Journal of the Korean earth science society (한국지구과학회지)

The Korean Earth Science Society (한국지구과학회)
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Planktic Foraminiferal Assemblages of Core Sediments from the Korea Strait and Paleoceanographic Changes

대한해협 코아 퇴적물의 부유성 유공충 군집 특성과 고해양 환경 변화

  • Kang, So-Ra (Environmental Science Laboratory, South Sea Institute, Korea Ocean Research and Development Institute) ;
  • Lim, D.I. (Environmental Science Laboratory, South Sea Institute, Korea Ocean Research and Development Institute) ;
  • Rho, K.C. (Environmental Science Laboratory, South Sea Institute, Korea Ocean Research and Development Institute) ;
  • Jung, H.S. (Marine Geoenvironment Research Division, Korea Ocean Research and Development Institute) ;
  • Choi, J.Y. (Department of Oceanography, Kunsan National University) ;
  • Yoo, H.S. (Marine Geoenvironment Research Division, Korea Ocean Research and Development Institute)
  • 강소라 (한국해양연구원 남해특성연구본부) ;
  • 임동일 (한국해양연구원 남해특성연구본부) ;
  • 노경찬 (한국해양연구원 남해특성연구본부) ;
  • 정회수 (한국해양연구원 해양환경연구본부) ;
  • 최진용 (군산대학교 해양정보과학과) ;
  • 유해수 (한국해양연구원 해양환경연구본부)
  • Published : 2006.08.30
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Abstract

The paleoceanography since 14 ka was reconstructed based on the planktic foraminiferal assemblages of core sediments from the outer shelf of the Korea Strait. Planktic foraminifera in the core sediments can be divided into four assemblages: A, B, C, and D. Assemblage A consists mainly of Globigerinoides ruber group and Globigerinoides conglobatus with low abundance (less than 10%), indicating the tropical-subtropical water mass. Assemblage B is composed of Pulleniatina obliquiloculata and Neogloboquadrina dutertrei, the indicator of Kuroshio Current, and shows the aspect of the inflow of the Tsushima Current into the Korea Strait. Assemblage C yields polar-subpolar species, mainly Neogloboquadrina incompta and N. pachyderma. It decreases upward of the core. Assemblage D contains coastal water species such as Globigerina bulloides and G. quinqueloba. It is abundant in the lower to middle region of the core. From the analysis of distributions of each assemblage and the result of age datings in the core, it is suggested that the Korea Strait played a role of channelling the East China Sea and the East Sea after the LGM (ca. 14 ka). During this time, the coastal water, affected by fresh waters originated from the river systems of China and/ or the Korean Peninsula, flourished around the Korea Strait and theses coastal water might entered to the East Sea. Around 8.5 ka, the effect of the Tsushima Current started to strengthen in this region, and the present current system seems to be formed at about $7{\sim}6ka$.

지난 최대 빙하기 이후 대한해협에서의 고해양 환경 변화를 이해하고자 대한해협 외대륙붕에서 채취한 코아 퇴적물에 대한 $^{14}C$ 연대 측정과 함께 부유성 유공충의 군집 변화를 분석하였다. 코아 퇴적물은 모래 50%, 실트 30%, 점토 20%의 사니질 퇴적상으로 약하게 생물 교란된 모래/니질 교호층리들이 발달하고 있다. 코아 퇴적물의 연대는 최하부에서 약 14 ka이며, 최상부 30 cm에서 약 6 ka로 지난 최대 빙하기에서 현세 중기까지 발달한 퇴적층이다. 코아 퇴적물에서 산출되는 부유성 유공충은 크게 4개의 군집으로 구분된다. 군집 A는 열대-아열대종인 Globigerinoides ruber group, Globigerinoides conglobatus로 대표되며, 코아의 전 깊이에서 약 10% 이내로 산출되며, 상부 약 30cm에서 증가한다. 군집 B는 쿠로시오 해류의 지류인 대마 난류를 지시하는 Pulleniatina obliquiloculata, Neogloboquadrina dutertrei 등으로 구성되며, 대한해협에 대마 난류의 유입 양상을 보여준다. 군집 C는 Neogloboquadrina incompta, Neogloboquadrina pachyderma 등 한대-아한대성 종들로 구성되며, 코아의 하부에서 상부로 갈수록 감소하는 양상을 보인다. 군집 D는 Globigerina bulloides, Globigerina quinqueloba 등 연안수를 지시하는 종으로 구성되며, 코아의 중 하부에서 가장 우세 하게 나타난다. 이러한 부유성 유공충 군집분석 특성과 연대 측정 결과에 근거할 때, 최대 빙하기 이후 약 14 ka부터 7 ka까지 대한해협은 중국 대륙 및 한반도에서 기원한 담수의 영향으로 저염수의 특성을 가지는 연안수의 영향을 많이 받았으며, 이 시기에 대한해협을 통하여 많은 양의 담수가 동해로 유입되었을 것으로 사료된다. 대한해협에 대마 난류의 영향력이 강해지기 시작한 것은 약 8.5 ka 이후로 보이며, 이후 난류의 영향은 더욱 강해져 약 $7{\sim}6ka$를 전후하여 거의 현재와 같은 해양 환경이 형성된 것으로 해석된다.

