秋吉帯高山石灰岩層群の褶曲構造 [in Japanese] Folded structure of the Carboniferous Ko-yama Limestone Group, Akiyoshi Belt, SW JAPAN [in Japanese]
Access this Article
Search this Article
The fold structure of the Akiyoshi Belt was analyzed in Kawakami-cho, Okayama Prefecture, where the LowerCarboniferous to Middle Permian Ko-yama Limestone Group (Yokoyama et al., 1979), Permian Yoshii Group(Sano et al., 1987) and Triassic Nariwa Group (Teraoka, 1959) are distributed. The Nariwa Group unconformablycovers the Paleozoic successions (Otoh, 1985). The Lower Carboniferous to Middle Permian Ko-yama LimestoneGroup, dated by foraminifers and fusulinids (Yokoyama et al., 1979), is mainly composed of massive limestonewith basic volcanics, acidic tuff and chert. The Paleozoic successions of the Akiyoshi Belt were folded during theMiddle to Late Permian (Suzuki et al., 1990). Strata of the Ko-yama Limestone Group generally strike E-W anddip to the north. The Hoya section about 300 m thick is composed of limestone, basic tuff, chert and acidic tuff,limestone, basic lava and tuff in ascending order. In this section, Ishida et al. (2012) recognized a nearly completeconodont faunal succession ranging from the upper Visean to the lower Moscovian. The faunal successionindicates younging southward, and the strata are overturned. A folded strucuture of tight overfold withnorth-dipping axial plane was reconstructed. Similar style of small scale overfolds of banded chert and turbiditewere observed in the overlying Yoshii Group.
- Okayama University Earth Science Report
Okayama University Earth Science Report 19(1), 5-11, 2012-12-26