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== Paleogeography == |
== Paleogeography == |
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The Baykonur Formation constitutes the northern and eastern edges of the Syrdarya and Tarim microcontinents.<ref>Kiselev V. V. (2001). Analogues of the Sinian complex in the central and northern Tien Shan ”Geology and Geophysics” 2001 ”42” 1453-1463</ref> |
The Baykonur Formation constitutes the northern and eastern edges of the Syrdarya and Tarim microcontinents.<ref>Kiselev V. V. (2001). Analogues of the Sinian complex in the central and northern Tien Shan ”Geology and Geophysics” 2001 ”42” 1453-1463</ref> |
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== References == |
== References == |
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{{Reflist}} |
{{Reflist}} |
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Latest revision as of 22:15, 3 February 2026
Geological formation in Kazakhstan and Kyrgyzstan
| Baykonur Formation | |
|---|---|
| Type | Geological formation |
| Unit of | Ulutau Group |
| Underlies | Koktal Formation Kurumsak Formation, Kurmenty Formation, Terreneuvian shale (unconformity) |
| Overlies | Kurayly Formation, Aksumbe Formation, Dzakhbolot Formation, Tonian–Cryogenian boundary (unconformity) |
| Thickness | up to 600 metres (1,970 ft)[2] |
| Primary | Diamictite, shale |
| Other | Phyllite, feldspar, dolomite, conglomerate |
| Region | Ulytau, Bolshoi Karatau, Aksu-Zhabagly, Middle Tian Shan, Kyrgyzstan-China border |
| Country | Kazakhstan and Kyrgyzstan |
| Named for | Baikonyr |
| Region | Rang River, Kazakhstan |
The Baykonur Formation[3] is a geological formation of Neoproterozoic (Ediacaran) age which outcrops in Kazakhstan and Kyrgyzstan.[1] It is correlated in age with the Hankalchough Formation in China where glaciation also occurred.[4]
The presence of diamictites was identified in the Baykonur Formation in 1924 by Dmitry Nalivkin,[4] and the Baykonur Formation was studied for the first time by Ergaliev (1965).[5] Chumakov (2009) and Chumakov (2011) standardised the stratigraphy of the Baykonur Formation and formalised the name of the formation.[2][4]
The Baykonur Formation is an upper unit of the Ulutau Group and it outcrops in the mountains of Kazakhstan and Kyrgyzstan towards the border with China.[1][4] It was formed during a period of heavy glaciation known as the Baykonurian glaciation which spread for at least 1,600 kilometres (990 mi),[1] and it has been posited as a contributor to the Cambrian explosion.[6] During the Ordovician and Devonian, the Baykonur Formation experienced faulting and folding during the Caledonian orogeny.[4]
The Baykonur Formation is formed of diamictite and phyllite with dropstones,[7] a shale layer and in some sections a feldspar layer and conglomerate layers increasing in abundance towards the western sections;[8] it has unconformities between its upper and lower boundaries with Terreneuvian shale and granosyenite of Tonian–Cryogenian boundary age respectively, although in places it does comfortably underly the Koktal, Kurumsak, and Kurmenty Formation and comfortably overlies the Kurayly, Aksumbe, and Dzakhbolot Formation.[4] It is up to 600 metres (2,000 ft) in places with localised diamictite outcrops reaching 30 metres (98 ft) in thickness.[2][9]
The age of the Baykonur Formation was initially suggested to be Late Paleozoic age in 1924 before the date was suggested to be Cambrian age by Borovikov (1953)[10] and then Precambrian age by Korolev (1963).[11] This was then changed to ?Ediacaran to Early Cambrian age by Chumakov (2011).[4] Alexeiv (2025) refined the age to 556–540 Ma.[1]
The Baykonur Formation constitutes margins believed to be related to the northern and eastern edges of the Syrdarya and Tarim microcontinents.[12]
- ^ a b c d e Alexeiev, D. V. (2025). “LATE EDIACARAN GLACIAL DEPOSITS OF THE BAYKONUR FORMATION, MIDDLE TIANSHAN OF EAST KYRGYZSTAN: AGE SUBSTANTIATION BASED ON DETRITAL ZIRCON U–Th–Pb (LA-ICP-MS) GEOCHRONOLOGICAL STUDY”. Доклады Российской академии наук. Науки о Земле / Doklady Earth Sciences. 521 (1): 5. doi:10.7868/s3034506525030015. ISSN 3034-5065.
- ^ a b c Chumakov, N. M. (2009). “The Baykonurian glaciohorizon of the Late Vendian”. Stratigraphy and Geological Correlation. 17 (4): 373–381. doi:10.1134/s0869593809040029. ISSN 0869-5938.
- ^ “Project 512 Neoproterozoic ice ages” (PDF). Russian National Committee for IGCP—Annual Report on IGCP-related Activities 2010. Russian National Committee for IGCP. 2010. p. 11. Retrieved 7 November 2016.
- ^ a b c d e f g Chumakov, N. M. (30 November 2011). “Chapter 26 Glacial deposits of the Baykonur Formation, Kazakhstan and Kyrgyzstan”. Geological Society, London, Memoirs. 36 (1): 303–307. doi:10.1144/M36.26.
- ^ Ergaliev, G.K. (1965). On stratigraphy of Vendian and Cambrian Baykonur Karatau–Dzhebagly zone. Izvestia of Academy of Sciences of Kazakh SSR. Geological series, 6: 31–43 (in Russian).
- ^ Germs, G.J.B.; Gaucher, C. (2012). “Nature and extent of a late Ediacaran (ca. 547 Ma) glacigenic erosion surface in southern Africa”. South African Journal of Geology. 115 (1): 91–102. Bibcode:2012SAJG..115…91G. doi:10.2113/gssajg.115.91.
- ^ Korolev V. G., Maksumova R. A. (1984). Precambrian Tillites and Tilloids of Tien Shan Frunze Ilim (in Russian)
- ^ Kheraskova T. N. (1986). Vendian-Cambrian Rock Associations of Caledonides of Asia Moscow Nayka (in Russian)
- ^ “Geological Map of Khan Tengri Massif” (PDF). www.kyrgyzstan.ethz.ch. 2008.
- ^ Borovikov L. I. (1953). Lower Paleozoic of Dzhezkazgan-Ulutau Region of West Part of Kazakhstan 1955 Nedra, Moscow (in Russian)
- ^ Korolev V. G. (1963). About Cambrian boundaries in the Middle Asia (in Russian) Trudy Frunzinskogo politekhnicheskogo institute, Geologiya, Gornoe delo 1963 10 16-21
- ^ Kiselev V. V. (2001). Analogues of the Sinian complex in the central and northern Tien Shan Geology and Geophysics 2001 42 1453-1463
