Search

Dolerites of the parallel dikes formed in a back-arc spreading setting have been dated by Sm–Nd to the Silurian (426 ± 34 Ma) for Mount Azov in the Central Urals. The age coincides with that for zircons (428.5 ± 3.7 Ma) from the East Ural Megazone dolerites, which indicates the regional extent of the back-arc spreading processes. Study of the ontogeny and mineral inclusions in the Middle–Upper Devonian zircons from the dikes of Mount Azov showed that the formation of zircons occurred during regional metamorphism of the dolerite and hosting basalts. This metamorphism coincides with time of onset of the Late Devonian collision, when collision processes engulfed practically the entire region. [ABSTRACT FROM AUTHOR]

This work presents the results of studying srilankite, a rare zirconium titanate (ZrTi2O6), associated with ilmenite, rutile, zircon, uraninite, and other minerals discovered in high-pressure garnetites of the lherzolite Mindyak massif (Southern Urals). Srilankite occurs as inclusions in ilmenite and rutile of up to several tens of microns in size. It was established for the first time that srilankite contains a significant UO2 admixture (up to 20%). The negative correlation between Zr and U is evidence of isomorphism in the srilankite-brannerite system. The association of srilankite with high-Zr rutile indicates that formation of these minerals occurred at T > 850°С. [ABSTRACT FROM AUTHOR]