著者

佐沢 豪 Legrand Julien 矢部 淳 指田 勝男 上松 佐知子

出版者

一般社団法人 日本地質学会

雑誌

日本地質学会学術大会講演要旨 第124年学術大会(2017愛媛) (ISSN:13483935)

巻号頁・発行日

pp.233, 2017 (Released:2018-03-30)

著者

大関 仁智 清水 紀和 上松 佐知子 指田 勝男

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.130, no.3, pp.311-329, 2021-06-25 (Released:2021-07-20)

参考文献数

69

被引用文献数

2

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Zircons in Cretaceous sandstones have recently been the focus of a new provenance analysis technique. Microfossil-bearing clasts in conglomerate are also used in this analysis; however, there are few reports on clasts, including microfossils, which are mainly found in the vicinity of Shikoku and Hokuriku districts. Although the Ishido Formation, Sanchu Group, in the Kanto Mountains, is considered to be Barremian in age based on the occurrences of ammonoids, interbedded with conglomeratic beds, there have been no reports of microfossil-bearing clasts from this bed. To confirm whether each fore-arc basin in the whole of southwest Japan had a common hinterland during the Late Mesozoic, microfossils are extracted from gravels in the Ishido Formation to examine their ages. As a result of acidic treatment, Permian and Triassic radiolarians and Triassic conodonts are obtained from eight chert and siliceous mudstone pebbles of the Ishido Formation. On the basis of their lithofacies and ages, these pebbles of this formation are likely to derive from the Chichibu Belt, which constitutes a large part of the Kanto Mountains. These results indicate that, in the Early Cretaceous period, not only granitic rocks but also Jurassic accretionary complexes were exposed as hinterlands of each fore-arc basin in the Shikoku and Kanto districts. Moreover, based on previous reports on the zircon spectra in Cretaceous sandstones and microfossil-bearing clasts in the conglomerates, hinterlands, such as granitic rocks and Jurassic accretionary complexes, of each fore-arc basin in the whole of southwest Japan including the Kanto district, as well as Kyushu and Shikoku districts, indicate common exposure and denudation histories.

著者

伊藤 剛 鈴木 紀毅 指田 勝男

出版者

国立研究開発法人 産業技術総合研究所 地質調査総合センター

雑誌

地質調査研究報告 (ISSN:13464272)

巻号頁・発行日

vol.72, no.4, pp.359-370, 2021-10-13 (Released:2021-10-20)

参考文献数

54

被引用文献数

2 3

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本論では,主に群馬県みどり市大間々町に分布する足尾帯ジュラ紀付加体大間々コンプレックスから得られた放散虫化石及び有孔虫の産出を報告する.チャートからはグアダルピアン世~ローピンジアン世(中期~後期ペルム紀)・中期~後期三畳紀・ジュラ紀の放散虫が,珪質泥岩からは前期及び中期ジュラ紀の放散虫が産出した.また,石灰岩からはシスウラリアン世~グアダルピアン世(前期~中期ペルム紀)のフズリナと小型有孔虫が産出した.

著者

歌川 史哲 指田 勝男 上松 佐知子 髙津 翔平

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.123, no.11, pp.969-976, 2017-11-15 (Released:2018-02-23)

参考文献数

15

被引用文献数

1

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The Neogene Chikura Group, which is widely exposed in the southeastern part of Minamiboso City, Chiba Prefecture, Japan, is made up of a thick sequence of marine sedimentary rocks deposited in a middle to upper bathyal environment. The group comprises (in ascending order) the Shirahama, Shiramazu, Mera and Hata formations. The upper Pliocene Shirahama Formation is composed mainly of red-brown volcaniclastic sandstone and the Nojimazaki Conglomerate Member. This member comprises volcaniclastic conglomerate with granules to boulders of basalt and andesite, and is characterized by pebbles of andesite, basalt, granodiorite, gabbro, sandstone, siltstone, greenish tuff, and chert. We obtained Anisian and Ladinian (Middle Triassic) radiolarians from chert pebbles, and Bajocian to Callovian (Middle Jurassic) radiolarians from a siliceous siltstone pebble. These Mesozoic pebbles were probably derived from a Mesozoic accretionary complex (present-day Kanto District) in the northwestern part of Boso Peninsula.