RUSSIAN JOURNAL OF EARTH SCIENCES VOL. 8, ES3002, doi:10.2205/2006ES000196, 2006
[2] Alpine-type dunite-harzburgite-lherzolite massifs are components of gabbro-ultramafic belts in mountaineous areas. They have long attracted much attention of geologists as reference objects for geological and petrological models and as massifs hosting economic deposits of Cr, Ni, and asbestos. Russia's largest deposits of Cr ores, Ni ores in weathering crusts, as well as deposits PGE, asbestos, and some other minerals are hosted by Alpine-type ultrabasic massifs of the Urals. Another noteworthy feature of these massifs in Urals, which are sometimes strongly altered and disturbed elsewhere, is a broad spectrum of metamorphic grades of these rocks, from unaltered varieties to eclogites, and their weak tectonic disturbance, which makes it possible to trace all alterations and transformation stages of the rocks themselves and their mineralogy. This applies, first of all, to the ultrabasic rocks in the Polar Urals (Figures 1-5).
[3] We conducted topomineralogical studies of Alpine-type ultrabasic massifs in the Polar Urals for more than two decades with the aim of collecting materials on the compositions of the rocks and minerals, determining the crystallization successions and thermodynamic conditions of mineral assemblages and related complex ore mineralization. Our conclusions are based on more than 2500 chemical analyses of rocks, Cr-spinels, and rock-forming silicates [Bryanchaninova, 2004; Bryanchaninova et al., 2004a, 2004b; Makeyev, 1989, 1990, 1992a, 1992b, 1994; Makeyev and Bryanchaninova, 1999; Makeyev and Zaripova, 1984; Makeyev et al., 1982, 1984, 1984].
[4] In this research we widely utilized microprobe analyses. We also examined the physical properties of minerals, including their magnetic susceptibility, unit cell parameters, dispersion of their reflectance, hardness, and density. Numerous IR spectroscopic determinations were carried out to evaluate the compositions of the accessory Cr-spinels. Selected samples were additionally studied by luminescence and absorption spectroscopy within the optical region, electronic microscopy of the ultrabasic rocks and their minerals, electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), nuclear gamma resonance (Mössbauer spectroscopy) of minerals, and the geochemistry of oxygen and carbon isotopes [Bryanchaninova et al., 2004a; Makeyev, 1989, 1990, 1992a, 1992b, 1994; Makeyev and Bryanchaninova, 1999; Makeyev and Zaripova, 1984; Makeyev et al., 1982, 1984, 1984].
Citation: 2006), Typomorphic features of Cr-spinel and mineralogical prospecting guides for Cr ore mineralization, Russ. J. Earth Sci., 8, ES3002, doi:10.2205/2006ES000196.
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