The Novosibirsk massif is composed of porphyritic biotite granites, granosyenites and biotite-containing leucogranites (Mochishche stock).
The main area of the massifs is mediumgrained biotite leucogranites.
In addition, Figures 4 and 5, and the log f[O.sub.2]-T diagram for biotites (Figure 6) at [P.sub.H20] = 207.0 MPa (Wones and Eugster, 1965), suggest that these biotites were crystallized at log f[O.sub.2] values between-11.6 and-12.5.
However, the biotites within the Wushan granodiorite are unaltered (Figure 2), and Etsuo et al.
Gilkes RJ, Suddhiprakarn A (1979) Biotite
alteration in deeply weathered granite.
5b; Vernon 1986) defined by minute, oriented euhedral biotite
inclusions (Mg/(Mg+Fe) atomic ratio (Mg#)--0.55; Rb/Sr = 162-244).
Matejovska, O.: 1970, Composition of coexisting garnets and biotites
from some granulites of Moldanubicum, Czechoslovakia, N.
in this study refers to a regular 1:1 interstratified (mixed-layer) biotite-vermiculite, a mineral recognized in many vermiculite deposits (Boettcher, 1966).
Geochemistry of biotite
in meta-bentonites as an age discriminant, indicator of regional magma sources and potential correlating tool.
The smallest effect of heterogeneities is observed in the samples of biotite
(h003), garnet (h014) and mineralized chloritized garnet amphibolite (h028) with a fairly strict one-way orientation of crystalline-acoustic axes in mineral grains.
Subhedral grains of biotite
, plagioclase and euhedral grains of zircon are enclosed in bigger quartz grains.
Adopted nomenclature differentiates phlogopite from biotite
on the basis of the Mg:Fe molar proportions: phlogopite (>2:1) and biotite