Oxygen isotope equilibrium between muscovite and water

摘要: Oxygen isotopes have been equilibrated between muscovite and aqueous alkali chloride solution paragonite in the temperature range of 400°–650°C at 1 1.5 kb fluid pressure. Isotopic equilibrium was inferred from fact that compatible fractionation factors were obtained using 3 different chemical reactions to produce mica: (1) or prepared by reacting natural kaolinite with 2–3 molal KCl NaCl solutions; (2) crystallized pure water a gel; (3) synthetic reacted solution, producing an ion exchange reaction. The M modification mica made every experiment. In several cases extent oxygen traced running companion equilibrations solutions unusually low O^(18)/O^(16) ratio. No isotopic discernible studied. Per mille fractionations are given expression 10^3 α = 2.38(10^6T^(−2)) − 3.89. These data can be combined results other laboratory equilibration studies establish set calibrated isotope geothermometers. Analogous feldspar systems previously reported, direct relationship cation suggests some type solution-redeposition mechanism operated during muscovite-paragonite transformations solutions. Also, extensive (with solution) accompanies formation implies breakdown structure. This notion does not concur hypotheses based on rate X-ray measurements unaltered structure is partially inherited mica.