Activity of proto-Pacific superplume from the viewpoint of Paleozoic ophiolites in Southwest Japan.

从日本西南部古生代蛇绿岩的角度看原太平洋超羽流活动。

• 批准号: 08640572
• 负责人: HAYASAKA Yasutaka
• 金额: $ 1.28万
• 依托单位: HIROSHIMA 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 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640572/
• 关键词: Pacific superplume; Southwest Japan; Paleozoic ophiolite; Oe-yama ophiolite; Yakuno ophiolite; Paleozoic accretionary complex; Jurassic accretionary complex; オフィオライト; 舞鶴帯; 夜久野岩類; U-Pb年代; HIMU玄武岩; 緑色岩; 島弧-背弧盆系; 海台

1. Oe-yama ophiolite : Ashidachi complex shows the Sm-Nd isotopic ages of 560 Ma for coarse-grained gabbro, and 350 to 450Ma for the fine-grained gabbro.2. Yakuno ophiolite : Gneissose metagabbro shows the Sm-Nd isotopic ages from 340 to 38OMa. U-Pb dating for the zircon from two samples of tonarite in the Asago-cho area yield ages of 282 and 285Ma respectively. Gabbro migmatite was discovered from the Lower gabbro member in the Asago-cho area, at where the partial melting process was well documented at the base of immature island arc.3. Greenstones in the Jurassic accretionary complex : Greenstone of Masuda area shows the Sm-Nd isotopic ages of ca. 340Ma Alkaline basalt such as ankaramite was found from the greenstones in Mochigase-cho area, which shows very high Nb/Zr ratio that it was similar to HIMU basalt.4. Cphiolite of other areas : Age determinations using Sm-Nd, Rb-Sr isochron methodand the U-Pb for zircon by SHRIMP were carried out about the Schmidt Peninsula ophiolite of the northern Sakhalin, and the ages ca. 125Ma were obtained. Metamorphic facies and geochemical analysis were enforced about the Mariana forearc ophiolite, and a resemblance with the Yakuno ophiolite was found.5. construction of the geochemical data base : Data base system using "filemaker Pro ver. 3.O" was composed as a relational database for geochemistry.6. Summary : A coeval activities from 350 to 400Ma among Paleozoic ophiolitic rocks such as fine-grained gabbro and diabase intruded in the Ce-yama ophiolite, the sea mount group of the Akiyoshi terrane, the gneissose metagabbro of the Yakuno ophiolite, greenstones in the Jurassic accretionary complex are prominent in Southwest Japan. The simultaneous activities might be occurred to make superplume lasted from Devonian to early Carboniferous time in the proto-Pacific region.

1. 粗粒辉长岩的Sm-Nd同位素年龄为560 Ma，细粒辉长岩的Sm-Nd同位素年龄为350 ~ 450Ma。雅库诺蛇绿岩：片麻岩变质辉长岩Sm-Nd同位素年龄为340 ~ 38OMa。阿散古-丘地区2个滑石样品锆石U-Pb定年，产龄分别为282 ma和285Ma。2 .在Asago-cho地区的下辉长岩段发现了辉长岩混长岩，在未成熟岛弧的底部有部分熔融作用的记录。3 .侏罗纪增生杂岩中的绿岩：增田地区绿岩显示出约340Ma的Sm-Nd同位素年龄，在莫奇加斯-丘地区绿岩中发现了ankaramite等碱性玄武岩，其Nb/Zr比值非常高，与HIMU玄武岩相似。其他地区蛇绿岩：对库页岛北部施密特半岛蛇绿岩进行了Sm-Nd、Rb-Sr等时线测年和SHRIMP锆石U-Pb测年，得到了其年龄约为125Ma。对马里亚纳弧前蛇绿岩进行了变质相和地球化学分析，发现其与雅库诺蛇绿岩有相似之处。地球化学数据库的构建：基于filemaker Pro的数据库系统。3.构建了一个地球化学关系型数据库。摘要：日本西南地区在350 ~ 400Ma的古生代蛇绿岩中，侵入的细粒辉长岩和辉绿岩、秋吉地体海山群、雅库诺蛇绿岩的片麻岩变质岩、侏罗纪增生杂岩中的绿岩等蛇绿岩的同期活动较为突出。这些同时发生的活动可能使得超级羽流在原太平洋地区从泥盆纪持续到早石炭世。

项目成果

鈴木 盛久: "蛍光X線分析法による岩石中の主要元素および微量元素の定量分析" 広島大学学校教育学部紀要,第II部. 20. 29-36 (1998)

Morihisa Suzuki：“使用 X 射线荧光分析对岩石中的主要元素和微量元素进行定量分析”广岛大学学校教育学院通报，第 II 部分 20. 29-36 (1998)。

Herzig,C.T.: "Late Cretaceous U/Pb zircon ages and Precambrian crustal inheritance in Ryoke belt granitoids,Kinki and Yanai districts,Japan" Geochemical Journal. 32. 21-31 (1998)

Herzig,C.T.：“日本近畿和柳井地区 Ryoke 带花岗岩中的晚白垩世 U/Pb 锆石年龄和前寒武纪地壳继承”《地球化学杂志》。

Makoto Watanabe: "Metallogenic epochs in the Inner Zone of southwest Japan." Ore Geology Reviews. 12. 267-288 (1998)

Makoto Watanabe：“日本西南部内区的成矿时代。”

Herzig, C.T., Kimbrough, D.L.and Hayasaka, Y.: "Early Permian zircon uranium-leadages for plagio-granites in the Yakuno ophiolite, Asago district, Southewest Japan." Island Arc. vol.6. 396-403 (1997)

Herzig, C.T.、Kimbrough, D.L. 和 Hayasaka, Y.：“日本西南部朝来地区 Yakuno 蛇绿岩中早二叠世锆石铀矿的斜长花岗岩。”

Herzig,C.T.: "Early Permian zircon uranium-lead ages for plagiogranites in the Yakuno ophiolite,Asago district,Southewest Japan." Island Arc. 6. 396-403 (1997)

Herzig, C.T.：“日本西南部朝来地区 Yakuno 蛇绿岩中斜长花岗岩的早二叠世锆石铀铅年龄。”