A study on the grain size change, sedimentary facies and age indicator of volcanic tephra was analysis through four cores (P1 ～ P4) at the Ulleung Basin in the East Sea of Korea. The two cores (P1 and P2) were collected in the northeastern side of the Ulleung Basin (about 2,000 m in water depth), while the other two cores (P3 and P4) with the water depth of about 1,500 m and 1,700 m, respectively, were collected from the continental slope of the southwestern and western side of the Ulleung Basin. Four sedimentary facies and eight sedimentary subfacies were identified. The four facies were massive sand, bioturbated mud, homogeneous mud, and laminated mud. The eight subfacies were further divided as pumiceous ash massive sand, scorieaous massive sand, plain bioturbated mud, pyrite filamented bioturbated mud, distinctly laminated mud, indistinctly laminated mud, thinly laminated mud and homogeneous mud. The homogeneous mud was not found in the core of P3 which is located in the western side of Ulleung Basin (close to the Korean coast). In the case of laminated mud facies, the thinly laminated mud facies was dominated in the lower part of core sequences of the Ulleung Basin (P1 and P2), while the indistinctly laminated mud were overally distributed in the core sequences from the continental slope of Ulleung Basin. The Tephra layers from the core sequences of central Ulleung Basin were more dominated and distinctive than those from the core sequences of continental slope. This is related to the distance from the volcanic source and the amount of sediment supply. The core locations of Ulleung-Oki Tephra layers in the central Ulleung Basin were in the upper part of core sequences, while those in the continental slope were in the lower part of core sequences. This is indicated that the amounts of sediment supply in the continental slope after the Ulleung-Oki eruption were very high and different sedimentary environment between upper and lower of Tephra layer.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 연구지역
  2.2. 시료 채취 및 분석
 3. 결과 및 고찰
  3.1. 울릉분지 코어의 퇴적상 및 입도특성
  3.2. 울릉분지의 퇴적작용과 퇴적환경
 4. 결 론
 참 고 문 헌

• 이병관(국립환경과학원 물환경연구부) | Byoung-Kwan Lee (National Institute Environmental Research) Corresponding Author
• 이수웅(국립환경과학원 물환경연구부) | Su-Woong Lee (National Institute Environmental Research)
• 김홍태(국립환경과학원 물환경연구부) | Hong-Tae Kim (National Institute Environmental Research)
• 김석윤(부경대학교 해양학과) | Seok-Yun Kim (Department of Oceanography, Pukyung National University)