geobarometry based on the limiting assemblage with K-feldspar, phlogopite, and quartz.
In argillite rock, the minerals glauconite, phengite
and illite, observed by DRX, constitute the main potential K sources (Figure 1C).
cooling ages in the Caledonides of western Norway.
The content of phengite
component is therefore very low.
The composition of the white-mica is muscovite to phengite
(Willner et al.
Analyses of the multiequilibrium between chlorite and phengite
solide solution following Lanari et al (2010) method, allow the estimation of metamorphic conditions at 400degC for 5 Kbar for this last event.
These cavities are partially filled with chlorite, Mg-celadonite, illite, phengite
micas or quartz.
Eclogites are fine-grained rocks consisting of garnet porphyroblasts set in a matrix of omphacite (25%), amphibole (hornblende or barroisite) (20%), plagioclase and zoisite; rutile often rimmed by titanite occurs as the main accessory mineral phase, phengite
is quite rare whereas quartz is nearly absent.
Jitang metamorphic complexes: 40Ar/39Ar age of Phengite
in Mica-quartzose Schist 230+-1 Ma (Wang GH, 2008); Gemuri metamorphic complexes: Ar-Ar age of Glaucophane 222Ma, Crossite 223-220Ma or 221Ma, and Phengite
215Ma (Table 1); Jitang metamorphic complexes in this study: 40Ar/39Ar ages of Phengite
in Mica-quartzose Schist 219.
0,5] micas Increasing amounts of Si [right arrow] Increasing amount of Fe [left arrow] Phengite
However the corresponding P-T curve (2 kbar, 350[degrees]C; 4 kbar, 310[degrees]C) of the reaction chlorite + K-feldspar = muscovite/ phengite
+ biotite + quartz + [H.
Mg, Fe, and K addition) modified hydrothermal muscovite into a high-pressure phengite