11:39 AM - 11:42 AM
[SRD41-P04] REE-bearing Minerals in Granitoids at Sibolga and Panyabungan, North Sumatra, Indonesia
3-min talk in an oral session
Keywords:Sibolga, Panyabungan, Granitoids, A-type, I-type, ilmenite-series
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.