The Journal of the Petrological Society of Korea (암석학회지)

The Petrological Society of Korea (한국암석학회)
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Source Evaluation of Rhyolitic Dike Swarm from Compositional Correlations of Igneous Intrusions in the Northern Cheongsong, Korea

청송 북부 화성관입체들의 조성대비에 의한 청송 암맥군의 공급원 고찰

  • Hwang, Sang Koo (Department of Earth and Environmental Sciences, Andong National University) ;
  • Kwon, Tae Ho (Department of Earth and Environmental Sciences, Andong National University) ;
  • Kim, Hyo Jin (Stainless Steel Raw Materials Procurement Division, POSCO) ;
  • Ahn, Ung San (World Heritage Office, Jeju Special Self-Governing Provincial Government) ;
  • Jeong, Gi Young (Department of Earth and Environmental Sciences, Andong National University)
  • 황상구 (안동대학교 지구환경과학과) ;
  • 권태호 (안동대학교 지구환경과학과) ;
  • 김효진 (포스코 스틸원료구매부) ;
  • 안웅산 (제주도 자연유산본부) ;
  • 정기영 (안동대학교 지구환경과학과)
  • Received : 2018.05.01
  • Accepted : 2018.05.28
  • Published : 2018.06.30
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Abstract

In the northern Cheongsong, there are occurred igneous intrusions: Cheongsong dike swarm, Jungtaesan laccolith, Galpyeongji stock. The swarm is composed of rhyolitic dikes that have developed many various spherulites. The dikes represent an geometrically radical pattern centering the Galpyeongji stock, but also geochemistry of the intrusions indicate the swarm source. Here we report the compositional data for 28 samples from the three intrusions. All of the intrusions belong to rhyolitic composition, but according to compositional correlation, there are considerable overlaps between intrusion compositions. In particular, the Cheongsong dike swarm is divided into several dike groups by rock color and shows compositional diversity, but the composition of the dikes generally overlap with compositions of other intrusions. The Jungtaesan laccolith is enriched in alkali, $K_2O$ and $Al_2O_3$ and depleted in $Fe_2O_3{^t}$, $TiO_2$ and REE compared to the Cheongsong dike swarm. In contrast, the Galpyeongji stock is narrow in composition range, and commonly has sharp compositional overlaps with the Cheongsong dike swarm. According to the compositional correlations, the stock is considered to be a source of the swarm and it is connected to an episode of volcanism.

청송 북부에는 청송 암맥군, 중태산 병반과 갈평지 암주 등의 화성관입체를 산출한다. 청송 암맥군은 다양한 구과를 발달시키는 유문암질 암맥들로 구성된다. 암맥들의 분포는 갈평지 암주를 중심으로 기하학적으로 방사상 패턴을 나타낼 뿐만 아니라, 관입체들의 화학조성은 암맥군의 공급원을 지시한다. 여기서 우리는 3개 관입체로부터 28개의 시료에 대한 조성적 자료를 보고한다. 관입체들은 같은 유문암질 조성이지만, 조성대비에 의하면, 관입체 조성 간에 상당히 중첩된다. 특히 청송 암맥군은 암석 색깔에 의해 몇몇 암맥그룹으로 구분되고 조성 다양성을 나타내지만, 대체로 기타 관입암 조성과 중첩을 나타낸다. 중태산 병반은 청송 암맥군과 비교하면 알칼리, $K_2O$와 $Al_2O_3$이 더 풍부하며 $Fe_2O_3{^t}$, $TiO_2$과 REE가 더 고갈되어 있다. 이와 대조적으로, 갈평지 암주는 화학조성이 더 좁은 범위를 나타내며, 청송 암맥군과 흔히 예리한 조성중첩을 가진다. 이러한 조성대비에 의하면 갈평지 암주는 조성적으로 청송 암맥군의 공급원으로 판단되며 화산작용의 에피소드로 연결된다고 생각된다.

Keywords

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