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Vol. 10 (2007 year), No. 2

Astrakhantsev Yu.G., Guberman D.M., Diakonov B.P., Pevzner S.L., Troyanov A.K., Yakovlev Yu.N.
Geoacoustic noises in the Kola Superdeep Borehole

The intrusive body of rhyodacitic porphyry having a thickness about 110 m was fixed in the section of the Early Proterozoic Pechenga Complex of the Kola Superdeep Borehole (SG-3) in an interval of 4673.0-4831.6 m. Rhyodacites correspond to the hypersthene-normative calc-alkalic rocks with normal alkalinity oversaturated by Al2O3 and enriched by Fe and Mg. On a set of ore-minerals (oxides – magnetite, ilmenite, hematite, rutile; sulfides – chalcopyrite, pyrite, pyrrhotite, millerite, zygenite) rhyodacites are close to the host-volcanites of the Orshoaivi-Pirttijarvi Suite and host-sediments of the Luchlompolo Suite, but they differ by stability of chemical composition and by deficiency of isomorphic admixtures. They have a high natural radioactivity, which is caused by the increased contents of U and especially Th. U-Pb age of zircones from rhyodacites – 2043+/–18 Ma. Probably, their introduction preceded formation of the Ni-bearing gabbro-wehrlitic intrusives of the Pechenga Area.

(in Russian, стр.5, fig. 6, tables. 0, ref 6, Adobe PDF, Adobe PDF 0 Kb)