岡山県川上町地頭地域における上部三畳系成羽層群地頭層の層相解析

Facies analysis and analysis of stratigraphy together with folded structure of the Norian Jito Formation were studied in Jito Area, Kawakami, Okayama Pref., SW Japan. Results of regional mapping and measured sections reconstruct three-dimensionally distribution of the Jito Formation. The Jito Formation is sub-divided into the four new members; the Shimohira Muddy Sandstone Member, the Otofuji Coarse-grained Turbidite Member, the Misawa Fine-grained Turbidaite Member, and the Ide Conglomerate Sandstone Member in ascending order. The shimohira Muddy Sandstone Member is interpreted to be deposited in an inner-bay. The Otofuji Coarse-grained Turbidite Member and The Misawa Fine-grained Turbidite Member are considered to be deposited on a continental shelf. The Ide Conglomerate Sandstone Member is inferred to be a shallow marine deposit. As a result, the Jito Formation is regarded as one transgressive-regressive package.