Experimental Study of Silicon Isotope Dynamic Fractionation and Its Application in Geology

Silicon shows no variation in its chemical valence in nature and exists mainlyin the form of silicon-oxygen tetrahedra, so very small silicon isotope thermodynamic fractionation occurs and the resultant silicon isotope variation is limited. Dynamic fractionation of Si isotopes during precipitation of SiO2 from a solution is a main factor leadingto substantial variations in silicon isotopes in nature. In this experimental study, wedetermined the dynamic fractionation factor a for silicon isotopes during precipitationof SiO2 from the solution. And in combination of α, a theoretical explanation is presented of the considerably low δ30Si values of black smokers on modern seafloor, Archeanbanded magnetite-quartzite and clay minrals of weahering origin, and of clearly highδ30Si values of siliceous rocks in shallow-sea carbonate platforms.