LOWER LAYERED HORIZON OF THE FEDOROVO-PAN A MASSIF, KOLA-PENINSULA - FEATURES OF STRUCTURE, COMPOSITION AND FLUID-PHASE DISTRIBUTION

The inner structure of the Lover Layered Horizon (LLH) of the Fedorovo -Pana Massif was studied in detail on the northern slope of Mt. Wester n Kievey. The LLH cross section is characterized by rhythmic layering mainly of gabbronorites and gabbros with different granularity, percen tage of mafic minerals, and fabric. Microrhythms have typically two-an d three-member structure. The microrhythms become thicker, and relativ e volume of leucogabbros and anorthosites increases up the cross secti on of the horizon. The lower part of the LLH, where the low-sulfide PG E mineralization is localized at the plagiopyroxenites and taxitic nor ites, is distinguished by the finest, most complicated and contrasting interlayering. Signs of viscous Flow of the magmatic melt are strikin gly displayed in the middle and upper parts of the cross section. The composition and distribution of the fluid components (H2O, H-2, CO2, C O, CH4) in plagioclase monofractions were studied by gas chromatograph y. It has been shown that the gas phase evolution proceeded from hydro carbon-hydrogenous to mainly carbon dioxide on the background of a gen eral decrease in H2O concentration and its share during the differenti ation of a magmatic melt. This led to the conclusion that the low oxid izing potential (or more reducing conditions) and relative high H2O pr essure in a fluid phase were most favorable for concentrating PGM.