INTERACTION BETWEEN MELT INCLUSIONS AND SYNTHETIC HOST PERICLASE ON HEATING

Abstract

Detailed studies of meh incIusions in synthetie pericIase, obtained from natural magnesite by are-fusion, showed that their eompositions essentially differ from the composition of the starting melt. They are to a greater extent enriehed in elements (Si, Ca, Al, Fe) whieh are present in small amounts in the starting melt (does not exeeed 4-5 wt. % in total). It is assumed that the trapping of these incIusions is intimately assoeiated with segre­ gation of eomponents whieh do not enter the pericIase lattiee at the front of erystallization of the host mineral. Heating of the sampies resulted in diffusive exchange of components between melt incIusions and host mineral (diffusion of iron from the incIusions into the matrix, and of magnesium from pericIase into the incIusions takes plaee on heating). This proeess starts at 950°C and is eonsiderably aeeelerated with the appearanee of the first portions of melt (I250°C). Key-words: melt incIusion, synthetie periclase, iron diffusion.