ON THE COMPOSITION AND ZONING OF ACCESSOR Y MINERALS OF ALKALINE-ULTRABASIC ROCKS AS AN INDICATOR OF THE COMPOSITION AND PECULARITIES OF PRIMARY MAGMATIC DIFFERENTIATION
It. Rass et Ip. Laputina, ON THE COMPOSITION AND ZONING OF ACCESSOR Y MINERALS OF ALKALINE-ULTRABASIC ROCKS AS AN INDICATOR OF THE COMPOSITION AND PECULARITIES OF PRIMARY MAGMATIC DIFFERENTIATION, Geohimia, (5), 1995, pp. 720-732
The composition and zoning of perovskite and apatite crystals of 30 sa
mples of alkaline-ultrabasic rocks and carbonatites from massifs (Guli
, Kugda) of Meimecha-Kotuy province (NW of Siberian platform) and Turi
y of Karelian-Kola province (Kola peninsula) was studied. It was estab
lished that main components of studied minerals are weakly variable wh
ereas the content of FeO, Mb(2)O(5), SrO, La2O3 and CeO2 in perovskite
s and SrO, La2O3, and CeO2 in apatites are found to be variable along
3 trends: from the center to the peripheric zones of crystals; in succ
essive derivates of the alkaline-ultrabasic rocks; in different massif
s. It was shown that the distribution of elements in the zonal crystal
s is governed by the petrological type of alkaline-ultrabasic rocks. T
he latter are differing in melilite content and are considered as repr
esentatives of two different rocks series being derived from different
initial magmas.