
The relevance of the research is caused by the absence of research of geochemical peculiarities and ore mineralization of exocontact rocks of ore-bearing massifs belonging to Khudolaz layered complex. The aim of the research is mineralogical and geochemical characteristics of exocontact zone of Tashly-Tau massif and salt composition and PT-parameters of ore-forming fluid. Analytical methods: geological field works, optical and electronic microscopy, EDS and WDS analyses of minerals compositions, XRF and ICP MS analyses of chemical compositions of rocks. Results. Co-Pd-Ag и Th-REE mineralization consisted of Fe-Ni-cobaltite, Fe-Co-gersdorffite, michenerite, hessite, and Th-monazite was found in exocontact rocks of Khudolaz complex massifs. We subdivided the far and near exocontact zones of ore-bearing Tashly-Tau massif varying in the grade of sandstones metamorphism and metasomatism. In near exocontact zone, quartz-calcite veins with Co-Pd-Ag mineralization are identified. Sulfoarsenides contain Pd admixture up to 0,44 % correlating with nickel content. Quartz and quartz-chlorite-feldspar veins from near and far exocontacts zones contain disseminated Th-REE mineralization. Also, in late quartz veins, we detected goethite-hematite grains with impurity of Pd (up to 0,17–0,32 %) and Rh (up to 0,03 %). It is determined that the source of Co-Pd-Ag mineralization in host rocks is Tashly-Tau massif which rocks and ores were altered by hydrothermal fluid during the post-magmatic stage. We suppose that the source of Th-REE mineralization of exocontact zone are the rocks of Byagoda Suit (sandstones with clayey cement). According to fluid inclusion data, the earlier sulfide-quartz and late sulfide-quartz-carbonate veins are formed from the same hydrothermal Na-K-Mg-chloride fluid at temperatures from 370–320 up to 280–250 °С diluted from 10,6 up to 6 wt %, respectively.
exocontact zone, fluid inclusions, monazite, TA703-712, cobaltite-gersdorffite solid solution, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, mineralogy, lithochemistry, lithology, quartz, calcite
exocontact zone, fluid inclusions, monazite, TA703-712, cobaltite-gersdorffite solid solution, Engineering geology. Rock mechanics. Soil mechanics. Underground construction, mineralogy, lithochemistry, lithology, quartz, calcite
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