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Vol. 5 (2002 year), No. 1
Skuf'in P.K.
The formation analysis of the Pechenga Early Proterozoic volcanic rocks (the North-East Baltic Shield)
The formation analysis of the Pechenga volcanic rocks fulfilled in the paper has been based on the paleovolcanological, petrogeochemical and isotopic geochemical investigations. As a result of formation analysis, the new volcanic formations and formation sets have been found. And as a result of typification of volcanic formations and formation sets, the cyclic development of tectono-magmatic processes in the Early Proterozoic of the Baltic Shield has been established. The Karelian Endogenic Megacycle (pre-2550-1700 Ma) consists of four main tectono-magmatic cycles: Lapponian (pre-2550-2325 Ma), Sariolan-Jatulian (2325-2115 Ma), Ludicovi-Kalevian (2115-1905 Ma) and Svecofenno-Vepsian (1905-1700 Ma). Within the framework of each main endogenic cycle there are separate secondary endogenic cycles.
(in Russian, стр.16, fig. 4, tables. 4, ref 23, MS Word 95, MS Word 95 1000 Kb)
Vol. 10 (2007 year), No. 2
Yakovlev Yu.N., Skuf'in P.K., Bayanova T.B.
The rhyodacitic porphyry body in the section of the SG-3 Pechenga area (age and ore mineralization)
By geological, geophysical, petrological and isotopic-geochronological data the Archaean complex in the SG-3 section correlates with amphibolite-gneiss complexes of the granite-greenstone area of the Svanvik-Neiden segment located in the Kola-Norwegian block. Plagiogneisses of tonalite-trondhjemite composition, being one of the major components of the SG-3 Archaean complex and the borehole surroundings, include two types. Plagiogneisses of type A are depleted in heavy lanthanoids to a different degree and their ?Nd ranges from +2 to +0.5. Plagiogneisses of type B are rich in HREE, incompatible trace elements and are characterized by negative ?Nd values which is evidence of contamination of the primary melt by the ancient crust material. Amphibolites associated with plagiogneisses are close to tholeiitic basalts of modern oceanic plateaus and Archaean greenstone belts in the trace element composition. By the experimental data, tonalite-trondhjemite melts corresponding to plagiogneisses of types A and B and depleted in heavy lanthanoids to a different degree, formed during metabasic rocks melting at Р ? 10-15 and ? 8 kbar respectively. Model metabasite sources of tonalite-trondhjemite melts that are initial for plagiogneisses of type A are comparable with basalts of modern oceanic plateaus and Archaean basalts of plume origin in the trace element patterns and their indicator ratios. Low Mg# of plagiogneisses excludes the contribution of mantle peridotites in their formation and, hence, does not correlate with subduction oceanic plate. Variations of trace element and isotopic composition of plagiogneisses more likely point to formation of tonalite-trondhjemite melts at different levels of the thickened mafic crust which includes metabasalt material that is heterogeneous in trace element and isotopic composition. The composition peculiarities of amphibolites and model metabasite sources of tonalite-trondhjemite melts suggest that formation of the thickened crust might be caused by accretion of oceanic plateaus.
(in Russian, стр.9, fig. 3, tables. 6, ref 10, Adobe PDF, Adobe PDF 0 Kb)
Vol. 12 (2009 year), No. 3
Skuf'in P.K., Elizarov D.V., Zhavkov V.A.
Geological and geochemical features of the South-Pechenga volcanics
The analysis and systematization data of the petrophysics characteristics of phanerozoic and paleoproterozoic rocks have permitted to establish general regularities in their formation in response to geodynamic and metamorphism processes.
(in Russian, стр.20, fig. 7, tables. 3, ref 33, Adobe PDF, Adobe PDF 0 Kb)
Vol. 15 (2012 year), No. 2
Skuf'in P.K., Elizarov D.V.
Tuffisite rocks in the basement of the early Proterozoic Pechenga Structure
The problematical Early Proterozoic fluidizite-explosive tuffisites have been considered in the Televi Sedimentary Fm of the Northern Pechenga volcano-sedimentary complex. Fluidizite-explosive "pseudoconglomerates" occur as irregular clastic rocks, without evidence of sorting by size and shape. Clastic fragments are represented by plagiogranites, granodiorites, diorites and quartz pebbles. Fragments have an angular or subround shape. There are a number of the plastic picrobasaltic lava fragments that were deformed by hard granitic clasts. This fact indicates high-temperature conditions of tuffisite-forming process. These conditions are also confirmed by a fact of volumetric decompaction processes in tuffisite fragments. Quartz grains from the granitic clasts are partly replaced by diaplectic glass. Such decompaction processes and quartz transformations are typical of latest diamond-bearing tuffisites of Polar Ural and Timan Area. The matrix of the Pechenga tuffisites is enriched in such compatible elements as Ni, V, Cr, and РЎРѕ, that is typical for tuffisitic rocks and for endogenic "pseudoastroblems". Rb-Sr isochrone with the age of 2595 В± 79 Ma has been received for these rocks.
(in English, стр.7, fig. 3, tables. 1, ref 19, Adobe PDF, Adobe PDF 0 Kb)