A Xenolithic Pegmatite in the Dalbeattie “Granite”

Abstract

SUMMARY AND CONCLUSION A pegmatite cutting granodiorite contains abundant xenoliths which are in various stages of assimilation. Assimilation involved the conversion by the process of “reciprocal reaction” of the minerals of the xenoliths into species which were in equilibrium under the prevailing magmatic conditions, and the subsequent “mechanical disintegration” of the xenoliths with the strewing of their minerals in the pegmatite. Solution of xenolithic material was not important, probably only affecting potash-felspar. The fact that the active magma was a pegmatite suggests that high temperatures were not available, and its assimilating power must be attributed to its large volatile content. The xenoliths were probably derived from the walls of the pegmatite vein both in the granodiorite and in the country-rocks.