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Viktor Garanin, Lomonosov Moscow State University (Russian Federation)
Konstantin Garanin, Lomonosov Moscow State University (Russian Federation)
Vladimir Tretyacheko, YNIGP CNIGRI ALROSA Cp Ltd (Russian Federation)
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Within the southeastern White Sea area (Archangelsk region, NW Russia), it is known already more than hundred Early Hercinic occurences (pipes, stocks, sills and dikes) of the kimberlites, convergent its rocks, also with basic composition. Magmatic bodies are located within different basement structures and sedimentary cover. Intrusions can be described by significant variety of the diamond grade, mineral composition, internal structure, etc.
According the targets of the research efforts the main aspects of the formation analyzing, tectonic position, mineragenetic zoning and evaluation of the diamond potential and grade were done for kimberlitic area in Archangelsk region. By the formation analyze results there were two subformaitons identified: (1) kimberlitic-non-pyroxene picrites (Zimneberezhny megacomplex consists of: Zolotitsky (M.V. Lomonosov diamonds deposit), Chernoozersky (V. Grib diamonds deposit), Kepinsky, Megorsky, Verkhotinsky and Melsky complexes), and (2) feldspar picrites-olivine melilitites (Nenoksko-Chidvinsky megacomplex consists of Chidvinsky-Izhmozersky, Nenoksky and Suksomsky complexes). Within the limits of the Early-Hercynic tectonic-magmatic circle there were three epochs identified: 400-385; 375-360 and 360-345 m.y.
According the developed schemes of the tectonic positioning of the crystalline basement and Riphean rocks complex from Archangelsk region, the structural position of the Zimneberezhny (in Kola-Kuloisky craton) and Nenoksko-Chidvinsky megacomplex (in Belomorsky mobile belt) is defined by their location in Archangelsk kimberlites controlling zone. In Late Proterozoic Kola-Kuloisky craton and Belomorsky mobile belt were homologically inherited Pritimansky pericraton and Kandalaksha-Dvinsky avlacogen. Identified interblocks of the Paleo Proterozoic reworked tectonical-thermal zone controls location all of the kimberlitic complexes.
The Earth crustal block with kimberlites and convergent rocks from Zimny Bereg and Onezhky peninsuila was identified in kimberlite area range of the southeastern White sea territory, which in same time is a part of the Baltic-White Sea alkaline-ultrabasic subprovince.
Allocation of the second (zone) and third (field) ranges of the mineragenetic units is based on the identification of the formation taxons: subprovince (megacomplex) - kimberlite (picrite) zone - kimberlite (picrite) field. Therefore, the main mineragenetic taxons in southeastern White Sea area are: (1) Zimneberezhny kimberlite zone, include M.V. Lomonosov and V. Grib diamond deposits and low- or non-diamondiferous Verkhotinskoe, Kepinskoe, Megorskoe and Melskoe fields, and (2) Archangelsk zone of the feldspar picrites-olivine melilitites, include Nenokskoe, Chidvinskoe-Izhmozerskoe and Suksomskoe fields. By the mineragenetic zoning for diamonds the evaluation of diamondiferous potential was done for different range taxons. Prognosis for discoveries of the new industrial diamond deposits is given.
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