西南日本の新生代火成活動とテクト二クス

日本西南部的新生代岩浆作用和构造

• 批准号: 06302028
• 负责人: NAGAO Takashi
• 金额: $ 4.35万
• 依托单位: Yamaguchi University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06302028/
• 关键词: Southwest Japan; Island arcs; Cenozoic; Igneous activity; Magma; Tectonics; Radiogenic age; Isotope; 玄武岩; 安山岩; プルトニズム

(1) Cenozoic magmatism in southwest Japan was reviewed and some ideas of origin of island arc magmatism were proposed.(2) Late cenozoic basalts are widely distributed along the southwest Japan arc. In the Chugoku district, an enriched mantle plume with an EM I signature ascended from deep in the mantle. On the other hand, mantle diapirs characterized by an EM II signature rose slowly and were entrained an overlying N-MORB like depleted mantle below the north Kyushu district.(3) The magmas of Higashi-Matsuura alkali basalts (HMB) attract attention by their three cyclic variation in composition (magmatic cycles). It has been found that each magmatic cycle starts with the eruption of primitive basalts followed by fractionated ones. This suggests that the magma chambers of HMB were compositionally stratified.(4) The rocks of Uku island represent four magmatic cycles. Each cycle began with the eruption of basic magma, followed by eruption of andesitic to dacitic magma. The chemical variatio … More n of these rocks are controlled by fracitonal crystallization, with minor wall rock assimilation.(5) Adakite-like magmas in Daisen volcanic zone were derived from partial melting of lower crust or mixing of mantle derived magma and adakite-like magma.(6) A dacite dome at Unzen volcano grew mainly exogeneously when it was small and the effusion rate was high, but endogeneously when the dome became large and the effusion rate declined.(7) In Cenozoic southern Kyushu, moderate to high potassic "flood andesites" were derived from high-magnesian andesite and voluminous low potassic andesites were produced by fractional crystallization of basalt magmas.(8) Many high-magnesian andesites (HMA) in Cenozoic southwest Japan were petrographically described and the origin of HMA magmas was discussed.(9) Mechanisms of Cretaceos to Paleogene plutonism were explained by the plate motions.(10) The low potassium analytical method with ordinary flame photometry in convenience and high precision was developed. This method was applied to the K-Ar dating of igneous and metamorphic hornblendes from ophiolites and coexisting hornblende and clinopyroxene from volcanic rocks. Less

(1)对日本西南部新生代岩浆活动进行了评述，提出了岛弧岩浆活动成因的一些看法。(2)晚新生代玄武岩沿日本西南弧广泛分布。在Chugoku地区，一个具有EM - I特征的富集地幔柱从地幔深处上升。另一方面，以EM II型特征为特征的地幔底液上升缓慢，并被上覆的N-MORB型衰竭地幔挟持。(3)东松浦碱玄武岩（HMB）岩浆以其组成的三旋回变化（岩浆旋回）引起人们的注意。研究发现，每一次岩浆旋回都始于原始玄武岩的喷发，然后是分次喷发。这表明HMB岩浆房在成分上是分层的。(4)乌库岛的岩石代表了四个岩浆旋回。每个旋回都以基性岩浆的喷发开始，接着是安山岩到英安岩岩浆的喷发。这些岩石的化学变化受分数结晶控制较多，围岩同化作用较小。(5)岱森火山带埃达克岩类岩浆来源于下地壳的部分熔融或幔源岩浆与埃达克岩类岩浆的混合作用。(6)云禅火山英安岩穹丘在小的时期主要是外生发育，而在大的时期主要是内生发育。(7)九州南部新生代中、高钾“洪泛安山岩”来源于高镁安山岩，大量低钾安山岩由玄武岩岩浆分步结晶而成。(8)对日本西南部新生代多处高镁安山岩进行了岩石学描述，并对其岩浆成因进行了探讨。(9)用板块运动解释了白垩纪-古近纪的深部成矿作用机制。（10）建立了简便、精度高的普通火焰光度法低钾分析方法。该方法应用于蛇绿岩中火成岩角闪石和变质角闪石以及火山岩中角闪石和斜辉石共存的K-Ar定年。少

项目成果

Morris, P.A.and Itaya, T.: "The Matsu Formation : Evidence for gross mantle heterogeneity beneath southwest Japan at 11Ma." The Island Arcs. (in press). (1997)

Morris, P.A. 和 Itaya, T.：“马祖地层：11 Ma 时日本西南部地幔粗大地幔异质性的证据”。

Nakada, S., Miyake, Y., Sato, H., Oshima, O.and Fjinawa, A.: "Endogeneous growth of dacite dome at Unzen volcano (Japan), 1993-1994." Geology. 23. 157-160 (1995)

Nakada, S.、Miyake, Y.、Sato, H.、Oshima, O. 和 Fjinawa, A.：“云仙火山（日本）英安岩穹顶的内生生长，1993-1994 年”。

Nagao, T., Hase, Y., Ikawa, T., Nagamine, S., Sakaguchi, K., Yamamoto, M., Shuto, K.and Hayashida, K.: "Characteristics of andesites forming lave plateaus, in Kyushu, SW Japan : proposal of "flood andesite"." Mem.Geol.Soc.Japan. 44. 155-164 (1996)

Nagao, T.、Hase, Y.、Ikawa, T.、Nagamine, S.、Sakaguchi, K.、Yamamoto, M.、Shuto, K. 和 Hayashida, K.：“九州熔岩高原安山岩的特征

Yano, T.and Wu, G.: "Middle Jurassic to Early Cretaceous arch tectonics in East Asian continental margin." Proc.15th International Sympo.Kyungpook Naitonal Univ.177-192 (1995)

Yano, T. 和 Wu, G.：“东亚大陆边缘的中侏罗世至早白垩世拱构造”。

Shiraki,K.,Yoshioka,K.and Matsumoto,Y.: "Magnesian andesites in the Oono volcanic rocks,central Kyushu : westward continuation of the Setouchi volcanic. belt" Jour.Geol.Soc.Japan. 101. 387-392 (1995)

Shiraki, K.、Yoshioka, K. 和 Matsumoto, Y.：“九州中部大野火山岩中的镁质安山岩：濑户内火山带的向西延续”Jour.Geol.Soc.Japan。