The Emeishan Traps constitute a flood basalt volcanic province, or large igneous province, in south-western China, centred in Sichuan province. It is sometimes referred to as the Permian Emeishan Large Igneous Province or Emeishan Flood Basalts. Like other volcanic provinces or "traps", the Emeishan Traps are multiple layers of igneous rock laid down by large mantle plume volcanic eruptions. The Emeishan Traps eruptions were serious enough to have global ecological and paleontological impact.[1]

It is named for Emeishan, a mountain in Sichuan.

Etymology

The term "trap" has been used in geology since 1785–1795 for such rock formations. It is derived from the Swedish word for stairs ("trappa") and refers to the step-like hills forming the landscape of the region.[2]

Formation and development

The eruptions that produced the Emeishan Traps began 265 million years ago (Ma) or earlier.[3][4] The main eruptive period is between 262 and 261 Ma, and the volcanism activities end 259 Ma.[5][6]

In volume, the Emeishan Traps are dwarfed by the massive Siberian Traps, which occurred, in terms of the geological time scale, not long after, at approximately 252 Ma. The Emeishan basalts covers an area of more than 250,000 km2 with thicknesses ranging from several hundred meters up to 5.5 km (the average flood basalt thickness throughout the entire region is estimated to be around 700 m), but the Emeishan traps may have initially covered an area as much as 500,000 km2.[7] Thus the entire volume of the Emeishan basalts is estimated to be 300,000 km3.[8] Evidence suggests that the initial volcanism of the central Emeishan Traps occurred in a deep submarine environment without any significant prevolcanic uplift.[9]

The Emeishan Traps are associated with the end-Capitanian mass extinction event, the extinction of animal and plant life that occurred at the end of the Capitanian stage of the Guadalupian epoch of the Permian period.[10] Limestone within the traps show the extinction to occur immediately below the first eruptive unit, with the mass extinction marked at the onset of explosive Emeishan volcanism.[3] The formation of volcaniclastics suggest violent phreatomagmatic-style eruptions.[4] The synchrony between the Emeishan Traps and the end-Guadalupian extinction has been taken to support the argument of Vincent Courtillot and others that volcanism is the main driver of mass extinctions.[11]

After their emplacement, the Emeishan Traps were eroded and their minerals became encased in coals that formed after their emplacement.[12]

See also

References

Citations
  1. ↑ Bond, D. P. G.; Wignall, P. B.; Joachimski, M. M.; Sun, Y.; Savov, I.; Grasby, S. E.; Beauchamp, B.; Blomeier, D. P. G. (2015-04-14). "An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification" (PDF). Geological Society of America Bulletin. 127 (9–10): 1411–1421. Bibcode:2015GSAB..127.1411B. doi:10.1130/B31216.1. ISSN 0016-7606.
  2. ↑ Trap at dictionary.reference.com
  3. 1 2 Wignall, PB; et al. (2009). "Volcanism, Mass Extinction, and Carbon Isotope Fluctuations in the Middle Permian of China". Science. 324 (5931): 1179–82. Bibcode:2009Sci...324.1179W. doi:10.1126/science.1171956. PMID 19478179. S2CID 206519019.
  4. 1 2 Jerram, DA; et al. (2015). "Submarine palaeoenvironments during Emeishan flood basalt volcanism, SW China: Implications for plume–lithosphere interaction during the Capitanian, Middle Permian ('end Guadalupian') extinction event" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology. 441: 65–73. doi:10.1016/j.palaeo.2015.06.009.
  5. ↑ Zheng, LD; et al. (2010). "Magnetostratigraphic constraints on two‐stage eruptions of the Emeishan continental flood basalts". Geochemistry, Geophysics, Geosystems. 11 (12): Q12014. Bibcode:2010GGG....1112014Z. doi:10.1029/2010GC003267.
  6. ↑ Zhong, YT; et al. (2014). "CA-TIMS zircon U–Pb dating of felsic ignimbrite from the Binchuan section: Implications for the termination age of Emeishan large igneous province". Lithos. 204: 14–19. Bibcode:2014Litho.204...14Z. doi:10.1016/j.lithos.2014.03.005.
  7. ↑ Zhou, MF; et al. (2002). "A temporal link between the Emeishan large igneous province (SW China) and the end-Guadalupian mass extinction". Earth and Planetary Science Letters. 196 (3–4): 113–122. Bibcode:2002E&PSL.196..113Z. doi:10.1016/s0012-821x(01)00608-2.
  8. ↑ Ali, JR; et al. (2005). "Emeishan large igneous province, SW China". Lithos. 79 (3–4): 475–489. Bibcode:2005Litho..79..475A. doi:10.1016/j.lithos.2004.09.013.
  9. ↑ Zhu, B; et al. (2014). "No pre-eruptive uplift in the Emeishan large igneous province: New evidences from its 'inner zone', Dali area, Southwest China". Journal of Volcanology and Geothermal Research. 269: 57–67. Bibcode:2014JVGR..269...57Z. doi:10.1016/j.jvolgeores.2013.11.015.
  10. ↑ Wignall, PB; et al. (2001). "Large igneous provinces and mass extinctions". Earth-Science Reviews. 53 (1): 1–33. Bibcode:2001ESRv...53....1W. doi:10.1016/s0012-8252(00)00037-4.
  11. ↑ Courtillot, VE; et al. (2003). "On the ages of flood basalt events". Comptes Rendus Geoscience. 335: 113–140. Bibcode:2003CRGeo.335..113C. CiteSeerX 10.1.1.461.3338. doi:10.1016/S1631-0713(03)00006-3.
  12. ↑ Shen, Minglian; Dai, Shifeng; Nechaev, Victor P.; French, David; Graham, Ian T.; Liu, Shande; Yu. Chekryzhov, Igor; Tarasenko, Irina A.; Zhang, Shaowei (1 January 2023). "Provenance changes for mineral matter in the latest Permian coals from western Guizhou, southwestern China, relative to tectonic and volcanic activity in the Emeishan Large Igneous Province and Paleo-Tethys region". Gondwana Research. 113: 71–88. doi:10.1016/j.gr.2022.10.011. ISSN 1342-937X. Retrieved 10 December 2023.
Bibliography
  • Dobretsov, N. L. (2005). "Large Igneous Provinces of Asia (250 Ma): Siberian and Emeishan traps (plateau basalts) and associated granitoids". Geologiya I Geofizika. 46: 870–890.
  • He, Bin; Xu, Yi-Gang; Chung, Sun-Ling; Huang, Xiao-Long; Wang, Ya-Mei (2003). "Sedimentary evidence for a rapid kilometer-scale crustal doming prior to the eruption of the Emeishan flood basalts". Earth and Planetary Science Letters. 213 (3–4): 391–405. Bibcode:2003E&PSL.213..391H. doi:10.1016/s0012-821x(03)00323-6.
  • He, Bin; Xu, Yi-Gang; Huang, Xiao-Long; Luo, Zhen-Yu; Shi, Yu-Ruo; Yang, Qi-Jun; Yu, Song-Yue (2007). "Age and duration of the Emeishan flood volcanism, SW China: Geochemistry and SHRIMP zircon Uranium–U-Lead–Pb dating of silicic ignimbrites, post-volcanic Xuanwei Formation and clay tuff at the Chaotian section". Earth and Planetary Science Letters. 255 (3–4): 306–23. Bibcode:2007E&PSL.255..306H. doi:10.1016/j.epsl.2006.12.021.
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