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Title :3次元有限歪解析―沖縄島国頭層群嘉陽層について―
Title alternative :Three dimensional finite strain analysis -with reference to Kayo Formation, Kunchan Group, Okinawa-jima-
Authors :林, 大五郎
Authors alternative :Hayashi, Daigoro
Issue Date :15-Oct-1988
Abstract :Pre-Tertiary Kayo Formation, a member of Kunchan Group, has developed along the eastern coast of Okinawa-jima. The Kayo Formation is composed of the flysch type alternation of sandstone and mudstone. The isoclinal folds are well developed around Kayo, Ban-zaki and Teniya (subject area), and their axial planes are inclined to northwest. The subject area is divided into 5 zones of the normal and reverse polarity based on the trace fossils and sedimentary structures. Considering quartz grains of the sandstone of the Kayo Formation as a strain marker, strain analyses have been performed by using the SHIMAMOTO and IKEDA's method, Rf/φ method and RAMSAY's method. The strain field within the isoclinal fold has not coincide with the theoretical solution obtained by HOBBS (1972). This may be due to the competency contrast between the strain marker and matrix. This leads us to envisage that the isoclinal folds have been caused by folding under conditions where the strata had not yet consolidated.
沖縄島東海岸に分布する先新第三系国頭層群嘉陽層はフリッシュ型砂泥互層であり,北西に傾く軸面を持つ等斜褶曲が嘉陽,バン崎,天仁屋周辺(対象地域)で良く発達する.生痕化石や堆積構造をもとに対象地域は5帯の正常・逆転帯に分けられる. 歪解析は,嘉陽層砂岩中の石英粒子を歪マーカーとし,SHIMAMOTO and IKEDA法,Rf/φ法とRAMSAY法を用いた.等斜褶曲内の歪場は,HOBBS(1972)による理論解と一致しない.この原因はおそらく歪マーカーと基質のコンピテンシーの違いによるのであろう.この解釈はこの等斜褶曲が未固結時の褶曲作用によって形成されたことを暗示する.
Type Local :雑誌掲載論文
ISSN :0016-7630
Publisher :日本地質学会
URI :http://hdl.handle.net/20.500.12000/2990
Citation :地質学雑誌 Vol.94 no.10 p.757 -768
Appears in Collections:Peer-reviewed Journal Articles (Faculty of Science)

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