著者

大泉 製次

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.58, no.3, pp.103-115, 1967-09-05 (Released:2008-08-07)

参考文献数

15

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Takagami Mine is situated 22 kilometers south of Yamagata City. The mine area and the neighboring region is underlain by Miocene sediments, with granodiorite exposed in the southern part serving as the basement. The ore-deposits are of fissure-filling type, with some network and impregnation portions. The deposits occurring in fissure zones and faults are controlled by the geological structure of the basement and the sediments. Oreshoots occur as chimneys crossing fractures and faults. Ore minerals are mainly pyrite and chalcopyrite with accompanying sphalerite, gold and argentite. In some portions the grade of gold is high. Gangue minerals are mainly quartz and clay minerals. This report is part of the relation between geological structures and ore deposits of the Yamagata Basin.

著者

大泉 製次

出版者

Japan Association of Mineralogical Sciences

雑誌

岩石鉱物鉱床学会誌 (ISSN:00214825)

巻号頁・発行日

vol.58, no.1, pp.31-38, 1967-07-05 (Released:2008-08-07)

参考文献数

10

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Shirataka Mine is situated between On Mountains and Dewa Hills in the southern part of Central Yamagata Prefecture. The Mine Area is underlain by Miocene strata, i.e.: 1) Yoshinogawa formation, 2) Motozawagawa formation, 3) Shimoyama formation, 4) Ose tuffaceous sandstone member and 5) Sugiyama formation. Shimoyama formation is interfingered with Yoshinogawa and Motozawagawa formations. Yoshinogawa formation is correlated to the Daijima and Nishikurosawa formations, while Motozawagawa formation is correlated to the Onnagawa formation. In the western part of the region, hornblende-biotite granodiorite basement rocks are exposed. In the northeastern part, Quaternary volcanics in the Shirataka Mountain, andesite flows and pyroclastics are found. The ore deposit is of the network type, and it is strongly controlled by geologic structures. Fractured zone generally trend N30E. Ores shoots follow the same trend, but, they dip more steeply. At the upper reaches of the Kaaehorizawa River, kaolinization and pyritization with accompanying mineralization is pronounced. This report presents the studies made on the relationship between ore deposition and structural control of volcanism inherent to the Zao-Shirataka volcanic structural line.