Mesoarchean

The Mesoarchean (/ˌmzɑːrˈkən/, also spelled Mesoarchaean) is a geologic era within the Archean Eon, spanning 3,200 to 2,800 million years ago. The era is defined chronometrically and is not referenced to a specific level in a rock section on Earth. Fossils from Australia show that stromatolites have grown on Earth since the Mesoarchean. The Pongola glaciation occurred around 2,900 million years ago.[1] The first supercontinent Vaalbara broke up during this era about 2,800 million years ago.

Mesoarchean Eon
3200–2800 million years ago
-4500 
-4000 
-3500 
-3000 
-2500 
-2000 
-1500 
-1000 
-500 
0 

The earliest reefs date from this era, and were probably formed by stromatolites[2][3]. Analysis of oxygen isotopes in cherts led to an oceanic temperature estimate around 55-85º C [4], while other studies of weathering rates postulate average temperatures below 50º C[5]. Dinitrogen content in the atmosphere is thought to have been fundamentally similar to today's, and the partial pressure of carbon dioxide was probably lower than 0.7 bar[6].

See also

References

  1. Robert E. Kopp; Joseph L. Kirschvink; Isaac A. Hilburn & Cody Z. Nash (2005). "The Paleoproterozoic snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis". Proc. Natl. Acad. Sci. U.S.A. 102 (32): 11131–6. Bibcode:2005PNAS..10211131K. doi:10.1073/pnas.0504878102. PMC 1183582. PMID 16061801.
  2. Allwood, Abigail C.; Walter, Malcolm R.; Kamber, Balz S.; Marshall, Craig P.; Burch, Ian W. (8 June 2006). "Stromatolite reef from the Early Archaean era of Australia". Nature. 441 (7094): 714–718. Bibcode:2006Natur.441..714A. doi:10.1038/nature04764. PMID 16760969.
  3. Nelson, Jon (15 April 1997). "Stromatolites: Our Mysterious Ancient Reefs". Lake Superior Magazine. Retrieved 10 March 2018.
  4. Knauth, L. P. Lowe, D. R. High Archean climatic temperature inferred from oxygen isotope geochemistry of cherts in the 3.5 Ga Swaziland group, South Africa, Geol. Soc. Amer. Bull. 115 (2003) 566 – 580.
  5. Sleep, Norman H.; Hessler, Angela M. (January 2006). "Weathering of quartz as an Archean climatic indicator" (PDF). Earth and Planetary Science Letters. 241 (3–4): 594–602. Bibcode:2006E&PSL.241..594S. doi:10.1016/j.epsl.2005.11.020. Retrieved 10 March 2018.
  6. Marty, Bernard; Zimmermann, Laurent; Pujol, Magali; Burgess, Ray; Philippot, Pascal (4 October 2013). "Nitrogen Isotopic Composition and Density of the Archean Atmosphere". Science. 342 (6154): 101–104. arXiv:1405.6337. Bibcode:2013Sci...342..101M. doi:10.1126/science.1240971. ISSN 0036-8075.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.