The Journal of the Petrological Society of Korea (암석학회지)

The Petrological Society of Korea (한국암석학회)
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Formation Mechanism of Recumbent Fold observed in the Bangrim-ri, Pyeongchang-gun, Korea

평창군 방림리에 발달하는 횡와습곡의 형성 기작

  • Cheon, Youngbeom (Geology Division, Korea Institute of Geoscience and Mineral Resources) ;
  • Kang, Hee-Cheol (Department of Geological Sciences, Pusan National University) ;
  • Ha, Sangmin (Department of Geological Sciences, Pusan National University) ;
  • Lee, Sun-Kap (Department of Geological Sciences, Pusan National University) ;
  • Son, Moon (Department of Geological Sciences, Pusan National University) ;
  • Ryoo, Chung-Ryul (Geology Division, Korea Institute of Geoscience and Mineral Resources)
  • 천영범 (한국지질자원연구원 국토지질연구본부) ;
  • 강희철 (부산대학교 지질환경과학과) ;
  • 하상민 (부산대학교 지질환경과학과) ;
  • 이선갑 (부산대학교 지질환경과학과) ;
  • 손문 (부산대학교 지질환경과학과) ;
  • 류충렬 (한국지질자원연구원 국토지질연구본부)
  • Received : 2019.09.02
  • Accepted : 2019.09.24
  • Published : 2019.09.30
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Abstract

This study describes a large recumbent fold, which occurs at the north entrance slope of the Batjae tunnel, Pyeongchang-gun, Gangwon-do, and interprets its formation mechanism. The several-hundred-meter scale fold, developed in the Jeongseon Limestone of the Paleozoic Joseon Supergroup, has a nearly horizontal axial plane and its head is facing north. Stretching lineations ($L_1$) observed on the composite foliations of bedding and axial plane cleavage plunge southward at about $10^{\circ}$. Small A-type or eye-shaped sheath folds together with S-shaped asymmetrical folds are often observed in the fold limbs and their axes are nearly parallel to the lineations ($L_1$) within center and rear parts of the fold. It is thus interpreted that the recumbent fold is a large sheath fold produced by the top-to-the-north ductile shearing due to the Songrim orogeny during the late Paleozoic to Triassic.

강원도 평창군 뱃재터널의 북쪽 입구 사면에서 대규모 횡와습곡이 확인되어 이를 기재하고 형성기작에 관해 해석하였다. 이 습곡은 고생대 조선누층군 정선석회암층 내에 수백 m 규모로 발달하고 있다. 습곡의 머리는 북쪽을 향하며, 층리와 축면엽리의 복합엽리면상에 발달하는 신장선구조($L_1$)는 남쪽으로 약 $10^{\circ}$ 침강하고 있다. 습곡 날개부에는 S-형 비대칭 습곡과 함께 A-형 또는 안상 칼집습곡들이 흔히 관찰되며 이들 습곡의 축은 습곡의 중앙부와 후면부에서 확인된 신장선구조($L_1$) 방향과 거의 평행하다. 따라서 이곳 대규모 횡와습곡은 상부가 북쪽으로 향하는 강한 연성전단작용에 의해 생성된 칼집습곡으로 고생대말-트라이아스기 송림조산운동의 결과로 해석된다.

