Rhyacian
| Rhyacian | ||||||||||||||||||||
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A sample of a Rhyacian banded iron formation found in North America | ||||||||||||||||||||
| Chronology | ||||||||||||||||||||
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| Etymology | ||||||||||||||||||||
| Name formality | Formal | |||||||||||||||||||
| Usage information | ||||||||||||||||||||
| Celestial body | Earth | |||||||||||||||||||
| Regional usage | Global (ICS) | |||||||||||||||||||
| Time scale(s) used | ICS Time Scale | |||||||||||||||||||
| Definition | ||||||||||||||||||||
| Chronological unit | Period | |||||||||||||||||||
| Stratigraphic unit | System | |||||||||||||||||||
| Time span formality | Formal | |||||||||||||||||||
| Lower boundary definition | Defined Chronometrically | |||||||||||||||||||
| Lower GSSA ratified | 1990[2] | |||||||||||||||||||
| Upper boundary definition | Defined Chronometrically | |||||||||||||||||||
| Upper GSSA ratified | 1990[2] | |||||||||||||||||||
The Rhyacian (/raɪˈeɪsiən/) is the second geologic period in the Paleoproterozoic Era. It spans 250 million years and lasted from 2300 to 2050 million years ago (Ma), following the Siderian Period and preceding the Orosirian Period. Instead of being based on stratigraphy, these dates are defined chronometrically.
Etymology and history
The name Rhyacian is derived from the Greek word rhyas, meaning "stream of lava", and refers to the layered intrusions of the Bushfeld Complex in South Africa. The term was proposed by the Subcommission on Precambrian Stratigraphy as a subdivision of the Proterozoic Eon, and was ratified by the International Union of Geological Sciences in 1990.[2][3] In 2012, there have been suggestions to replace the Rhyacian with an alternate name, bearing a time interval of 2250 to 2060 Ma, and decided on the basis of its stratigraphy. The name Jatulian was proposed in reference to the Lomagundi-Jatuli excursion event, while the term Eukaryian was chosen due to the period's existing signs of the earliest eukaryotic fossils.[4] As of December 2024, a replacement for the Rhyacian has not been officially adopted by the IUGS.[5] The term Jatulian, however, has been used in the regional stratigraphy of Fennoscandia.[6]
Paleogeography
The Bushveld Igneous Complex and some other similar intrusions formed during this period.[7]
Climate
The Huronian (Makganyene) global glaciation began at the start of the Siderian and lasted approx. 300 million years. It lasted about 40% of this period.[8]
Life
This period is when the eukaryotes are thought to have originated from the symbiosis between asgardarchaea and alphaproteobacteria, as well as the sexual reproduction found within the eukaryotes only, thus the alternative name Eukaryian.[9][10][11] Possible signs of Macroscopic life have been found in Rhyacian aged rocks,[12][13] although these are heavily disputed due their age and probable abiotic origins.[14][15]
References
Citations
- ^ Teitler, Yoram; Hir, Guillaume Le; Fluteau, Frédéric; Philippot, Pascal; Donnadieu, Yannick (June 2014). "Investigating the Paleoproterozoic glaciations with 3-D climate modeling". Earth and Planetary Science Letters. 395: 71–80. Bibcode:2014E&PSL.395...71T. doi:10.1016/j.epsl.2014.03.044. eISSN 1385-013X. ISSN 0012-821X. LCCN 66009932. OCLC 1567193. Retrieved December 10, 2025.
- ^ a b c Plumb, Kenneth A. (June 1991). "New Precambrian time scale". Episodes. 14 (2): 139–140. doi:10.18814/epiiugs/1991/v14i2/005. eISSN 2586-1298. ISSN 0705-3797. LCCN 78646808. OCLC 4130038. S2CID 126954461.
- ^ Cowie, John W.; Ziegler, Willi; Remane, Jürgen (June 1989). "Stratigraphic Commission Accelerates Progress, 1984 to 1989" (PDF). Episodes. 12 (2): 79–82. doi:10.18814/epiiugs/1989/v12i2/003. eISSN 2586-1298. ISSN 0705-3797. LCCN 78646808. OCLC 4130038. S2CID 204264548. Archived (PDF) from the original on October 10, 2022. Retrieved December 11, 2025.
- ^ Kranendonk 2012, pp. 361, 363.
- ^ "International Chronostratigraphic Chart" (PDF). International Commission on Stratigraphy. December 2024. Retrieved October 23, 2025.
