Revealing Prospects of New Gold–Copper-Porphyry Deposits of the Malmyzh Type in the Lower Amur Region (Russian Far East)

In this paper, we discuss new data obtained by petrographical, geochemical, geochronological, and isotopic–geochemical study of magmatic rocks within the Malmyzh and Gion gold–copper-porphyry ore fields. Geochronological data show a Late Cretaceous age of their magmatic crystallization: Cenomanian (97–99 Ma) and Campanian (76–82 Ma) ages, respectively. Based on a comparative analysis of the studied samples igneous rocks with each other and with magmatic rocks of worldwide porphyry deposits, the results of a study using a secondary ion mass spectrometer of the patterns of distribution of trace elements (REE + Y, Hf, Ti, U, Th, and Pb) in accessory zircons from igneous rocks of the Malmyzh and Gion ore fields are discussed in order to estimate their potential ore content in the gold–copper-porphyry mineralization. Despite the fact that economic gold–copper ore mineralization within the potential Gion ore field was previously unknown, an analysis of the results shows, that according to the obtained values of indicative geochemical parameters of accessory zircons, the granitoids involved in its geological structure practically do not differ from the granitoids of both the neighboring Malmyzh deposit and most of the worldwide porphyry gold–copper deposits.