Silicon (Si) is an element present in all natural environments, including the biosphere. It has three stable isotopes of mass 28, 29, and 30, respectively. Its isotopic composition is expressed in the delta notation δ30Si (30Si/28Si) and δ29Si (29Si/28Si) in per mil units normalized to a standard reference (see “Delta, Isotopic”). The δ30Si and δ29Si vary in the solar system by up to 10 ‰ and 5 ‰, respectively. These isotopic changes in Earth and extraterrestrial materials are used to constrain diverse processes such as the origin of the solar system, core-mantle segregation, the appearance of life on the early Earth, the temperatures of the early oceans, the weathering of silicate rocks, or the role of siliceous organisms in C-Si cycles.
The potential role of silica (SiO2) in the emergence of life has been often questioned, especially because SiO2-rich deposits (cherts) host the oldest putative evidence for life. Others have wondered about the biological...
KeywordsArchean cherts Bulk silicate earth Early life Meteorites Siliceous organisms Weathering
References and Further Reading
- Armytage RMG, Georg RB, Savage PS, Williams HM, Halliday AN (2011) Silicon isotopes in meteorites and planetary core formation. Geochim Cosmochim Acta 75:3362–3676Google Scholar
- Reynolds BC, Aggarwal J, André L, Baxter D, Beucher C, Brzezinski MA, Engström E, Georg RB, Land M, Leng MJ, Opfergelt S, Rodushkin I, Sloane HJ, Van den Boorn SHJM, Vroon PZ, Cardinal D (2007) An inter-laboratory comparison of Si isotope reference materials. J Anal Atom Spectrom 22:561–568CrossRefGoogle Scholar