Abstract
Major- and minor-element site occupancies have been determined for Ni- and Mn-rich synthetic forsteritic olivines that were equilibrated to 300, 600, 900, or 1,050° C, by analyzing electron-channeling-enhanced x-ray emissions. Site preferences for minor elements (Ni>Cr for M1; Ca>Mn for M2) are consistent with those reported in previous studies. Degrees of ordering at different elevated temperatures differ less than analytical errors, although there may be significant differences in ordering between olivines that have been rapidly quenched from 300° C or higher and those that have undergone normal lava-flow cooling histories. An x-ray structure refinement of San Carlos olivine (R=0.031) gives major-element occupancies similar to those determined by electron-channeling on the same material. Thus, the channeling technique gives results that are consistent with other methods, and it may be possible to use the technique to identify olivines that have undergone very rapid quenching.
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Aikawa N, Kumazawa M, Tokonami M (1985) Temperature dependence of intersite distribution of Mg and Fe in olivine and their associated change of lattice parameters. Phys Chem Minerals 12:1–8
Bish DL, Burnham CW (1984) Structure energy calculations on optimum distance model structures: application to the silicate olivines. Am Mineral 69:1102–1109
Brown GE (1980) Olivines and silicate spinels. Reviews in Mineralogy 5:275–381
Finger LW, Prince E (1975) A system of Fortran IV computer programs for crystal structure computations. National Bureau of Standards Technical Note 854
Lumpkin GR, Ribbe PH (1983) Composition, order-disorder and lattice parameters of olivines: relationships in silicate, germanate, beryllate, phosphate and borate olivines. Am Mineral 68:164–176
Otten MT, Buseck PR (1986) TEM determination of site occupancies in pyrope garnet (abstr.) Internat Mineral Assoc 1986:193
Rager H (1977) Electron spin resonance of trivalent chromium in forsterite, Mg2SiO4. Phys Chem Minerals 1:371–378
Self PG, Buseck PR (1983) High-resolution structure determination by ALCHEMI. In Bailey GW (ed) Proceedings of the 41st Annual Meeting of the Electron Microscopy Society of America. San Francisco Press, San Francisco, pp 178–181
Smyth JR, Taftø J (1982) Major and minor element site occupancies in heated natural forsterite. Geophys Res Lett 9:1113–1116
Taftø J (1982) The cation-atom distribution in a (Cr,Fe,Al,Mg)3O4 spinel as revealed from the channeling effect in electron-induced x-ray emission. J Appl Crystallogr 15:378–381
Taftø J, Buseck PR (1983) Quantitative study of Al-Si ordering in an orthoclase feldspar using an analytical transmission electron microscopy. Am Mineral 68:944–950
Taftø J, Spence JCH (1982) Crystal site location of iron and trace elements in a magnesium-iron olivine by a new crystallographic technique. Science 218:49–51
Will G, Nover G (1979) Influence of oxygen partial pressure on the Mg/Fe distribution in olivines. Phys Chem Minerals 4:199–208
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McCormick, T.C., Smyth, J.R. & Lofgren, G.E. Site occupancies of minor elements in synthetic olivines as determined by channeling-enhanced X-ray emission. Phys Chem Minerals 14, 368–372 (1987). https://doi.org/10.1007/BF00309812
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DOI: https://doi.org/10.1007/BF00309812