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Volcanic Activity of the Volcanoes in the Hallasan Natural Reserve, Jeju Island, Korea
한라산천연보호구역 소화산들의 화산활동 기록
Econ. Environ. Geol. 2021 Feb;54(1):1-19
Published online February 28, 2021;  https://doi.org/10.9719/EEG.2021.54.1.1
Copyright © 2021 the Korean society of economic and environmental gelology.

Sei Sun Hong1,*, Choon Oh Lee2, Jaesoo Lim1, Jin Young Lee1, Ung San Ahn3
홍세선1,* · 이춘오2 · 임재수1 · 이진영1 · 안웅산3

1Geologic Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea
2Geo-Environmental Hazard Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Republic of Korea
3World Heritage Office, Jeju Special Self-Governing Provincial Government, Jeju 63341, Republic of Korea
1한국지질자원연구원 지질연구센터 2지질환경재해연구센터 3제주특별자치도 세계유산본부
Received November 25, 2020; Revised December 18, 2020; Accepted December 29, 2020.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
This study reports the Ar-Ar dating results for the volcanic rocks from small volcanoes(oreum) of the Hallasan Nature Reserve. According to the age of 40Ar/39Ar, the volcanic activity of the Hallasan Natural Reserve was started from about 192 ka ago. The basaltic trachyandesite and trachyte located in the Y valley near the Eorimok in the western part of the Hallasan Natural Reserve represent an age of about 191~192 ka, showing the oldest record of volcanic activity in the Hallasan Natural Reserve. In the Hallasan Natural Reserve, the small volcanoes older than 100 ka are Y Valley in Eorimok area (192±5 and 191±5 ka), Dongsu-Ak (184±19 ka), Mansedongsan (153±5 ka), Janggumok-Orum (135±6 ka), Eoseungsaengak (123±9 ka), Samgagbong (105±2 ka). And the small volcanoes younger than 100 ka are Witbangae-Oreum, Seongneol-Oreum, Muljangol, Yeongsil, Bori-Ak, Witsenueun-Oreum, Witsejokeun-Oreum, Heugbuleun-Oreum, Bangae-Oreum, Albangae-Oreum, Witsebuleun-Oreum, Baengnokdam, Nongo-Ak. According to the eruption of trachytes, the Hallasan Natural Reserve can be interpreted as having about 8 volcanic activities. Among them, 4 volcanic activities are related with the formation of trachyte dome, such as Wanggwanneung, Samgakbong, Yeongsil, and Baengnokdam, and 4 volcanic activities are related with flow or dyke of trachyte. The volcanic activity at the Hallasan Natural Reserve was started from northwest area, to in the southern area, and in the eastern area, and finally volcanic activity related to the formation of Baengnokdam.
Keywords : Hallansan Natural Reserve, 40Ar/39Ar age, volcanism, Jeju Island, small volcano(Oreum)

 

February 2021, 54 (1)