ИСТИНА

The Kekura gold deposit, amongst other volcanogenic Au-Ag, intrusion-related Au and porphyry Cu-Mo-Au deposits in the Western Chukotka, is considered to be of economic importance. It is associated with the central part of the Early Cretaceous stock-shaped three-phase Kekura granitoid intrusive. Gold-bearing quartz veins and lenses occur within the intrusive and near-contact country rocks. The following alterations were recognized at the deposit: (1) unmineralized quartz-calcite-tourmaline-albite-muscovite, (2) propylitic accompanied with rare thin quartz veinlet and pockets containing Sn-W-Cu-Bi-As mineralization, (3) quartz-tourmaline-albite-muscovite alteration rimming quartz-molybdenite veinlets, (4) beresite (quartz-muscovite-dolomite ± arsenopyrite ± pyrite type) rimming gold-bearing quartz-dolomite veins with arsenopyrite and pyrite, (5) quartz-muscovite-illite-siderite-dolomite alteration containing quartz veinlets and pockets with Au-Ag-Sb mineralization, and (6) rare kaolinite type with disseminated pyrite related to faults. The major economic gold grade is related to the fourth stage. The Kekura deposit combines features of reduced and oxidized intrusion-related gold deposits with the late epithermal mineralization.