Sedimentary petrological comparison of Jurassic clastic rocks between the Mino terrane and the Chichibu terrane

美浓地体与秩父地体侏罗纪碎屑岩沉积岩石学比较

• 批准号: 60480025
• 负责人: ADACHI Mamoru
• 金额: $ 3.9万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60480025/
• 关键词: Detrital garnet; Jurassic clastic rocks; Mino terrane; Chichibu terrane; 重鉱物解析

The main results of this study are as follows:1. EPMA analyses of detrital garnets in Jurassic sandstones of the Mino terrane have revealed that the garnets are generally of Mg-rich almandine with small amounts of Mn and Ca. These garnets were probably derived from granulite facies pelitic gneisses.2. Unlike detrital garnets in the Mino terrane, garnets in Jurassic sandstones of the Chichibu terrane are more enriched in Mn and Ca. From the chemical composition of detrital garnets, there was a significant difference in provenance rocks between the Mino and Chichibu terranes.3. Sandstones of Jurassic Tetori Group in the Hida terrane contain a number of Mg-rich garnets, compositionally similar to those in the Mino terrane. Re-examinations of the Kamihirose conglomerate in the circum-Hida tectonic zone have revealed the occurrence of a garnet-bearing gneiss cobble.4. Chert clasts containing Permian radiolarians have been found from the Yokoo conglomerate in the circum-Hida tectonic zone.5. Petrological and geochemical investigations of "Mn-nodules" in Jurassic siliceous shales in the Mino terrane have shown that barite and length-slow chalcedony occur within the nodules. Chemically the Jurassic "Mn-nodules" are quite different from those on the Pacific ocean floor.

本研究的主要结果如下： 1．对米诺地体侏罗纪砂岩中碎屑石榴石的 EPMA 分析表明，石榴石通常为富镁铁铝榴石，并含有少量锰和钙。这些石榴石很可能来源于麻粒岩相泥质片麻岩。2．与美浓地体中的碎屑石榴石不同，秩父地体侏罗纪砂岩中的石榴石富含锰和钙。从碎屑石榴石的化学成分来看，美浓地体和秩父地体的物源岩存在显着差异。 3．飞弹地体侏罗系手取群砂岩含有大量富镁石榴石，其成分与美浓地体相似。对环飞驒构造带上广砾岩的重新考察揭示了含石榴石片麻岩卵石的存在。 4．环飞驒构造带横尾砾岩中发现含有二叠纪放射虫的燧石碎屑。5．对米诺地体侏罗纪硅质页岩中“锰结核”的岩石学和地球化学研究表明，结核内存在重晶石和长慢玉髓。从化学角度看，侏罗纪“锰结核”与太平洋海底的锰结核有很大不同。

项目成果

Adachi,M , Yamamoto,K and Sugisaki,R: "Hydrothermal chert and associated siliceous rocks from the northern Pacific: their geological significance as indication of ocean ridge activity" Sedimentary Geology. 47. 125-148 (1986)

Adachi,M、Yamamoto,K 和 Sugisaki,R：“来自北太平洋的热液燧石和相关硅质岩石：它们作为洋脊活动指示的地质意义”沉积地质学。

足立守: 地質学雑誌. (1987)

安达守：地质杂志（1987）。

Kojima,S.: "Occurrence of Permian radiolarians from chert pebbles in conglomerate at Yokoo, Nyukawa village, Gifu Prefecture, central Japan" News of Osaka Micropaleontologists. Special volume no.7. 175-179 (1986)

小岛，S.：“日本中部岐阜县入川村横尾砾岩中燧石卵石中发现二叠纪放射虫”《大阪微古生物学家新闻》。

足立守: 大阪微化石研究会誌. 特別号 第7号. 275-286 (1986)

安达卫：大阪微化石研究会杂志特刊第 7 期。275-286（1986 年）

Adachi,M: "The chemical composition of garnets from gneiss clasts in the Kamihirose conglomerate and the Kamiaso conglomerate" Bull.Mizunami Fossil Museum. no.12. 183-196 (1985)

Adachi,M：“Kamihirose 砾岩和 Kamiaso 砾岩中片麻岩碎屑中石榴石的化学成分”Bull.Mizunami 化石博物馆。