|Budget Amount *help
¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1992 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1991 : ¥1,300,000 (Direct Cost : ¥1,300,000)
The project plans to obtain basic geological and petrological data for granitic rocks in the Hida complex, and focuses the problem, what granitic activity is responsible for the origin of Kamioka-type Pb-Zn deposits. The results obtained are;
(1) Clinopyroxene-bearing migmatite, the most common country rocks of the deposits, has been considered to relate to the mineralization, but the compositions of clinopyroxenes are mainly controlled by the bulk chemistry of rocks and have no systematic relation with the distribution of ore deposits. The migration of iron accompanied by mineralization is limited in narrow zones near orebodies.
(2) Early Mesozoic granites are most widespread in the complex, and have long been believed that they are homogeneous in chronology and lithology called totally "Funatsu granites" of the Jurassic age. The detailed field observations, however, clarified that: (a) they can be divided into two stages: the older Triassic granites and younger Jurassic ones, (b) the older Funatsu granites have been partly deformed and metamorphosed to be augen gneiss and recrystallized by the thermal effect of the younger Shimonomoto granite, (c) the older granites can be correlated with the Indosinian granites and the younger ones with the Yenshanian granites of the Asian continent, and this means that the Hida granites involve the turning point of granitic activities from late Paleozoic to Mesozoic in the eastern margin of the continent.