著者

岡田 篤正 植村 善博 東郷 正美 竹村 恵二 吉岡 敏和 堤 浩之 梅田 康弘 尾池 和夫 松井 和夫 杉森 辰次 杉山 直紀 園田 玉紀 梅田 孝行 松村 法行 山田 浩二 古澤 明

出版者

一般社団法人 日本活断層学会

雑誌

活断層研究 (ISSN:09181024)

巻号頁・発行日

vol.2005, no.25, pp.93-108, 2005-06-30 (Released:2012-11-13)

参考文献数

36

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The Kameoka basin is located to the west of the Kyoto basin. On the northeast side of the basin, two faults trending the northwest to southeast direction exist along the foot and the former edge of a mountain, respectively. They compose of the Kameoka fault zone with the length of about 13km (Okada&Togo ed.,2000).To elucidate such characteristics as distribution, subsurface structure and activity of those faults, we have carried out seismic reflections (P-waves) and deep drilling surveys across the faults. Volcanic ash and pollen analysis were also performed using core samples obtained by drillings. In this paper, we report the results of these surveys, especially about the characteristics of the concealed faults related to basin formation.By these surveys, three faults were detected along the three sections by the seismic reflection crossing the eastern half of the Kameoka basin, named as Fl, F2 and F3 faults from west to east. All faults incline to the northeast to form the reverse fault type uplifting to the northeast side.The Fl fault is concealed under the alluvial plain of the Katsura River and is an active fault having remarkable displacement of vertical direction to a few hundreds of meters. An accumulation of the displacement in the vertical direction is plainly recognized on the topographical and geological sections.The F2 fault appears in the wide deformation zone on the hanging. wall of Fl fault and is thought to be a subordinate fault of the F1 fault. From the distribution, the F2 fault is corresponded to be an active fault described by Okada&Togo ed. (2000) and identified at former edge of a mountain in the Kameoka basin. In this paper, we will call the Fl fault and the F2 fault as“ the Kameoka fault within the basin”. It is surely distributed about 4.6 km from the Umaji to the Hozu settlements in the southeast direction.Of the Kawarabayashi reflection profile, one reflection layer C has vertical displacement of 65m resulted from the activity of“ the Kameoka fault within the basin”. A pure seam from core samples of the layer is confirmed as so-called Oda Volcanic ash at 420-450ka. Therefore, the average slip rate of the vertical displacement is estimated at 0.15m per thousand of years or less, during the last about 430,000 years.We also found a fault scarplet (relative height 1.5-2.5m) on a low terrace. It seems to be formed by the F2 faulting since about 20,000 years ago. Hence the faulting of“ the Kameoka fault within the basin” since the late Pleistocene is certain, and also there is a possibility of the activity in the Holocene from the existence of the reverse-inclined terrace II at Umaji.Judged from distribution, the F3 fault is corresponding to "the Kameoka fault in the foot of a mountain" described by Okada&Togo ed. (2000). There is no evidence of the F3 faulting during the late Quaternary.

著者

亀高 正男 菅森 義晃 石田 直人 松井 和夫 岸本 弘樹 梅田 孝行 東 篤義 山根 博 杉森 辰次 魚住 誠司 永田 高弘 松場 康二 桑島 靖枝 岩森 暁如 金谷 賢生

出版者

一般社団法人 日本地質学会

雑誌

地質学雑誌 (ISSN:00167630)

巻号頁・発行日

vol.125, no.11, pp.793-820, 2019-11-15 (Released:2020-03-26)

参考文献数

152

被引用文献数

1

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舞鶴-小浜地域の5万分の1精度の地質図を新たに作成し,上林川断層の破砕帯の観察結果などと合わせて,超丹波帯と丹波帯の地質構造発達史を検討した.超丹波帯は後期ペルム紀〜三畳紀(?)付加体の上月層・大飯層・氷上層に,丹波帯はジュラ紀付加体の周山・雲ヶ畑・灰屋・鶴ヶ岡・由良川の5つのコンプレックスと古屋層に区分される.これらの地質体は衝上断層によって境され,大局的には北に向かって構造的上位かつ古い地質体が分布するパイルナップ構造を形成している.超丹波帯および丹波帯は東西~北西-南東走向で西〜北西に傾斜した軸を持つ半波長数kmの褶曲構造を形成している.この褶曲構造を切って北東-南西方向に,左横ずれカタクレーサイト帯を伴う地質断層としての上林川断層が延びている.活断層としての上林川断層は右横ずれ成分が卓越し,より古い地質断層の一部が横ずれインバージョンによって再活動していることが判明した.