Keywords

References

  1. Cheong, C.H., Lee, D.Y., Ryu Y.S., and Kang, K.W., 1979, Explanatory text of the Geological Map of the Pyeongchang and Yeongweol Sheet. Korea Research Institute of Geoscience and Mineral Resources. 19p.
  2. Choi, D.K., 1998, The Yeongwol Group (Cambrian-Ordovician) redefined: a proposal for the stratigraphic nomenclature of the Joseon Supergroup. Geosciences Journal, 2, 220-234. https://doi.org/10.1007/BF02910166
  3. Choi, D.K., Chough, S.K., Kwon, Y.K., Lee, S.-B., Woo, J., Kang, I., Lee, H.S., Lee, S.M., Sohn, J.W., Shinn, Y.J., and Lee, D.-J., 2004, Taebaek Group (Cambrian-Ordovician) in the Seokgaejae section, Taebaeksan Basin: a refined lower Paleozoic stratigraphy in Korea. Geosciences Journal, 8, 125-151. https://doi.org/10.1007/BF02910190
  4. Chough, S.K., Lee, H.S., Woo, J., Chen, J., Choi, D.K., and Lee, S.-B., 2010, Cambrian stratigraphy of the North China Platform: revisiting principal sections in Shandong Province, China. Geosciences Journal, 14, 235-268. https://doi.org/10.1007/s12303-010-0029-x
  5. Cobbold, P.R. and Quinquis, H., 1980, Development of sheath folds in shear regimes. Journal of Structural Geology, 2, 119-126. https://doi.org/10.1016/0191-8141(80)90041-3
  6. GICTR (Geological Investigation Corps of the Taebaegsan Region), 1962, Report on the Geology and Mineral Resources of the Taebaegsan Region, Geological Society of Korea, Seoul, 89p.
  7. Kim, H.S., 2012, Metamorphism and Deformation of the Late Paleozoic Pyeongan Supergroup in the Taebaeksan Basin: Reviews on the Permo-Triassic Songrim Orogeny. Journal of Petrological Society of Korea, 21, 151-171 (in Korean with English abstract). https://doi.org/10.7854/JPSK.2012.21.2.151
  8. Kim, H.S. and Ree, J.-H., 2013, Permo-Triassic changes in bulk crustal shortening direction during deformation and metamorphism of the Taebaeksan Basin, South Korea using foliation intersection/inflection axes: implications for tectonic movement at the eastern margin of Eurasia during the Songrim (Indosinian) orogeny. Tectonophysics, 587, 133-154. https://doi.org/10.1016/j.tecto.2012.08.033
  9. Kim, S.-W., Choi, E.-K., Ryoo, C.-R., and Kim, I.-S., 1997, South and North China collision boundary in southern Korea : Paleomagnetic and tectonic approaches. In Lee, Y.I. and Kim, J.H. (eds.), Tectonic Evolution of Eastern Asian Continent: Geological Society of Korea 50th Anniversary International Symposium, Seoul, Korea, 79-83.
  10. Kobayashi, T., 1942, Two new trilobite genera, Hamashania and Kirkella. Journal of the Geological Society of Japan, 59, 37-40. https://doi.org/10.5575/geosoc.49.37
  11. Kobayashi, T., 1966, The Cambro-Ordovician formations and faunas of South Korea. Part 10. Stratigraphy of the Chosen group in Korea and south Manchuria and its relation to the Cambro-Ordovician formations of other areas. Section A. The Chosen group of South Korea. Journal of the Faculty of Science, University of Tokyo, Section 2, 16, 1-84.
  12. Lacassin, R. and Mattauer, M., 1985, Kilometer-scale sheath fold at Mattmark and implications for transport direction in the Alps. Nature, 316, 739-742. https://doi.org/10.1038/315739a0
  13. Ryoo, C.-R., 1995, Recherches tectoniques en Coree. These de Doctorat, Universite de Montpellier 2, France, 135p.
  14. Ryoo, C.-R., 1997, Tectonics in the contact zone between the Precambrian basement (Gyeonggi Massif) and the Paleozoic sedimentary cover (Okchon Belt, Korea. In Lee, Y.I. and Kim, J.H. (eds.), Tectonic Evolution of Eastern Asian Continent: Geological Society of Korea 50th Anniversary International Symposium, Seoul, Korea, 59-64.
  15. Ryoo, C.-R., 2008, Discussion on the relationship between the collision belt and the mineralized zone around Korean Peninsula. Economic Mineral Deposits in Korea, The 7th Geology of Korea Symposium, December 5th 2008, Korea Institute of Geoscience and Mineral Resources, Daejeon, Korea, 30-37.
  16. Ryoo, C.-R. and Mattauer, M., 2006, Structural geology and regional tectonic significance in the Ogcheon Fold Belt, Korea. Resumes de la Congres annuel de l'AGC-AMC(Abstracts of the GAC-MAC Annual Meeting), May 14-17 2006, Montreal, Canada, Volume 31, 131.