The Steptoean Positive Carbon Isotope Excursion (SPICE) was a geological event which occurred about 495 million years ago near the beginning of the International Furongian Epoch of the Cambrian Period.[1] The SPICE represents an increase in the atmospheric 13C to 12C ratio, known as the δ13C, and lasted for around 2 to 4 million years.[2][3][4]

A rise in the atmospheric δ13C ratio doesn't necessarily infer a rise in abolute atmospheric carbon concentration. An increase of δ13C such as during SPICE is rather interpreted as the result of increased carbon fixation primarily by plants, which fix 12C more readily than 13C, and the subsequent burial of this organic carbon in sedimentary rocks. This removal of atmospheric 12C in higher proportion than 13C signifies increased proliferation of life and shifts the ratio towards 13C.[5] This shift during SPICE is interpreted to be a global disturbance in the carbon cycle, affecting the atmosphere and the oceans in equal proportion as described by Henry's law. Regional sea level changes,[6][7][8] a rise in sea water temperatures,[9] ocean anoxia,[10] and trilobite and brachiopod extinctions[11][12] are associated with the SPICE event, although the exact mechanisms causing these events are still unconfirmed.

One proposed cause of the SPICE is an increase in the burial of organic carbon, perhaps caused by increased primary productivity (e.g. photosynthesis) or enhanced organic matter preservation due to ocean deoxygenation (i.e. anoxia or euxinia).[13][14][15][16][17] The spread of seafloor anoxia, facilitated by higher ocean temperatures, has also been proposed as the kill mechanism for the extinctions of marine organisms.[18][19]

