地域地質研究報告

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1 550.85(084.32)(522.8)[1:50,000](083) 5 1 (15) 80 46

3 Abstract 1

5 km 1,573km 2 12km 50t km 174m 5 1

6 m 10

7 m m 2.7m m m m 60 70m 20 30m

8 N50 80 E N40 50 W

9 N45 50 W 2 2 Ht mm mm 3 P

10 Pecten kimurai YOKOYAMA Lagenonodosaria sp. Globigerinidae Dentalina sp. Nodosaria sp. 1 2mm mm 100 4

11 H 3mm mm 4 Hh

12 8 1mm 0.3 1mm 4 Hb mm 1 2.5mm 4 Hp 0.8 2mm mm 4mm

13 It m Ih 1.5 5mm 0.8 2mm

14 mm 0.5 2cm 2 4

15 m m 120m m 220m 220m 200m 120m 60cm 11

16 12 120m 300m 100m 6 1 a t 1 3km Fagus crenata BRUME Quercus serrata THUNB. Ulmus japonica SARG. Magnolia sp. Cornus kousa BUERG. 1.2km 2.5km 420m

17 13 7 R 3 11m 9m 2 8 Ps 5 m

18 mm 0.8mm mm mm mm mm mm mm

19 m mm mm Hk mm mm 4 Hd

20 16 N45 50 W 70m mm 0.5 3mm 20mm m 1 (1) (6) (7) (8) 1966 B 2 m mm 0.5 1mm

21 17 1 Bo 174m mm mm

22 mm mm Ba mm mm mm Bh mm Ab mm 2 3mm 100

23 Wp 12 8 m mm

24 m 14 C 23, , W mm mm 4 S 12 N

25 cm 20 30cm 14 a III 1 2

26 22?.2 500m 3km t/d 14 1,300t/d 380 t 27.2t t/d 7

27 t/d t/d ,610t An6.1g/t Ag58g/t NEEW SES 7 1 L m 50m L L6

28 24 N50 E N70 80 E N80 W N40 60 W 4 2 N40 50 W 3 12km Au5.5g/t Ag35g/t Au5 6g/t Ag 4 2,500t/M m 41 5,096t Au8.5g/t Ag58g/t2 3 10

29 N85 E N70 W2 180m 10m km cm 6g/t Au 5 Ag Au14g/t Ag65g/t 1.5 4m 45m 25

30 m 450m SK m

31 : C No 80 p 38 FUKUYAMA, K 1954 :Geology and Ore Deposit of the Arakawa Mine, Kagoshima Prefecture., Kumamoto Jour., Sci., ser. B no 4, p : : C no 133 p : p : p : p : vol 20 no 6 p : p : p : no p : p : vol 17 no p : vol 2 no 12 p : p : vol 20 no 2 p : p : vol 8 no 27 p : vol 28 no 7 p 26 29

32 : Geological and Petrological Studies of the Shirasu in South Kyushu, Japan, Part III., Mem. Fac. Sci. Kyushu Univ., ser. D. vol. 6, no.2, p : vol 56 no 1 p 1 20

33 1 QUADRANGLE SERIES SCALE 1:50,000 Kagoshima (15) No.80 GEOLOGY OF THE SENDAI DISTRICT By Ryohei OTA (Written in 1969) (Abstract) GEOLOGY The mapped area mainly consists of various kinds of volcanic rocks of Neogene to Pleistocene with a few sedimentary rocks of Pleistocene and Recent. The rocks in the area are summarized as follows from the oldest one toward younger. The oldest rock is Tenguhana hornblende andesite. Kushikino pyroxene andesite, composed of alternation of lava and pyroclastic rock, extensively distributes over the area and it was suffered from hydrothermal alteration, though uneven in its grade depending on locality, gold and silver ore deposits being found in it. Among them Kushikino and Arakawa Mines are most famous. This andesite is of Miocene, because fossils indicating that epoch were found in the pyroclastic rock of Arakawa Mine. Ichihino hornblende andesite occurred as independent lava domes or their aggregates. Imuta Volcano is composed of hornblende andesite lava domes and their underlying pyroclastic rocks, having a depression caldera lake on the top. Ichihino hornblende andesite was suffered from the hydrothermal alteration as well. Sendai welded tuff is rough, fragile and weakly to

34 2 moderately welded in its lithological character, being supposed to be one of welded tuffs probably of Neogene found seperately throughout Southern Kyushu. Kokubu formation of the earliest Pleistocene is not always extensive in its distribution, being composed of alternation of tuffaceous sandstone and tuffaceous shale and thick layer of tuff. The above-mentioned alternation is safely considered to be correlated to the middle member of Kokubu formation in its type locality and the thick layer the upper member. Rhyolite dykes are found in lchihino hornblende andesite and Kokubu formation at the west foot of Imuta Volcano. The gold and silver ore deposit of Iriki Mine was formed in Rhyolite and Kokubu formation and the clay ore deposit of the mine is the one altered from tuffaceous rock of Kokubu formation. Sendai pyroxene andesite is comparatively fresh, being free from the hydrothermal alteration, and its original topography is well preserved. Komugigawa hornblende andesite occurred as lava domes and as dyke. Sendai basalts can be divided into five types as shown in the legend, some of them showing typical topography of lava plateau. Aira Volcano is famous for a huge caldera and tremendous amounts of effusive products. Its activity happened in the fourth ice age of Pleistocene. Ito pumice flow, believed to have extensively flowed out just before the formation of the caldera, is mainly composed of pumice tuff-breccia, popularlycalled "Shirasu", with a small amount of welded tuff at the base. Kamo pumice flow can be seen along rivers under Ito pumice flow, being black and fragile in lithological character. Pumice sand and gravel bed is a secondary sediment, being composed of fragments of the "Shirasu". And there is Alluvium along rivers. ECONOMIC GEOLOGY Kushikino Mine in the southwestern part of the area is one of the biggest gold and silver ore mines in Japan, being composed of nineteen ore veins in parallel in Kushikino pyroxene andesite. Arakawa Mine of the same type was once worked on a large scale, but at present it is not as it used to be. Iriki Mine was famous for the production of gold, silver and tellurium ores, but it is now working clay ore deposit which is closely related to the metal ore deposit from the genetical point of view. Pyroxene andesite and welded tuff are quarried for building stone here and there. And also there are three hot springs in the area.

地質図幅説明書

地質図幅説明書 550.85(084.32)(521.77)[1 50,000](083) 109 40 ... 1... 5 1... 5 2... 7 2 1... 7 2 2... 10 3... 14 3 1... 14 3 2... 19 3 3... 22 4... 23... 23 1... 23 2... 24... 24 Abstract... 1 1 1 50,000 39 109 38 22