Литосфера (Jun 2018)
New data on geochemical features, fluid mode, age and potential ore content of granitoids of Isherim anticlinorium (North Ural)
Abstract
Granitoids of Ishirim anticlinorium which is one of the major Precambrian structures of the North Urals, are poorly studied by modern geochemical and isotope-geochronological methods that led to the existence of different points of view on formation conditions and age of these rocks. The authors performed a study of the composition of rocks from three massifs - Vels, Moiva and Pos’mak, by chemical analysis and ICP-MS; age determination on zircons by the methods of LA-ICP-MS and SHRIMP, as well as the study of the composition of rock-forming and accessory minerals using microprobe SX-100, which allowed us to obtain fundamentally new data about the age, fluid regime of formation and potential ore content of granitoids. It is shown that the granitoids were probably formed in environments of active continental margin and orogen; the first has the Ediacaran (567.2-558 Ma), the second - Cambrian (530.3-511.1 Ma) age. Discrete intervals of the formation and a fairly significant geochemical differences of Precambrian and Paleozoic granites, allow to attribute them to different complexes - the Ediacaran Moiva complex and Cambrian Vels complex. The complexes are different in composition of fluids which change over time from substantially chlorine to fluorine. With more ancient (Ediacaran) granitoids of Moiva massif can be associated gold-bearing Mo-W mineralization, and with Cambrian granites - rare-metal mineralization (W, Nb, Ta, REE).
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