CHARACTERISTICS OF CRETACEOUS IGNEOUS ACTIVITY IN JAPAN ARC

日本弧白垩纪火成岩活动特征

• 批准号: 03452067
• 负责人: KANISAWA Satoshi
• 金额: $ 2.88万
• 依托单位: TOHOKU 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: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-03452067/
• 关键词: Cretaceous; igneous activity; plutonism; shoshonite; slab-melting; origin of magma; tectonics; 微量成分; 深成岩; 火山岩

1) The pre-Cretaceous lithology, stratigraphy, age and geolgic structures were investigated to clarify the background of the Cretaceous igneous activity in Japan.2) Petrographic description, compositional zonation and measurements of Sr-isotopic ratios of some plutons were carried out for the basic data.3) Some dyke rocks in Zone IV plutons are shoshonite and high-K andesite having higher Nb content than those in island-arc tholeiites, and have different mineral compositions, therefore, the occurrence of those rocks has a important significance for the tectonic setting of the Kitakami Mountains during the Cretaceous age.4) The high-Sr series rocks of Zone II plutons in the Kitakami Mountains are characterized by high SiO_2 greater than 61 wt. %, higher Na_2O and lower K_2O, slightly higher Al_2O_3 and lower FeO* and MgO.They are richer in Sr and Ga, and poorer in Rb, Pb and Y.These characteristics are similar in composition to those of the high-Al_2O_3 trondhjemite, tonalite and dacite (high-TTD). Slab-melting was playda greater role for the origin of high-Sr series rocks.5) On the characteristics of the Southwest Japan-are from thecretaceous to Miocene age, it is clarified that the products of the Shimanto-autochthonous activity is those of the bimodal ones at the outer-uprifted zone developed at the fore-arc in the active continental margin.

1)通过对前白垩纪岩石学、地层学、时代和地质构造的研究，阐明了日本白垩纪岩浆活动的背景; 2）对部分岩体进行了岩石学描述、成分分带和Sr同位素比值测定，作为基础资料; 3）Ⅳ带岩体中的部分岩墙岩石为钾玄岩和高钾安山岩，其Nb含量高于岛弧拉斑玄武岩，（4）北山II带岩体中的高Sr系列岩石以SiO_2大于61 wt. %为特征，其特征为SiO_2含量高，SiO_2含量高。富Sr、Ga，贫Rb、Pb、Y，这些特征与高Al_2O_3奥长花岗岩、英云闪长岩和英安岩（高TTD）的成分相似。（5）根据日本西南地区白垩纪至中新世的地质特征，阐明岛根原地活动的产物是活动大陆边缘弧前发育的外隆升带双峰式活动的产物。

项目成果

Tsuchiya,N.: "Early Cretaceous Sr-rich silicic magmatism by slab melting in the Kitakami Mountains,Northeast Japan.(in press)." J.Geophys.Res.,. 99. (1994)

Tsuchiya,N.：“日本东北部北上山脉的早白垩世富锶硅质岩浆作用，由板片熔化引起。（正在印刷中）。”

蟹澤聰史: "北上山地,IV帯の深成岩類を貫くアルカリに富む岩脈類.(印刷中)" 岩鉱. 89. (1994)

Satoshi Kanizawa：“富含碱的堤坝穿透北上山脉 IV 区的深成岩。（正在出版）”Iwako 89。（1994）

Tsuchiya, N.: "Early Cretaceous Sr-rich silicic magmatism by slab melting in the Kitakami Mountains, Northeast Japan." J.geophys.Res.99 (in press). (1994)

Tsuchiya, N.：“日本东北部北上山脉的早白垩世富锶硅质岩浆作用，由板片熔化引起。”

蟹澤聰史: "北上山地,IV帯の深成岩類を貫くアルカリに富む岩脈類." 岩鉱. 89(印刷中). (1994)

Satoshi Kanizawa：“富含碱的堤坝穿透北上山脉 IV 区的深成岩。”89（出版中）。

Kanisawa, S.: "K-Ar ages of amphibolites from the Matsugadaira-Motai Metamorphics and their significance." JOURNAL, VOLUME-NUMBER PAGES, CONCERENED, YEAR J.Japan.Assoc.Min.Pet.Econ.Geol.87-10. 412-419 (1992)

Kanisawa, S.：“Matsugadaira-Motai 变质岩角闪岩的 K-Ar 年龄及其意义。”