동해 퇴적물에 대한 지화학적 기록: 육지-해양의 관계

Abstract

Two piston cores (94PC-2 and 95PC-4) taken from the Onnuri basin and northern part of the Ulleung basin show four geochemical stratigraphic units on the basis of major element concentration. Most major element switching in each facies and distinctive changes of concentration in typical terrigenous elements are the strong evidence for different sources of terrigenous materials and of the potential climatic linkage. The weathering indices exhibit high degree in Core 94PC-2 and low degree in Core 95PC-4 at the center of the Ulleung Basin. The changing degree of weathering index can be distinguished by the lowest value occurred at 11 kyr in Core 94PC-2, and by a gradual decrease from top to bottom in Core 95PC-4. The profiles of potassium and sodium exhibit specific excursion between the Holocene and the late Pleistocene. The distinct two group distributions in K2O/CaO vs. Na2O/K2O support that different provenance in aluminosilicate materials at the boundary of 11 kyr. Thus, supply patterns of terrigenous materials are difference between the Holocene and the last glacial period. A distinct geochemical boundary was observed in from the two core sediment of the Hupo bank near the 10-ka sediment layer, based on differences in major element concentration and organic carbon content. The vertical shift in most of the major elemental concentrations at this boundary is a strong characteristic of the sediments. The distinctive boundary at the onset of Holocene is interpreted to be largely due to differences in source material. The TiO2/Al2O3 ratios in the core samples confirm the difference in source areas. Organic carbon and carbonate content records also differ notably between the Holocene and the glacial period. The C/N ratio of the organic matter exceeds 10 during the glacial period, and is below 10 during Holocene, suggesting that terrigenous organic matter were transported during glacial times. In the case of the core sediment (95PC-1) collected from the Ulleung basin, th