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Hydrothermal activity and segmentation in the Magnitogorsk-West Mugodjarian zone on the margins of the Urals palaeo-ocean

1996; Geological Society of London; Volume: 118; Issue: 1 Linguagem: Inglês

10.1144/gsl.sp.1996.118.01.12

2041-4927

V. V. Zaykov, В. В. Масленников, E. V. Zaykova, Richard Herrington,

Marine and environmental studies

Abstract The Magnitogorsk-West Mugodjarian zone is interpreted to have developed as a marginal rift to the main Urals palaeo-ocean. In this zone, seven distinct tectonic segments each with a strike extent between 140 and 220 km have been identified. These segments can be distinguished on the basis of volcanic facies and features of hydrothermal activity. In the three southernmost segments the volcanics comprise basaltic and rhyolite-basalt complexes. The former contain massive sulphides of Cyprus-type and cherty iron-formation whilst the latter contain massive sulphides of ‘Uralian’ type, cherty iron-formation and manganese oxide deposits. In the two central segments rhyolite-basalt complexes are developed associated with giant massive sulphide deposits (Sibay > 100 million tonnes massive sulphides). In the two northernmost segments rhyolite-basalt and andesite-basalt complexes are developed, both associated with cherty iron-formation and manganese oxide deposits. It is proposed that the variations in frequency, size and composition of the metalliferous deposits between the segments are a result of differences in the sequence of Palaeozoic oceanic development. Rifting started during the Eifelian in the south (current position) and in Late Givetian times in the north. This diachronous rifting and tectonic development has influenced the major geological features of the segments.