Earth:Oncolite

From HandWiki

Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by the growth of one or more species of microorganisms,[1] usually containing cyanobacteria.[2] Oncolites are very similar to stromatolites, but, instead of forming columns, they form approximately spherical structures.[3] The oncoids often form around a central nucleus, such as a shell fragment,[4] and a calcium carbonate structure is deposited by encrusting microbes. Oncolites are indicators of warm waters in the photic zone, but are also known in contemporary freshwater environments.[5] These structures rarely exceed 10 cm in diameter.

Oncolites may have either a porostromate or spongiostromate texture. Most oncolites are spongiostromate, having no recognisable cellular texture or microstructure. Porostromate oncolites are mostly unknown during the Precambrian; since the Eocene they have mostly been confined to freshwater environments.[6]

Distribution

The appearance of recent or near-recent freshwater oncoids has been documented in two rivers in Bavaria: the Alz, whose source is the Chiemsee, and the Moosach, near Freising.[7][8][9] Modern oncoids also grow in some springs in Atacama Desert in South America. In one particular case a system of oncoids have been observed interface between Salar de Antofalla and an adjacent wetland.[10]

References

  1. ↑ Zafar, Tehseen; Frontalini, Fabrizio; Rehman, Hafiz Ur; Khan, Danish; Ullah, Zaheen; Rahim, Hamad ur; Oyebamiji, Abiola; Hussain, Zahid et al. (June 2024). "Understanding the origin of Cambrian marine oncoids: A petrologic, geochemical, and isotopic perspective". Sedimentary Geology 466. doi:10.1016/j.sedgeo.2024.106638. Bibcode: 2024SedG..46606638Z. 
  2. ↑ Hägele, Daniela; Leinfelder, Reinhold; Grau, Jürke; Burmeister, Ernst-Gerhard; Struck, Ulrich (August 2006). "Oncoids from the river Alz (southern Germany): Tiny ecosystems in a phosphorus-limited environment". Palaeogeography, Palaeoclimatology, Palaeoecology 237 (2–4): 378–395. doi:10.1016/j.palaeo.2005.12.016. Bibcode: 2006PPP...237..378H. 
  3. ↑ Corsetti, Frank A.; Awramik, Stanley M.; Pierce, David (15 April 2003). "A complex microbiota from snowball Earth times: Microfossils from the Neoproterozoic Kingston Peak Formation, Death Valley, USA". Proceedings of the National Academy of Sciences 100 (8): 4399–4404. doi:10.1073/pnas.0730560100. PMID 12682298. Bibcode: 2003PNAS..100.4399C. 
  4. ↑ Gutschick, R. C.; Perry, T. G. (1959). "Sappington (Kinderhookian) Sponges and Their Environment". Journal of Paleontology 33 (6): 977–985. 
  5. ↑ Calcareous Algae and Stromatolites. 1991. p. 32. doi:10.1007/978-3-642-52335-9. ISBN 978-3-642-52337-3. 
  6. ↑ Monty, C. L. (1981). "Spongiostromate vs. Porostromate Stromatolites and Oncolites". Phanerozoic Stromatolites. pp. 1–4. doi:10.1007/978-3-642-67913-1_1. ISBN 978-3-642-67915-5. 
  7. ↑ Hägele, Daniela (2007). Morphogenese, Wachstum und Ökologie der modernen Süßwasser-Onkoide der Alz (Thesis). Ludwig-Maximilians-Universität München. doi:10.5282/edoc.8314.
  8. ↑ E. Rott (1994), "Der Algenaufwuchs in der Oberen Alz (Oberbayern)" (in de) (Online-Version; pdf-Datei; 7,6 MB), Berichte des Naturwissenschaftlich-medizinischen Vereins in Innsbruck (Innsbruck) 81: 229–253, http://www.biologiezentrum.at/pdf_frei_remote/BERI_81_0229-0253.pdf 
  9. ↑ Arp, Gernot (2008). "Stop 7: Tufa oncoids of the river Moosach, Molasse Basin". in Reitner, Joachim; Quéric, Nadia-Valérie; Reich, Mike. Geobiology of Stromatolites: International Kalkowsky-Symposium, Göttingen, October 4-11, 2008: Abstract Volume and Field Guide to Excursions. Universitätsverlag Göttingen. pp. 193–197. ISBN 978-3-940344-52-6. https://univerlag.uni-goettingen.de/bitstream/handle/3/isbn-978-3-940344-52-6/kalkowsky.pdf. 
  10. ↑ Villafañe, Patricio Guillermo; Lencina, Agustina Inés; Soria, Mariana; Saona, Luis Alberto; Gómez, Fernando Javier; Alonso, Guido Ezequiel; Farias, María Eugenia (31 May 2021). "Las Quínoas oncoids: a new deposit of microbialites in the Salar de Antofalla (Catamarca, Argentina)". Andean Geology 48 (2): 281. doi:10.5027/andgeoV48n2-3292. 




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