Вестник Кольского научного центра РАН. 2011, №1.

CONTENTS P.V. Pripachkin, T.V. Rundkvist ROLE OF SCIENTISTS OF THE KOLA BRANCH AS USSR AND KOLA SCIENCE CENTRE IN RESEARCH AND PROCESSING OF THE FEDOROVA-PANA TUNDRAS Scientists o f the Kola Branch of the USSR Academy o f Sciences (since 1988 - KSC RAS) greatly contributed to the study and processing o f PGE deposits o f the Fedorova-Pana tundras in the central part of the Kola Peninsula. PGE objects are connected with the Early Proterozoic layered basic-ultrabasic intrusion. Prospecting for rich Cu-Ni ores that saw the dawn in early 1930-s and ended up in 1980-s had no results. The change o f focuses and prospecting for PGE mineralization started in the late XX century resulted in three deposits o f PGE group being put on the State balance (2007-2009) and a number of ore occurrences and mineralization pits being discovered. Keywords: history o f study, basic rocks, ultrabasic rocks, layered intrusions, PGE mineralization, Kola Peninsula. N.Yu. Groshev PT-BEARING FEDOROVA TUNDRA MASSIF (FEDOROVA-PANA LAYERED COMPLEX, KOLA PENINSULA): NEW PETROCHEM ICAL AND GEOCHEM ICAL DATA Fedorova tundra massif is the western part of the Fedorova-Pana Pt-bearing layered complex. The massif comprises layered and marginal rock series, which resulted from the first and second intrusive phases. Compositions o f the intrusive phases have major differences. The magma composition of the first intrusive phase differs from that o f the second one by a lower content o f SiO2, FeO, Mg and greater content o f Ti, Al2O3, Ca и Na. The regular mineralogical composition o f the first stage magma corresponds with the leucocratic quartz gabbronorite, while that of the second stage magma corresponds with the mesocratic quartz gabbronorite. The second intrusive phase magma is rich in ore components, namely, Cr, Cu, Ni, S. The data on REE distribution prove the statement that the composition and differentiation directions o f the first and second phase magmas differ. Keywords: Basic rocks, ultrabasic rocks, Pt-bearing layered intrusions, petrochemistry, geochemistry, rare Earth elements. V.K. Karzhavin MECHANISM OF ORE COMPONENTS CONCENTRATION IN INTRUSION CRYSTALLIZATION Any distortions in thermal conditions of a medium within which a large-in-volume magmatic melt is solidifying at definite depths can reduce the rate o f melt cooling, influence the extent of its overcooling and create chemical inhomogeneity in the front o f crystallization. If heat withdrawal from the crystallizing system is weakening, the temperature reduces and at the phase interface the temperature even slightly increases. Diffusion o f the liquid phase components at this stage facilitates chemical homogeneity recovering by changing the temperature o f liquidus and creating the preconditions for the next wave o f crystallization. The non-linear process o f crystallization and periodical chemical inhomogeneity setting in the “floating” front of crystallization is determined by the differences in the rates o f the solid phase formation and o f the heat withdrawal from the system through the host rocks to the environment. The consequence o f this is that impurities are periodically concentrated and fractionated in the melt before the front o f crystallization, then being trapped, followed by rhythmicity formation within the intrusives (for instance, chrimites, PGE compounds) - in the places determined by the conditions of the host rocks. In nature, this phenomenon is shown as alternating rhythmic inhomogeneity (cryptic and distinct) in mineral composition of rocks of layered intrusive rock masses. Keywords: crystallization, melt, diffusion, phases. admixture, concentration, diffezentiation, heat crystallization. P.V. Amosov, N.V. Novozhilova PREDICTION ASSESSMENT OF ECOLOGICAL SAFETY 124