Ip. Solovova et al., COMPOSITION AND FORMATION CONDITIONS OF INCLUSIONS IN THE MINERALS OFANDESITES FROM CENTRAL SLOVAKIA, PETROLOGY, 5(6), 1997, pp. 570-585
Melt inclusions with high-density (>1 g/cm(3)) aqueous fluids were fou
nd in andesite minerals (Solovova et at, 1992). Conditions of magma ge
neration and crystallization were determined from data on the composit
ions of glass and minerals from the inclusions. Initial melt was enric
hed in aluminum, potassium, and chlorine and contained no more than 2
wt % of water. The occurrence of resorbed amphibolite xenoliths in the
rock minerals suggests a contribution of this rock in the formation o
f andesite melt under crustal conditions, Shallow-level ma,ama differe
ntiation at 1100-1000 degrees C, accompanied by crustal contamination,
resulted in the formation of a wide spectrum of silicic melts with up
to 76 wt % SiO2. Possible scenarios are discussed for the formation o
f melt inclusions with high-density fluids in plagioclase. The entrapm
ent of these inclusions during plagioclase crystallization from magma
is demonstrated to contradict the available experimental data on cryst
allization in the system silicic melt-water. We propose that later reb
illing processes were responsible for the formation of this fluid phas
e.