ABSTRACT

Detrital ilmenite grains carry unique chemical fingerprints that can be used in provenance research. The elemental composition (Mn, Ti, V, Mg, Cr, Al; reported in weight percent oxide as determined by electron probe microanalysis) of homogeneous detrital ilmenite grains from felsic plutonic and volcanic, intermediate volcanic, and marie plutonic and volcanic parent rocks indicates that chemical signatures obtained in felsic and marie igneous parent rocks are retained by detrital ilmenite grains in daughter sands. Grains from marie igneous sources are enriched in TiO₂ (50 ± 1%) and have a more narrow range then grains from felsic igneous sources (48 ± 2%). In addition, grains with MnO > 2.0% are most prevalent in sands from felsic rocks. Stepwise discriminan function analysis, using the oxides MnO, TiO₂, V₂O₃, MgO, Cr₂O₃, and Al₂O₃ as the discriminating variables, found that grains from felsic and marie igneous rocks could be correctly classified 86% of the time. However, when grains from intermediate volcanic sources were added to the model, correct classification dropped to 62%. The complex chemical nature of detrital ilmenite grains from intermediate igneous sources indicates that there is much yet to learn about the composition of detrital ilmenite grains. However, if used in conjunction with other methods, chemical fingerprinting in detrital ilmenite may be a valuable addition to provenance research.