References

  1. ↑ Rooney, Alan D.; Millikin, Alexie E.G.; Ahlberg, Per (2022-06-01). "Re-Os geochronology for the Cambrian SPICE event: Insights into euxinia and enhanced continental weathering from radiogenic isotopes". Geology. 50 (6): 716–720. Bibcode:2022Geo....50..716R. doi:10.1130/G49833.1. ISSN 0091-7613. S2CID 247687735.
  2. ↑ Saltzman, Matthew R.; Ripperdan, Robert L.; Brasier, M.D.; Lohmann, Kyger C.; Robison, Richard A.; Chang, W.T.; Peng, Shanchi; Ergaliev, E.K.; Runnegar, Bruce (October 2000). "A global carbon isotope excursion (SPICE) during the Late Cambrian: relation to trilobite extinctions, organic-matter burial and sea level". Palaeogeography, Palaeoclimatology, Palaeoecology. 162 (3–4): 211–223. Bibcode:2000PPP...162..211S. doi:10.1016/S0031-0182(00)00128-0.
  3. ↑ Saltzman, M. R.; Cowan, C. A.; Runkel, A. C.; Runnegar, B.; Stewart, M. C.; Palmer, A. R. (2004-05-01). "The Late Cambrian Spice (13C) Event and the Sauk II-SAUK III Regression: New Evidence from Laurentian Basins in Utah, Iowa, and Newfoundland". Journal of Sedimentary Research. 74 (3): 366–377. Bibcode:2004JSedR..74..366S. doi:10.1306/120203740366. ISSN 1527-1404.
  4. ↑ Sørensen, Aske L.; Nielsen, Arne T.; Thibault, Nicolas; Zhao, Zhengfu; Schovsbo, Niels H.; Dahl, Tais W. (October 2020). "Astronomically forced climate change in the late Cambrian". Earth and Planetary Science Letters. 548: 116475. Bibcode:2020E&PSL.54816475S. doi:10.1016/j.epsl.2020.116475. S2CID 224864664.
  5. ↑ Canfield, Donald E.; Ngombi-Pemba, Lauriss; Hammarlund, Emma U. (15 October 2013). "Oxygen dynamics in the aftermath of the Great Oxidation of Earth's atmosphere". Proceedings of the National Academy of Sciences of the United States of America. 110 (42): 16736–16741. Bibcode:2013PNAS..11016736C. doi:10.1073/pnas.1315570110. PMC 3801071. PMID 24082125.
  6. ↑ Saltzman, Matthew R.; Ripperdan, Robert L.; Brasier, M. D.; Lohmann, Kyger C.; Robison, Richard A.; Chang, W. T.; Peng, Shanchi; Ergaliev, E. K.; Runnegar, Bruce (2000-10-01). "A global carbon isotope excursion (SPICE) during the Late Cambrian: relation to trilobite extinctions, organic-matter burial and sea level". Palaeogeography, Palaeoclimatology, Palaeoecology. 162 (3): 211–223. Bibcode:2000PPP...162..211S. doi:10.1016/S0031-0182(00)00128-0. ISSN 0031-0182.
  7. ↑ Saltzman, M. R.; Cowan, C. A.; Runkel, A. C.; Runnegar, B.; Stewart, M. C.; Palmer, A. R. (2004-05-01). "The Late Cambrian Spice ( 13C) Event and the Sauk II-SAUK III Regression: New Evidence from Laurentian Basins in Utah, Iowa, and Newfoundland". Journal of Sedimentary Research. 74 (3): 366–377. Bibcode:2004JSedR..74..366S. doi:10.1306/120203740366. ISSN 1527-1404.
  8. ↑ Wang, Zhaopeng; Chen, Jitao; Liang, Taitao; Yuan, Jinliang; Han, Chao; Liu, Jiaye; Zhu, Chenlin; Zhu, Decheng; Han, Zuozhen (May 2020). "Spatial variation in carbonate carbon isotopes during the Cambrian SPICE event across the eastern North China Platform". Palaeogeography, Palaeoclimatology, Palaeoecology. 546: 109669. Bibcode:2020PPP...54609669W. doi:10.1016/j.palaeo.2020.109669. S2CID 213605108.
  9. ↑ Elrick, Maya; Rieboldt, Sarah; Saltzman, Matt; McKay, Robert M. (October 2011). "Oxygen-isotope trends and seawater temperature changes across the Late Cambrian Steptoean positive carbon-isotope excursion (SPICE event)". Geology. 39 (10): 987–990. Bibcode:2011Geo....39..987E. doi:10.1130/G32109.1. ISSN 1943-2682.
  10. ↑ Mackey, Justin E.; Stewart, Brian W. (15 August 2019). "Evidence of SPICE-related anoxia on the Laurentian passive margin: Paired δ13C and trace element chemostratigraphy of the upper Conasauga Group, Central Appalachian Basin". Palaeogeography, Palaeoclimatology, Palaeoecology. 528: 160–174. Bibcode:2019PPP...528..160M. doi:10.1016/j.palaeo.2019.04.018. S2CID 155803833. Retrieved 4 December 2022.
  11. ↑ Smith, Patrick M.; Brock, Glenn A.; Paterson, John R. (2020-01-02). "Shelly fauna from the Cambrian (Miaolingian, Guzhangian) Shannon Formation and the SPICE event in the Amadeus Basin, Northern Territory". Alcheringa: An Australasian Journal of Palaeontology. 44 (1): 1–24. Bibcode:2020Alch...44....1S. doi:10.1080/03115518.2019.1660405. ISSN 0311-5518. S2CID 210735142.
  12. ↑ Gerhardt, Angela M.; Gill, Benjamin C. (2016-11-01). "Elucidating the relationship between the later Cambrian end-Marjuman extinctions and SPICE Event". Palaeogeography, Palaeoclimatology, Palaeoecology. 461: 362–373. Bibcode:2016PPP...461..362G. doi:10.1016/j.palaeo.2016.08.031. ISSN 0031-0182.
  13. ↑ Gill, Benjamin C.; Lyons, Timothy W.; Young, Seth A.; Kump, Lee R.; Knoll, Andrew H.; Saltzman, Matthew R. (January 2011). "Geochemical evidence for widespread euxinia in the Later Cambrian ocean". Nature. 469 (7328): 80–83. Bibcode:2011Natur.469...80G. doi:10.1038/nature09700. ISSN 0028-0836. PMID 21209662. S2CID 4319979.
  14. ↑ Wotte, Thomas; Strauss, Harald (2015). "Questioning a widespread euxinia for the Furongian (Late Cambrian) SPICE event: indications from δ13C, δ18O, δ34S and biostratigraphic constraints". Geological Magazine. 152 (6): 1085–1103. Bibcode:2015GeoM..152.1085W. doi:10.1017/S0016756815000187. ISSN 0016-7568. S2CID 130781686.
  15. ↑ LeRoy, Matthew A.; Gill, Benjamin C.; Sperling, Erik A.; McKenzie, N. Ryan; Park, Tae-Yoon S. (2021-03-15). "Variable redox conditions as an evolutionary driver? A multi-basin comparison of redox in the middle and later Cambrian oceans (Drumian-Paibian)". Palaeogeography, Palaeoclimatology, Palaeoecology. 566: 110209. Bibcode:2021PPP...56610209L. doi:10.1016/j.palaeo.2020.110209. ISSN 0031-0182. S2CID 233650992.
  16. ↑ Gill, Benjamin C.; Dahl, Tais W.; Hammarlund, Emma U.; LeRoy, Matthew A.; Gordon, Gwyneth W.; Canfield, Donald E.; Anbar, Ariel D.; Lyons, Timothy W. (November 2021). "Redox dynamics of later Cambrian oceans". Palaeogeography, Palaeoclimatology, Palaeoecology. 581: 110623. Bibcode:2021PPP...58110623G. doi:10.1016/j.palaeo.2021.110623.
  17. ↑ Dahl, Tais W.; Boyle, Richard A.; Canfield, Donald E.; Connelly, James N.; Gill, Benjamin C.; Lenton, Timothy M.; Bizzarro, Martin (September 2014). "Uranium isotopes distinguish two geochemically distinct stages during the later Cambrian SPICE event". Earth and Planetary Science Letters. 401: 313–326. Bibcode:2014E&PSL.401..313D. doi:10.1016/j.epsl.2014.05.043. PMC 4326682. PMID 25684783.
  18. ↑ Palmer, Allison R. (1984). "The Biomere Problem: Evolution of an Idea". Journal of Paleontology. 58 (3): 599–611. ISSN 0022-3360. JSTOR 1304904.
  19. ↑ Gill, Benjamin C.; Lyons, Timothy W.; Young, Seth A.; Kump, Lee R.; Knoll, Andrew H.; Saltzman, Matthew R. (January 2011). "Geochemical evidence for widespread euxinia in the Later Cambrian ocean". Nature. 469 (7328): 80–83. Bibcode:2011Natur.469...80G. doi:10.1038/nature09700. ISSN 0028-0836. PMID 21209662. S2CID 4319979.
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