Genesis of Zn-Cu deposits in the basic Ransko massif (Eastern Bohemia)

Watkinson et al. (1978) have reinterpreted the Zn-Cu deposits in the Ransko massif as xenoliths of volcanogenic ores enclosed in and contact-metamorphosed by a basic magma. A detailed reexamination of different xenoliths within the massif, and their comparison with the cordierite hornfelses carriers of Zn-Cu ores, has shown essential differences between them, and confirmed the previous opinions on the metasomatic origin of the deposits. The cordierite hornfels originated by selective magnesian metasomatism of intrusive rocks rich in feldspar (quartz diorite, troctolite), particularly by the replacement of feldspars by cordierite. Around the stocks of cordierite hornfels, a conspicuous concentric metasomatic zonation of rocks developed in mafic intrusives. The Zn-Cu deposits of the Ransko massif resemble sulfide deposits connected with magnesian metasomatism, especially those of the Hitachi area in Japan.