Mica chemistry of lamprophyres from the Bohemian Massif, Czechoslovakia
Schulze, D. J.; Smith, J. V.; Němec, D.
Neues Jahrbuch für Mineralogie - Abhandlungen Band 152 Heft 3 (1985), p. 321 - 334
29 references
published: Sep 13, 1985
ArtNo. ESP154015203004, Price: 29.00 €
Abstract
Electron and ion microprobe analyses are given for mica grains separated from lamprophyres of the Bohemian Massif, comprising 6 “alkaline minettes”, 7 minettes, 2 leucocratic minettes and 3 kersantites. [Following Rock (1984), the term “alkaline minette” is replaced by “soda-minette”; however, the term “alkali minette” is preferred by S. W. Bachinski.] Although the lamprophyres come from three geographic regions, the element correlations for the entire group of micas fall into a single general scheme in which Ba, Ti, Mn, F/(F + OH) and total iron increase while Mg, Ni and Cr decrease. The micas from the soda-minettes form a tight compositional cluster, and their high Cr and Mg/Fe and their low Ba and Ti imply an early position in any crystal-liquid differentiation scheme. The micas of the Bohemian minettes are compositionally similar to micas in the Navajo minettes and kimberlites which undoubtedly originated as magmas in the upper mantle.
Keywords
Mica • minette • kersanite • lamprophyre • Bohemia • Czechoslovakia