Oncolite

From Wikipedia, the free encyclopedia

 This article is orphaned as few or no other articles link to it.
Please help introduce links in articles on related topics. (April 2007)
Oncolites from the upper Burgsvik beds, with shell fragments as nuclei. Large flower is 2 cm in diameter.
Oncolites from the upper Burgsvik beds, with shell fragments as nuclei. Large flower is 2 cm in diameter.

Oncolites are sedimentary structures formed out of oncoids, which are layered spherical growth structures formed by cyanobacterial growth. Oncolites are very similar to stromatolites, but instead of forming columns they form approximately spherical structures.[1] Often the oncoids form around a central nucleus, such as a shell particle,[2] and the calcium carbonate structure is precipitated by encrusting microbes. Oncolites are indicators of warm waters in the photic zone, but are also known in contemporary freshwater environments [3]. These structures rarely exceed 10 cm in diameter.

[edit] References

  1. ^ Corsetti, F.A.; Awramik, S.M.; Pierce, D. (2003-04-15). "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. 
  2. ^ Gutschick, R.C.; Perry, T.G. (1959-11-01). "Sappington (Kinderhookian) sponges and their environment [Montana]". Journal of Paleontology 33 (6): 977–985. 
  3. ^ Riding, Robert. 1991. Calcareous Algae and Stromatolites, pp 32. Springer-Verlag Press.
 This geology article is a stub. You can help Wikipedia and WikiProject Geology by expanding it.