Abstract
Regional lateral zoning of the late Mesozoic to early Tertiary endogenic lead-zinc and copper deposits is known in Japan and Korea. The lead-zinc deposits are distributed on the Japan Sea side and the copper deposits on the Pacific Ocean side of Japan. The lead-zinc deposits occupy the northern half and the copper deposits the southern half of Korea. Sikhote-Alin Province may belong to the lead-zinc zone. According to the latest geological data available, a similar regional lateral zoning of the Mesozoic endogenic lead-zinc and copper deposits is recognizable in the area south of the Yangtze River in China. The lead-zinc deposits occupy the western part and the copper deposits the eastern part of that area. Moreover, a similar tendency toward zoning of ore deposits may be present in Southeast Asia, although the data available are scarce.
Deformation of the continental plate, due to subduction of the oceanic plate during Mesozoic to early Tertiary time may be one of the most important causes of the lateral zoning of ore deposits in the areas cited. As the result of this deformation, fracturing and following generation of magma took place within the continental plate. The lead-zinc and copper deposits were formed in close genetic connection with the granitic magma originating from the more acidic upper portion and the more basic lower portion, respectively, of the continental plate.
Generally speaking, the gentler the inclination of the subduction zone, the broader the copper zone tends to become. The copper zone south of the Yangtze River in China may be one of the best examples of this broadening in East Asia. The zone has a width of more than 500 km. In contrast, in the Burmese-Malayan peninsula, the inclination of the Mesozoic subduction zone may be large; no extensive copper zone is known in that area, and lead-zinc mineralization is poor. Drifting of the Japanese Islands is estimated to have begun about 50 Ma ago.
[Correction] Mining Geology Vol.35 No.190 (1985) pp.e1b-e1b
