Photon-activation analysis of volcanic rocks from Northeast Japan Arc.

日本东北弧火山岩的光子活化分析。

• 批准号: 63460048
• 负责人: YOSHIDA Takeyoshi
• 金额: $ 4.54万
• 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: 1988
• 资助国家: 日本
• 起止时间: 1988 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63460048/
• 关键词: Photon-activation analysis; Volcanic rock; Northeast Japan Arc; Volcanic zone; Lateral variation; Incompatible trace element; Source mantle; Mantle heterogeneity; γ線自動計測システム; 島弧; 海溝系; 火山岩組成; 帯状配列; 組成の時間的変還; 東北日本弧γ線自動計測システム; 起源物質

The Northeast Japan Arc has been divided into four volcanic zones, Aoso-Osore, Sekiryo, Moriyoshi and Chokai, from the trench to back arc side. The lateral variation of the volcanic rocks from the four volcanic zones was investigated. In the Aoso-Osore zone, low-K calc-alkaline rocks with subordinate low-K tholeiites erupted. Medium-K calc-alkaline rocks are associated with, and often follow low-K tholeiites at the volcanoes of the Sekiryo zone. The Moriyoshi zone is characterized by medium-K calc-alkaline rocks with subordinate medium-K tholeiites. The Chokai zone contains medium-K calc-alkaline rocks on the eastern side, and high-K calc-alkaline rocks on the western side. These are associated with high-alumina basalts and alkali basalts, respectively.Instrumental photon-activation analysis has been used to determine 13 trace elements: Sc, Cr, Co, Ni, Zn, Rb, Cs, Sr, Ba, Ce, Y, Nb and Zr in these volcanics. Quaternary volcanic rocks from the Northeast Japan arc are enriched in K, Ba, Rb and Sr and depleted in Nb, Ti and Zr relative to Y and Ce. These rocks, also, show a distinct lateral variation of trace elemental abundances. Across the segment in Northeast Honshu, P_2O_5, Rb, Ce, Sr, Ba and Cs contents increase gradually with distance from the volcanic front; K_2O, Y, Zr and Nb also increase by smaller enrichment factors than the former elements. on the basis of the abundance of incompatible trace elements of each volcanic center, the degree of partial melting and the abundances of the incompatible elements of the source mantle have been calculated. The back-calculated source compositions show chemical heterogeneity within the mantle wedge.

日本东北弧从海沟到弧后可划分为青总、关良、盛吉和长海四个火山带。研究了四个火山岩带火山岩的横向变化。在Aoso-Osore带，低钾钙碱性岩石与次级低钾拉斑玄武岩爆发。中钾钙碱性岩石与Sekiryo带火山的低钾拉斑玄武岩相关，并经常跟随低钾拉斑玄武岩。Moriyoshi带的特征是中钾钙碱性岩石和次级中钾拉斑玄武岩。Chokai带东侧包含中钾钙碱性岩石，西侧包含高钾钙碱性岩石。用仪器光活化分析法测定了这些火山岩中Sc、Cr、Co、Ni、Zn、Rb、Cs、Sr、Ba、Ce、Y、Nb、Zr等13种微量元素。日本岛弧东北部第四纪火山岩相对于Y和Ce，富集K、Ba、Rb和Sr，亏损Nb、Ti和Zr。这些岩石，也表现出明显的微量元素丰度的横向变化。P_2O_5、Rb、Ce、Sr、Ba和Cs含量在本州东北段随远离火山前缘而逐渐增加，K_2O、Y、Zr和Nb也以较小的富集因子增加。根据各火山中心的不相容微量元素丰度，计算了源区地幔的部分熔融程度和不相容元素丰度。反算的源区成分显示了地幔楔内部的化学不均匀性。

项目成果

中村洋一・宇賀神俊彦・石川賢一・吉田武義・青木謙一郎: "足尾山地東縁地域に分布する中新世玄武岩類の微量元素組成" 核理研報告. 22. 86-103 (1989)

Yoichi Nakamura、Toshihiko Ugagami、Kenichi Ishikawa、Takeyoshi Yoshida、Kenichiro Aoki：“分布在足尾山脉东缘的中新世玄武岩的微量元素组成”核研究所报告22. 86-103（1989）。

福留高明・吉田武義・長尾敬介・板谷徹丸・田上誠二: "日本海久六島の鮮新世アルカリ玄武岩" 岩鉱. 85. 10-18 (1990)

Takaaki Fukudome、Takeyoshi Yoshida、Keisuke Nagao、Tetsumaru Itaya 和 Seiji Tagami：“日本海黑六群岛的上新世碱性玄武岩”Iwamine 85. 10-18 (1990)。

Yoshida, T., Sakayori, A. and Aoki, K.: "Regional variation of volcanic rock compositions in the Northeast Honshu arc. (in Japanese)" Res. Rep. Lab. Nucl. Sci. Tohoku Univ., 21, 281-300 (1988).

Yoshida, T.、Sakayori, A. 和 Aoki, K.：“本州岛东北部弧火山岩成分的区域变化。（日语）”Res。

Ohguchi, T., Yoshida, T. and Okami, K.: "Historical change of the Neogene and Quaternary volcanic field in the Northeast Honshu Arc, Japan. (in Japanese with English abstract)" Memoirs of Geological Society of Japan, No. 32, 431-455 (1989).

Ohguchi, T.、Yoshida, T. 和 Okami, K.：“日本本州东北弧新近纪和第四纪火山场的历史变迁。（日文，英文摘要）”日本地质学会回忆录，第 1 期。

Aoki, K., Yoshida, T. and Zhe, J.Y.: "Petrology and geo-chemistry of Pleiocene dacitic and rhyolitic pyroclastic flows from southern part of northeast Honshu, Japan." Jour. Min. Pet. Econ. Geol. 84, 1-14 (1989).

Aoki, K.、Yoshida, T. 和 Zhe, J.Y.：“来自日本本州东北部南部的更新世英安岩和流纹质火山碎屑流的岩石学和地球化学。”