보하이만, 황해 남동해역 및 동중국해 양자강 하구역 니질 퇴적물의 지화학적 조성과 기원지 연구

Abstract

Major, trace and rare earth element (REE) chemistry of the muddy sediments, situated in the Yellow and northern East China Seas, have been investigated. Calcium carbonate and total organic carbon of the Gulf of Bohai Sea sediments are more enriched in the southwestern muddy sediments than in the muddy sand facies northeastern part. The sedimentation rate calculated by Pb210 geochronology in the Gulf of Bohai Sea muddy sediments shows 0.65cm/yr. suggesting that the Huanghe River suspended sediments were supplied to the Bohai Sea. The C/N ratios in the study area varies between 7.2 to 14.46 and the large amount of the organic matter have been supplied from the terrigenous. The discrimination diagrams including Sc/Al, Cr/Th, Nb/Co, Th/Sc, Ti/Nb and Zr/Sc were thus used as provenance indicators to identify the sediment origins of the study area. Based on the discriminated diagrams distinctly that the sediments in the Gulf of Bohai Sea are mostly derived from the Huanghe River and the Changjiang River's submerged delta sediments came from Changjiang River, whereas the southeastern Yellow Sea muddy sediments originated from Korean and Chinese rivers. The most of study area sediments show very similar chondrite-normalized REE pattern having enriched LREE (La(N)/Sm(N))>3.8 and obvious negative Eu anomaly, typical of average shales. The UCC-normalized pattern of the Bohai Sea sediments depleted REE forms with notable negative anomaly both of Eu and Tm is similar to that of the Huanghe sediment. The REE patterns of the Changjiang River's submerged delta sediments are more linear and display convex shapes with enrichment of middle REE, which indicate they are derived from Changjiang River. In contrast, REE patterns for southeastern Yellow Sea mud showed similar to REE patterns both of the Keum and Huanghe Rivers sediment.