GEOCHEMICAL MODEL OF DEVELOPMENT OF THE PEGMATITE-FORMING ORE-MAGMATIC SYSTEM IN WESTERN MORAVIA

摘要

Geochemical model of the PFOMS development in Western Monrovia (Czech Republic) has been elaborated on the base of regulations in distribution of trace elements (Rb, Cs, Li, Ba, et al.) within rock forming minerals (K-feldspar, biotite, muscovite) in the "maternal" granitoids and the "daughter" pegmatites of various texture-mineral types. It is shown that syenite-diorites (durbachites) -rocks of the mantle-crust origine, initially enriched in Ba, Rb and Cs, were the ancestors of the PFOMS. They produced the small intrusions of two-mica leucogranites, from one side, and, from the other side, the barren pegmatites of the K-feldspar type. The two-mica granites deviated an ore-bearing residue during subsequent crystallization differentiation. This residue penetrated mainly in the vein system of barren K-feldspar pegmatites and induced their metasomatic alteration with Superimposed rare metal mineralization (Li-Sn-Be). Rather rarely it produced the structurally autonomous small individual pegmatite bodies of the lepidolite-albitic type. Such a peculiarity of the PFOMS development was determined by geological conditions the whole system formed as a product of Herzinian tectono-magmatic activization in the Precambrian Czech crystalline massif.