PECULIARITIES OF CHEMICAL COMPOSITION OF STAUROLITE FROM THE HIGHLY ALUMINIFEROUS ROCKS OF KEIVSKY BLOCK

摘要

The new data obitained by the geochemicalstudy of rocks and staurolites from Keivsky block allow tomake the following conclusions. Staurolites from the highlyaluminiferous rocks show significant variation in the rareelements contents. The strongest effect upon geochemistry ofthese minerals (in particular, Zr, Y, Nb, Cr, V contents) is madeby composition of the host rocks. Thermal conditions of theProterozoic mineral forming processes were quite similar formetamorphic and metasomatic rocks. Variations in contents asfor major, so for trace elements in composition of stauroliteshave direct links with character of mineral parageneses.Distinct effect upon contents of some rare elements in themineral is shown by presence in the rock of kyanite, Mg-chlorite, garnet, plagioclase. Variations in the trace elementscontents depend also upon contents of the major ones (FeO,MgO, TiO_2, etc.). Metamorphic staurolites are similar bytheir composition to staurolites of metasomatic genesis.Development of an Fe-metasomatism has been reflected invalues of Zr and FeO contents. Distribution of Co, V and Cubetween coexisting staurolites and garnets is quite close to theideal one and, thus, testify to equilibrium of their paragenesis.