Geologicheskii Vestnik

Geological studies of the Talkas gabbro massif, localized at the Talkassko-Sosnovskiy fault of the reversestrike-slip type were carried out. The morphology and structural position of the massif was clari ed, the mineralogical, petrographic and petrogeochemical characteristics of the rocks were described. The rocks have undergone intensive metasomatic alteration. It was determined that one of the main minerals of the rocks is hornblende, crystallized at the late magmatic and early hydrothermal stages at temperature of 432–511°С. One of the main minerals of hydrothermal stage, chlorite, was formed at temperature of 56–115°C. It was de ned that the apatite composition (low chlorine and very low sulfur contents) indicates a weak potential of Talkas massif for the sul de mineralization. Based on the similarity of the geological structure and material composition, the Talkas massif was correlated with the intrusions of the III-d magmatic phase of the Khudolaz differentiated complex, localized in the Khudolaz trough. The Sr and Nd isotopic composition of a sample of the Talkas massif (ISr(325) = 0.7032, εNdCHUR(325) = 6.7) ts into the range of isotopic values of the rocks of Khudolaz complex: ISr(325) = 0.7032–0.7041, εNdCHUR(325) = 5.3–10.3. However, it was revealed that the Talkas massif rocks have differences in geochemical characteristics — the absence of negative Nb-anomaly and noticeable fractionation of rare-earth elements in comparison with Khudolaz trough gabbro massifs.

hazardous geological processes, Southern Urals and the Urals, carbonate karst, karst activation, karst hazard, chemical composition of underground waters, GIS technologies

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