Geology and Ore Deposits of the Oe Mine, Hokkaido (3)

On the Control of Ore Shoot

Abstract

The geological occurrences of ore shoots of the Oe ore deposits are controlled by many factors, such as difference in country rocks, pre-ore faults, mineralization-sequence, zonal arrangement of ore mine-rals according to depth, and supergerie enrichment.
Among those factors, faults and mineralization-sequence are most important. All veins of the Oe ore deposits are controlled by Senzaizawa faults which were formed before the mineralization, and occur only on the eastern side of those faults with the exception of the Senzai vein which extends to the western side.
The Oe ore deposits are made up of the repeated mineralization, and those ore minerals of repeated mineralization have different characters according to mineralization-sequence and occurrence, for example, the rhodochrosite at the later stage of mineralization gradually increases in Fe which depends on siderite morecule, and at the deep part of the ore deposits increases in quartz.
The sulfide ore minerals of the Oe ore deposits consist of pyrite, galena, sphalerite and small amount of chalcopyrite. Those sulfide ore minerals may be classified into two groups, sulfide (1) and sul-fide (2), by mineralization-sequence.
The sulfide (1) bears only Ag, while the sulfide (2) bears Ag and Au, and forms a large ore shoot at the eastern side of Senzai-Hisaki fault. All those special characteristics should be utilized not only in prospecting but also in mining, milling, as well as in the management of this mine.