Alkenone-based SST changes in western part of the East Sea since the last glacial period: paleoceanographical implicatioin

Abstract

Reconstruction of late Quaternary sea surface temperature (SST) in south eastern coastal area of Korean peninsula was investigated using long-chain alkenones and bulk organic parameters (TOC, Corg/N). The alkenone-based SSTs decreased from 20~21℃ during Holocene to 17~18℃ in LGM. Hexatria-contadiem-3-one, C36:2 EK was present in this core during Holocene and %37:4 value significantly increased also in this period. The C37 concentration gradually increased from core top (84.1ng/g) to MIS 3 (1795ng/g) and variable fluctuation was observed in MIS 4. During MIS 3 and 4 however, the SST was abnormally warmer in this area ranging between 17~19℃. This could have been caused by changes in alkenone producer, variation in salinity, changes in nutrient concentration due to transport from land and increased growth rate during the glacial period. This relatively shallow (water depth: 187m) coastal area could have been highly influenced by riverine input or influx of terrestrial organic matter. Therefore, in addition to Uk37 temperature, long chain n-Alkanes were also analyzed to estimate terrigenous input into marine sediments.20~21℃ during Holocene to 17~18℃ in LGM. Hexatria-contadiem-3-one, C36:2 EK was present in this core during Holocene and %37:4 value significantly increased also in this period. The C37 concentration gradually increased from core top (84.1ng/g) to MIS 3 (1795ng/g) and variable fluctuation was observed in MIS 4. During MIS 3 and 4 however, the SST was abnormally warmer in this area ranging between 17~19℃. This could have been caused by changes in alkenone producer, variation in salinity, changes in nutrient concentration due to transport from land and increased growth rate during the glacial period. This relatively shallow (water depth: 187m) coastal area could have been highly influenced by riverine input or influx of terrestrial organic matter. Therefore, in addition to Uk37 temperature, long chain n-Alkanes were also analyzed to estimate terrigenous input into marine sediments.