SOME FEATURES OF LOCALIZATION OF EPITHERMAL MINERALIZATION IN CONTINENTAL VOLCANIC BELTS

Abstract

The association of many epithermal ore deposits with focal and dome volcanic structures, as well as the control of mineralization by major fault zones with no relationship to the volcanic structure, are expressed fairly clearly in various regions. It is these two types of structural position that are most typical of the localization of epithermal mineralization in fields of continental extrusives. In various ore districts of the Soviet Union and abroad, though, a third type of characteristic structural environment in which epithermal mineralization is localized in continental volcanic belts can now be outlined increasingly clearly. Ore deposits here are not controlled either by the architecture of the volcanic structures, or by major fault zones. They are controlled by local faults, often cutting the main faults and appearing far from any volcanic apparatus. Ore bodies in volcanic fields are located far from volcanic domes and often even cut major fault zones; neither type of structure controls their distribution or has any appreciable effect on its localization. In such a structural position the ore bodies generally seem to be upper mineralized zones. This is indicated by examples of various deposits, where further exploration of their lower levels revealed new, large ore bodies in the rocks of the substrate, larger than those known for volcanic rocks.