초록 ▼

■ 2011년부터 2016년까지 관할해역중 제주도 서부 및 남부 해역의 지질특성과 황해 군산분지에서 해성층의 구조와 지질특성에 대한 조사와 연구가 수행되었음
▶ 제주도 서부 및 남부 지질특성 조사
- 총 1,921 line-km의 중천부 탄성파탐사 수행
- 퇴적물(피스톤 코어 21점, 표층 247점)채취 분석
- 제4기 상부퇴적층 층서 구분, 퇴적물의 기원 확인, 고환경변화 해석
▶ 황해 군산분지 해성층 구조와 지질특성 조사
- 고해상 에어건 탄성파탐사(Air-Gun Seismic) 2,120 lin

■ 2011년부터 2016년까지 관할해역중 제주도 서부 및 남부 해역의 지질특성과 황해 군산분지에서 해성층의 구조와 지질특성에 대한 조사와 연구가 수행되었음
▶ 제주도 서부 및 남부 지질특성 조사
- 총 1,921 line-km의 중천부 탄성파탐사 수행
- 퇴적물(피스톤 코어 21점, 표층 247점)채취 분석
- 제4기 상부퇴적층 층서 구분, 퇴적물의 기원 확인, 고환경변화 해석
▶ 황해 군산분지 해성층 구조와 지질특성 조사
- 고해상 에어건 탄성파탐사(Air-Gun Seismic) 2,120 line-km, 중천부 탄성파탐사(Sparker) 2,138 line-km
- 퇴적물(피스톤 코어 17점, 표층 41점) 및 해수(CTD 14점) 채취 후 분석
- 해성층 층서구분, 퇴적물 기원 확인, 고환경변화 추적, 온실가스(메탄) 플럭스, 유해물질 분포 등 해양영토 관리를 위한 자료 축적

(출처 : 보고서 요약서 6p)

Abstract ▼

Ⅳ. Results

1. The geologic characteristics in the southwestern sea off Jeju Island (2011 to 2012)

● Sparker seismic data showed several internal reflectors, suggesting that the Heuksan Mud Belt was formed in a short period of time after the LGM (Last Glacial Maximum).
However, the p

Ⅳ. Results

1. The geologic characteristics in the southwestern sea off Jeju Island (2011 to 2012)

● Sparker seismic data showed several internal reflectors, suggesting that the Heuksan Mud Belt was formed in a short period of time after the LGM (Last Glacial Maximum).
However, the piston-core sediments showed several signs of inverted ages along the column as a result of erosion rather than continuous sedimentation.
- The wide distribution of the thin acoustically-transparent layer at the sea-bottom surface in the western sea off Jeju Island indicates occurrence of Holocene mud accumulation since the sea level reached the present highstand. The acoustic (Chirp) facies of the uppermost sedimentary layer were largely affected by the Yellow-Sea Warm Current (YSWC) which influences on the distribution patterns of sand ridges, mounds and rocky seabeds near Jeju Island.

● To identify the origins of the sediments in the eastern Yellow Sea and the SouthWest Cheju Island Mud (SWCIM), their clay mineral compositions were compared with those of the estuarine sediments of Hwanghe, Yangtze, Han, Keum, and Yeongsan rivers. However, no distinctive characteristics of the origins were found. The SWCIM clays contain more chlorite and less smectite and kaolinite compared to the sediments from the rivers mentioned above.
- In sediment cores (07YS-PC01 and 07YS-PC12 in the South Sea and in SWCIM, respectively), clay mineral and major element compositions were barely changed along the core column, despite the changes in sediment grain sizes. This suggests that the sediments were constantly supplied from various origins and mixed between them during sedimentation.
- The chemical characteristics of C/N ratio and C isotopes in the sediment cores revealed that the marine organic sediments have increased compensating for the decreased terrestrial components as ages of the sediments are younger.

● Based on the lipid biomarker (alkenone) characteristics of sediments in the eastern Yellow
Sea, sea surface temperature (SST) was 1.8 ℃ lower than the averaged value of the 10-year observations. The difference may result from the effect of alkenone contained in the relict pre-Holocene sediments.
- The analysis results of the sediment core from SWCIM (07YS-PC12) was consistent with the chronological climate changes. The eastern Yellow Sea went through two periods of cold and dry weather and two periods of warm and humid climate during the last 16,000 years with the temperature difference of 3~5 ℃.

