  5. ^ Morgan, W. Jason; Morgan, Jason Phipps (2007), "Plate velocities in hotspot reference frame: electronic supplement" (PDF), in Foulger, Gillian R. and Jurdy, Donna M.; (editors), Plates, Plumes, and Planetary Processes, Geological Society of America (Special Paper 430), retrieved 2017-02-25
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  7. ^ Ivanov, Alexei V.; He, Huayiu; Yan, Liekun; Ryabov, Viktor V.; Shevko, Artem Y.; Palesskii, Stanislav V.; Nikolaeva, Irina V. "Siberian Traps large igneous province: Evidence for two flood basalt pulses around the Permo-Triassic boundary and in the Middle Triassic, and contemporaneous granitic magmatism". Earth-Science Reviews. 122: 58–76. Bibcode:2013ESRv..122...58I. doi:10.1016/j.earscirev.2013.04.001.
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  11. ^ https://www.nytimes.com/2017/07/29/opinion/sunday/when-life-on-earth-was-nearly-extinguished.html
  12. ^ Becker, Luann; Poreda, Robert J.; Hunt, Andrew G.; Bunch, Theodore E.; Rampino, Michael (23 Feb 2001). "Impact Event at the Permian-Triassic Boundary: Evidence from Extraterrestrial Noble Gases in Fullerenes". Science. 291: 1530–1533. Bibcode:2001Sci...291.1530B. doi:10.1126/science.1057243.
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  17. ^ Sun, Yadong; Joachimski,Wignall,Yan,Chen,Jiang,Wang,La (October 27, 2013). "Lethally Hot Temperatures During the Early Triassic Greenhouse". Science. 338: 366–70. Bibcode:2012Sci...338..366S. doi:10.1126/science.1224126. PMID 23087244.
  18. ^ Burgess, Seth D.; Bowring, Samuel A. (28 August 2015). "High-precision geochronology confirms voluminous magmatism before, during, and after the Earth's most severe extinction". Earth Science. 1 – via Science Advances.
  19. ^ a b Burgess, Seth D.; Bowring, Samuel A. (28 August 2015). "High-precision geochronology confirms voluminous magmatism before, during, and after the Earth's most severe extinction". Earth Science. 1 – via Science Advances.
  20. ^ Mattinson, James M. (July 2005). "Zircon U-Pb chemical abrasion ("CA-TIMS") method: Combined annealing and multi-step partial dissolution analysis for improved precision and accuracy of zircon ages". Chemical Geology. 220: 47–66. Bibcode:2005ChGeo.220...47M. doi:10.1016/j.chemgeo.2005.03.011 – via Elsevier.
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  22. ^ a b c d Allen, M.B.; et al. (January 2009). "The Timing and Extent of the Eruption of the Siberian Traps Large Igneous Province: Implications for the End-Permian Environmental Crisis". Earth and Planetary Science Letters. 277: 9–20 – via Elsevier.
  23. ^ a b Basu, A.R.; Renne, P.R. (July 1991). "Rapid Eruption of the Siberian Traps Flood Basalts at the Permo-Triassic Boundary". Science. 253: 176–179 – via Google scholar.
  24. ^ Ryabov, V. V.; Shevko, A. Ya.; Gora, M. P. (2014). Trap Magmatism and Ore Formation in the Siberian Noril'sk Region (Volume 1: Trap Petrology). Springer Netherlands. ISBN 978-94-007-5021-0.
  25. ^ Becker, Luann; Poreda, Robert J.; Hunt, Andrew G.; Bunch, Theodore E.; Rampino, Michael (23 Feb 2001). "Impact Event at the Permian-Triassic Boundary: Evidence from Extraterrestrial Noble Gases in Fullerenes". Science. 291: 1530–1533. Bibcode:2001Sci...291.1530B. doi:10.1126/science.1057243.
  26. ^ Barnes, Stephen; Mungall, Emma; Mungall, James; Le Vaillant, Margaux (February 2017). "Role of Degassing of the Noril'sk Nickel Deposits in the Permian-Triassic Mass Extinction Event". Proceedings of the National Academy of Sciences of the United States of America. 10: 1–6.
  27. ^ Bowring, S.A.; Muirhead, J.D.; Burgess, S.D. (July 2017). "Initial Pulse of Siberian Traps Sills As The Trigger of the End-Permian Mass Extinction". Nature Communications. 8: 1–6. Bibcode:2017NatCo...8....1B. doi:10.1038/s41467-016-0009-6.
  28. ^ Burgess, Seth D.; Bowring, Samuel A. (28 August 2015). "High-precision geochronology confirms voluminous magmatism before, during, and after the Earth's most severe extinction". Earth Science. 1 – via Science Advances.

External links[edit]