Zhidoy Alkali-Ultramafic Rock and Carbonatite Massif: GeochemicalFeatures, Its Sources And Ore-Bearing

The article considers the geological position of the Zhidoy massif and its age. The scheme of magmatism of the massif has been developed. The graphs of paired correlations of petrogenic elements in massif rocks which had a consistent trend in composition are given for validation purposes. The present article provides graphs of REE spectra and the spider diagram of rare elements concentration in the massif rocks. Pyroxenites are the early rocks of the massif, which are the ores for titanium. Titanium is concentrated in three minerals: titanium magnetite, ilmenite and perovskite. The main type of titanium ores, perovskite, is known only in the Zhidoy massif. A conclusion about the mantle sources of the primary magma of the massif
is drawn based on the geochemistry of the isotopes Sr and Nd.

Fig. 1 Spectra of rare-earth elements in rocks of the Zhidoy massif (chondrite-normalized).
Symbols: 1−pyroxenite, 2−ijolite, 3−syenite, 4−phenite

 

Fig. 2 Spider-diagram of the Zhidoy massif rocks

Conclusions
1. Three varieties of ore pyroxenites have been defined−titanium-magnetite, ilmenite and perovskite ore.
2. The petrochemical diagrams show a common trend in the composition of rock- forming elements, indicating the homomorphism of the rocks and their crystallization from a single primary magma.
3. Geochemical data also confirm the genetic relation of the Zhidoy massif.
4. Mantle source, the depurated mantle for the primary magma of the Zhidoy massif, has been determined on the basis of isotope data.