Geology and petrology of volcanic conduits and lava domes

火山管道和熔岩穹顶的地质学和岩石学

• 批准号: 08640569
• 负责人: SAWADA Yoshihiro
• 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-08640569/
• 关键词: volcanic conduit; lava dome; pyroclastic flow; evolved magma; dacite; partial melting; magma mixing; Southwest Japan; 岩脈; マグマ・ミキシング; マグマの発泡; マグマの砕砕化; 解析された火山体

Research results are summarized as follows : 1) Geological, petrographical and geochemical studies have carried out for origin of shoshonite, trachyte and rhyolite magmas, and features of volcanic conduits of evolved magmas which are widely distributed in the Oki Islands. Some rhyolite magmas were generated by partial melting of crustal materials under different P-T conditions and degree of partial melting. Magma mixing took place during uprising of magma or in conduit. 2) There are some granulite xenoliths including partial melt glasses with rhyolitic composition in late Cenozoic basalts in the west San'in region. This demonstrates the potential for generation of felsic magma beneath the west San'in region in late Cenozoic time. 3) The temperature of pyroclastic flow was estimated by ^<13>C/^<12>C isotope ratio, H/C ratio and infrared spectroscopy (absorption) of carbonaceous woods made under given temperature and times. ^<13>C/^<12>C isotope ratio is not available, but H/C ratio and infrared spectroscopy (absorption) are very affectable, especially in the case of less than 400ﾟC.4) Many Quanternary volcanoes with dacite compositions are sporadically distributed from the San'in region to northern Kyushu. Systematic differences of chemical characteristics are recognized from Daisen and Sambe volcanoes to Taradake volcano through Oetakayama, Aonoyama and Kunisaki Peninsula. 5) Fluid components, such as S,CO_2, Cl and F,in volcanic glass from Sambe dacite lava and pyroclstics have been analyzed for examination of relationship between eruption and non-eruption felsic magmas.

研究成果总结如下：1)对广泛分布于冲木群岛的粗面岩、粗面岩和流纹岩岩浆的成因及演化岩浆的火山导管特征进行了地质、岩石学和地球化学研究。有些流纹岩岩浆是在不同的P-T条件和部分熔融程度下由地壳物质部分熔融而产生的。岩浆混合发生在岩浆上升过程中或管道中。2)西三隐地区晚新生代玄武岩中存在含流纹岩成分的部分熔融玻璃的麻粒岩包体。这说明了晚新生代西三印地区具有长英质岩浆的生成潜力。3)通过给定温度和时间下的碳质木材的^<13>C/^<12>C同位素比值、H/C比值和红外光谱（吸收）估算火山碎屑流温度。^<13>C/^<12>C同位素比值没有得到，但H/C比值和红外光谱（吸收）是非常受影响的，特别是在低于400‰的情况下。4)从三音地区到九州北部，零星分布着许多英安岩成分的第四纪火山。从大森火山和三部火山到Taradake火山，再到大高山、青山和国崎半岛，发现了化学特征的系统差异。5)分析了三部英安岩熔岩和火山碎屑中火山玻璃的流体组分S、CO_2、Cl和F，探讨了喷发和非喷发长英质岩浆的关系。

项目成果

古山 勝彦 ほか: "近畿北部、鮮新世照宋層群寺田火山岩層のK-Ar年代" 地球科学. 52. 38-43 (1998)

Katsuhiko Furuyama 等：“近畿北部上新世 Teruso 群寺田火山岩层的 K-Ar 年龄”地球科学 52. 38-43 (1998)。

沢田 順弘 ほか: "島根県大田市の掘削コアから発見された欝陵島の完新世初期火山活動由来の漂着軽石" 第四紀研究. 36. 1-16 (1997)

Junhiro Sawada 等：“从岛根县大田市的挖掘核心中发现的郁陵岛全新世早期火山活动衍生的浮石”第四纪研究。 36. 1-16 (1997)。

Furuyama K., Sawada Y., Itaya T., Miyake Y., Inoue Y.and Kotaki A.: "K-Arages of some volcanic rocks from the Yoka Formation, Miocene Hokutan Group, northern Kinki district." Earth Science. 51. 452-457 (1997)

Furuyama K.、Sawada Y.、Itaya T.、Miyake Y.、Inoue Y.和 Kotaki A.：“来自近畿地区北部中新世北丹群 Yoka 组的一些火山岩的 K-Arages。”

Furuyama K., Sawada Y., Itaya T.and Miyake Y.: "K-Ar ages of some volcanic rocks from the Terada Volcanics, Pliocene Teragi Group, northern Kinki district." Earth Science. 52. 38-43

Furuyama K.、Sawada Y.、Itaya T. 和 Miyake Y.：“来自近畿地区北部上新世 Teragi 群 Terada 火山的一些火山岩的 K-Ar 年龄。”

沢田順弘ほか: "島根県大田市の掘削コアから発見された欝陵島の完新世初期火山活動の由来の漂着軽石" 第四紀研究. 36. 1-16 (1997)

Nobuhiro Sawada 等：“从岛根县大田市的挖掘核心中发现的郁陵岛全新世早期火山活动衍生的浮石”第四纪研究。 36. 1-16 (1997)。