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Vol. 10 (2007 year), No. 1

Lyutoev V.P., Vinogradova N.P., Glukhov Yu.V., Kotova E.N.
Crystal structure defects of rock-forming minerals as genetic marks of metamorphic rocks in the Kola Superdeep Borehole section.

The results of the study of ore minerals contained in ferruginous-siliceous rocks in the SG-3 Archaean unit IX and their surface homologues in various blocks of the north-north-eastern framing of the Pechenga structure have been considered. The compositions of ore mineralization of the ferruginous-siliceous rocks in the SG-3 Archaean unit IX and Rovensky block were found to be similar but they differ from that in Liinakhamary and Suormus blocks. The prevailing content of iron sulfides over the ferrotitanium oxides in the studied rocks of the Rovensky block is likely to be related to the primary ore specialization of the replaced rocks. These ferruginous-siliceous rocks and their magnetites are demonstrated to be of metasomatic genesis.

(in Russian, стр.19, fig. 14, tables. 14, ref 32, Adobe PDF, Adobe PDF 0 Kb)

Vol. 10 (2007 year), No. 1

Skufin P.K., Lyutoev V.P., Yakovlev Yu.N., Smirnov Yu.P., Glukhov Yu.V., Kotova E.N.
Properties and structural peculiarities of rock forming minerals and Early Proterozoic sedimentary rocks in the SG-3 section and their homologues at the surface

Actinolites and hornblendes from the SG-3 Archaean rocks and from the surface Archaean complex (Allarechka block) have been studied. The Allarechka block used to be considered a surface analogue of the SG-3 Archaean complex. The mineral structure, the nature and degree of structural defects have been investigated by X-ray powder diffractometry, infrared and Mossbauer spectroscopy. The chemical composition was determined by the wet chemistry and microprobe methods. The comprehensive investigations resulted in establishing composition stoichiometry of deep and surface amphiboles. Vacancies are present only in rare samples and in minor amounts. The majority of the studied amphiboles had a high degree of the unit cell deformation and its elongation along the c axis. A high and about the same degree of Fe2+ and other cations was observed in both groups of specimens. At the same time the patterns of the site occupation by Fe2+ are slightly different: Fe(M3)>Fe(M2)?Fe(M1) – for deep samples and Fe(M3)>Fe(M1)>Fe(M2) – for surface ones. The degree of iron oxidation is established to be similar (from 5 to for 20 %) for both surface and deep samples. Actinolite and low-alumina hornblende have no marked difference in their structural state at a depth of 7900-11350 m and at the surface. The data on the crystalline substance state at the crust deep zones may be useful for reliable interpretation of geophysical measurements, development of correct models of the crust structure and for choosing the proper sites for disposal of radioactive wastes. The structural state of amphibole (actinolite, low-alumina hornblende) from amphibolite and crystalline schist of the SG-3 Archaean complex and their surface homologues has been studied. The aim was to elucidate whether the structural state of those amphiboles differs and whether the amphiboles from the SG-3 Archaean rocks preserve any information about the physical state of the crystalline substance at great depths during their extraction to the surface. We have studied the composition, degree of iron oxidation, nature and degree of structural defects and the availability of various forms of water in the structure of amphiboles from the SG-3 Archaean rocks (7930-11330 m) and their surface homologues from the Allarechka block (southern framing of the Pechenga structure). According to the modern nomenclature (Leake, 1997), the actinolite and hornblende pertain to the calcic amphibole group.

(in Russian, стр.19, fig. 11, tables. 8, ref 25, Adobe PDF, Adobe PDF 0 Kb)