Restoration of the Paleo Ryoke Terrane - Geotectonic Evolwtion of Kyshu

古Ryoke地体的恢复-九州大地构造演化

• 批准号: 09640551
• 负责人: TAKAGI Hideo
• 金额: $ 1.22万
• 依托单位: Waseda University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640551/
• 关键词: Paleo-Ryoke Terrane; Higo Terrane; Mizukoshi Formation; K-Ar age; CHIME age; Kyushu; Onogawa Group; Higo metamophic rocks; 花崗岩礫; 山中花崗閃緑岩; 唐崎マイロナイト

K-Ar age determinations were carried out for granitic clasts from the Cretaceous Onogawa Group, Yamanaka Granodiorite distributed to the north of Onogawa Group in eastern Kyushu, and granitic clast from Permian Mizukoshi Formation in the Higo Terrane, western Kyushu. CHIME monazite and zircon age determina-tions were also carried out for Higo metamorphic rocks. The major results are as follows :1. K-Ar hornblende and biotite ages for four granitic clasts from Onogawa Group are concentrated in 103-108 Ma.K-Ar hornblende, biotite and K-feldspar ages for Yamanaka granodiorite are 103, 104 and 75.1Ma, respectively. These results suggest that the granitic clasts in the Onogawa Group were supplied from the Asaji metamorphic terrane on the north. However, the origin of Asaji metamorphic rocks remains unsolved.2. K-Ar hornblende age for tonalite clast from the Mizukoshi Formation is 260 ± 13 Ma. The initial isotopic Sr ratio ranges from 0.7037 to 0.7053. The XRF whole rock analyses show that the granitic clasts in the Mizukoshi Formation has characteristics of M-type volcanic arc granite. These results are identical to the characteristics of the granitic clasts in the Usuginu-type conglomerate in the South Kitakami and Kurosegawa Terranes, and also as those of the Permian granitic rocks constituting Paleo-Ryoke Terrane. Accordingly, the terrane from where the granitic clasts were supplied in Permian time must be immature island arc extending an order of 1000 km where M-type granitic rocks were exposed.3. CHIME monazite ages of the Higo metamorphic rocks concentrate about 120 Ma, whereas CHIME zircon ages have a peak of 250 Ma. The younger age shows peak metamorphic age, whereas the older age is considered to be inherited age retained in the detrital zircon.

对九州东部白垩纪小野川群北部的山中花岗闪长岩和九州西部日吾地体二叠纪水越组的花岗岩碎屑进行了K-Ar年龄测定。对日吾变质岩进行了CHIME独居石和锆石年龄测定。主要研究结果如下：1.小野川群4个花岗质碎屑的K-Ar角闪石和黑云母年龄集中在103-108 Ma，山中花岗闪长岩的K-Ar角闪石、黑云母和钾长石年龄分别为103、104和75.1Ma。这些结果表明，小野川群中的花岗质碎屑来自北部的浅地变质碎屑岩。然而，浅地变质岩的成因至今仍是一个未解之谜.水越组英云闪长岩碎屑的K-Ar角闪石年龄为260 ± 13 Ma。初始Sr同位素比值为0.7037 ~ 0.7053。X射线荧光全岩分析表明，水越组花岗质碎屑具有M型火山弧花岗岩的特征。这一结果与北上地体和黑濑川地体的牛杉型砾岩中的花岗质碎屑特征一致，也与构成古良屋地体的二叠纪花岗质岩石的特征一致。因此，二叠纪花岗岩碎屑的来源地应为出露M型花岗岩的、延伸约1000 km的未成熟岛弧. Higo变质岩的CHIME独居石年龄集中在120 Ma左右，而CHIME锆石年龄的峰值为250 Ma。较年轻的年龄显示变质峰年龄，而较年长的年龄被认为是碎屑锆石中保留的遗传年龄。

项目成果

鈴木和博 ほか3名: "CHIME年代測定法とその造山帯形成過程解析への応用" 地球化学. 33(印刷中). (1999)

Kazuhiro Suzuki等3人：“CHIME测年方法及其在造山带形成过程分析中的应用”地球化学33（出版中）。

Yoshmura, J. and Takagi, H.: "Structural analyses and geotectonic correlation of the Karasaki mylonites, western Shikoku"Journal of the Geological Soc. of Japan. Vol. 105, No. 11. 739-756 (1999)

Yoshmura, J. 和 Takagi, H.：“四国西部唐崎糜棱岩的结构分析和大地构造关联”地质学会杂志。

吉村浄治・高木秀雄: "四国西部・宮崎マイロナイトの構造解析と地体構造上の位置づけ"地質学雑誌. 105-11. 739-756 (1999)

Joji Yoshimura 和 Hideo Takagi：“四国西部宫崎糜棱岩的构造分析和地质构造位置”地质杂志 105-11 (1999)。

Takagi, H., Soda, Y. and Shibata, K.: "K-Ar ages of the granitic clasts from the Onogawa Group, eastern Kyushu"Memoirs of the Geological Soc. of Japan. No. 56. 213-220 (2000)

Takagi, H.、Soda, Y. 和 Shibata, K.：“九州东部小野川群花岗岩碎屑的 K-Ar 年龄”地质学会回忆录。

戸邉恵里・高木秀雄・柴田賢: "九州肥後帯水越層中の花崗岩礫のK-Ar年代"地質学論理. 第56号. 221-228 (2000)

Eri Tobe，Hideo Takagi，Ken Shibata：“九州肥后含水层溢流组花岗岩砾石的 K-Ar 年龄”《地质逻辑》No. 56. 221-228 (2000)。