Substitution of Mn+2 for Fe+2 in Fe-Ti Oxide Minerals: Application to Provenance Determination of Detrital Ilmenites

Ten Fe-Ti oxide grains from Wisconsinan till in Ohio, including two exhibiting exsolution lamellae, were analyzed for iron, titanium, manganese, silicon, and aluminum using an electron microprobe. The grains had a wide range of iron and titanium concentrations extending from magnetite and titanomagnetite to ilmenite and to ferrorutile. The ilmenite grains and lamellae contained 0.60 ± 0.31 % MnO, which is about ten times more than the average MnO concentration of the magnetite grains (0.06 ± 0.04%). The MnO content of ilmenites from igneous rocks in the Oslo Graben, Norway, (Neumann, 1974) increased with the silica content of the host rocks. This relationship was applied to the ilmenite grains from the Wisconsinan till in Ohio to reveal that the ilmenite from the till originated in low-silica rocks on the Precambrian shield of Canada. The result of this study was a new method of determining the possible source(s) of detrital Fe-Ti oxide grains.No embarg