串木野地域にける秩父・四万十両帯の境界と熱水活動 [in Japanese] Boundary between the Chichibu and Shimanto terranes and hydrothermal activities in the Kushikino area, southwestern Kyushu [in Japanese]
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This paper determines the location of the Butsuzo tectonic line (boundary between the Chichibu and Shimanto terranes) in the Kushikino area, southwestern Kyushu. Many epithermal gold deposits including the Kushikino and Hishikari de-posits occur mainly as veins in andesitic volcanic rocks in the Hokusatsu gold district, where basement rocks are rarely exposed.<BR>Drill hole 61MAHT-1, which is situated at Hashima in the Kushikino area, penetrates volcanic rocks, and reaches sedimentary rocks of the basement. Modal analysis of sandstone samples from drill hole 61MAHT-1 revealed that they are lithic wackes, rich in chert fragments and poor in quartz and feldspar. The sandstones are different in modal composition from those of the Shimanto terrane, however, they are similar to those of the Sambosan belt of the Chichibu terrane.<BR>The basement sedimentary rocks for most gold deposits in the Hokusatsu gold district are of the Northern Shimanto terrane (Saiki Subbelt), while the basement at Hashima proved to belong to the Sambosan belt. This is a possible reason why the δ<SUP>13</SUP>C values and REE patterns of hydrothermal veins in the Hashima area are slightly different from those in the Kushikino mine area.
- Mining Geology
Mining Geology 46(4), 189-195, 1996-08-31
The Society of Resource Geology