- ^ Bernard, Bingen; Solli, Arne; Viola, Giulio; Torgersen, Espen; Sandstad, Jan Sverre; Whitehouse, Martin J.; Røhr, Torkil S.; Ganerød, Morgan; Nasuti, Aziz (2015). "Geochronology of the Palaeoproterozoic Kautokeino Greenstone Belt, Finnmark, Norway: Tectonic implications in a Fennoscandia context" (PDF). Norwegian Journal of Geology. 95 (3–4): 365–396. doi:10.17850/njg95-3-09. eISSN 2387-5852. ISSN 0029-196X. LCCN sf81006060. OCLC 1760475. S2CID 30587404. Retrieved January 21, 2026.
- ^ James G. Ogg (2004). "Status on Divisions of the International Geologic Time Scale". Lethaia. 37 (2): 183–199. doi:10.1080/00241160410006492.
- ^ Kopp; Kirschvink, JL; Hilburn, IA; Nash, CZ; et al. (August 2005). "The Paleoproterozoic Snowball: A climate disaster triggered by the evolution of oxygenic photosynthesis" (PDF). PNAS. 102 (32): 11131–6. Bibcode:2005PNAS..10211131K. doi:10.1073/pnas.0504878102. PMC 1183582. PMID 16061801.
- ^ Strassert, Jürgen F. H.; Irisarri, Iker; Williams, Tom A.; Burki, Fabien (2021). "A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids". Nature. 12 (1): 1879. Bibcode:2021NatCo..12.1879S. doi:10.1038/s41467-021-22044-z. PMC 7994803. PMID 33767194.
- ^ Mänd, Kaarel; Lalonde, Stefan V.; Robbins, Leslie J.; Thoby, Marie; Paiste, Kärt; Kreitsmann, Timmu; Paiste, Päärn; Reinhard, Christopher T.; Romashkin, Alexandr E.; Planavsky, Noah J.; Kirsimäe, Kalle; Lepland, Aivo; Konhauser, Kurt O. (April 2020). "Palaeoproterozoic oxygenated oceans following the Lomagundi–Jatuli Event". Nature Geoscience. 13 (4): 302–306. Bibcode:2020NatGe..13..302M. doi:10.1038/s41561-020-0558-5. hdl:10037/19269. S2CID 212732729.
- ^ Van Kranendonk, Martin J. (2012). "16: A Chronostratigraphic Division of the Precambrian: Possibilities and Challenges". In Felix M. Gradstein; James G. Ogg; Mark D. Schmitz; abi M. Ogg (eds.). The geologic time scale 2012 (1st ed.). Amsterdam: Elsevier. pp. 359–365. doi:10.1016/B978-0-444-59425-9.00016-0. ISBN 978-0-44-459425-9.
- ^ Chi Fru, Ernest; Aubineau, Jérémie; Bankole, Olabode; Ghnahalla, Mohamed; Tamehe, Landry Soh; El Albani, Abderrazak (August 2024). "Hydrothermal seawater eutrophication triggered local macrobiological experimentation in the 2100 Ma Paleoproterozoic Francevillian sub-basin". Precambrian Research. 409 107453. doi:10.1016/j.precamres.2024.107453.
- ^ "Complex life on Earth began around 1.5 billion years earlier than previously thought, new study claims". phys.org. 2024-07-29.
- ^ Ossa Ossa, Frantz; Pons, Marie-Laure; Bekker, Andrey; Hofmann, Axel; Poulton, Simon W.; Andersen, Morten B.; Agangi, Andrea; Gregory, Daniel; Reinke, Christian; Steinhilber, Bernd; Marin-Carbonne, Johanna; Schoenberg, Ronny (June 2023). "Zinc enrichment and isotopic fractionation in a marine habitat of the c. 2.1 Ga Francevillian Group: A signature of zinc utilization by eukaryotes?". Earth and Planetary Science Letters. 611 118147. Bibcode:2023E&PSL.61118147O. doi:10.1016/j.epsl.2023.118147.
- ^ Fakhraee, Mojtaba; Tarhan, Lidya G.; Reinhard, Christopher T.; Crowe, Sean A.; Lyons, Timothy W.; Planavsky, Noah J. (May 2023). "Earth's surface oxygenation and the rise of eukaryotic life: Relationships to the Lomagundi positive carbon isotope excursion revisited". Earth-Science Reviews. 240 104398. Bibcode:2023ESRv..24004398F. doi:10.1016/j.earscirev.2023.104398. S2CID 257761993.
Sources
- Kranendonk, M.J. Van (2012). "A Chronostratigraphic Division of the Precambrian". In Gradstein, Felix M.; Ogg, James G.; Schmitz, Mark D.; Ogg, Gabi M. (eds.). The Geologic Time Scale 2012. Vol. 1. Elsevier. pp. 299–392. ISBN 978-0-44-459390-0. LCCN 2012538100. OCLC 773025121.
Further reading
- "Rhyacian Period". GeoWhen Database. Archived from the original on August 19, 2006. Retrieved January 5, 2006.