제주도 서부해역 표층퇴적물의 지화학적 연구

Abstract

To discriminate the provenance of shelf sediments in the western part of Jeju Island, the textual and elemental compositions were analyzed and compared with the sediments originated from Chinese rivers. The sediments in the study area are composed of coarse silt with a mean grain size of 3.6~8.5Φ and their CaCO₃ contents ranged from 0.92 to 9.75%(av. 3.65%). The major elements (Fe, Mg, Ti and Mn) show good positive correlation with Al, and trace elements also indicate the same characteristics; hence, clay minerals are likely to be the promising host for those elements. The ratios of Toc over total nitrogen(TN) show that the study area sediments contains more organic matters of marine origin than those of terrigenous origin. The high concentration of Fe/Al, Ti/Al and Mn/Al values are found in the southwestern part near the Changjiang esturay, indicating that it seems to result from the influence of the Changjiang River. Elemental ratios including Sc/Al, Ti/Nb, Cr/Th, Nb/Co and Th/Sc were thus used as provenance indicators to identify the sediment origins of the western part off Jeju Island. The discrimination diagrams clearly show that most of the sediment in the western part are originated from the Huanghe River, but the sediments in the southwestern part near the Changjiang esturay might come from the Changjiang River. In contrast, the sediment samples of the northwestern part show the highest values than those of the river sediments and other regions, suggesting that the sediments in the western part off Jeju Island are originated from diverse sources.