2. The sedimentary environments and geologic characteristics of the marine sedimentary sequence in the Kunsan Basin, Yellow Sea (from 2013 to 2015)

● A total of 2,109 line-km multichannel seismic profiles were acquired in the Kunsan Basin, eastern Yellow Sea using a 1,380 in3 air-gun array and 156 channel or 24 channel streamers with an interval of 12.5 m. The geologic structures of the marine sedimentary sequence (MSS) were constructed after data processing and analysis.
- The acoustic basement and shoals are distinguishable in the central small depression that lies deeper than 6,000 m in the depocenter (up to 8,000 m in depth) and less than 200 m in depth in the southern part, respectively.
- The basin sedimentary layers are divided into ten sequences by prominent seismic reflectors.
The depocenter of the central depression shows a northeast-southwest orientation, being consistent with the previous studies. In particular, many volcanic edifices are present in the southern shallow basement area.

● The MSS is delineated by the middle Miocene Unconformity (MMU, 13 Ma) that gradually increases in thickness from 500 m in the southeastern part to 1,100 m in the northwestern part of the Kunsan Basin. Therefore, it appears that subsidence occurred dominantly in the northwestern part after denudation in the early Miocene.
- Assuming a constant sedimentation rate from the MMU, the MSS contains 4 seismically prominent reflectors of H1 (about 10 Ma, Late Miocene), H2 (about 6.7 Ma, Late Miocene), H3 (25 ka, the early LGM), H4 (20 ka, the end of the LGM).
- The reflector H1, especially, is associated with distinct paleochannels, suggesting that it comprises an unconformity formed in the terrestrial environment during the sea level regression. However, the reflector H2 is assumed to have formed in the marine environment because it is relatively flat over a long distance.
- High-resolution shallow (Sparker) seismic profiles showed that multiple channels appeared in the uppermost part of MSS. Deep-drill core samples are needed to understand the sedimentary processes and environmental changes of MSS.

● Based on the acoustic and morphological characters of high-resolution shallow (Sparker and Chirp) seismic profiles, the sedimentary environments of the study area can fall into four zones: 1) mud zone; 2) deformed zone; 3) sand ridge zone; and 4) sandwaves zone from the west to the east in the Kunsan Basin.
- The deformed zone is characterized by strong acoustic-reflectors and there are numerous channels and erosional surfaces in the sedimentary layers of Pliocene, Pleistocene, and Holocene. The channels appeared to be distributed in the direction of NW-SE. Some piston sediment cores showed the pre-Holocene oxidized paleo-soils at shallow depth beneath the seafloor, resulting from non-deposition or erosion during the Holocene.
- Sand ridge and sandwave zones are dominant in the coastal region. Sand ridges or sandwaves are independently developed with a regular and repeated pattern. Overlying the transgressive sand sheet, the ridges are often associated with sandwaves, in thickness of 20~30 m, especially on the crest and stoss side, probably extending to those in Kyeonggi Bay.

