Abstract |
The Akiyoshi Limestone Group, the most representative Carboniferous and Permian carbonate succession in Japan, is widely distributed throughout the Akiyoshi plateau, Southwest Japan. The investigated ...area, Jigoku-dani, is located in the northwestern part of the plateau, and is underlain by the Middle Carboniferous and Early Permian limestones. Almost of limestones in the area are massive and are composed mainly of micritic limestones, showing lagoonal fades within the Akiyoshi organic reef complex. They are also characterized by abundant and well-preserved fusulinaceans, and the following nine zones including seven subzones, were recognized in ascending order as: 1. Fusulinella biconica Zone, 2. Fusulina cf. shikokuensis Zone: 2-1. Fusulinella cf. obesa subzone, 2-2. Pseudofusulinella hidaensis subzone, 3. Obsoletes obsoletus Zone: 3-1. Protriticites toriyamai subzone, 3-2. Protriticites matsumotoi subzone, 4. Montiparus sp. A Zone, 5. Triticites yayamadakensis Zone: 5-1. Triticites saurini subzone, 5-2. Schwagerina sp. A subzone, 5-3. Trticites biconicus subzone, 6. Schwagerina (?) cf. satoi Zone, 7. Pseudoschwagerina muongthensis Zone, 8. Pseudofusulina vulgaris globosa Zone, and 9. Pseudofusulina aff. ambigua Zone. The distribution of these fusulinacean zones disclosed the inverted structure of limestones in this area. Correlation of these divisions with the fusulinacean zones previously established in the Akiyoshi Limestone Group was also given.show more
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