Geologic factors of distribution of mineral deposits in eastern U.S.S.R.

The Pacific Mobile belt is differentiated into an outer (continental) zone of predominantly Mesozoic folding (Verkhoyansk -Chukotka, Mongolo-Okhotsk, and Sikhote-Alin folded provinces) and an inner oceanic zone of Cenozoic folding, adjacent to mobile provinces of the "island arc" type (Sakhalin, the Kuriles, Kamchatka). These zones are separated by the East-Asian volcanic belt associated with a fault system which cuts off the older Mesozoic Verkhoyansk-Chukotka and Sikhote- Alin structures. Two important mineralization epochs are evident - Sino-Cambrian and late Mesozoic- Cenozoic. The Mesozoic-Cenozoic mineralization epoch exhibits a definite tendency for “rejuvenation” of the mineralization processes, going away from the continent and toward the Pacific trough, from late Jurassic in the eastern Trans-Baykal region and parts of the northeast to Neogene in the province of the Okhotsk geosynclines. An outstanding feature of endogeneous mineralization in this region is the linear arrangement of the ore zones determined by a system of major magma-controlling and other faults.—C. E. Sears