The early stage of the development of the Sambagawa metamorphic belt estimated from the metamorphic clasts within the Kuma Group

从球磨群内的变质碎屑推测三波川变质带发育的早期阶段

• 批准号: 08640570
• 负责人: TAKASU Akira
• 金额: $ 1.34万
• 依托单位: SHIMANE UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640570/
• 关键词: Sambagawa; Kuma Group; clasts; accretionary prism; high-P metamorphism; geochronology; garnet; eclogite; P-T-t経路; ^<40>Ar; ^<39>Ar年代測定; Rb-Sr年代測定; Sm-Nd年代測定; フィッショントラック年代測定

Geological survery and sampling of the metamorphic rocks from the Kanto Mountains, Kii Peninsula and Shikoku in the Sambagawa metamorphic belt and Wakasa in the Sangun metamorphic belt have been done. We petrographically compared the high-grade metamorphic clasts with the high-P type metamorphic rocks presently exposed in southwest Japan together with the other metamorphic rocks such as those from the Hida, Himalayan and Kyrghstan metamorphic belts. We chemically analyzed the constituent minerals including garnet, amphibole, epidote and white micas by using an electron probe micro-analyzer, and also examined these minerals in respect to the chemical zoning, backscattered electron image and elemental color mapping. These studies revealed that the high-grade metamorphic clasts from the Kuma Group are very much similar to the epidote amphibolite facies metamorphic rocks within the tectonic blocks such as the Iratsu and Tonaru amphibolite masses.The 40Ar/39Ar dating results suggest that the peak metamorphic age of the Kuma metamorphic clasts is 145-189 Ma and obviously older than that of the Besshi nappe complex (90-100 Ma). The fission track age of the Kuma metamorphic clasts (65-70 Ma) is also older than that of the Besshi nappe complex (45-58 Ma). These studies suggest that the Kuma nappe complex is earlier stage metamorphic rocks compared with the Besshi nappe complex and it was exhumed earlier than the metamorphic rocks within the Besshi nappe complex.

对三钵川变质带的关东山脉、纪伊半岛和四国以及三郡变质带的若狭变质岩进行了地质调查和取样。我们从岩石学上比较了高级变质碎屑岩与目前在日本西南部出露的高P型变质岩以及其他变质岩，如来自希达、喜马拉雅和吉尔吉斯坦变质带的变质岩。利用电子探针对石榴石、角闪石、绿帘石和白色云母等矿物进行了化学分析，并对这些矿物进行了化学分带、背散射电子像和元素颜色图的研究。研究表明，熊群高级变质碎屑岩与伊劳、东那鲁等构造块体中的绿帘角闪岩相变质岩石非常相似，40 Ar/39 Ar测年结果表明，熊群高级变质碎屑岩的峰期变质年龄为145-189 Ma，明显早于别志推覆杂岩的峰期变质年龄（90-100 Ma）。熊麻变质碎屑的裂变径迹年龄（65-70 Ma）也比别志推覆杂岩的裂变径迹年龄（45-58 Ma）大。这些研究表明，熊马推覆杂岩是比别子推覆杂岩更早阶段的变质岩，它比别子推覆杂岩中的变质岩早被剥露。

项目成果

Puelles, P.and Takasu A: "Chemical compositions of constituent minerals of the kyrghystan high-P and ultra high-P met am or plic rosks" Geo science Rep.Shimane Univ.15. 115-135 (1996)

Puelles, P. 和 Takasu A：“吉尔吉斯斯坦高磷和超高磷 met am 或 plic rosks 的组成矿物的化学成分”地球科学 Rep.Shimane Univ.15。

Puelles,P.and Takasu,A.: "Chemical compositions of constituent minerals of the Kyrghyzstan high-Pand ultrahigh-P metamorphic belt." Geol.Report,Shimane Univ.15. (1997)

Puelles,P. 和 Takasu,A.：“吉尔吉斯斯坦高磷和超高磷变质带矿物的化学成分。”

Dallmeyer, R.D.and Takasu, A.: "40Ar/39Ar mineral ages from the Oki metamorphic complex, Oki-Dogo, southwest Japan" Jour.Asian Earth Sci.(in press). (1998)

Dallmeyer, R.D. 和 Takasu, A.：“来自日本西南部 Oki-Dogo 的 Oki 变质杂岩的 40Ar/39Ar 矿物年龄”Jour.Asian Earth Sci.（出版中）。

阪本志津枝・高須 晃: "青海-蓮華帯青海地域のひすい輝石岩からのコスモクロアの発見" 地質学雑誌. 103. 1093-1096 (1997)

Shizue Sakamoto 和 Akira Takasu：“青海-仁格带青海地区玉辉石岩中发现宇宙绿石”地质杂志 103. 1093-1096（1997）。

Dallmeyer, R.D.and Takasu, A: "40Ar/39Ar mineral ages from the Oki met am or phic complex,Olci-Dogs,Southwest Japan" Jour.Asian Eath Sci. (印刷中). (1998)

Dallmeyer, R.D. 和 Takasu, A：“来自日本西南部 Olci-Dogs 的 Oki met am 或 phic 复合体的 40Ar/39Ar 矿物年龄”Jour.Asian Eath Sci（出版中）。