日本地球惑星科学連合2015年大会

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セッション記号 S (固体地球科学) » S-RD 資源・鉱床・資源探査

[S-RD41] 資源地質学の新展開:鉱化流体の起源と進化

2015年5月25日(月) 18:15 〜 19:30 コンベンションホール (2F)

コンビーナ:*実松 健造(独立行政法人 産業技術総合研究所 地圏資源環境研究部門 鉱物資源研究グループ)、野崎 達生(海洋研究開発機構地球内部ダイナミクス領域)、大竹 翼(北海道大学大学院工学研究院 環境循環システム部門)、高橋 亮平(秋田大学国際資源学部)

18:15 〜 19:30

[SRD41-P04] REE-bearing Minerals in Granitoids at Sibolga and Panyabungan, North Sumatra, Indonesia

*Setiawan IWAN1Ogata TAKEYUKI2Ryohei TAKAHASHI2Akira IMAI2 (1.Graduate School of Engineering and Resource Science, Akita University, Japan、2.Department of Earth Resource Science, Faculty of International Resource Sciences, Akita University,)

キーワード:Sibolga, Panyabungan, Granitoids, A-type, I-type, ilmenite-series

Granitoids in the western part of North Sumatra are being studied to elucidate the genesis of REE mineralization on the basis of mineralogical and geochemical methods. Eleven samples were analyzed by petrography, XRF, SEM and ICP-MS to identify REE-bearing minerals and determine REE concentration.
The granitoids at Sibolga and Panyabungan are separated by 166 km distance, which formed in different settings, but both of the two magmas share ilmenite-series and metaluminous affinity. Petrographic study revealed that granitoids in Sibolga are A-type and ilmenite-series alkali feldspar granite and quartz syenite, formed within plate setting, and that I-type and ilmenite-series quartz syenite in Panyabungan was formed in volcanic arc setting. Allanite, apatite and titanite in the granitic rocks at Sibolga and Panyabungan contain Y, Ce, La, Pr, Nd, and Yb.
The setting changed due to change in tectonics during Late Permian to Cretaceous, from continental rift to magmatic arc setting. The enrichment of REE in the Sibolga and Panyabungan granitoids was caused by crystallization of allanite, apatite, and titanite.