Study on the relation between sedimentation and igenous activity in the forearc area.

弧前区沉积与自然活动关系研究.

• 批准号: 62420014
• 负责人: OGAWA Yujiro
• 金额: $ 12.03万
• 依托单位: Kyushu University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62420014/
• 关键词: accretionary comples; subduction zone; MORB; hotspot; oceanic crust; 海山; EDS化学分析; 前弧域玄武岩; MORB; ホットスポット起源

We defined the tectonic origin of basaltic rock blocks within several accretionary complex of Permian to Tertiary ages in Southwest Japan based on major and minor element analysis. Basalt chemistry suggests the tectonic settings, ie. within plate basalt of hotspot origin (alkalic or tholeiite), mid-oceanic basalt (MORB)(N-or T-type), and island arc basalt. The field observations, especially the mode of occurrence between the surrounding sediments, the capped limestone or chert, degree of deformation and metamorphism are intimately related to the tectonic settings of those basalts. Basalts which are of MORB are highly deformed and metamorphosed, and capped by bedded chert, indicating the underplated oceanic crust in the deeper levels during oceanic plate subduction, while basalts which are of hotspot origin are weakly deformed and metamorphosed, and capped by reef limestone, indicating the offscraped in the shallower levels or trench collapsed seamount. The former examples are in the Northern Shimanto belt, and the latter examples are in the Akiyoshi, Mino and Konose terranes.

通过主、微量元素分析，确定了日本西南部二叠纪至第三纪几个增生杂岩中玄武质岩块的构造成因。玄武岩化学表明构造环境，即。热点成因的板块玄武岩（碱性或拉斑玄武岩）、大洋中玄武岩（MORB）（N型或T型）和岛弧玄武岩。野外观察，特别是与周围沉积物、盖层灰岩或硅质岩的产状关系、变形变质程度等，与玄武岩形成的构造环境密切相关。MORB型玄武岩变形变质程度高，被层状硅质岩覆盖，表明在大洋板块俯冲过程中，深部存在底侵洋壳;而热点型玄武岩变形变质程度低，被礁灰岩覆盖，表明在浅部存在碎屑岩或海沟崩塌海山。前一个例子是在北方四万十带，后一个例子是在秋吉，美浓和小野濑。

项目成果

OGAWA,Y.;TANIGUCHI,H.: Modem Geology. 12. 147-168 (1988)

小川，Y.；谷口，H.：现代地质学。

SANO,H.;KANMERA,K.: Geology. 16. 600-603 (1988)

SANO,H.；KANMERA,K.：地质学。

SANO H.; K. KANMERA: Geology. (1988)

萨诺 H.；

PICKERING,K.T.;AGAR,S.M.;OGAWA,Y.: Geology. 16. 881-885 (1988)

皮克林，K.T.；琼脂，S.M.；小川，Y.：地质学。

佐野弘好,勘米良亀齢,SANO,H.;KANMERA,K.: Geology. 16. 600-603 (1988)

佐野博吉 (Hiroyoshi Sano)，SANO，H.；KANMERA，K.：地质学。16. 600-603 (1988)