2, 3のタングステン錫鉱脈付近の地質構造上の特徴とくに茨城県高取鉱山の鉱脈系統

抄録

The Takatori district is geologically composed of Paleozoic sandstone, clayslate and quartzite, which generally strike NE and dip monoclinally to NW. The ore deposit belongs to the hypothermal quartz vein, accompanied by wolframite, cassiterite, arsenopyrite, pyrrhotite, pyrite, chalcopyrite, sphalerite, galena, stannite, bismuthinite, lithia mica, monazite, fluorite, topaz, rhodochrosite, : calcite, sericite, chlorite and others. The veins are classified into two groups from the attitude, i. e., (a) the veins which strike NW, dipping steeply to NE or SW, (b) the horizontal or flat veins which link the steeply dipping veins of group (a). The original fissures of the both types of veinsare tension cracks. So, it may be interpreted that these fissures correspond to the plane of the maximum normal stress resulted from the NW-SE compressive force, which caused the folding of the Paleozoic formation with the axis of NE-SW. Judging from the locally disturved structure of the Paleozoic formation, a mass of cryptobatholith is inferred to occur beneath the area of the are deposit. The country rocks suffered sericitization and silicification, partly impregnated by tourmaline, fluorite and topaz.
Similar features of the vein system have been reported in some tin-tungsten vein deposits such as in the Kuga tin-tungsten mine, the Akenobe tin-tungsten-copper-zinc-lead mine, the tin-tungsten mines in the eastern Andes of Bolivia and others.