제목: Volatile Geochemistry of Cenozoic Magmatism and Mantle in Korea​

​​​​​​​​​​​​​​​​​​연사: 이현우 교수 (서울대학교)​​​

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일시: 2026년 6월 12일 금요일 16:30

장소: 과학관 B101호​​​

Abstract:

​In NE Asia, including the Korean Peninsula, intraplate magmatism became dominant after the  East  Sea  opening  during  the  Miocene.  Baekdusan,  Jeju  Island,  Ulleungdo,  Dokdo, Hantangang  are  representative  volcanic  areas. According  to  previous  petro-geochemical studies, it is reported that the Cenozoic magmas in Northeast Asia are enriched based on trace elements and radiogenic isotopes. A recent hypothesis is that the stagnant slab of the Pacific plate, which is thought to be located in the mantle transition zone in underneath Northeast Asia, contributed to the enriched characteristics. Until now, it can be seen as the main model that crustal  materials  recycled  through  subduction  caused  the  enrichment  of  the  NE Asian asthenosphere. Our research group is conducting studies using volatiles that have not been well carried out in Korea to identify origins of enriched Cenozoic magmas in Northeast Asia. First, by analyzing noble gas isotopes (He, Ne and Ar) of basalts and mantle xenoliths, we suggested that the origin of the Cenozoic volcanic rocks is somewhat influenced by subcontinental lithospheric  mantle  (SCLM).  However,  the  relative  dominance  of  volatiles  from  the asthenospheric mantle in regions such as Baekdusan, Jeju Island, and Hantangang may indicate the heterogeneous distribution of the NE Asian SCLM. Moreover, volatiles show that the NE Asia region has experienced SCLM metasomatism for a long time through subduction. In Ulleungdo, Jeju Island, and the Korean Peninsula fault zones, mantle volatiles are released in the form of CO2-rich gases. In particular, in addition to Baekdusan, Jeju, and the East Sea, lithospheric thinning is suggested in the eastern part of the Korean Peninsula, and our results indicate that mantle volatiles are degassed somewhat over a wide area. Thus, our studies show the implication that the Earth’s mantle may be emitting significant amounts of volatiles not just through magmatism but also through faults.