Introduction Periodicals Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze 2010/18/1 Negranitické pegmatity - přehled výzkumů
Negranitické pegmatity - přehled výzkumů
|Citation||GADAS, Petr. Negranitické pegmatity - přehled výzkumů. Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze. Prague: National Museum, 2010, 18(1), 51-72. DOI: https://doi.org/. ISSN 1211-0329 (print), 1804-6495 (online). Also available from: https://publikace.nm.cz/en/periodicals/bmpholnrhmvp/18-1/negraniticke-pegmatity-prehled-vyzkumu|
Currently, we regard pegmatites as rocks displaying more or less different mineral composition, provided that these display pegmatite-like textures (grain size, zonation, skeleton crystals development, graphic intergrowths, etc.). Like common granitic pegmatites, they also originated by solidification of residual magma of molten plutonic complexes or, on the contrary, by anatexis of the metamorphosed rocks. High variability of mineral composition, reflecting both the heterogenity of the protolite and differentiation processes (fractionation, contamination) that took place the melt before its solidification. That is why only those pegmatites whose non-granitic character originated from a melt are listed in the overview. Other types of pegmatite which have become non-granitic in subsolidus such desilicated or rodingitized pegmatite are not listed. The classification of non-granitic pegmatites follows from protolite character, if known, or from character of rocks to which it is closest regarding its composition. It is therefore possible to differenciate the group of non-granitic pegmatites derived from ultramafic, mafic and alkaline rocks which we can subdivide into several subgroups acording to their origin and/or mineral composition. Also, in the Czech Republic there were found several occurences of non-granitic pegmatites, some of them showing quite unique composition.