Keywords

References

  1. Be, A.W.H., 1977, An ecological, zoo-geographical and taxonomic review of Recent planktonic foraminifera. In Ramsay, A.T.S. (ed.), Ocean Micropaleontology. 1, Academic Press, London, 1-100
  2. Folk, R.L. and Ward, W.C., 1957, Brazos river bar: a study in the significance of grain size parameter. Journal of Sedimentary Petrology, 27, 3-27 https://doi.org/10.1306/74D70646-2B21-11D7-8648000102C1865D
  3. Ijiri, A., Wang, L., Oba, T., Kawahata, H., Huang, C-Y., and Huang, C-Y., 2005, Paleoenvironmental changes in the northern area of the East China Sea during the past 42,000 years. Palaeogeography, Palaeoclimatology, Palaeoecology, 219, 239-261 https://doi.org/10.1016/j.palaeo.2004.12.028
  4. Ingram, R.L., 1971, Sieve analysis. In Carver, R.E. (ed.), Procedures in Sedimentary Petrology, Willey-Inter Science, New York, 49-67
  5. Jian, Z., Wang, P., Saito, Y., Wang, J., Pflaumann, U., Oba, T., and Cheng, X., 2000, Holocene variability of the Kuroshio Current in the Okinawa Trough, northwestern Pacific Ocean. Earth and Planetary Science Letters, 184, 305-319 https://doi.org/10.1016/S0012-821X(00)00321-6
  6. Keigwin, L.D. and Gobarenko, S.A., 1992, Sea level, surface salinity of the Japan Sea, and the Younger Dryas Event in the northwestern Pacific Ocean. Quaternary Research, 37, 346-360 https://doi.org/10.1016/0033-5894(92)90072-Q
  7. Kim J-M., Kennett, J.P., Park, B-K., Kim D.C., Kim, G.Y., and Roark, E.B., 2000, Paleoceanographic change during the last deglaciation, East Sea of Korea. Paleoceanography, 15 (2), 254-266 https://doi.org/10.1029/1999PA000393
  8. Lee, E. and Nam, S., 2003, Freshwater supply by Korean rivers to the East Sea during the last glacial maximum: a review and new evidence from the Korea Strait region. Geo-Marine Letters, 23, 1-6 https://doi.org/10.1007/s00367-003-0118-1
  9. Li, B., Jian, Z., and Wang, P., 1997, Pulleniatina obliquiloculata as a paleoceanographic indicator in the southern Okinawa Trough during the last 20,000 years. Marine Micropaleontology, 32, 59-69 https://doi.org/10.1016/S0377-8398(97)00013-3
  10. Matsui, H., Tada, R., and Oba, T., 1998, Low-salinity isolation event in the Japan Sea in response to eustatic sea-level drop during LGM: Reconstruction based on salinity-balance model. The Quaternary Research, 37 (3), 221-233 https://doi.org/10.4116/jaqua.37.221
  11. Moorely, J.J., Heuser, L.E., and Sarro, T., 1986, Latest Pleistocene and Holocene paleoenvironment of Japan and its marginal sea. alaeogeography, Palaeoclimatology, Palaeoecology, 53, 349-358 https://doi.org/10.1016/0031-0182(86)90068-4
  12. Moriyasu, S., 1972, Hydrography of the Japan Sea. Marine Science, 4, 27-33
  13. Oba, T., Kato, M., Kitazato, H., Koizumi, I., Omura, A., Sakai, T., and Takayama, T., 1991, Paleoenvironmental changes in the Japan Sea during the last 85,000 years. Paleoceanography, 6 (4), 499-518 https://doi.org/10.1029/91PA00560
