부산 기장군에 분포하는 백악기 이천리층 사암 조성의 예비 연구 : 기원지와 조구조 역사 해석에의 의의 = Preliminary Results from Sandstone Petrography of the Icheonri Formation in Gijang-gun, Busan: Implications for Provenance and Tectonic Setting

다국어 초록 (Multilingual Abstract)

While numerous previous studies investigated the provenance and tectonic history of the GyeongsangSupergroup, less are known about other Cretaceous strata in South Korea. This study presents preliminary results frompetrographic analysis of the Cretaceous Icheonri Formation distributed in Gijang-gun, Busan. Based on the immaturetexture and composition of the Icheonri sediments, we interpret that they were derived from weakly denudated Cretaceousarc volcanoes developed along the eastern margin of the Asian continent, with limited weathering and transport.
Additionally, the presence of chrome spinel grains in the sediments suggests the existence of ultramafic bodies exposed intheir provenance. Further studies will advance our understanding of the tectonic developments in the southeasternGyeongsang Basin, and facilitate a comprehensive correlation between the Icheonri Formation and the GyeongsangSupergroup.

국문 초록 (Abstract)

한반도에 분포하는 백악기 육성퇴적층 중 경상누층군 퇴적물의 기원지 조성과 조구조 환경에 대한 연구는 활발하게 이루어진 반면에 그 외 퇴적층에 대한 사암의 암석학적 연구는 아직 부족하다 . 본 연구에서는 부산 기장군 일광읍 신평리 해안가 일대에 분포하는 백악기 이천리층의 사암을 대상으로 암석기재학적 연구를 수행하여 기원지의 특성에 대한 예비 해석 결과를 보고하였다 . 이천리층 사암은 미성숙한 조성과 조직을 나타내며 백악기 당시 유라시아 동쪽연변부에서 일어난 고태평양판의 섭입에 의해 융기하여 발달한 화산호로부터 단시간에 퇴적물이 생성되어 운반된 것으로 보인다 . 그리고 사암 내 부수광물로 크롬 첨정석이 다수 관찰되는데 , 이는 기원지에 초고철질암이 분포하였음을 의미한다 . 향후 추가 연구를 바탕으로 크롬 첨정석 기원암의 형성 환경 뿐만 아니라 이천리층 퇴적 당시 경상분지 동남부의 조구조 환경에 대한 해석과 경상누층군과의 층서 대비가 가능할 것으로 기대된다 .

참고문헌 (Reference)

• 1 김현주 ; 백인성 ; 박정규 ; 정은경 ; 김경식 ; 백승균 ; 서영교 ; 김영석 ; 이호일, "부산 기장군 신평리 해안에 분포하는 백악기 이천리층: 산상과 지질유산으로서의 가치" 대한지질학회 58 (58): 1-22, 2022
• 2 임현수 ; 최태진 ; 이효종 ; 이용일, "백악기 경상분지 신동층군의 미량원소 조성과 이의 기원암에 대한 의의" 대한지질학회 55 (55): 531-549, 2019
• 3 Seo, J., "Unique sodic-calcic skarn hosted by ultramafic rocks and albitite at the Ulsan skarn deposit, Gyeongsang Basin, South Korea" 105 : 537-550, 2019
• 4 Ingersoll, R. V., "The effect of grain size on detrital modes; a test of the Gazzi-Dickinson pointcounting method" 54 : 103-116, 1984
• 5 Chough, S. -K., "Tectonic and sedimentary evolution of a Cretaceous continental arc-backarc system in the Korean peninsula: new view" 101 : 225-249, 2010
• 6 Kang, H. -C., "Structural chracteristics and evolution of the Ilgwang Fault, SE Korea" 39-, 2014
• 7 Lee, D. -W., "Strike-slip fault tectonics and basin formation during the Cretaceous in the Korean Peninsula" 8 : 21-231, 1999
• 8 Lee, J. I., "Provenance of the Lower Cretaceous Hayang Group, Gyeongsang Basin, southeastern Korea: implications for continental-arc volcanism" 70 : 151-158, 2000
• 9 Lee, Y. I., "Provenance of the Hayang Group (Early Cretaceous) in the Yeongyang Subbasin, SE Korea and its bearing on the cretaceous palaeogeography of SW Japan" 228 : 278-295, 2005
• 10 Joo, Y. J., "Provenance of Jurassic accretionary complex: Mino terrane, inner zone of south-West Japan: implications for palaeogeography of eastern Asia" 515-543, 2007
• 11 Dickinson, W. R., "Provenance of Arenites" North Atlantic Treaty Organization, Advanced Study Institute 333-361, 1985
• 12 Lee, Y. I., "Provenance analysis of the Cretaceous Gyeongsang Basin, SE Korea: A synthesis and tectonic implications for active continental margin in East Asia" 238 : 104334-, 2023
• 13 Kim, S. W., "Phanerozoic highpressure eclogite and intermediate pressure granulite facies metamorphism in the Gyeonggi Massif, South Korea : implications for the eastward extension of the Dabie-Sulu continental collision zone" 92 : 357-377, 2006
• 14 Arai, S., "Petrology of serpentine sandstone as a key to tectonic development of serpentine belts" 195 : 65-81, 1991
• 15 Folk, R. L., "Petrology of Sedimentary Rocks" Hemphill Publishing Company 182-, 1974
• 16 Kim, N. K., "Petrogenesis of late Triassic ultramafic rocks from the Andong Ultramafic Complex, South Korea" 264 : 28-40, 2016
• 17 Lee, Y. I., "Paleogeographic reconstructions of the East Asia continental margin during the middle to late Mesozoic" 17 : 458-470, 2008
• 18 Jeong, G. Y., "Mineral ages and zircon Hf isotopic composition of the Andong ultramafic complex: implications for the evolution of Mesozoic subduction system and subcontinental lithospheric mantle beneath SE Korea" 151 : 765-776, 2014
• 19 Seo, J., "Genetic implications of two different ultramafic rocks from Hongseong area in the southwestern Gyeonggi massif, South Korea" 8 : 539-552, 2005
• 20 Kim, D. H., "Explanatory text of the geological map of Pusan sheet (1:250,000)" Korea research Institute of Geoscience and Mineral Resources 62-, 1998
• 21 Son, C. M., "Explanatory text and Geological map of Dongrae and Weolnae sheets (1:50,000)" Korea Research Institute of Geoscience and Mineral Resources 27-, 1978
• 22 Hisada, K. -i., "Early Cretaceous paleogeography of Korea and Southwest Japan inferred from occurrence of detrital chromian spinels" 17 : 471-484, 2008
• 23 Chae, Y. U., "Detrital zircon provenance of the Lower Cretaceous Duwon Formation based on LA-MCICPMS U-Pb ages and morphology in the Goheung area, southern Korea : A new supply mechanism of Early Cretaceous zircons" 128 : 104955-, 2021
• 24 Chae, Y.U., "Detrital zircon U-Pb ages of the Cretaceous Dadaepo Formation in Busan, Korea and their geological implication"
• 25 Lee, Y. I., "Detrital chromian spinels in the Cretaceous Sindong Group, SE Korea : implications for tectonic emplacement of hydrated mantle peridotites" 179 (179): 2022
• 26 Chang, K. H., "Cretaceous stratigraphy of Southeast Korea" 11 : 1-23, 1975
• 27 Irvine, T. N., "Chromian spinel as a petrogenetic indicator, Part II : petrological applications" 4 : 71-103, 1967