H-isotopes in magmatic rocks from Cu-Mo deposits in Siberia and Mongolia

摘要

The Siberian and Mongolian porphyry Cu-Mo deposits were generated from Devonian to late Mesozoic in subduction- and collision-related environments. On the continental margin of the Paleo-Tethys, magmatic rocks of the deposits are characterized generally by low H-isotope ratios. Mantle-derived variably D-depleted magma is supposed to have been responsible for formation of magmatic wallrock complexes of these deposits. At the Chubachi deposit that occurs on the continental margin of the Pacific ocean, the host and porphyry complexes are drastically different in 8D values. The variation of H-isotopes in magmatic rocks of this deposit is assumed to be accounted for by an important role of old crust in magma generation. The collision-related deposits are characterized by higher 5D values of magmatic rocks. From Paleozoic to Mesozoic, the H-isotope composition of these deposits became lighter due to an increasingly higher contribution of the crustal component to their formation.