Geochemistry of Carbonate Rocks in the Early Precambrian and Phanerozoic Metamorphic Complexes of East Siberia, North-West Russia, and Pamirs

Abstract

Abstract—The geochemical study of carbonate rocks of Early-Precambrian and Phanerozoic metamorphic complexes was carried out and their differences were revealed. The Precambrian marbles and calciphyres were studied in the Оnot Greenstone Belt, Kitoy and Sharyzhalgay granulite complexes of the Prisayan inlier and the Yenisei Group of the Angara–Kan inlier of the Siberian craton, the Belomorian and Lapland Complexes, the North Pechenga Structure, the Sortavala Formation of the Fennoscandian Shield, and the Wakhan Complex of the Badakhshan massif. Phanerozoic marbles and calciphyres were analyzed in the Olkhon, Slyudyanka, and Svyatoi Nos complexes of the Baikal region, Bokson Group and Irkut Formation of the East Sayan, Derbin Complex and Alkhadyr Formation of the Sayan region, Yudin Formation and Panimba–Rybinsk Zone of the Yenisei Ridge, Muzkol Complex of the East Pamirs. As compared to the Phanerozoic rocks, the Precambrian carbonate rocks are enriched in Fe, Mn and depleted in Sr, Ba at a close low level of REE content. The enrichment of Archean protoliths of marbles and calciphyres in Fe and Mn is caused by the predominance of basic and ultrabasic rocks in source areas. As compared to the Phanerozoic carbonates, the Paleoproterozoic carbonate rocks demonstrated a decrease of Fe and Mn and increase of Al, K, Ba, and Sr owing to the contribution of granite-metamorphic layer in the formation of their protoliths. The distribution of major and trace elements in marbles and calciphyres is determined by their modes of occurrence: 1) admixture of Fe, Mn, Ba, Sr, and REE in the isomorphic series of Ca–Mg carbonates; 2) the presence of Na, K, Ba, Sr minerals in marbles; 3) the presence of fine (in marbles) and coarse (calciphyres) fractions of minerals with Fe, Mn Al, Ti, Zr, Cr, V, Ni, S. The paleoreconstruction based on REE behavior in the carbonate rocks revealed the predominant development of intracratonic shallow sea in the Archean and Early-Paleoproterozoic. Open oceans appeared at the turn of 2–1.9 billion years, but the widespread development of carbonate rocks occurred in the Meso-Neoproterozoic and Phanerozoic. The revealed features serve as the basis for age paleoreconstructions of protoliths using petrogeochemical characteristics of carbonate rocks of Precambrian and Phanerozoic metamorphic complexes.