Vs. Antipin et al., EVOLUTION OF LI-F-GRANITES WITH THE FORMA TION OF RARE-METAL MICA SCHLIEREN (BEZYMYANSKY MASSIF, PREBAIKALIA), Geologia i geofizika, 38(7), 1997, pp. 1216-1227
Detailed geochemical studies were first carried out in Eastern Prebaik
alia for race-metal Li-F-granites of the Bezymyanny Massif, which date
from the Jurassic. The main facies rock varieties of the massif are m
icrocline-albite and amazonite-albite granites, where the evolution of
mica composition proceeds from Fe-biotites to protolithionites and Li
-phengites. Unlike typical Li-F-granites of the Mongolo-Transbaikalian
Province, associating with rare-metal mineralization, the granites of
the Bezymyanny Massif have relatively low contents of Li, F, Rb, Be,
Sn, Ta, Nb, with regularities of their distribution being dependent, c
hiefly, on the processes of crystallization differentiation of granite
magma. The melanocratic mica schlieren found in the Li-F-granites are
not foreign inclusions but are autholiths formed with the significant
participation of a fluid phase in the process of magmatic evolution o
f the Bezymyanny Massif. Geochemical data on rocks, feldspars, and mic
a confirm the genetic relationship of amazonite-albite granites and me
lanocratic amazonite-mica schlieren. Exemplified by the latter it is s
hown that during the fluid-magmatic evolution of the massif of Li-F-gr
anites with moderate contents of many lithophile rare elements there c
ould be favorable conditions for essential concentration of Li, Rb, Sn
, Ta, Nb, Zr, and other elements to form unusual ultrarare-metal mica
schlieren. Their further study will be useful in interpretation of way
s of Li-F-granite magma evolution.