The effect of fluorine and titanium on the vapour-absent melting of phlogopite and quartz

Abstract

A table published by Bowell (1992; Table 3) failed to cite all four sources of the given data which were: a compilation by Groen et al. (1990) with additional information from Puddephatt (1978; 1987) and Bjerrum (1971), and calculations by this author based on reported values of Gibbs free energies. The last group were incorrectly calculated and should be ignored. The literature sources are, in turn, compila

Stability of F-Ti-phlogopite in the system phlogopite–sillimanite–quartz: an experimental study of dehydration melting in H2O-saturated and undersaturated conditions

“…The wide divariant field of dehydration melting of phlogopite in their experiments may be attributed to the combined effects of MgO and A1 (vI) in phlogopite and continued buffering of Ti in their reaction. This is evident from the earlier report of Tareen et al (1995) in which the Ti content of phlogopite in the Phl-Qtz system was un-buffered and as a result, phlogopite did not persist for more than 50~ above the enstatitein boundary and it disappeared when the runs were seeded with enstatite.…”

“…(1) was reported by Tareen et al (1995). They showed an increase in the reaction boundary temperature by about 140~ relative to an F-Tifree system (Vielzeuf and Clemens, 1992) with their natural phlogopite containing 1.31 wt.% TiO2 and 3.5 wt.% F (XMg = 0.97 and Xv = 0.39).…”

“…A comparison of the results of Peterson et al (1991) and Tareen et al (1995) indicates that the combined effect of F and Ti is additive on the thermal stability of phlogopite. The flourine content of (3.5 wt.%) in natural phlogopite used by Tareen et al, (1995) produced an enstatite-in boundary at temperatures higher by 50~ than that of Peterson et al (1991) who used synthetic phlogopite with a higher flourine content of 5.09 wt.%. This discrepancy may be due to the presence of 1.31 wt.% of TiO2 in the natural phlogopite used by the former.…”

Occurrences and chemical compositions of ultrapotassic mafic dyke rocks from Skallevikshalsen and Rundvågshetta, Lützow-Holm Complex, East Antarctica

“…Partial melting during the UHT metamorphism to form felsic melt has been reported (Hiroi et al, 2019(Hiroi et al, , 2023: it has been suggested that the composition of the melt produced at that time is A-type granite-like with weakly peraluminous to weakly peralkaline affinity, ferroan character, high alkali contents, high K/Na and Ga/Al, and low Ca, Ba, Sr, and H 2 O concentrations (Carvalho et al, 2023). When biotite melts at high temperatures, it crystallizes orthopyroxene to produce melt, and the higher the Ti and F contents of biotite, the longer the stable condition of the bio-tite extends to higher temperatures (Tareen et al, 1995). Furthermore, when biotite enriched with Ti and F coexists with sillimanite, specifically when the starting material is like pelitic rocks, melting results in cordierite crystallization, and at a higher temperature (about 1100 °C), sapphirine is produced together with the melt.…”

Halogen-dominant mineralization at Mt. Calvario dome (Mt. Etna) as a response of volatile flushing into the magma plumbing system

“…In this regard, understanding of the differences in the physical and/or chemical conditions leading to crystallization of these two phases could be a relevant issue to evaluate the relative role of P-T-X on hydrothermal fluids in developing diverse assemblages. Phase equilibria of phlogopite in the presence of fluorine have been widely investigated (e.g., Shell and Ivey 1969;Munoz and Ludington 1974;Foley et al 1986;Vukadinovic and Edgar 1993;Foley 1996, 2000;Tareen et al 1995Tareen et al , 1998Veksler et al 1998;Pichavant 1999, 2000). Foley et al (1986), in particular, verified experimentally that the thermal stability of fluorine-rich phlogopite in the system KAlSiO 4 -Mg 2 SiO 4 -SiO 2 -F 2 O -1 is enhanced up to ~300 °C at high pressure by substitution of fluorine for OH groups.…”