● A total of 60 surface sediment samples including 15 piston-core samples were collected from the Kunsan Basin from 2013 to 2015, to investigate the general geological characters of the MSS. The sediments were analyzed to examine sedimentary and geochemical characteristics (grain size, texture, clay minerals, ages, organic compounds, chemical elements, organic carbon and nitrogen, lipid biomarkers, methane, carbon isotopes of methane and organic matters). In addition, the amounts of dissolved methane in the water column were measured from the water samples collected by the Conductivity, Temperature and Depth (CTD) recorder at 14 stations.
- The surface sediments consisted of sand (56.6% on the average), silt (18.4%), and clay (25.0%) with the mean grain size of 1.5 to 7.8 ∅. Sand was prevalent (63.8 to 98.3%) along the Yellow Sea Trough lying in the eastern part of the basin. The sandy sediments were regarded as relict sediments deposited in the LGM.
- Fine-grained sediment fraction comprises illite (63.4 to 71.9%), chlorite (15.1 to 20.2%), kaolinite (10.3 to 14.2%), and smectite (0.2 to 6.9%). Illite and chlorite were abundant in northwest part of the Kunsan Basin and the coastal area of Korea, whereas smectite was abundant in the southern apart of the basin. According to the triangular relationship of smectite, chlorite, and kaolinite, the sediments in the northern part of the basin appeared to have derived from Keum and Han rivers, whereas the sediments in the southern part were similar to those from Han, Yeongsan, and Yangtze rivers. From the sediment cores, there were an increase in chlorite content and a decrease in smectite toward the surface layer, meaning that the supply of sediments from Han and Keum rivers to the Kunsan Basin increased.
- The sediment data collected in the eastern Yellow Sea and Northern East China Sea from 1998 to 2015 showed that total organic carbon (TOC, 0.1 to 1.9%) content was generally higher in the region of fine-grained sediments. C/N and δ13C values were 5.8~20 and -25~-19‰, respectively, revealing that their distributions result from the transport, mixing and deposition of marine organisms and terrestrial detrital sediments from the rivers.
- The surface sediments of the Kunsan Basin contained 0.2 to 16.9 μM of methane produced by microbial fermentation of the organic materials in the shallow sediment layer, which is indicated by the light values of δ13CCH4 (-70.2~-50.7‰). In the sediment cores, the methane content ranged from 1 to 20 μM, regardless of grain size and organic matter content. The values of δ13CCH4 ranged in -62.0~-18.0‰, that is, mixtures of thermogenic- and biogenic-originated methane through the whole cores. The methane flux to the water layer was calculated to be 0.002~0.029 mM·m-2·day-1 (0.012 mM·m-2·day-1 on the average) (0.04~0.47 mgm-2day-1) by a careful examination of methane distribution within the uppermost 10-cm sediment layer of box cores.
- In the water column, methane concentration was 2.2~3.8 nM in the upper water layer and 3.9~8.5 nM in the lower water layer that is separated by the thermocline of which depth is variable depending on the time of sampling. This characteristic distribution of methane seems to be caused by decomposition of organic matters produced in the upper water layer and supply of methane from the underlying sediment layer toward the lower water layer beneath the thermocline.

● To reconstruct the paleo-environment, the relative composition of C27 and C31 from the long piston sediment core (11YS-PCL14, 7 m in length) were analyzed. The result indicates that cold and dry climates prevailed for about 500 years around 15,000 yrBP and for 1,000 years around 12,000 yrBP; warm and humid climate prevailed about 1,800 years from 12,800 to 14,600 yrBP and has continued since 11,600 yrBP. The sea surface temperature was calculated 7.7~14.1℃ for the last 16,000 yrBP. The cold and dry climate is characterized by the abundance of C27 derived from woody plants, whereas the hot and humid climate is marked by C31 from herbaceous plants.

(출처 : Summary 19p)

목차 Contents

• 표지 ... 1
• 제출문 ... 4
• 보고서 요약서 ... 6
• 요 약 문 ... 8
• SUMMARY ... 16
• CONTENTS ... 24
• Appendices ... 26
• 목차 ... 28
• List of Tables ... 32
• List of Figures ... 34
• 제 1 장 연구개발과제의 개요 ... 52
• 제 1 절 연구 목적 ... 54
• 제 2 절 연구 필요성 ... 56
• 제 3 절 추진 체계 ... 58
• 제 4 절 연도별 탐사내용 ... 63
• 제 2 장 국내외 연구개발 현황 ... 72
• 제 1 절 국외 해양지질 및 지구조 연구 현황 분석 ... 74
• 제 2 절 국내 관할해역 해양지질 및 지구조 연구 현황 분석 ... 77
• 제 3 장 연구개발 수행 내용 및결과 ... 80
• 제 1 절 제주 남부/서부해역(흑산분지 남부) 중.천부 지층 및 해양지질 특성 연구 ... 82
• 제 2 절 황해 군산분지의 지질특성과 지질구조 ... 117
• 2-1 해성층의 지질구조 특성 ... 117
• 2-2 해저면 고환경 복원 및 지질특성 ... 199
• 제 4 장 표달성도 및 관련분야에의 기여도 ... 314
• 제 1 절 목표 달성도 ... 316
• 제 2 절 연구개발 기여도 ... 332
• 제 5 장 연구개발 결과의 활용계획 ... 334
• 제 1 절 연구결과의 세부내용에 따른 파급효과 및 기술수준 ... 336
• 제 6 장 참고문헌 ... 338
• 부록 A 해양지질 및 지구조과학 자료 DB ... 352
• 부록 B 과학조사 분석자료 ... 374
• 끝페이지 ... 452