Writers : Razm Ara, M.; Asadi, M.;
Refference : 28th Symposium on Geosciences and the 14th Symposium on Geological Society of Iran
Publishing Year : 1389

Abstract :

Titanomagnetite forms placer deposits enriched in Ti, Cr and V elements along the northwest of Rivash area. The magnetic sand is composed mainly of titanomagnetite and hematite, with small quartz impurities quantities, pyroxene, etc. The percentage of opaque minerals (mainly titanomagnetite) was extremely high in the upper 25 cm of the alluvium, where these opaque minerals were gradually replaced with variable amounts of lighter pyroxene, hornblende, plagioclase and quartz. The physicochemical, structural and magnetic characterization of the titanomagnetite sands can clarify aspects of their geological formation; as well as suggest applications from them. The magnetic sand is composed mainly of titanomagnetite and hematite, with very small quartz impurities quantities, pyroxene, etc.
The refinement of X-rays diffraction patterns by the method of Rietveld indicates an 83.04% in weight of titanomagnetite and a 17.96% in weight of hematite. A lattice parameter a = 8.434 Å was determined for the titanomagnetite with a cubic structure, while for the hematite with structure rhombohedra, the lattice parameters were a = b = 5.062Å and c = 13.833 Å. The deviations from ideal cell parameters indicate different amounts of substitution by Ti, Cr and V elements in magnetite and hematite structures.
The iron was found mainly in the magnetic component of the particles, while the greater quantity of silicon, titanium and vanadium is in the non-magnetic component. This indicated that different genesis of Ti, Cr and V elements in titanomagnetite and hematite, while Cr originated from ultramaphic rocks (lherzolite and serpentinites), Fe and Ti from mafic rocks (gabbros, diabase and basalts) but V originated from intermediate to more acidic rocks (andesite to probably plagiogranite). The anomalous concentrations of Ti (6.8%), and V (1%) in titanomagnetite suggest that the magma enrichment during of differentiation of magma crystallization at depth.

Subject List : Placer