  14. Oba, T., Murayama, M., Matsumoto, E., and Nakamura, T., 1995, AMS-14C ages of Japan Sea cores from the Oki Ridge. The Quaternary Research, 34 (4), 289-296 https://doi.org/10.4116/jaqua.34.4_289
  15. Oda, M. and Takemoto, A., 1992, Planktonic foraminifera and paleoceanography in the domain of the Kuroshio Current around Japan during the Last 20,000 years. The Quaternary Research, 31 (5), 341-357 https://doi.org/10.4116/jaqua.31.341
  16. Park, S.C. and Yoo, D.G., 1988, Depositional history of Quaternary sediments on the continental shelf off the southeastern coast of Korea (Korea Strait). Marine Geology, 79, 65-75 https://doi.org/10.1016/0025-3227(88)90157-0
  17. Park, S.C., Yoo, D.G., Lee, C.W., and Lee, E.I., 2000, Last glacial sea-level changes and paleogeography of the Korea (Tsushima) Strait. Geo-Marine Letters, 20, 64-71 https://doi.org/10.1007/s003670000039
  18. Tada, R. and Irino, T., 1999, Land-ocean linkages over orbital and millennial timescales recorded in late Quaternary sediments of the Japan Sea. Paleoceanography, 14 (2), 236-247 https://doi.org/10.1029/1998PA900016
  19. Takemoto, A. and Oda, M., 1997, New planktoc foraminiferal transfer functions for the Kuroshio-Oyashio Current region off Japan. Paleontological Research, 1 (4), 291-310
  20. Thompson, P.R., 1981, Planktonic foraminifera in the western north Pacific during the past 150,000 years: comparison of modern and fossil assemblages. Palaeogeography, Palaeoclimatology, Palaeoecology, 35, 241-279 https://doi.org/10.1016/0031-0182(81)90099-7
  21. Ujiié, H. and Ujiié, Y., 1999, Late Quaternary course changes of the Kuroshio Current in the Ryukyu Arc region, northwestern Pacific Ocean. Marine Micropaleontology, 37, 23-40 https://doi.org/10.1016/S0377-8398(99)00010-9
  22. Ujiié, Y., Ujiié, H., Taira, A., Nakamura, T., and Oguri, K., 2003, Spatial and temporal variability of surface water in the Kuroshio source region, Pacific Ocean, over the past 21,000 years: evidence from planktonic foraminifera. Marine Micropaleontology, 49, 335-364 https://doi.org/10.1016/S0377-8398(03)00062-8
  23. Wang, P., Zhang, J., and Min, Q., 1985, Distribution of foraminifera in surface sediments of the East China Sea. In Wang, P. (ed.), Marine Micropaleontology of China, China Ocean Press, Beijing, 34-69
  24. Watkins, J.M., Mix, A.C., and Wilson, J., 1998, Living planktic foraminifera in the central tropical Pacific Ocean: articulating the equatorial 'cold tongue' during La Ni?a, 1992. Marine Micropaleontology, 33, 157-174 https://doi.org/10.1016/S0377-8398(97)00036-4
  25. Xu, X. and Oda, M., 1999, Surface-water evolution of the eastern East China Sea during the last 36,000 years. Marine Geology, 156, 285-304 https://doi.org/10.1016/S0025-3227(98)00183-2
  26. Yoo, D-G., Park, S-C., Sunwoo, D., and Oh, J-H., 2003, Evolution and chronology of late Pleistocene shelfperched lowstand wedges in the Korea Strait. Journal of Asian Earth Sciences, 22, 29-39 https://doi.org/10.1016/S1367-9120(03)00020-8